[Federal Register Volume 77, Number 200 (Tuesday, October 16, 2012)]
[Proposed Rules]
[Pages 63440-63536]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-24151]



[[Page 63439]]

Vol. 77

Tuesday,

No. 200

October 16, 2012

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Proposed Endangered 
Status for the Neosho Mucket, Threatened Status for the Rabbitsfoot, 
and Designation of Critical Habitat for Both Species; Proposed Rule

  Federal Register / Vol. 77 , No. 200 / Tuesday, October 16, 2012 / 
Proposed Rules  

[[Page 63440]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-ES-R4-2012-0031; 4500030113]
RIN 1018-AX73


Endangered and Threatened Wildlife and Plants; Proposed 
Endangered Status for the Neosho Mucket, Threatened Status for the 
Rabbitsfoot, and Designation of Critical Habitat for Both Species

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to list the 
Neosho mucket (Lampsilis rafinesqueana), a freshwater mussel, as 
endangered and rabbitsfoot (Quadrula cylindrica cylindrica), a 
freshwater mussel, as threatened under the Endangered Species Act; and 
propose to designate critical habitat for both species. This rule 
fulfills our obligation under a settlement agreement. The effect of 
this regulation is to conserve the Neosho mucket and rabbitsfoot and 
their habitats under the Endangered Species Act.

DATES: We will accept comments received or postmarked on or before 
December 17, 2012. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES section, below) must be received by 
11:59 p.m. Eastern Time on the closing date. We must receive requests 
for public hearings, in writing, at the address shown in the ADDRESSES 
section by November 30, 2012.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Keyword box, enter Docket No. FWS-R4-ES-
2012-0031, which is the docket number for this rulemaking. Then, in the 
Search panel on the left side of the screen, under the Document Type 
heading, click on the Proposed Rules link to locate this document. You 
may submit a comment by clicking on ``Send a Comment or Submission.''
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R4-ES-2012-0031; Division of Policy and 
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax 
Drive, MS 2042-PDM; Arlington, VA 22203.
    We request that you send comments only by the methods described 
above. We will post all comments on http://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see the Public Comments section below for more information).

FOR FURTHER INFORMATION CONTACT: James F. Boggs, Field Supervisor, U.S. 
Fish and Wildlife Service, Arkansas Ecological Services Office, 110 
South Amity Road, Suite 300, Conway, AR 72032, by telephone 501-513-
4470 or by facsimile 501-513-4480. Persons who use a telecommunications 
device for the deaf (TDD) may call the Federal Information Relay 
Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: This document consists of: (1) A proposed 
rule to list the Neosho mucket (Lampsilis rafinesqueana) as endangered 
and rabbitsfoot (Quadrula cylindrica cylindrica) as threatened; and (2) 
a proposed critical habitat designation for both species.

Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act 
(Act), a species may warrant protection through listing if it is 
endangered or threatened throughout all or a significant portion of its 
range. The Neosho mucket and rabbitsfoot are highly restricted in their 
ranges and the threats occur throughout their ranges; therefore, the 
species qualify for listing. We are proposing to list the Neosho mucket 
as an endangered species and rabbitsfoot as a threatened species. Their 
protection under the Act can only be done by issuing a rule.
     We estimate the Neosho mucket has been extirpated (no 
longer in existence) from approximately 62 percent of its historical 
range with only 9 of the 16 historical populations remaining (extant). 
This mussel is declining rangewide (eight of the nine extant 
populations) with only one remaining large viable population.
     We estimate the rabbitsfoot has been extirpated from 
approximately 64 percent of its historical range. While 51 of the 140 
historical populations are extant (remain), only 11 populations (22 
percent of extant populations or 8 percent of the historical 
populations) are viable; 23 populations (45 percent of extant 
populations) are at risk of extirpation; and 17 populations (33 percent 
of extant populations) show limited recruitment with little evidence of 
sustainability. Rabbitsfoot is extirpated from 2 States within its 
historical range.
     The majority (8 of the 11 or 73 percent) of the viable 
rabbitsfoot populations live in waters considered impaired under 
section 303(d) of the Clean Water Act or have numerous tributaries in 
their watersheds also listed as impaired. Thus, these mussels are 
subjected to water quality and quantity and sediment quality 
constraints. These constraints (impairment) are expected to be 
exacerbated by increased water demand, habitat degradation, and climate 
change. Therefore, the viability of the majority of rabbitsfoot 
populations is uncertain.
     The majority of extant rabbitsfoot populations are 
marginal to small (40 of 51 extant populations (78 percent)) and 
isolated (41 of 51 extant populations (80 percent)); because of the 
isolation, it is unlikely that recruitment between populations or 
establishment of new populations could occur naturally.
     We are proposing to list the Neosho mucket as an 
endangered species in Arkansas, Kansas, Missouri, and Oklahoma and the 
rabbitsfoot as a threatened species in Alabama, Arkansas, Georgia, 
Kansas, Kentucky, Illinois, Indiana, Louisiana, Mississippi, Missouri, 
Ohio, Oklahoma, Pennsylvania, Tennessee, and West Virginia.
    The basis for our action. Under the Endangered Species Act, a 
species may be determined to be endangered or threatened based on any 
of five factors: (1) Destruction, modification, or curtailment of its 
habitat or range; (2) overuse; (3) disease or predation; (4) inadequate 
existing regulations; or (5) other natural or manmade factors.
    We have determined that both species are threatened by destruction, 
modification, or curtailment of habitat or range, inadequate existing 
regulatory mechanisms, and other manmade factors:
    This rule designates critical habitat for each species.
     We are proposing to designate critical habitat for the 
Neosho mucket in Arkansas, Kansas, Missouri, and Oklahoma and for the 
rabbitsfoot in Alabama, Arkansas, Illinois, Indiana, Kansas, Kentucky, 
Mississippi, Missouri, Ohio, Oklahoma, Pennsylvania, and Tennessee.
     In total, approximately 779 river kilometers (rkm) (484 
river miles (rmi)) in the Cottonwood, Elk, Fall, Illinois, Neosho, 
Shoal, Spring, North Fork Spring, and Verdigris Rivers are being 
proposed for designation as critical habitat for the Neosho mucket in 
Arkansas, Kansas, Missouri, and Oklahoma.
     The proposed critical habitat for the Neosho mucket is 
located in:
    [cir] Benton and Washington Counties, Arkansas;

[[Page 63441]]

    [cir] Allen, Chase, Cherokee, Coffey, Elk, Greenwood, Labette, 
Montgomery, Neosho, Wilson, and Woodson Counties, Kansas;
    [cir] Jasper, Lawrence, McDonald, and Newton Counties, Missouri; 
and
    [cir] Adair, Cherokee, and Delaware Counties, Oklahoma.
     In total, approximately 2,662 rkm (1,654 rmi) in the 
Neosho, Spring (Arkansas River system), Verdigris, Black, Buffalo, 
Little, Ouachita, Saline, Middle Fork Little Red, Spring (White River 
system), South Fork Spring, Strawberry, White, St. Francis, Big 
Sunflower, Big Black, Paint Rock, Duck, Tennessee, Red, Ohio, 
Allegheny, Green, Tippecanoe, Walhonding, Middle Branch North Fork 
Vermilion, and North Fork Vermilion Rivers and Bear, French, Muddy, 
Little Darby and Fish Creeks in Alabama, Arkansas, Kansas, Kentucky, 
Illinois, Indiana, Mississippi, Missouri, Ohio, Oklahoma, Pennsylvania, 
and Tennessee are being proposed for designation as critical habitat 
for the rabbitsfoot.
     The proposed critical habitat for the rabbitsfoot is 
located in:
    [cir] Colbert, Jackson, Madison, and Marshall Counties, Alabama;
    [cir] Arkansas, Ashley, Bradley, Clark, Cleveland, Dallas, Drew, 
Fulton, Grant, Hot Spring, Independence, Izard, Jackson, Lawrence, 
Little River, Marion, Monroe, Montgomery, Newton, Ouachita, Randolph, 
Saline, Searcy, Sevier, Sharp, Van Buren, White, and Woodruff Counties, 
Arkansas;
    [cir] Allen and Cherokee Counties, Kansas;
    [cir] Ballard, Green, Hart, Livingston, Logan, Marshall, and 
McCracken Counties, Kentucky;
    [cir] Massac, Pulaski, and Vermilion Counties, Illinois; Carroll, 
Pulaski, Tippecanoe, and White Counties, Indiana; Hinds, Sunflower, 
Tishomingo, and Warren Counties, Mississippi;
    [cir] Jasper, Madison, and Wayne Counties, Missouri;
    [cir] Coshocton, Madison, Union, and Williams Counties, Ohio;
    [cir] McCurtain and Rogers Counties, Oklahoma; Crawford, Erie, 
Mercer, and Venango Counties, Pennsylvania; and
    [cir] Hardin, Hickman, Marshall, Maury, and Robertson Counties, 
Tennessee.
    Peer review of our methods. During the public comment period, we 
will obtain review and opinions from knowledgeable individuals with 
scientific expertise on our technical assumptions, analysis, adherence 
to regulations, and whether or not we used the best available 
information in developing the proposed rule.

Information Requested

    We intend that any final action resulting from this proposal will 
be based on the best scientific and commercial data available and be as 
accurate and as effective as possible. Therefore, we request comments 
or information from the public, other concerned governmental agencies, 
Native American tribes, the scientific community, industry, or any 
other interested party concerning this proposed rule. We particularly 
seek comments concerning:
    (1) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to these species and regulations that may 
be addressing those threats.
    (2) Additional information concerning the historical and current 
status, range, distribution, and population size of these species, 
including the locations of any additional populations of these species.
    (3) Any information on the biological or ecological requirements of 
the species and ongoing conservation measures for the species and their 
habitat.
    (4) Any information regarding water quality data that may be 
helpful in determining the water quality parameters necessary for 
Neosho mucket and rabbitsfoot.
    (5) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et 
seq.), including whether there are threats to the species from human 
activity, the degree of which can be expected to increase due to the 
designation, and whether that increase in threat outweighs the benefit 
of designation such that the designation of critical habitat is not 
prudent.
    (6) Specific information on:
    (a) The amount and distribution of Neosho mucket and rabbitsfoot 
habitat;
    (b) What areas, that were occupied at the time of listing (or are 
currently occupied) and that contain features essential to the 
conservation of the species, should be included in the designation and 
why;
    (c) What areas not occupied at the time of listing are essential 
for the conservation of the species and why.
    (7) Land use designations and current or planned activities in the 
areas occupied by the species or proposed to be designated as critical 
habitat, and possible impacts of these activities on these species and 
proposed critical habitat.
    (8) Information on the projected and reasonably likely impacts of 
climate change on the Neosho mucket and rabbitsfoot and proposed 
critical habitat.
    (9) Any foreseeable economic, national security, or other relevant 
impacts that may result from designating any area that may be included 
in the final designation. We are particularly interested in any impacts 
on small entities, and the benefits of including or excluding areas 
from the proposed designation that are subject to these impacts.
    (10) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    (11) The likelihood of adverse social reactions to the designation 
of critical habitat and how the consequences of such reactions, if 
likely to occur, would relate to the conservation and regulatory 
benefits of the proposed critical habitat designation.
    Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is a threatened or endangered 
species must be made ``solely on the basis of the best scientific and 
commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We request 
that you send comments only by the methods described in the ADDRESSES 
section.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the Web site. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on http://www.regulations.gov. 
Please include sufficient information with your comments to allow us to 
verify any scientific or commercial information you include.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on http://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Arkansas Ecological Services Office, Conway, Arkansas 
(see FOR FURTHER INFORMATION CONTACT).

[[Page 63442]]

Previous Federal Actions

Neosho Mucket

    The Neosho mucket was first identified as a candidate for 
protection under the Act in the May 22, 1984, Federal Register (49 FR 
21664) notice. As a candidate, it was assigned a status Category 2 
designation, which was given to those species with some evidence of 
vulnerability but for which additional biological information was 
needed to support a proposed rule to list as endangered or threatened. 
In our Notices of Review dated January 6, 1989 (54 FR 554), November 
21, 1991 (56 FR 58804), and November 15, 1994 (59 FR 58982), we 
retained a status Category 2 designation for this species. We 
discontinued assigning categories to candidate species in our Notice of 
Review dated February 28, 1996 (61 FR 7596), and only species for which 
the Service had sufficient information on biological vulnerability and 
threats to support issuance of a proposed rule were regarded as 
candidate species. Thus, Neosho mucket was no longer considered a 
candidate species.
    On October 30, 2001, we identified the Neosho mucket in the Federal 
Register (66 FR 54808) as a candidate species based on available 
information to support a proposed rule. Candidate species are assigned 
listing priority numbers (LPNs) based on immediacy and magnitude of 
threats, as well as taxonomic status. The lower the LPN, the higher 
priority that species is for us to determine appropriate action using 
our available resources. We assigned an LPN of 5 to Neosho mucket. In 
our Notices of Review dated June 13, 2002 (67 FR 40657), and May 4, 
2004 (69 FR 24876), we maintained an LPN of 5.
    We published a petition finding for the Neosho mucket on May 11, 
2005 (70 FR 24870), in response to a petition received on May 11, 2004, 
stating in the finding that the Neosho mucket would retain an LPN of 5. 
In our Notices of Review dated September 12, 2006 (71 FR 53756), 
December 6, 2007 (72 FR 69034), and December 8, 2008 (73 FR 75176), we 
maintained an LPN of 5, reflecting the nonimminent threats of high 
magnitude. The LPN was elevated to 2 in our Notice of Review dated 
November 10, 2010 (75 FR 69222), to reflect the change from nonimminent 
to imminent threats of high magnitude.

Rabbitsfoot

    The rabbitsfoot was first identified as a candidate for protection 
under the Act in the November 15, 1994, Federal Register (59 FR 58982). 
As a candidate, it was assigned a status Category 2 designation. The 
category 2 list was eliminated in 1996 (61 FR 7596). On November 9, 
2009, we added the rabbitsfoot to our candidate list in the Federal 
Register (74 FR 57804) with an LPN of 9. An LPN of 9 indicates threats 
of a moderate magnitude; some of the threats are nonimminent, most are 
ongoing, and the threats are imminent overall. In our Notice of Review 
dated November 10, 2010 (75 FR 69222), it was again identified as a 
candidate species with an LPN of 9.

Status Assessment for Neosho Mucket and Rabbitsfoot

Background

    It is our intent to discuss below only those topics directly 
relevant to the listing of the Neosho mucket as endangered and the 
rabbitsfoot as threatened in this section of the proposed rule.

Introduction

    North American freshwater mussel fauna is the richest in the world 
and historically numbered around 300 species (Williams et al. 1993, p. 
6). Freshwater mussels are in decline, however, and in the past century 
have become more imperiled than any other group of organisms (Williams 
et al. 2008, p. 55). Approximately 66 percent of North America's 
freshwater mussel species are considered vulnerable to extinction or 
possibly extinct (Williams et al. 1993, p. 6). Within North America, 
the southeastern United States is the hot spot for mussel diversity. 
Seventy-five percent of southeastern mussel species are in varying 
degrees of rarity or possibly extinct (Neves et al. 1997, pp. 47-51). 
The central reason for the decline of freshwater mussels is the 
modification and destruction of their habitat, especially from 
sedimentation, dams, and degraded water quality (Neves et al. 1997, p. 
60). These two mussels, like many other southeastern mussel species, 
have undergone reductions in total range and population density.

General Biology

    Freshwater mussels generally live embedded in the bottom of rivers, 
streams, and other bodies of water. They siphon water into their shells 
and across four gills that are specialized for respiration and food 
collection. Food items include algae, bacteria, detritus (disintegrated 
organic debris), and microscopic animals (Strayer et al. 2004, pp. 430-
431). It also has been surmised that dissolved organic matter may be a 
significant source of nutrition (Strayer et al. 2004, p. 430). Adults 
are filter feeders and generally orient themselves on or near the 
substrate surface to take in food and oxygen from the water column. 
Juveniles typically burrow completely beneath the substrate surface and 
are pedal (foot) feeders (bringing food particles inside the shell for 
ingestion that adhere to the foot while it is extended outside the 
shell) until the structures for filter feeding are more fully developed 
(Yeager et al. 1994, pp. 200-221; Gatenby et al. 1996, p. 604).
    Sexes in unionid (refers to taxonomic family Unionidae) mussels, 
such as the Neosho mucket and rabbitsfoot, are usually separate. Males 
release sperm into the water column, which are drawn in by females 
through their siphons during feeding and respiration. Fertilization 
takes place inside the shell, and success is apparently influenced by 
mussel density and water flow conditions (Downing et al. 1993, pp. 153-
154). The eggs are retained in the gills of the female until they 
develop into mature larvae called glochidia. The glochidia of most 
freshwater mussel species, including the two species addressed in this 
rule, have a parasitic stage during which they must attach to the 
gills, fins, or skin of a fish to transform into a juvenile mussel. 
Depending on the mussel species, females release glochidia either 
separately, in masses known as conglutinates (gelatinous or jelly-
like), or in one large mass known as a super-conglutinate. The duration 
of the parasitic stage varies by mussel species, water temperature, and 
perhaps host fish species. When the transformation is complete, the 
juvenile mussels drop from their fish host and sink to the stream 
bottom where, given suitable conditions, they grow and mature into 
adults. Host specificity is discussed in more detail below.
    Growth rates for mussels are highly variable among individual 
mussel species, but overall, mussels tend to grow relatively rapidly 
for the first few years (Scruggs 1960, pp. 28-30; Negus 1966, pp. 517-
518) then slow appreciably (Bruenderman and Neves 1993, p. 88; Hove and 
Neves 1994, pp. 34-36). This reduction in growth rate is correlated to 
sexual maturity, probably as a result of energy being diverted from 
growth to gamete production (Baird 2000, pp. 63-71). Heavy-shelled 
species, such as Neosho mucket and rabbitsfoot, grow slowly relative to 
thin-shelled species (Coon et al. 1977, pp. 19-21; Hove and Neves 1994, 
p. 38).
    Strayer (1999a, pp. 468 and 472) demonstrated that mussels in 
streams occur chiefly in ``flow refuges'' (relatively stable areas that 
displayed little movement of substrate particles during flood events). 
Other researchers

[[Page 63443]]

also concluded that mussel location and density are greatest in areas 
where shear stress (stream's ability to entrain and transport bed 
material created by the flow acting on the bed material) is low and 
sediments remain generally stable during flooding (Layzer and Madison 
1995, p. 341; Strayer 1999a, pp. 468 and 472; Hastie et al. 2001, pp. 
111-114). These ``flow refuges'' conceivably allow relatively immobile 
mussels, such as the Neosho mucket and rabbitsfoot, to remain in the 
same general location throughout their life span. However, these areas 
may be more important for the rabbitsfoot since it typically does not 
burrow like the Neosho mucket, making it more susceptible to 
displacement into unsuitable habitat. However, flow refuges are not 
created equally and other habitat variables are important, but poorly 
understood (Roberts 2008, pers. comm.).

Taxonomy, Life History, and Distribution

    The Neosho mucket and rabbitsfoot are freshwater mussels in the 
family Unionidae. Both species are currently deemed valid by the 
Committee on Scientific and Vernacular Names of Mollusks of the Council 
of Systematic Malacologists and the American Malacological Union 
(Turgeon et al. 1998, pp. 35 and 37).
Neosho Mucket
    Neosho mucket was originally described as Lampsilis rafinesqueana 
from Indian Creek, McDonald County, Missouri (Frierson 1927, pp. 69-
70). There is no synonomy (scientific names previously describing the 
same species) of the Neosho mucket. Frierson (1927, pp. 69-70) 
described the Neosho mucket as a dimorphic (male and female shape 
differs) species; the male is elliptical, rounded before biangulate 
behind, with dorsal and basal margin equally arched, while the female 
is ovate with a widely expanded fan-shaped posterior. The shell is up 
to 9.5 centimeters (cm) (4 inches (in)), compressed, and relatively 
thin (Oesch 1984, pp. 219-221). The epidermis is olive-yellow to brown, 
becoming darker brown with age; green rays cover the surface, but are 
often discontinuous. Oesch (1984, pp. 219-221) describes the left valve 
as having two stout, divergent, striated, triangular pseudocardinal 
teeth. The two lateral teeth are short, stout, and slightly curved. The 
right valve has a single, tall, triangular to columnar, striated 
pseudocardinal tooth. The nacre (crystalline carbonate shell material 
of freshwater mussels) is bluish white to white.
    Neosho mucket glochidia are an obligate parasite on smallmouth bass 
(Micropterus dolomieu), largemouth bass (Micropterus salmoides), and 
spotted bass (Micropterus punctulatus) (Barnhart and Roberts 1997, p. 
18; U.S. Fish and Wildlife Service 2005, p. 7). Neosho mucket is 
unusual among other Lampsilis species in the timing of reproduction. 
Neosho mucket spawns in late April and May, and female brooding occurs 
May through August. Most other Lampsilis spawn in the late summer or 
fall and brood glochidia throughout the winter months into the 
following spring or summer. Barnhart (2003, p. 9) reported an average 
fecundity to be approximately 1.3 million glochidia per female in the 
Spring River, Kansas. The female Neosho mucket inflates and extends a 
pair of mantle flaps (actually an extension of the inner lobe of the 
mantle edge) that, from a side angle, remarkably resembles a small 
fish. Each mantle flap in addition to its fish-like shape has 
pigmentation that resembles an eyespot as well as a fish's lateral 
line. Muscular contractions of the mantle flaps create an undulating or 
``swimming'' motion that suffices to lure fish hosts (Obermeyer 2000, 
p. 9).
    The Neosho mucket is associated with shallow riffles and runs 
comprising gravel substrate and moderate to swift currents. The species 
is most often found in areas with swift current, but in Shoal Creek and 
the Illinois River it prefers near-shore areas or areas out of the main 
current (Oesch 1984, p. 221; Obermeyer 2000, pp. 15-16). Neosho mucket 
historically occurred in at least 16 streams within the Illinois, 
Neosho, and Verdigris River basins covering four states (Arkansas, 
Kansas, Oklahoma, and Missouri). It is endemic to the Arkansas River 
system (Gordon 1980, pp. 318 and 347; Harris and Gordon 1987, pp. 53-
54; Obermeyer 1996, pp. 3-4; Vaughn 1996, pp. 3-5; Mather 1990, pp. 7-
13; Obermeyer et al. 1997a, pp. 44-47; Harris et al. 2009, p. 68). The 
Neosho mucket's known river and creek occurrences and current status 
are shown in Table 1.
    For the purposes of this rule, a population is considered extant if 
live individuals or fresh dead specimens have been located since 1985. 
A population is considered viable if it is sizeable, comprised of 
different age classes, recruiting juveniles, and able to sustain itself 
over several decades without human intervention (Butler 2005, p. 23). 
Population trend estimates were generally made with a 20- to 30-year 
perspective when adequate historical information was available. 
Populations were deemed to have improving, stable, declining, or 
unknown status (Table 1).

                Table 1--Neosho Mucket River and Creek Occurrences and Current Population Status
----------------------------------------------------------------------------------------------------------------
                                                                                                  Date of last
         River basin              River/Creek           State(s)            Current status        observation
----------------------------------------------------------------------------------------------------------------
Neosho River.................  Neosho River....  KS, OK...............  Declining............  2000.
                               Cottonwood River  KS...................  Unknown..............  2011.
                               South Fork        KS...................  Extirpated...........  Pre-1979.
                                Cottonwood
                                River.
                               Spring River....  KS, MO, OK...........  Stable...............  2010.
                               North Fork        MO...................  Declining............  1995.
                                Spring River.
                               Center Creek....  KS, MO...............  Extirpated...........  1995.
                               Shoal Creek.....  KS, MO...............  Declining............  2001.
                               Elk River.......  MO, OK...............  Declining............  1995.
                               Indian Creek....  MO...................  Extirpated...........  Pre-1980.
                               Little Sugar      MO...................  Extirpated...........  Pre-1980.
                                Creek.
Illinois River...............  Illinois River..  AR, OK...............  Declining............  2008
Verdigris River..............  Verdigris River.  KS, OK...............  Declining............  2010
                               Otter Creek.....  KS...................  Extirpated...........  Pre-1993.
                               Fall River......  KS...................  Declining............  2004.
                               Elk River.......  KS...................  Extirpated...........  Pre-1979.
                               Caney River.....  KS, OK...............  Extirpated...........  Pre-1979.
----------------------------------------------------------------------------------------------------------------


[[Page 63444]]

Neosho River Basin

    Neosho River: The Neosho River drains southeast through Kansas and 
Oklahoma. Historical data of Neosho mucket densities for the Neosho 
River are not available prior to the late 1970s (Obermeyer et al. 
1997b, p. 112). Mussel harvest records from the early 1900s provide 
useful insight on the abundance of mussels in the river. From 1911 
through 1912, the Neosho River provided 17 percent or approximately 85 
million mussels used in the nation's pearl button industry. Many of the 
30 tons of mussel shells processed weekly in 1918 at a shell blank 
factory in Iola, Kansas, came from the Neosho River near LeRoy, Kansas 
(Obermeyer et al. 1997b, p. 112).
    Since the 1990s, extant populations have been found downstream of 
John Redmond Reservoir Dam to near Parsons, Kansas, in Allen, Coffey, 
Labette, and Neosho Counties, Kansas. In addition, fresh dead or relict 
(shell shows no sign of recent mortality, such as tissue inside shell 
or outer shell material (periostracum) is weathered) shells were 
collected at 11 sites extending to near the Kansas-Oklahoma state line 
in Cherokee County, Kansas (Obermeyer et al. 1997a, pp. 44-46; 
Obermeyer 2000, pp. 8-9). In 1994, Obermeyer et al. (1995, p. 24) 
collected 32 live Neosho mucket specimens (relative abundance = 0.6 
percent) at 7 of 19 sites in Kansas. The Neosho mucket is becoming 
increasingly rare in the Oklahoma segment of the river (Tabor 2011, 
pers. comm.) with searches yielding no live or recently dead specimens. 
However, relict Neosho mucket shells confirm the historical presence of 
the species (Mather 1990, pp. 16-17; Vaughn 1996, p. 3; 1997, pp. 7-9).
    Cottonwood River: The Cottonwood River drains easterly through 
eastern Kansas. There are few historical records of Neosho mucket from 
the Cottonwood River prior to the late 1970s. Obemeyer et al. (1997a, 
p. 111) collected 59 live mussels from 6 sites surveyed from 1993 
through 1995, but only found weathered dead shells of Neosho mucket. 
Neosho mucket was considered extirpated from the Cottonwood River until 
Kansas Department of Wildlife and Parks (KDWP) reintroduced mature male 
and brooding female Neosho mucket individuals at two sites east of 
Cottonwood Falls, Chase County, Kansas, in 2011 (Tabor and Barnhart 
2012, pers. comm.).
    Spring River: The Spring River drains southwesterly through 
southwest Missouri, southeast Kansas, and eastern Oklahoma. There are 
few historical records of Neosho mucket from the Spring River prior to 
the late 1970s. Miscellaneous records from 1979 to 2010 report 10 
localities yielding 119 live Neosho mucket specimens between Missouri 
Highway 97 near Stott City, Lawrence County, Missouri, and the Missouri 
and Kansas state line (McMurray 2011, pers. comm.). Cope (1985, pp. 19-
20, 26-27, 33-34) collected 424 live Neosho mucket specimens out of 993 
live mussels collected in 79 total one-square-meter quadrat samples 
from three Kansas sites upstream of Empire Lake.
    Obermeyer (1996, p. 11) provides the most comprehensive status 
assessment of Neosho mucket in the Spring River. He collected 1,104 
live Neosho mucket specimens from 13 of 20 sites extending from 
Missouri Highway 97 downstream to near the Turkey Creek confluence in 
Kansas. The KDWP surveyed a site approximately 0.5 to 0.8 rkm (0.3 to 
0.5 rmi) downstream of the Kansas and Missouri state line in 2003 and 
collected 201 live Neosho mucket specimens (approximately 30 percent of 
live mussels collected). In 2006, KDWP collected 141 live Neosho mucket 
specimens (approximately 30 percent of live mussels collected) at a 
site just upstream of the Kansas and Missouri Highway YY (Miller 2011, 
pers. comm.). Eight to 10 percent of live Neosho mucket specimens 
collected at the 2006 site were quantitatively aged at less than 5 
years (Tabor 2008, pers. comm.). A 2010 survey, 6 km (4 miles) east of 
Crestline, Kansas, found 400 live mussel specimens, of which 
approximately half were Neosho mucket (Tabor 2011, pers. comm.). The 
Spring River Neosho mucket population represents the only viable 
population rangewide.
    North Fork Spring River: The North Fork Spring River is a tributary 
of the Spring River in Missouri. There are no historical records for 
Neosho mucket in the North Fork Spring River prior to 1980. Neosho 
mucket distribution is limited to a few sites downstream of the Dry 
Fork confluence southwest of Jasper, Jasper County, Missouri. Three 
sites yielded 136 live Neosho mucket specimens in the mid 1990s 
(Obermeyer et al. 1997a, p. 45; McMurray 2011, pers. comm.).
    Shoal Creek: Shoal Creek is a southern tributary of the Spring 
River draining portions of southwest Missouri and southeast Kansas. 
There are few historical records for Neosho mucket in Shoal Creek prior 
to 1979. Surveys of Shoal Creek conducted from 1979 to 2001 from 
Missouri Highway W near Ritchey, Missouri, to Empire Lake, Cherokee 
County, Kansas, yielded 75 live Neosho mucket specimens from 11 sites 
(Obermeyer et al. 1995, p. 45; McMurray 2011, pers. comm.). No 
specimens were found in the Kansas portion of Shoal Creek.
    Elk River: The Elk River, a tributary of the Spring River, drains 
southwestern Missouri and northeastern Oklahoma. The Oklahoma reach 
downstream of Buffalo Creek just west of the Missouri and Oklahoma 
state line is inundated by Grand Lake O' the Cherokees, resulting in 
the loss of Neosho mucket habitat. Live Neosho mucket individuals have 
been collected from two sites in Missouri, eight individuals in 1978 
and two individuals in 1995, and the species is rare from Noel, 
Missouri, to the Kansas and Missouri state line (McMurray 2011, pers. 
comm.). Brooding Neosho mucket females and juveniles were reported in 
this reach at two sites in 1992 and 1998 (Barnhart 2008, pers. comm.).

Illinois River Basin

    Illinois River: The Illinois River drains portions of northwest 
Arkansas and northeast Oklahoma. There are few historical records of 
Neosho mucket from the Illinois River prior to the late 1970s. In 1978, 
Gordon et al. (1979, pp. 35-36) surveyed 16 sites between Hogeye and 
Siloam Springs, Arkansas, but only report Neosho mucket as part of the 
mussel fauna. Eighteen live Neosho mucket specimens were reported from 
four Arkansas locations in the early 1990s, including the only specimen 
ever collected from the Muddy Fork Illinois River (Harris 1991, p. 7; 
Environmental and Gas Consulting, Inc. 1994, pp. field data sheets). 
Harris (1998) conducted a status survey of the Neosho mucket and found 
live specimens at 19 of 22 sites in the 48 rkm (30 rmi) reach, 
Washington and Benton Counties, Arkansas. Neosho mucket was the third 
most abundant species collected, but there was little evidence of 
recent recruitment (Harris 1998, p. 5).
    In 2005, 92 live Neosho mucket specimens were collected from two 
Benton County, Arkansas, sites (Robinson Road Bridge and 800 m (2,624 
feet) downstream of Chambers Spring Road, Benton County, Arkansas; 
Posey 2005, pers. comm.). The Arkansas Game and Fish Commission (AGFC) 
and the Service conducted a comprehensive status survey for Neosho 
mucket in the Arkansas portion of the Illinois River in 2008. Live 
specimens of Neosho mucket were collected at 9 of 15 survey sites. 
There was a 32 and 53 percent decline in number of extant (still in 
existence) mussel sites and sites inhabited by live Neosho mucket 
specimens, respectively, versus the Harris (1998) status survey. Sixty-
seven percent of the sites with

[[Page 63445]]

Neosho mucket present were represented by three or fewer live 
specimens. Neosho mucket was the fourth most abundant species in this 
portion of the river, but 3 sites accounted for 85 percent of live 
Neosho mucket specimens (52 individuals) collected during this survey. 
Of the 15 survey sites, only 2 appear stable with the rest in decline, 
indicating imminent extirpation. No mussels were collected at the sites 
AGFC sampled in 2005 in 2008 further documenting the precipitous 
decline of mussels in the Arkansas portion of the Illinois River 
(Davidson 2011, pers. comm.).
    Neosho mucket was locally common prior to the late 1990s in 
approximately 89 rkm (55 rmi) of the Illinois River from the Oklahoma 
and Arkansas state line downstream to Lake Tenkiller, Cherokee County, 
Oklahoma (Mather 1990, pp. 7-11). The population within the survey 
reach was estimated at more than 1,200 individuals in 1990. In 1995, 
Vaughn (1995, p. 3; 1997, p. 14) estimated the Neosho mucket population 
in the same reach surveyed by Mather in 1990 at between 500 and 1,000 
individuals and locally common at 9 of 52 sites. Although some evidence 
of reproductive potential was observed during 1990 and 1995 (for 
example, gravid females displaying mantle lures), there was little 
evidence of recruitment into the population. Neosho mucket specimens 
were not found in or downstream of Lake Tenkiller.

Verdigris River Basin

    Fall River: The Fall River is a southern tributary of the Verdigris 
River in southeast Kansas. There are few historical records from the 
Fall River prior to the mid 1990s (Obermeyer et al. 1995, p. 24). In 
1994, Obermeyer et al. (1995 p. 24) found 34 live specimens (relative 
abundance = 1.7 percent) from 5 sites in the Fall River, with little 
evidence of recruitment into the population. In 2004, two sites were 
resurveyed and Neosho mucket composed 1.0 and 0.5 percent of 
qualitative and quantitative surveys, respectively (Tabor 2008, pers. 
comm.). All specimens were found downstream of Fall River Lake in 
Greenwood, Elk, and Wilson Counties (Obermeyer et al. 1995, p. 24).
    Verdigris River: The Verdigris River flows through southeast Kansas 
and northeast Oklahoma until it reaches the Arkansas River in Oklahoma. 
There are few historical records from the Verdigris River in either 
State prior to the 1990s. Obermeyer et al. (1997a, p. 44; 1997b, p. 
111) collected five Neosho mucket specimens from 4 of 14 sites from 
1993 to 1995, representing 0.2 percent of the total sample from the 
Verdigris River between Altoona, Wilson County, Kansas, and Sycamore, 
Montgomery County, Kansas. The KDWP surveyed eight sites between the 
Fall and Verdigris River and Elk and Verdigris River confluences in 
2003 and 2010. Six live Neosho mucket specimens were collected from two 
of these sites in 2003 (0.1 percent of the total mussel community) and 
seven live specimens from four sites in 2010 (0.2 percent of the total 
mussel community). Overall relative abundance of Neosho mucket in the 
Verdigris River in Kansas has ranged between 0.1 to 0.3 percent in the 
years from 1993 to 2010 (Miller 2011, pp. 1-2).
    The majority of the Oklahoma reach has been inundated (Oologah 
Lake) and channelized as part of the McClellan-Kerr Arkansas River 
Navigation System. In 1996 and 1997, searches in the Verdigris in 
Oklahoma found no live Neosho mucket specimens at 32 sites. However, 
relict Neosho mucket shells confirmed the historical presence of the 
species (Vaughn 1996, p. 3; 1997, pp. 7-9). In 2008, researchers 
confirmed that the species is still extirpated from the Oklahoma reach 
(Boeckman 2008, pers. comm.).
Summary of Neosho Mucket Rangewide Population Status
    The Neosho mucket is declining rangewide, with the exception of one 
population. Based on historical and current data, Neosho mucket has 
been extirpated from approximately 1,342 rkm (834 rmi) of its 
historical range (62 percent). Most of this extirpation has occurred 
within the Oklahoma and Kansas portions of its range. The extirpation 
of this species from numerous streams and stream reaches within its 
historical range signifies that substantial population losses have 
occurred. Extant populations are disjunct (not contiguous) in 
approximately 819 rkm (509 rmi). The Spring River in Missouri supports 
the only viable population based on the presence of a large number of 
individuals and evidence of recent recruitment. Given this compilation 
of current distribution, abundance, and status trend information, the 
Neosho mucket exhibits range reductions and population declines 
throughout its range.
Rabbitsfoot
    The rabbitsfoot was originally described as Unio cylindricus (Say, 
1817, no pagination but p. 13 of publication). The type locality is the 
Wabash River (Parmalee and Bogan 1998, p. 210), probably in the 
vicinity of New Harmony, Posey County, Indiana, and adjacent Illinois. 
Parmalee and Bogan (1998, p. 210) summarize the synonomy of the 
rabbitsfoot. The rabbitsfoot has been considered a member of the genera 
Unio, Mya, Margarita, Margaron, and Orthonymus at various times in 
history. It was first considered a member of the genus Quadrula by 
Lewis (1870, p. 218). The description of U. cylindricus strigillatus 
B.H. Wright, 1898 (=Q. cylindrica strigillata, the federally endangered 
rough rabbitsfoot; Turgeon et al. 1998, p. 37), rendered the 
rabbitsfoot, Q. c. cylindrica, a subspecies for Q. cylindrica. Davis 
and Fuller (1981, p. 241) and Sproules et al. (2006, p. 3) conducted 
taxonomic and genetic studies on the rough rabbitsfoot (Q. c. 
strigillata) and rabbitsfoot (Q. c. cylindrica). Although discussion 
continues over the correct taxonomic placement of the rabbitsfoot, the 
designation of the rabbitsfoot as a species would not affect its 
qualification for listing under the Act as it would qualify as a 
listable entity whether it was a subspecies or a species.
    The rabbitsfoot is a medium to large mussel, elongate and 
rectangular, reaching 12 cm (6 inches) in length (Oesch 1984, pp. 91-
93). Parmalee and Bogan (1998, pp. 210-212) describe the beaks as 
moderately elevated and raised only slightly above the hinge line. Beak 
sculpture consists of a few strong ridges or folds continuing onto the 
newer growth of the umbo (raised or domed part of the dorsal margin of 
the shell) as small tubercles (small, rounded projection on surface of 
the shell). Shell sculpture consists of a few large, rounded, low 
tubercles on the posterior slope, although some individuals will have 
numerous small, elongated pustules (small raised spots) particularly on 
the anterior. The periostracum (external shell surface) is generally 
smooth and yellowish, greenish, or olive in color becoming darker and 
yellowish-brown with age and usually covered with dark green or nearly 
black chevrons and triangles pointed ventrally (Say 1817, p. 13). These 
patterns are absent in some individuals.
    Internally, the color of the nacre is white and iridescent, often 
with a grayish-green tinge in the umbo cavity. Specimens from the 
southern periphery of its range are occasionally purplish. Soft parts 
generally have an orange coloration (Oesch 1984, p. 91; Parmalee and 
Bogan 1998, pp. 211-212). However, Vidrine (1993, p. 55) noted that the 
rabbitsfoot in the Ouachita River system in Louisiana had black soft 
parts. Aspects of the soft anatomy are

[[Page 63446]]

described by Ortmann (1912, pp. 256-257), Utterback (1915, pp. 148-
149), Davis and Fuller (1981, pp. 228-233 and 241), and Oesch (1984, p. 
91).
    Suitable fish hosts for rabbitsfoot populations west of the 
Mississippi River include blacktail shiner (Cyprinella venusta) from 
the Black and Little River and cardinal shiner (Luxilus cardinalis), 
red shiner (C. lutrensis), spotfin shiner (C. spiloptera), and 
bluntface shiner (C. camura) from the Spring River, but host 
suitability information is lacking for the eastern range (Fobian 2007, 
p. ii). In addition, rosyface shiner (Notropis rubellus), striped 
shiner (L. chrysocephalus), and emerald shiner (N. atherinoides) served 
as hosts for rabbitsfoot, but not in all stream populations tested 
(Fobian 2007, p. 69).
    Rabbitsfoot populations west of the Mississippi River reach sexual 
maturity between the ages of 4 to 6 years (Fobian 2007, p. 50). 
Rabbitsfoot exhibit seasonal movement towards shallower water during 
brooding periods, a strategy to increase host fish exposure but one 
that also leaves them more vulnerable to predation and fluctuating 
water levels, especially downstream of dams (Fobian 2007, pp. 48-49; 
Barnhart 2008, pers. comm.). It is a short-term brooder, with females 
brooding between May and late August (Fobian 2007, pp. 15-16). Similar 
to other species of Quadrula, the rabbitsfoot uses all four gills as a 
marsupium (pouch) for its glochidia (Fobian 2007, p. 26). Female 
rabbitsfoot release glochidia as conglutinates (matrices holding 
numerous glochidia together and embryos and undeveloped ova), which 
mimic flatworms or similar fish prey. Fecundity (capacity of abundant 
production) in river basins west of the Mississippi River ranged from 
46,000 to 169,000 larvae per female (Fobian 2007, p. 19).
    Rabbitsfoot is primarily an inhabitant of small to medium sized 
streams and some larger rivers. It usually occurs in shallow water 
areas along the bank and adjacent runs and shoals with reduced water 
velocity. Specimens also may occupy deep water runs, having been 
reported in 2.7 to 3.7 m (9 to 12 feet) of water. Bottom substrates 
generally include gravel and sand (Parmalee and Bogan 1998, pp. 211-
212). This species seldom burrows but lies on its side (Watters 1988, 
p. 13; Fobian 2007, p. 24).
    Rabbitsfoot historically occurred in 140 streams within the lower 
Great Lakes Subbasin and Mississippi River Basin (Table 2). The 
historical range included Alabama, Arkansas, Georgia, Illinois, 
Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Ohio, 
Oklahoma, Pennsylvania, Tennessee, and West Virginia. Rabbitsfoot 
populations are considered to be extant in 51 streams in 13 states 
(Butler 2005, pp. 18-20; Boeckman 2008, pers. comm.), representing a 64 
percent decline (51 extant streams of 140 historical populations). In 
streams where it remains extant, populations are highly fragmented and 
restricted to short reaches. Based upon existing habitat use (need for 
flowing vs. impounded habitats) and fish host (small minnow species 
with limited individual ranges) data, it is unlikely that recruitment 
between populations or establishment of new populations could occur 
naturally.
    Although quantitative historical abundance data are rare for 
rabbitsfoot, relative abundance information can be gathered from museum 
lots. Historical museum data indicated stable rabbitsfoot populations 
occurred in the Ohio, Walhonding, Big Sandy, Scioto, Olentangy, Nolin, 
Wabash, North Fork Vermilion, Obey, Tennessee, White, Black, Spring 
(White River system), Strawberry, Illinois, Glover and Cossatot Rivers 
(Butler 2005, p. 20). Call (1895, p. 15) considered the rabbitsfoot 
``abundant in the St. Francis, Saline, and Ouachita Rivers in 
Arkansas.''

                 Table 2--Rabbitsfoot River and Creek Occurrences and Current Population Status
----------------------------------------------------------------------------------------------------------------
                                                                                                  Date of last
          River basin              River/Creek             States            Current status       observation
----------------------------------------------------------------------------------------------------------------
Lower Great Lakes.............  Maumee River.....  IN, OH................  Extirpated........  1927.
                                St. Joseph River.  IN, OH................  Extirpated........  1967.
                                Fish Creek.......  IN, OH................  Declining.........  2009.
                                Feeder Canal.....  IN....................  Extirpated........  1908.
                                St. Mary's River.  IN....................  Extirpated........  Circa 1920.
                                Auglaize River...  OH....................  Extirpated........  Mid 1900s.
Ohio River....................  Ohio River.......  IL, IN, KY, OH, PA, WV  Stable............  2005.
                                Allegheny River..  PA....................  Declining.........  2007.
                                French Creek.....  PA....................  Stable............  2008.
                                Le Boeuf Creek...  PA....................  Unknown...........  2006.
                                Muddy Creek......  PA....................  Declining.........  2003.
                                Conneautee Creek.  PA....................  Unknown...........  2006.
                                Monongahela River  PA....................  Extirpated........  Circa 1890.
                                West Fork River..  WV....................  Extirpated........  Pre-1913.
                                Beaver River.....  PA....................  Extirpated........  1898.
                                Shenango River...  PA....................  Unknown...........  2009.
                                Pymatuning Creek.  PA....................  Extirpated........  1909.
                                Mahoning River...  OH, PA................  Extirpated........  Unknown.
                                Muskingum River..  OH....................  Declining.........  2007.
                                Tuscarawas River.  OH....................  Extirpated........  Circa 1990.
                                Walhonding River.  OH....................  Declining.........  2009.
                                Killbuck Creek...  OH....................  Extirpated........  Pre-1990.
                                Mohican River....  OH....................  Extirpated........  1977.
                                Black Fork         OH....................  Extirpated........  Pre-1990.
                                 Mohican River.
                                Little Kanawha     WV....................  Extirpated........  Circa 1900.
                                 River.
                                Elk River........  WV....................  Extirpated........  Unknown.
                                Big Sandy River..  KY....................  Extirpated........  Circa 1800.
                                Levisa Fork......  KY....................  Extirpated........  1909.
                                Scioto River.....  OH....................  Extirpated........  1962.
                                Olentangy River..  OH....................  Extirpated........  1962.
                                Whetstone Creek..  OH....................  Extirpated........  Pre-1930.

[[Page 63447]]

 
                                Big Walnut Creek.  OH....................  Extirpated........  1961.
                                Alum Creek.......  OH....................  Extirpated........  1961.
                                Walnut Creek.....  OH....................  Extirpated........  Pre-1990.
                                Big Darby Creek..  OH....................  Declining.........  2002.
                                Little Darby       OH....................  Declining.........  2000.
                                 Creek.
                                Deer Creek.......  OH....................  Extirpated........  Pre-1980.
                                Ohio Brush Creek.  OH....................  Extirpated........  1970.
                                Little Miami       OH....................  Extirpated........  Circa 1900.
                                 River.
                                Licking River....  KY....................  Extirpated........  Circa 1990.
                                South Fork         KY....................  Extirpated........  Pre-1980.
                                 Licking River.
                                Kentucky River...  KY....................  Extirpated........  Circa 1920.
                                South Fork         KY....................  Declining.........  1998.
                                 Kentucky River.
                                Salt River.......  KY....................  Extirpated........  Pre-1980.
                                Green River......  KY....................  Improving.........  2009.
                                Russell Creek....  KY....................  Extirpated........  1908.
                                Nolin River......  KY....................  Extirpated........  1983.
                                Barren River.....  KY....................  Declining.........  1993.
                                Drakes Creek.....  KY....................  Extirpated........  1926.
                                West Fork Drakes   KY....................  Extirpated........  1927.
                                 Creek.
                                Rough River......  KY....................  Declining.........  1993.
                                Wabash River.....  IL, IN................  Declining.........  1988.
                                Mississinewa       IN....................  Extirpated........  Pre-1990.
                                 River.
                                Eel River........  IN....................  Declining.........  2007.
                                Tippecanoe River.  IN....................  Stable............  2005.
                                Vermilion River..  IL....................  Extirpated........  Pre-1990.
                                North Fork         IL....................  Declining.........  2006.
                                 Vermilion River.
                                Middle Branch      IL....................  Declining.........  2002.
                                 North Fork
                                 Vermilion River.
                                Middle Fork        IL....................  Extirpated........  1918.
                                 Vermilion River.
                                Salt Fork          IL....................  Extirpated........  Circa 1920.
                                 Vermilion River.
                                Sugar Creek......  IN....................  Extirpated........  1932.
                                Embarras River...  IL....................  Extirpated........  Circa 1980.
                                White River......  IN....................  Extirpated........  Circa 1960.
                                East Fork White    IN....................  Extirpated........  1964.
                                 River.
                                Driftwood River..  IN....................  Extirpated........  Circa 1940s.
                                Big Blue River...  IN....................  Extirpated........  Early 1900s.
                                Brandywine Creek.  IN....................  Extirpated........  Pre-1990.
                                Sugar Creek......  IN....................  Extirpated........  Mid 1990s.
                                Flatrock River...  IN....................  Extirpated........  Mid 1900s.
                                West Fork White    IN....................  Extirpated........  Pre-1990.
                                 River.
                                Black Creek......  IN....................  Extirpated........  Unknown.
Cumberland River..............  Cumberland River.  KY, TN................  Extirpated........  1979.
                                Rockcastle River.  KY....................  Extirpated........  1911.
                                Big South Fork...  KY....................  Extirpated........  1911.
                                Beaver Creek.....  KY....................  Extirpated........  1949.
                                Obey River.......  TN....................  Extirpated........  1939.
                                East Fork Obey     TN....................  Extirpated........  Unknown.
                                 River.
                                Caney Fork.......  TN....................  Extirpated........  1961.
                                Stones River.....  TN....................  Extirpated........  1964.
                                East Fork Stones   TN....................  Declining.........  2002.
                                 River.
                                West Fork Stones   TN....................  Extirpated........  1966.
                                 River.
                                Harpeth River....  TN....................  Extirpated........  Late 1800s.
                                Red River........  KY, TN................  Declining.........  1992.
                                Whippoorwill       KY....................  Extirpated........  Pre-1980.
                                 Creek.
Tennessee River...............  Tennessee River..  AL, KY, MS, TN........  Stable............  2009.
                                Holston River....  TN....................  Extirpated........  1915.
                                French Broad       TN....................  Extirpated........  Unknown.
                                 River.
                                Little Pigeon      TN....................  Extirpated........  Unknown.
                                 River.
                                Little Tennessee   TN....................  Extirpated........  Unknown.
                                 River.
                                Clinch River.....  TN....................  Extirpated........  1935.
                                Lookout Creek....  GA....................  Extirpated........  1973.
                                Sequatchie River.  TN....................  Extirpated........  Pre-1925.
                                Paint Rock River.  AL....................  Improving.........  2007.
                                Hurricane Creek..  AL....................  Extirpated........  1991.
                                Estill Fork......  AL....................  Extirpated........  1970.
                                Larkin Fork......  AL....................  Extirpated........  1966.
                                Flint River......  AL....................  Extirpated........  1955.
                                Elk River........  TN....................  Declining.........  2006.
                                Shoal Creek......  AL, TN................  Extirpated........  Pre-1990.
                                Bear Creek.......  AL, MS................  Declining.........  2005.
                                Duck River.......  TN....................  Improving.........  2009.
                                Big Rock Creek...  TN....................  Extirpated........  Pre-1990.

[[Page 63448]]

 
                                Buffalo River....  TN....................  Extirpated........  1969.
Lower Mississippi River.......  St. Francis River  AR, MO................  Declining.........  2008.
                                Big Creek........  MO....................  Extirpated........  1976.
                                Yazoo River......  MS....................  Extirpated........  Unknown.
                                Big Sunflower      MS....................  Declining.........  2004.
                                 River.
                                Big Black River..  MS....................  Declining.........  1980.
White River...................  White River......  AR, MO................  Stable............  2004.
                                War Eagle Creek..  AR....................  Unknown...........  2004.
                                Buffalo River....  AR....................  Declining.........  1995.
                                North Fork White   AR....................  Extirpated........  1914.
                                 River.
                                Black River......  AR, MO................  Declining.........  2005.
                                Current River....  AR....................  Declining.........  1983.
                                Spring River.....  AR....................  Declining.........  2004.
                                South Fork Spring  AR....................  Declining.........  2002.
                                 River.
                                Strawberry River.  AR....................  Unknown...........  2006.
                                Little Red River.  AR....................  Extirpated........  Circa 1970.
                                Middle Fork        AR....................  Stable............  2009.
                                 Little Red River.
                                Reeses Fork Cache  AR....................  Extirpated........  1980.
                                 River.
Arkansas River................  Verdigris River..  KS, OK................  Unknown...........  2009.
                                Fall River.......  KS....................  Extirpated........  Circa 1900.
                                Neosho River.....  KS, OK................  Declining.........  1999.
                                Cottonwood River.  KS....................  Extirpated........  Pre-1990.
                                Spring River.....  KS, MO................  Declining.........  2006.
                                Center Creek.....  MO....................  Extirpated........  Circa 1920.
                                Shoal Creek......  MO....................  Extirpated........  Pre-1920.
                                Illinois River...  AR, OK................  Declining.........  2008.
Red River.....................  Blue River.......  OK....................  Extirpated........  Circa 1900.
                                Little River.....  AR, OK................  Stable............  2006.
                                Glover River.....  OK....................  Declining.........  1996.
                                Mountain Fork      OK....................  Extirpated........  1968.
                                 Little River.
                                Cossatot River...  AR....................  Declining.........  2007.
                                Ouachita River...  AR, LA................  Stable............  2007.
                                Caddo River......  AR....................  Extirpated........  Pre-1986.
                                Little Missouri    AR....................  Declining.........  1996.
                                 River.
                                Saline River.....  AR....................  Declining.........  2006.
                                North Fork Saline  AR....................  Extirpated........  Pre-1986.
                                 River.
                                Bayou Bartholomew  LA....................  Declining.........  2005.
----------------------------------------------------------------------------------------------------------------

     Butler (2005, pp. 89-90) categorized the extant populations of 
rabbitsfoot into three groups based on population size, general 
distribution, evidence of recent recruitment, and assessment of current 
viability. Sizeable populations with evidence of recent recruitment 
were categorized as viable. Small populations were categorized based on 
limited levels of recent recruitment, generally highly restricted 
distribution, or doubtful or limited viability increasing its 
susceptibility to extirpation in the near future. Marginal populations 
were considered rare, with no evidence of recent recruitment, of 
doubtful viability, and possibly on the verge of extirpation in the 
immediate future.
    Many of the small and marginal populations are demonstrably 
(clearly evident) declining (Table 2). Of 21 streams with marginal 
populations, 9 streams (43 percent) are represented by a single recent 
living or fresh dead specimen. Although we have sporadic collections 
from the last century, trends indicate declining populations in other 
streams as well (for example, Allegheny River, Walhonding River, 
Cossatot River, Buffalo River, and Bear Creek). The following is a 
summary of relative abundance and trends of extant rabbitsfoot 
populations by river basin.

Lower Great Lakes Subbasin

    The Great Lakes Basin represents the most zoogeographically 
(geographic distribution of an animal) distinct population center for 
the rabbitsfoot. All known records for the rabbitsfoot in the Great 
Lakes Basin are from the Maumee River system, a tributary of western 
Lake Erie. Populations historically occurred in five streams in 
addition to a canal in this system, but Fish Creek is the only 
remaining stream population.
    Fish Creek: Fish Creek is a tributary of the St. Joseph River, 
flowing through Indiana and eastward into Ohio. In 1988, rabbitsfoot 
comprised 1.2 percent relative abundance of all mussels in the stream 
(Watters 1988, p. 17). From 1996 to 2005, 17 live specimens were 
collected during 3 surveys (Watters 1996 in Butler 2005, p. 23; Watters 
2000 in Butler 2005, p. 23; Brady et al. 2004 in Butler 2005, pp. 23-
24; Tetzloff 2009, pers. comm.). In 2009, Ahlstedt (2009, p. 3) found 
one fresh dead rabbitsfoot specimen in Fish Creek. This population is 
categorized as marginal.

Ohio River Basin

    Historically, rabbitsfoot populations were found in 66 streams 
within the Ohio River basin, the largest eastern tributary of the 
Mississippi River. Today, rabbitsfoot is extant in 20 streams, a 70 
percent decline from historical stream occurrences. Several of the 
extant populations are represented by single living or fresh dead 
specimens in recent years (Muskingum, Wabash, Eel, South Fork Kentucky, 
Barren, and Rough Rivers and Big Darby Creek).
    Ohio River: Historically, about 60 records for rabbitsfoot have 
been reported over 1,570 rkm (981 rmi) of the main stem (Butler 2005, 
p. 25). Linear river kilometers of mussel beds in the river declined 
greater than 20 percent from 1967 to 1982 (Williams and Schuster 1989, 
pp. 7-10). By 1982, a

[[Page 63449]]

1,069-rkm (664-rmi) mussel survey of the Ohio River (Ohio River Mile 
317.0 to 981.0) yielded one rabbitsfoot specimen from near the mouth of 
the Green River, Kentucky (Williams and Schuster 1989, p. 23).
    Currently, two extant rabbitsfoot populations exist in the Ohio 
River. One population is located near Spencer County, Indiana and 
Hancock County, Kentucky (Clarke 1995, p. 81). The largest Ohio River 
rabbitsfoot population is located downstream of Lock and Dam 52 and 53. 
Numerous live or fresh dead rabbitsfoot specimens have been reported 
over the past 25 years from this reach, mostly downstream of Lock and 
Dam 52 (approximately Ohio River km 1,511.2 or mile 939) near Paducah, 
Kentucky (Butler 2005, p. 26). In addition, the rabbitsfoot population 
downstream of Lock and Dam 52 and 53 includes multiple age or size 
classes (Butler 2005, p. 26). The Ohio River and lower Tennessee River 
(downstream of Kentucky Lake Dam) populations may be considered a 
single meta-population due to the absence of a significant barrier 
separating them and are considered to be a sizeable population (Butler 
2005, p. 26).
    Allegheny River: The Allegheny River begins in northwestern 
Pennsylvania, flows into New York, and then continues south into 
Pennsylvania before converging with the Monongahela River near 
Pittsburgh, Pennsylvania, to form the Ohio River. Historical records 
from Pennsylvania indicate rabbitsfoot was sporadically known from at 
least Armstrong County upstream to Warren County, Pennsylvania (Butler 
2005, p. 28), but little sampling effort was performed over the past 
100 years. Five live rabbitsfoot specimens were found from 1998 to 2001 
at three of four intensely sampled sites at Kennerdell, Venango County, 
Pennsylvania (Villella 2008, pers. comm.). During surveys from 2001 to 
2002 (25 sites) and 2007 (63 sites) encompassing 129 rkm (80 rmi), 
rabbitsfoot was found only at four sites, with very low densities. 
Three of four sites were downstream of the French Creek confluence 
(Villella 2008, pers. comm.). A 2006-2007 survey yielded no evidence of 
rabbitsfoot at five pools within the Allegheny River, approximately 60 
rkm (37 rmi) (Smith and Meyer 2010, p. 558). The lower Allegheny River 
and French Creek likely represent a metapopulation because no barriers 
exist between the streams, but the Alleghany population is considered 
marginal (Butler 2005, p. 29).
    French Creek: French Creek is a major tributary of the Allegheny 
River, with rabbitsfoot known from downstream of Union City Reservoir 
to approximately 11 rkm (7 rmi) above the Allegheny River confluence, a 
total of 121 rkm (75 rmi) (Butler 2005, p. 31). Museum records from 
1985 to 1994 indicate that rabbitsfoot was known from 12 sites (Butler 
2005, p. 30). Intensive quantitative sampling at 4 sites in Venango 
County from 1998 to 1999 yielded 205 live rabbitsfoot specimens (Butler 
2005, p. 30). In 2003 and 2004, timed searches (qualitative) yielded 41 
live rabbitsfoot specimens from 12 of 25 sites in Erie, Crawford, 
Mercer, and Venango Counties, Pennsylvania, while a quantitative survey 
at 7 of 10 sites yielded 57 live rabbitsfoot specimens (Smith and 
Crabtree (2010 p. 391-398). Rabbitsfoot abundance at the seven sites 
was estimated to be from 43 to 372 individuals (standard error = 30 to 
123). Evidence of recent recruitment was found at three sites (Smith 
and Crabtree 2010, p. 400). The French Creek population appears to be 
healthy and stable, with evidence of recruitment.
    LeBoeuf and Conneautee Creeks: LeBoeuf and Conneautee Creeks are 
tributaries of French Creek in Pennsylvania. Historical surveys for 
rabbitsfoot in these creeks are restricted to one relict found in 1991 
from LeBoeuf Creek. In 2006, live rabbitsfoot specimens were confirmed 
near the confluence of each creek with French Creek. Recruitment has 
not been confirmed in either creek and the populations are considered 
marginal and likely a single meta-population with French Creek.
    Muddy Creek: Muddy Creek is a tributary of French Creek in Crawford 
County, Pennsylvania. Dennis (1984 p. 34) first reported the 
rabbitsfoot from Muddy Creek in the 1970s from a site near its 
confluence with French Creek. Three live rabbitsfoot specimens were 
collected at 3 of 20 sites in 2003, a 3-rkm (2 rmi) reach located 6 rkm 
(4 rmi) upstream of its confluence with French Creek (Butler 2005 p. 
32; Mohler et al. 2006, pp. 574 and 581). The rabbitsfoot population is 
categorized as small.
    Walhonding River: The Walhonding River converges with the 
Tuscarawas River to create the Muskingum River near Coshocton, 
Coshocton County, Ohio. The rabbitsfoot was historically common at some 
sites in the Walhonding River (Butler 2005, p. 32). While subsequent 
surveys in the early 1990's collected live mussels, relative abundance 
of rabbitsfoot was 0.3 percent with limited evidence of recruitment 
(Hoggarth 1995-1996, pp. 157, 166-174). In 2009, five live rabbitsfoot 
were collected from four sites located 1,203 m (3,947 ft) to 2,014 m 
(6,608 ft) upstream of Six Mile Dam. No live or dead rabbitsfoot 
individuals were collected from Six Mile Dam downstream 2,267 m (7,438 
ft) (EnviroScience 2010, Figure 5). The rabbitsfoot population is 
categorized as small and appears to be in decline (Butler 2005, p. 33).
    Shenango River: The Shenango River is a tributary of the Beaver 
River in Mercer County, Pennsylvania. Nelson and Villelo (2010, p. 1) 
surveyed the Shenango River from Pymatuning Reservoir to Shenango River 
Lake in 2009 and they collected 34 live rabbitsfoot specimens (relative 
abundance = 1.1 percent) from this reach (Nelson and Villelo 2010, pp. 
9-10). Prior to this survey, rabbitsfoot was believed to be extirpated 
from the Shenango River (Butler 2005, p. 96).
    Muskingum River: The Muskingum River is a major tributary of the 
Ohio River. Rabbitsfoot was believed to be extirpated circa 1980 until 
two live specimens were found in 2007 near Dresden, Muskingum County, 
Ohio (Service 2010, p. 10). This population is categorized as marginal.
    Big Darby Creek: Big Darby Creek is a tributary of the Scioto River 
in central Ohio. Watters (1994, p. 99) claimed the creek had the 
highest mussel diversity of any stream its size in North America. Many 
rabbitsfoot records exist for Big Darby Creek, dating back to the late 
1950's (Butler 2005, p. 34). However, only weathered rabbitsfoot 
specimens were found during two intensive sampling years, 1986 and 1990 
(Watters 1990, p. 31; 1994, p. 101). Since 1990, live and fresh dead 
rabbitsfoot records are limited to five live specimens from two 
localities (Tetzloff 2008, pers. comm.; Butler 2005, p. 35). Currently, 
the population is considered marginal.
    Little Darby Creek: Little Darby Creek is the main tributary for 
Big Darby Creek. Rabbitsfoot were known from Little Darby Creek dating 
back to circa 1960, primarily in Madison County, Ohio (Butler 2005, p. 
35-36). Watters (1994, p. 101) located seven live rabbitsfoot specimens 
at three sites during a 1990 survey. The population in Little Darby 
Creek, although categorized as small, appears to be persisting and 
stable in approximately 32 rkm in Union and Madison Counties, Ohio (20 
rmi) (Watters 1994, p. 106; Tetzloff 2008, pers. comm.).
    South Fork Kentucky River: The South Fork Kentucky River is a 
tributary of the Kentucky River in southeastern Kentucky that 
essentially converges to form the latter near Beattyville, Lee County, 
Kentucky. The rabbitsfoot was

[[Page 63450]]

first discovered in the river in the late 1990s in Owsley County; a 
single relict rabbitsfoot specimen was collected in 1996 and a single 
live specimen was observed in 1998. The population is considered 
marginal and of questionable viability (Butler 2005, p. 37).
    Green River: The Green River is a major Ohio River tributary, 
located in west-central Kentucky. Rabbitsfoot occurrences span almost 
241 rkm (150 rmi) of the upper Green River (Butler 2005, p. 37). 
Historical rabbitsfoot records date back to circa 1900 (Butler 2005, p. 
38). Periodic sampling from 1984 to 1996 produced live and fresh dead 
rabbitsfoot specimens from nine Green River sites between Green River 
Lake Dam and Munfordville, Kentucky (Cicerello 1999, p. 23). Cicerello 
(1999, Figure 1 and Table 1) sampled 40 sites from 1996 to 1998 over 
the 153-rkm (95-rmi) reach between Mammoth Cave National Park and Green 
River Lake Dam and reported the rabbitsfoot to be ``uncommon'' at 13 
sites extending from Green River km 373.0 to 489.1 (mile 231.8 to 
303.9; relative abundance of 0.1 percent) upstream of Munfordville, 
Kentucky. Sampling from 2000 to present has produced high numbers of 
fresh dead and numerous living specimens in Adair, Green, and Hart 
Counties (Butler 2005, pp. 38-39). The Green River population is one of 
a few rabbitsfoot populations that appear to be sizeable and improving, 
based on evidence of recruitment.
    Barren River: The Barren River is the largest tributary of the 
Green River and flows in a northwesterly direction towards its 
confluence with the Green River in west-central Kentucky. Historical 
records of rabbitsfoot in the Barren River prior to the 1990s are 
limited to a couple collections in the 1920s and 1940s (Butler 2005, p. 
40). Two surveys since the 1990s have yielded one live rabbitsfoot and 
relicts in small numbers (Gordon and Sherman 1995, Appendix A). If 
extant, the rabbitsfoot population in the Barren River is marginal and 
its viability is highly doubtful (Butler 2005, p. 41).
    Rough River: The Rough River is a major Green River tributary 
flowing westward towards its confluence in western Kentucky. There are 
no historical rabbitsfoot records from the Rough River prior to the 
1990s (Butler 2005, p. 41). A single fresh dead specimen collected in 
1993 is the only known record of the rabbitsfoot in the Rough River 
(Gordon and Sherman 1995, Appendix A). This single specimen suggests a 
marginal and nonviable population (Butler 2005, p. 41).
    Wabash River: The Wabash River is the largest northern tributary of 
the Ohio River. It originates in west-central Ohio, flows across 
Indiana, and then forms the boundary between southwestern Indiana and 
southeastern Illinois. The rabbitsfoot was once widespread throughout 
the Wabash River prior to the 1960s (Cummings and Mayer 1997, p. 137). 
Surveys conducted from the 1960s through 2004 yielded a single live 
rabbitsfoot specimen and a few relicts (Cummings et al. 1992, p. 3; 
Butler 2005, p. 42). Fisher (2006, p. 107) considered the rabbitsfoot 
``functionally extirpated (in the Wabash River) and restricted to the 
tributaries.''
    Eel River: The Eel River is a northern tributary of the Wabash 
River in north-central Indiana. Historical records from the Eel River 
prior to 1997 are sparse (Henschen 1987 in Butler 2005, p. 43), but 
rabbitsfoot was considered common by Daniels (1903, p. 651). 
Collections since 1997 are limited to nine live rabbitsfoot specimens 
found at sites in Miami and Cass Counties, Indiana (Butler 2005, p. 
43). The rabbitsfoot is no longer considered common in the Eel River, 
restricted to less than 32 rkm (20 rmi) of the lower main stem, and is 
now categorized as marginal (Butler 2005, p. 43).
    Tippecanoe River: The Tippecanoe River flows across north-central 
Indiana until reaching its confluence with the Wabash River. Daniels 
(1903, p. 651) considered the rabbitsfoot to be common in the 
Tippecanoe River. Surveys conducted between 1987 and 2001 yielded 
numerous live rabbitsfoot specimens at numerous sites (Cummings and 
Berlocher 1990, pp. 84-87; Ecological Specialists, Inc. 1993, pp. 47-
50, 55-67, 84). Survey efforts over the past decade continue to produce 
similar results (EnviroScience, Inc. 2005, p. 35; Ecological 
Specialists, Inc. 2003, p. 9-15; Fisher 2008 and 2009, pers. comm.). 
The rabbitsfoot population is sizable, stable and viable in the 
Tippecanoe River, but at disjunct localities within the lower two-
thirds of the river in Fulton, Pulaski, White, Carroll, and Tippecanoe 
Counties (Butler 2005, p. 45).
    North Fork Vermilion River: The North Fork Vermilion River flows 
south out of western Indiana into eastern Illinois until reaching its 
confluence with the Wabash River. Through 45 years of collection 
history, four sites in an approximately 10-rkm (6-rmi) reach have 
produced rabbitsfoot records. Since 1980, researchers have documented 
28 live and 6 fresh dead rabbitsfoot specimens (Illinois Natural 
History Survey (INHS) museum records; Cummings et al. 1998, p. 99). 
Cummings et al. (1998, p. 92) considered the North Fork to have 
``perhaps the last reproducing population of the rabbitsfoot in the 
state [Illinois].'' The North Fork Vermilion River is considered a 
small metapopulation with the Middle Branch North Fork Vermilion River 
population (Butler 2005, p. 47).
    Middle Branch North Fork Vermilion River: The Middle Branch North 
Fork Vermilion River is a tributary of the North Fork Vermilion River. 
Headwaters of the Middle Branch drain northwestern Warren County, 
Indiana, and northeastern Vermilion County, Illinois. The rabbitsfoot 
was discovered in the lowermost reach of the Middle Branch North Fork 
Vermilion River in 1998 (Butler 2005, p. 47). Since that time, a few 
live and fresh dead rabbitsfoot specimens are known from two sites 
sampled in 2000 and 2002. The population is very small and apparently 
contiguous with the rabbitsfoot population occurring in the North Fork 
Vermilion River (Butler 2005, p. 47).

Cumberland River Basin

    The Cumberland River is a large southern tributary of the Ohio 
River. Historically, the rabbitsfoot was known from the main stem and 
12 tributaries. Most records for the species were prior to 1950. 
Parmalee et al. (1980, pp. 93-95) found shells of the rabbitsfoot in 
shellers cull and stock piles in 1977, 1978, and 1979. Rabbitsfoot was 
considered rare at the time, comprising less than one percent of 1,000 
specimens. No more recent records exist for the main stem. Recent 
collections suggest populations may still exist in only two tributaries 
of the Cumberland River, an 85 percent decline of stream populations. 
The East Fork Stones and Red Rivers are the only tributaries with 
extant populations, and their continued survival is tenuous.
    East Fork Stones River: The East Fork Stones River is one of two 
major headwater tributaries, the other being the West Fork Stones 
River, which converge to form the Stones River. Researchers sampled 
numerous pre-impoundment sites from 1964 to 1967 on the East Fork 
Stones River, reporting rabbitsfoot from two sites but never more than 
three live specimens per site (Butler 2005, p. 49). Schmidt et al. 
(1989, pp. 56-59) sampled 23 East Fork Stones River sites during 1980 
to 1981 and reported the rabbitsfoot to be ``rare'' at two lower sites. 
Sampling in 2002 at these two sites produced a single fresh dead 
specimen (Butler 2005, p. 48). The rabbitsfoot in the East Fork Stones 
River is considered very rare and declining;

[[Page 63451]]

thus it is categorized as marginal (Butler 2005, p. 49).
    Red River: The Red River is a large tributary of the lower 
Cumberland River that drains southwestern Kentucky and northwestern 
Tennessee. Despite its size, no thorough survey of the stream has ever 
been attempted, although there are intermittent sampling dates to the 
1960s. Records indicate that a small population of the rabbitsfoot 
existed from a few sites on the main stem in Logan County, Kentucky, 
and Robertson County, Tennessee. From 1988 to 1990, the rabbitsfoot has 
been found live and fresh dead at five sites in Kentucky (Butler 2005, 
p. 49). Subsequent sampling efforts in Kentucky have yielded no 
additional specimens. In 1990 and 1992, the Aquatic Resources Center 
(ARC) (1993, p. 1 and Appendix 1) qualitatively surveyed a reach of the 
Red River in Tennessee and collected a total of four live rabbitsfoot 
(relative abundance of 2.1 and 1.3 percent, respectively). The Red 
River rabbitsfoot population is categorized as marginal due to its 
small size, distribution and doubtful viability (Butler 2005, p. 50).

Tennessee River Basin

    The Tennessee River is the largest tributary of the Ohio River. 
Historically the rabbitsfoot was known from the entire length of the 
Tennessee River and 17 of its tributaries. Today, it is known only from 
five streams in the Tennessee River basin, a 71 percent reduction in 
stream populations. Almost the entire length of the 1,046-rkm (650-rmi) 
Tennessee River main stem has been impounded beginning in 1925, 
destroying hundreds of km of riverine habitat for the rabbitsfoot. 
Extant rabbitsfoot populations persist in the two lowermost tail waters 
of the Tennessee River, Duck River, Paint Rock River, Elk River, and 
Bear Creek.
    Tennessee River: The Tennessee River is formed from the confluence 
of the Holston and French Broad Rivers near Knoxville, Tennessee. 
Historically, the rabbitsfoot was found throughout the length of the 
Tennessee River (Ortmann 1925, p. 337). Today, extant populations only 
occur in the two lowermost tail waters, downstream of Pickwick Landing 
Dam and Kentucky Dam (Hubbs 2008, pers. comm.).
    Over 20 live rabbitsfoot specimens were located along the marginal 
shelf of the Pickwick Lake tail waters in 1991 (Butler 2005, p. 51). 
From 1993 to 2000, live and fresh dead rabbitsfoot specimens were found 
at Tennessee River km 316.7 (mile 196.8, Diamond Island) and km 321.9 
(mile 200). Fresh dead rabbitsfoot specimens aged at less than 10 years 
have been found in this same general reach of river as late as 2003 
(Butler 2005, p. 124). This portion of the rabbitsfoot population 
exhibited recruitment in the 1990s (Hubbs 2010, pers. comm.).
    Downstream of Kentucky Lake Dam, the rabbitsfoot has been found 
live and fresh dead at several sites in low numbers from 1985 to 2005 
(Butler 2005, p. 52). In 1999, a 3.0-cm (1.2-inch) fresh dead 
rabbitsfoot juvenile was found at Tennessee River km 28.2 (mile 17.5) 
(Butler 2005, p. 52). In 2011, surveyors found greater than 80 live 
rabbitsfoot from Kentucky Lake Dam to the confluence with the Ohio 
River. Rabbitsfoot were found to occur most frequently in a narrow band 
of transitional substrate from clay and silt to sand and gravel along 
the toe of descending banks. Although not considered common, there were 
a few locations at which rabbitsfoot occurred in greater numbers (Koch 
2012, pers. comm.). This population is likely contiguous with the 
population in the lower Ohio River, although the rabbitsfoot appears to 
be concentrated from Tennessee River km 16 to 32 (mile 10 to 20) 
(Butler 2005, p. 52). The Tennessee River rabbitsfoot population is 
considered sizable and viable (Butler 2005, pp. 89-90).
    Paint Rock River: The Paint Rock River is a northern Alabama 
tributary of the Tennessee River. Historically, the three headwater 
tributaries, Estill and Larkin Forks and Hurricane Creek, of the Paint 
Rock River had metapopulations of rabbitsfoot. Live rabbitsfoot 
specimens were collected at three of five Paint Rock River sites in 
1965 and 1967 (Isom and Yokley 1973, pp. 444-445). In 1980, only two 
live rabbitsfoot specimens were found in the middle reaches of the 
river during the first comprehensive survey (18 sites; Ahlstedt 1991a, 
p. 168). Ahlstedt (1995-96a, pp. 69-73) sampled 18 sites in 1991 and 
reported good numbers of rabbitsfoot. He collected 35 live rabbitsfoot 
specimens at 8 of 18 main stem sites. Seven tributary sites also were 
sampled, but no rabbitsfoot were found in tributaries.
    During more recent sampling efforts in 1995 and 2002, three fresh 
dead and nine relict shells were found at a main stem site and a single 
live specimen upstream of the Larkin Fork confluence, respectively 
(McGregor and Shelton 1995, Appendix A; Godwin 2002, pp. 10-11, 22-23). 
In 2004, two live and some fresh dead rabbitsfoot specimens were found 
at a site on the lower main stem (Butler 2005, p. 54). An intensive 
survey (42 main stem and 5 Estill Fork sites) in 2008 found 218 live 
and fresh dead rabbitsfoot at 19 sites. Rabbitsfoot was the second most 
abundant species (Fobian et al. 2008, pp. 6-37). This population is 
categorized as sizeable and viable (Butler 2005, pp. 89-90).
    Elk River: The Elk River is a tributary of the Tennessee River 
draining portions of south-central Tennessee to north-central Alabama. 
From 1965 to 1967, Isom et al. (1973, pp. 438-440) found the 
rabbitsfoot at three locations on the Elk River. Survey efforts on Elk 
River tributaries, Sugar and Richland Creek, did not yield any 
rabbitsfoot. In 1980, Ahlstedt (1983, pp. 44-45) found 10 live 
rabbitsfoot specimens at 6 of 108 sites in the Elk River, Lincoln 
County, Tennessee (Ahlstedt 1983, pp. 46-49). Two live rabbitsfoot 
specimens were found at approximately Elk River km 122 (mile 76) in 
1999 (Service 1999, p. 6). Tennessee Valley Authority conducted a 
survey in 2006 and found three live individuals, one objectively aged 
at 6 or 7 years (Chance 2008, pers. comm.). This population is 
categorized as marginal (Butler 2005, pp. 89-90).
    Bear Creek: Bear Creek is a southern tributary of the Tennessee 
River in northwestern Alabama and northeastern Mississippi. Historical 
records indicate rabbitsfoot occurred in 72 rkm (45 rmi; Ortmann 1925, 
p. 337; Butler 2005, pp. 56-57). In 1977, three live rabbitsfoot 
specimens were found at approximately Bear Creek km 90 (rmi 56) in 
Alabama (Butler 2005, p. 56). A 1991 record of a single fresh dead 
specimen is known from approximately Bear Creek km 40 (mile 25) in 
Colbert County, Alabama. McGregor and Garner (2004, p. 64) conducted 
the only comprehensive survey of the system from 1996 to 2001 and found 
rabbitsfoot live or fresh dead at two sites. It occurred on the main 
stem in the immediate vicinity of the Natchez Trace Parkway of the 
National Park Service (NPS) system in Colbert County, Alabama (Bear 
Creek km 39.4 and 40.9; mile 24.5 and 25.4). In Mississippi, one live 
and eight fresh dead specimens were found in a four-rkm (2.5-rmi) reach 
in 2002 and 2005 (Jones 2011, pers. comm.). Bear Creek is categorized 
as a small population (Butler 2005, pp. 89-90).
    Duck River: The Duck River is a large tributary of the lower 
Tennessee River in central Tennessee. Ortmann (1924, pp. 24-33) 
documented the presence of rabbitsfoot in the early 1920s, considering 
it ``all over the interior region (and elsewhere).'' Surveys conducted 
between 1965 and 1979 found similar results (Isom and Yokley 1968, p. 
36; Ahlstedt 1981, p. 62; Ahlstedt 1991, pp. 142-147).
    Using stratified random sampling, Barr et al. (1993-94, p. 205) in 
1981 estimated that 591 live rabbitsfoot

[[Page 63452]]

occurred at Lillards Mill. Twenty rabbitsfoot were collected from 
Lillards Mill and translocated to a site in Bedford County in 1988 
(Layzer and Gordon 1993, pp. 89-91). Resampling the Bedford County site 
in 2002, evidence of recruitment was noted by Ahlstedt et al. (2004, p. 
101). Madison et al. (1999, Table 1) reported 34 live rabbitsfoot 
specimens from a Maury County site in 1998.
    Ahlstedt et al. (2004, p. 101) conducted an extensive mussel survey 
in the system beginning in 2000. They reported 403 live and fresh dead 
rabbitsfoot specimens from 31 of 78 sites sampled (a few sites were 
sampled more than once). An average of 13 live or fresh dead 
rabbitsfoot specimens was found per site of occurrence. The rabbitsfoot 
population on the Duck River is primarily located between rkm 209 to 
288 (miles 179 to 130), and scattered in the lower river (rkm 60 to 61; 
rmi 37 to 38; Hickman County) (Hubbs 1995, p. 46; Schilling and 
Williams 2002, p. 409; Butler 2005, p. 59). The extant rabbitsfoot 
population extends over at least 274 rkm (170 rmi; approximately Duck 
River km 60 to 333, mile 37 to 207) and ``* * * represents one of the 
best known populations rangewide'' (Ahlstedt et al. (2004, p. 101).

Lower Mississippi River Subbasin

    The rabbitsfoot is known from five streams within the lower 
Mississippi River subbasin (excluding the White, Arkansas, and Red 
River systems). The five streams include St. Francis River, Big Creek, 
Yazoo River, Big Sunflower River, and Big Black River. Rabbitsfoot is 
extirpated from Big Creek and the Yazoo River (Butler 2005, p. 61).
    St. Francis River: The St. Francis River is a tributary of the 
Mississippi River draining portions of southeastern Missouri and 
northeastern Arkansas. In the 1800s the rabbitsfoot was considered 
abundant in the St. Francis River (Call 1895, p. 15). Extant 
rabbitsfoot records are from the upper part of the river in Butler and 
Wayne Counties, Missouri (Butler 2005, p. 61). Hutson and Barnhart 
(2004, pp. 84, 109) in 2002 found 16 live rabbitsfoot specimens at 3 
sites upstream of Lake Wappapello, Missouri; including 11 at rkm 277.0 
(rmi 172.1), 3 at rkm 294.5 (rmi 183.0), and 2 at rkm 306.6 (rmi 
190.5). At rkm 277.0 (rmi 172.1), 35 live rabbitsfoot specimens were 
found in the 1970s, but only 8 and 11 live specimens were found in 2001 
and 2002, respectively. In 2005, seven live rabbitsfoot specimens were 
sampled at a site in the same reach (Butler 2005, p. 62). With the 
exception of Call's description, no rabbitsfoot have been found in the 
St. Francis River, Arkansas (Butler 2005, p. 61). The rabbitsfoot is 
rare in the St. Francis River, may be at risk from extirpation (Hutson 
and Barnhart 2004, p. 84), and is categorized as a small population 
(Butler 2005, pp. 89-90).
    Big Sunflower River: A major tributary of the Yazoo River, the Big 
Sunflower River drains a large portion of the Mississippi Delta in 
west-central Mississippi. The rabbitsfoot was first reported in 1969 
from the lower portion of the river (Florida Museum of Natural History, 
museum lot  233299). Currently, rabbitsfoot occurs in a 32-rkm 
(20-rmi) reach upstream of the Quiver River confluence in Sunflower 
County. From 2000 to 2010, live and fresh dead rabbitsfoot specimens 
were collected at Blaine Road west of Blaine, Mississippi, downstream 
to near the Quiver River confluence (Jones 2011, pers. comm.). Butler 
(2005, pp. 89-90) categorized this population as small.
    Big Black River: The Big Black River is a tributary to the lower 
Mississippi draining central and southwestern Mississippi. Hartfield 
and Rummel (1985, pp. 117-119) sampled the lower three-quarters of this 
426-rkm (265-rmi) long river. The rabbitsfoot is restricted to a small 
portion of the lower river cutting through the Loess Hills 
physiographic division where mussels were generally found in gravel 
riffles and runs. At that time, 19 dead rabbitsfoot specimens were 
recorded at nine sites in Hinds and Warren Counties (Butler 2005, p. 
64). The only other record is for a dead specimen located in 2000. 
Rabbitsfoot is still considered extant in this reach (Jones 2011, pers. 
comm.), and the population is categorized as small.

White River Basin

    Historically, 13 rivers within the White River system harbored 
rabbitsfoot populations. Extant populations occur in 9 of 13 (69 
percent) rivers in the basin. Further, no other major river basin has 
as many sizeable populations. At one time, the main stem of White River 
and 11 of its tributaries had a large metapopulation of rabbitsfoot 
(Butler 2005, p. 65). Three of the streams may still contain a 
metapopulation (Black, Spring, and Strawberry Rivers). Unfortunately, 
many of the tributaries appear to have declining populations (Buffalo, 
Black, Current, Spring, and South Fork Spring Rivers).
    White River: The White River is a large western tributary of the 
Mississippi River. The rabbitsfoot population once extended throughout 
most of the 1,110-rkm (690-rmi) length of the White River and site 
records date back to circa 1910, but now it is restricted to the lower 
reaches downstream of Batesville, Independence County, Arkansas (Harris 
et al. 2009, p. 73). Historical abundance data are scarce. However, 
records indicate that the population was large (Butler 2005, p. 65).
    From the 1980s to late 2000s, numerous live and fresh dead 
rabbitsfoot specimens have been found at numerous sites in two disjunct 
reaches of the White River (rkm 319 and 410; rmi 198 and 255 and rkm 92 
to 146; rmi 57 to 91) (Bates and Dennis 1983, p. 42; AGFC Mussel 
Database 2011). In 1992, Christian (1995, pp. 146-197) estimated the 
total rabbitsfoot population from 13 sites on the lower White River at 
928 individuals. The rabbitsfoot population is categorized as sizable, 
but remains extant in two disjunct reaches separated by approximately 
161 rkm (100 rmi). The uppermost reach extends from the Batesville Dam 
at Batesville, Independence County, Arkansas, downstream to the Little 
Red River confluence north of Georgetown, White and Woodruff Counties, 
Arkansas. The lowermost reach extends from U.S. Highway 79 at 
Clarendon, Monroe County, Arkansas, downstream to Arkansas Highway 1 
near St. Charles, Arkansas County, Arkansas (Butler 2005, p. 66; AGFC 
mussel database 2011).
    War Eagle Creek: War Eagle Creek is a small, eastern White River 
tributary located in northwest Arkansas. Rabbitsfoot was not documented 
in War Eagle Creek until 1974. Since 1979, one live specimen was 
collected in 1981, and two fresh dead were found in 2004 (AGFC mussel 
database 2011). Little is known about the viability of this population. 
Therefore, it has been categorized as marginal (Butler 2005, pp. 89-
90).
    Buffalo River: The Buffalo River is a western White River tributary 
in north-central Arkansas. Rabbitsfoot was first documented in the 
Buffalo River in 1910 by Meek and Clark (1912, pp. 7-20). They reported 
rabbitsfoot as ``common'' at 11 of 26 sites; almost all specimens were 
located within the lower 40 rkm (25 rmi) within Searcy County, 
Arkansas. Two comprehensive surveys of the Buffalo River mussel fauna 
in 1995 and 2004 to 2005 found live rabbitsfoot specimens concentrated 
between Arkansas Highway 7 in Newton County to near the Cedar Creek 
confluence downstream of Rush, Arkansas (Harris 1996, p. 12; Matthews 
et al. 2009, pp. 116 and 122). NPS staff collected four live 
rabbitsfoot in 2008 from a site near the Cedar Creek

[[Page 63453]]

confluence near Rush, Arkansas (Hodges 2011, pers. comm.). During a 
2011 survey of this same site, changes in channel geomorphology caused 
by 2009 and 2011 flooding resulted in the entire site being covered 
with sand. Few live mussels were encountered, but one live rabbitsfoot 
was found and relocated to more suitable habitat downstream. While no 
live rabbitsfoot were encountered at the downstream relocation site, 2 
fresh dead and 23 weathered rabbitsfoot shells were found at this site. 
Two live rabbitsfoot also were collected in 2011 at two sites located 
between Arkansas Highway 7 and U.S. Highway 65. The Buffalo River 
population is small and very susceptible to extirpation based on recent 
surveys (Davidson 2011, pers. comm.).
    Black River: The Black River is the largest White River tributary 
draining southeastern Missouri and northeastern Arkansas. Based on data 
from the 1970s and 1980s, the rabbitsfoot was abundant at some Arkansas 
sites in the lower main stem between the confluences of the Current and 
Strawberry Rivers (approximately 121 rkm, 75 rmi; Ohio State University 
Museum of Biological Diversity (OSUM) museum lot s 47673 and 
47933; Miller and Hartfield 1986, pp. 8-9). In 1992, Rust (1993, 
Appendix 1.1) surveyed 48 sites in the Black River, finding rabbitsfoot 
live at 4 sites, and a combined population estimate of 1,503 
individuals, between rkm 105 to 124 (rmi 65 to 77). A 2000 to 2003 
survey at 51 sites in Missouri did not locate any rabbitsfoot (Hutson 
and Barnhart 2004, pp. 162-169). In 2005, AGFC collected 25 live 
rabbitsfoot specimens from a site located approximately two rkm (1 rmi) 
upstream of U.S. Highway 63 at Black Rock, Arkansas (AGFC Mussel 
Database 2011). The Black River population is considered one of the 
largest remaining range-wide (Butler 2005, pp. 89-90).
    Current River: The Current River is a Black River tributary 
draining southeastern Missouri and northeastern Arkansas. The 
rabbitsfoot is known only from the Arkansas portion of the stream. Few 
records exist for the species in the Current River, including several 
live and dead specimens in 1983-1984 and 1994 (AGFC mussel database). 
The rabbitsfoot population in the Current River is categorized as 
marginal.
    Spring River: The Spring River is a Black River tributary draining 
south-central Missouri and northeastern Arkansas. Based on pre-1986 
records, the rabbitsfoot was once known from at least 14 sites in the 
80-rkm (50-rmi) reach downstream of the South Fork Spring River 
confluence (Harris et al. 1997, pp. 80-82). Records from the 1980s also 
indicate that the rabbitsfoot was ``relatively common'' (Miller and 
Hartfield 1986, pp. 9-10; Harris and Gordon 1987, p. 54; ANSP 359907). 
A survey upstream of the South Fork Spring River confluence in 1985 did 
not find any rabbitsfoot (Miller and Hartsfield 1986, p. 9). In 1991, 
Rust (1993, Appendices 1.2 and 1.4) estimated rabbitsfoot relative 
abundance at 1.9 to 4.0 percent at 5 of 6 sites and total population 
size at 563 individuals at 3 of these sites. Sixty-eight live 
rabbitsfoot were collected in the river reach from near Ravenden to 
Imboden, Arkansas, during 2004 to 2005 (Harris et al. 2007, p. 16). The 
rabbitsfoot population appears to be recruiting, but the numbers of 
individuals are decreasing from the high numbers found in the mid-1980s 
(Butler 2005, p. 72). For this reason, the Spring River is categorized 
as a small rabbitsfoot population.
    South Fork Spring River: The South Fork Spring River is a Spring 
River tributary draining portions of Howell County, Missouri, and 
Fulton and Sharp Counties, Arkansas. The rabbitsfoot was discovered in 
the South Fork Spring River in 2002 in central Fulton County, Arkansas 
(Butler 2005, p. 72). Judging from the number of fresh dead and relict 
shells found, it appears to have been the dominant species at this 
site, although no live mussels were located (Butler 2005, pp. 72-73). 
In 2006, a qualitative survey to assess mussel communities at 35 sites 
in the South Fork Spring River did not yield any rabbitsfoot (Martin et 
al. 2009, pp. 106-107). However, one live rabbitsfoot specimen was 
located on the river a week later, representing the only live specimen 
ever collected from the river (AGFC mussel database 2011). Based on 
limited information collected over the past decade on the rabbitsfoot 
status in the South Fork Spring River, this population is categorized 
as small.
    Strawberry River: The Strawberry River is a Black River tributary 
draining portions of northeastern Arkansas. The most upstream record of 
live rabbitsfoot in the Strawberry River was collected 2.9 rkm (1.8 
rmi) upstream of Hars Creek southeast of Franklin, Arkansas, in 1998 
(AGFC Mussel Database 2011). From 1983 to 2006, 84 live rabbitsfoot 
specimens, including some juveniles, have been collected from 14 sites 
extending from the most upstream record downstream through Sharp and 
Lawrence counties (greater than 80 rkm or 50 rmi) (Rust 1993, p. 30; 
Harris et al. 2007, pp. 23-27; INHS 27526). The Strawberry River 
rabbitsfoot population is categorized as sizable.
    Middle Fork Little Red River: The Middle Fork Little Red River is a 
headwater tributary of the Little Red River in north-central Arkansas. 
Rabbitsfoot was first discovered in the Middle Fork in 1991 with a 
single specimen from 26 sites (Harris 1992, p. 64). The Middle Fork 
Little Red River has been extensively surveyed during the past decade. 
Winterringer (2003, p. 46 and Appendix F) found 28 live rabbitsfoot 
specimens, including 2 juveniles, at 2 sites sampled in 2001 downstream 
of Little Tick Creek. The AGFC and Service collected seven live 
rabbitsfoot, including one juvenile, from two sites in this same reach 
in 2009 (Davidson 2011, pers. comm.). The rabbitsfoot population is 
categorized as small.

Arkansas River Basin

    The rabbitsfoot distribution in the Arkansas River system is 
restricted to tributaries draining the western fringe of the Ozark 
Plateaus and adjacent Central Lowlands physiographic provinces located 
to the west. The rabbitsfoot range in the system includes east-central 
and southeastern Kansas, northeastern Oklahoma, extreme northwestern 
Arkansas, and extreme southwestern Missouri. Rabbitsfoot was once 
distributed throughout hundreds of km (miles) of streams in the basin, 
with populations in the Fall and Cottonwood Rivers and Center and Shoal 
Creeks now extirpated (50 percent reduction in stream populations). 
Scammon (1906, pp. 348-349) described rabbitsfoot as ``seeming to be 
nowhere abundant, it is not a rare species in [the Spring, Neosho, and 
Verdigris Rivers].'' Rabbitsfoot is now confined to reduced portions of 
the Verdigris, Neosho, Spring, and Illinois Rivers.
    Neosho River: The Neosho River is a large northern tributary to the 
Arkansas River in eastern Kansas and northeastern Oklahoma. Historical 
evidence indicates rabbitsfoot was present in almost the entire 740-rkm 
(460-rmi) main stem of the Neosho River (Butler 2005, p. 75). Live 
rabbitsfoot specimens, including some juveniles, have been collected in 
a 12.8-rkm (8-rmi) reach from near Iola to Humboldt, Allen County, 
Kansas, from 1994 to 1999 (Obermeyer et al. 1995, pp. 31-32; Mulhern et 
al. 2002, p. 243; Butler 2005, p. 76). Relict shells were collected at 
8 of 21 additional main stem sites from 1993 to 1995 (Obermeyer et al. 
1995, p. 63). The rabbitsfoot is thought to be extirpated from the 
Oklahoma portion and remaining stretches in Kansas. The extant 
population in Kansas is categorized as small.
    Spring River: The Spring River is a Neosho River tributary draining 
portions of southwest Missouri, southeast Kansas, and northeast

[[Page 63454]]

Oklahoma. Rabbitsfoot is extant in the Spring River from Missouri 
Highway 96 in Carthage, Jasper County, Missouri, downstream to the 
confluence of Turkey Creek north of Empire, Cherokee County, Kansas. 
Six live rabbitsfoot specimens were collected from four Missouri sites 
in the early 1990's and 2006 (Obermeyer et al. 1995, p. 48; Missouri 
Natural Heritage Database 2011). In 2003, a Kansas site (known as the 
Pierce Site) located approximately 0.5 to 0.8 rkm (0.3 to 0.5 rmi) 
yielded 10 live rabbitsfoot, including 7 gravid females (Miller 2011). 
In 2006, KDWP collected eight live rabbitsfoot specimens from one 30 
m\2\ quadrat sample (1.9 percent of live mussels collected) at a site 
just upstream of Kansas and Missouri Highway YY. This rabbitsfoot 
population is categorized as small.
    Illinois River: The Illinois River is an Arkansas River tributary 
draining portions of northwest Arkansas and northeast Oklahoma. Gordon 
et al. (1979, p. 35) surveyed 11 sites in Arkansas in the 1970s and 
found only a single shell. In 1994, Harris (1998, p. 4) found 34 live 
rabbitsfoot specimens at 7 of 22 sites in a 48-rkm (30-rmi) reach in 
Washington and Benton counties, Arkansas. In 1995, Vaughn (1997, pp. 
28-30) surveyed 45 sites in Oklahoma and found live rabbitsfoot at 2 
sites. A 2008 survey in Benton and Washington Counties found 10 live 
rabbitsfoot at 2 of 15 sites extending from just upstream of Muddy Fork 
to the Arkansas Highway 59 Bridge (Davidson 2011, pers. comm.). This 
population is categorized as marginal.
    Verdigris River: The Verdigris River is an Arkansas River tributary 
draining portions of Kansas and Oklahoma. Rabbitsfoot is extant in a 
short reach from Oologah Lake dam north of Claremore, Oklahoma, 
downstream to Interstate 44 (Will Rogers Turnpike) west of Catoosa, 
Rogers County, Oklahoma. Numerous live rabbitsfoot specimens were 
collected at three sites clustered upstream and downstream of Oklahoma 
Highway 20 west of Claremore, Oklahoma, in 2006 and 2007 (Boeckman 
2008, pers. comm.). Rabbitsfoot has been extirpated from reaches of the 
Verdigris River upstream of Oologah Lake in Kansas and Oklahoma. This 
population is categorized as marginal due to its restricted 
distribution.

Red River Basin

    Streams within the Red River basin primarily drain the Ouachita 
Mountains in southeastern Oklahoma and southwestern Arkansas, but 
extant populations still occur in three stream reaches within the Gulf 
Coastal Plain ecoregion in southern Arkansas and northern Louisiana. 
The rabbitsfoot is extant in 7 of 11 historical streams (64 percent) 
within the Red River basin.
    Little River: The Little River is a Red River tributary draining 
portions of southeastern Oklahoma and southwestern Arkansas. Isley 
(1924, p. 57) discovered one specimen in 1910. In 1983, six live 
individuals were located in Sevier County, Arkansas (AGFC mussel 
database 2011). Vaughn and Taylor (1999, p. 920) collected live 
rabbitsfoot specimens at six sites in the Little River located 
downstream of the Glover River confluence. Its ``abundance,'' defined 
as the number of mussels found per hour spent searching, ranged from 
0.6 to 8.0 at these sites. In 2002, survey work occurred in the 
lowermost section, downstream of Millwood Reservoir, and no rabbitsfoot 
were located at any of the 14 sites surveyed (Farris et al. 2003, 
Appendix A). From 2006 to 2008, the AGFC and Service collected 89 live 
rabbitsfoot specimens from 13 Little River sites extending from near 
the Arkansas and Oklahoma state line to near U.S. Highway 71 north of 
Ashdown, Arkansas (AGFC Mussel Database, 2011). The rabbitsfoot 
population is sizeable and considered viable in this reach of the 
Little River (Davidson 2011, pers. comm.).
    Glover River: The Glover River is a Little River tributary draining 
portions of southeastern Oklahoma. Museum records indicate a healthy 
population of rabbitsfoot once occupied a 48-rkm (30-rmi) reach of the 
river (Butler 2005, p. 82). An unspecified number of specimens were 
located in a 1993 to 1995 survey (Vaughn 2000, pp. 229). In 1996, 
researchers systematically surveyed 22 sites, and rabbitsfoot relative 
abundance was 0.7 and 3.0 percent at 2 sites (Vaughn 2003, p. 3). The 
Glover River appears to support a marginal population of rabbitsfoot 
that is greatly diminished from historical accounts (Vaughn 2003, p. 
1).
    Cossatot River: The Cossatot River is a Little River tributary 
draining portions of southwestern Arkansas. Few mussel collections have 
been made in the Cossatot River. Rabbitsfoot was first collected in 
1970, with evidence of population recruitment (Butler 2005, p. 83). 
Twelve specimens were found in 1983 at a site in Sevier County, 
Arkansas (AGFC mussel database 2011). In 2004, four live specimens were 
found at one site (AGFC mussel database 2011). Viability of the 
population is doubtful, based on its small size and isolated location, 
and the population is categorized as marginal. However, no 
comprehensive survey data for the river exists (Butler 2005, p. 83).
    Ouachita River: The Ouachita River is the largest tributary of the 
Red River, draining a large portion of southern Arkansas and eastern 
Louisiana. Wheeler (1918, pp. 122-123) observed rabbitsfoot in the 
Ouachita River and declared it ``in nearly every mussel bed of the 
river.'' Call (1895, p. 15) also considered the rabbitsfoot 
``abundant.'' The rabbitsfoot is extant in a short reach (two sites) of 
the Ouachita River from Arkansas Highway 379 south of Oden, Montgomery 
County, Arkansas, downstream to Arkansas Highway 298 east of Pencil 
Bluff, Montgomery County, Arkansas (AGFC Mussel Database, 2011). Three 
reservoirs (Lakes Ouachita, Hamilton, and Catherine) separate the 
headwaters in the Ouachita Mountains from the Gulf Coastal Plain 
reaches in southern Arkansas and Louisiana.
    Researchers collected 38 live specimens from 1992 to 2005 at 8 
sites in Clark, Hot Spring, and Ouachita Counties, Arkansas (Posey 
1997, Appendix 1.3; Butler 2005, p. 84, Harris 2006, Appendix 1e--1i; 
AGFC Mussel Database, 2011). Posey (1997, Appendix 1.3) estimated the 
rabbitsfoot population at 1,456 individuals in the Ouachita River from 
rkm 547 to 563 (rmi 340 to 350). Rabbitsfoot has not been observed in 
the Louisiana reach of the Ouachita River in over 100 years (Butler 
2005, p. 84). The Ouachita River population is categorized as small due 
to its greatly diminished distribution and limited evidence of recent 
recruitment.
    Little Missouri River: The Little Missouri River originates in the 
Ouachita Mountains and flows southeast to the Ouachita River in 
southwest Arkansas. The rabbitsfoot is known from a single collection 
in 1996 in the lower main stem in Clark County, Arkansas (Davidson 
1997, pp. 46 and 130). The Little Missouri population likely is a 
metapopulation with the Ouachita River population and is categorized as 
marginal (Butler 2005, p. 85).
    Saline River: The Saline River flows southward through south-
central Arkansas before converging with the Ouachita River at 
Felsenthal National Wildlife Refuge (NWR) north of the Arkansas and 
Louisiana State line. Call (1895, p. 15) considered the rabbitsfoot 
``abundant'' in the Saline River. Two fresh dead and one live specimen 
were documented in 1993 and 2006, respectively, in Grant County (AGFC 
Mussel database 2011). Davidson (1997) surveyed the Saline River from 
the northern boundary of Felsenthal NWR to its confluence with the 
Ouachita

[[Page 63455]]

River and was unable to locate any live rabbitsfoot. Davidson and Clem 
(2002, p. 17; 2004, p. 16) collected 26 live rabbitsfoot specimens from 
13 of 230 sites from near Tull, Arkansas, to the northern boundary of 
Felsenthal NWR. Rabbitsfoot comprised 0.2 percent of the total mussel 
community. In 2005, Harris (2006, Appendix 1b-1d) quantitatively 
sampled three of the sites sampled by Davidson and Clem in 2004. He 
collected 24 live rabbitsfoot, representing 0.1 to 0.8 percent of the 
total mussel community per site. These sites were resampled in 2011 and 
four live rabbitsfoot were collected, representing zero to 0.1 percent 
of the total mussel community (Davidson 2012, pers. comm.). In 2011, 
the AGFC and Service collected 33 live rabbitsfoot, representing 0.1 to 
0.3 percent of the total mussel community. Numerous dead rabbitsfoot 
were observed near the shoreline, apparently having succumbed to 
desiccation caused by severe drought conditions (Davidson 2012, pers. 
comm.). The rabbitsfoot population is categorized as small due to its 
``patchy'' distribution, but there is evidence of recent recruitment 
(Davidson and Clem 2004, p. 16; Davidson 2011, pers. comm.).
    Bayou Bartholomew: Bayou Bartholomew originates in southeast 
Arkansas and flows south into Louisiana before converging with the 
Ouachita River. The first record of rabbitsfoot in Bayou Bartholomew is 
from 1992 in Louisiana (Butler 2005, p. 87). One live specimen was 
found in Louisiana between 2000 and 2001 (Alley 2005, p. 75). From 2004 
to 2005, two sites yielded five live and six dead specimens. A 2004 
survey at 50 sites in the Arkansas portion of Bayou Bartholomew did not 
yield any live, dead, or relict rabbitsfoot specimens (Brooks et al. 
2008, pp. 9-10). All records since 2000 are from three sites in 
Louisiana, two in the middle Louisiana reach and one near the Arkansas 
state line (Butler 2005, p. 87). This population is categorized as 
marginal.
Summary of Rabbitsfoot Rangewide Population Status
    Based on historical and current data, the rabbitsfoot is declining 
rangewide. In ten of the 15 States comprising the rabbitsfoot's 
historical range, the species is considered by State law to be 
endangered (Illinois, Indiana, Kansas, Mississippi, Ohio, and 
Pennsylvania); threatened (Kentucky and Tennessee); of special concern 
(Arkansas); or it is assigned an uncategorized conservation status 
(Alabama). The American Malacological Union and American Fisheries 
Society also consider the rabbitsfoot to be threatened (in Butler 2005, 
p. 21). It is presently extant in 51 of the 140 streams of historical 
occurrence, a 64 percent decline. Further, in the streams where it is 
extant, populations with few exceptions are highly fragmented and 
restricted to short reaches. In addition, the species has been 
extirpated from West Virginia and Georgia. The extirpation of this 
species from numerous streams and stream reaches within its historical 
range signifies that substantial population losses have regularly 
occurred in each of the past several decades. Seventeen streams (33 
percent of extant populations or 12 percent of historical populations) 
have small populations with limited levels of recruitment and are 
generally highly restricted in distribution, making their viability 
unlikely and making them extremely susceptible to extirpation in the 
near future. In addition, 15 of those 17 streams (88 percent) have 
populations that are declining. In many of these streams, rabbitsfoot 
is only known from one or two documented individuals in the past 
decade. Its viability in these streams is doubtful and additional 
extirpations may occur if this downward population trend is not 
eliminated. Eleven populations located in historical streams (22 
percent of extant populations or 8 percent of historical populations; 
Ohio, Green, Tippecanoe, Tennessee, Paint Rock, Duck, White, Black, 
Strawberry, and Little Rivers and French Creek) are considered viable 
(Butler 2005, p. 88; Service 2010, p. 16). Given this compilation of 
current distribution, abundance, and status trend information, the 
rabbitsfoot exhibits range reductions and population declines 
throughout its range.

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations at 50 CFR part 424 set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on any of the following five factors: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; and (E) other natural or manmade 
factors affecting its continued existence. Listing actions may be 
warranted based on any of the above threat factors, singly or in 
combination. Each of these factors is discussed below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    The habitats of freshwater mussels are vulnerable to water quality 
degradation and habitat modification from a number of activities 
associated with modern civilization. The decline, extirpation, and 
extinction of mussel species are often attributed to habitat alteration 
and destruction (Neves et al. 1997, pp. 51-52). Bogan (1993, pp. 599-
600 and 603-605) linked the decline and extinction of mussels to a wide 
variety of threats including siltation, industrial and municipal 
effluents, modification of stream channels, impoundments, pesticides, 
heavy metals, invasive species, and the loss of host fish. Chief among 
the causes of decline in distribution and abundance of the Neosho 
mucket and rabbitsfoot, and in no particular order of ranking, are 
impoundment, channelization, sedimentation, chemical contaminants, 
mining, and oil and natural gas development (Mather 1990, pp. 18-19; 
Obermeyer et al. 1997b, pp. 113-115; Neves et al. 1997, pp. 63-72; 
Davidson 2011, pers. comm.). Neosho mucket and rabbitsfoot are both 
found within medium to large river drainages exposed to a variety of 
landscape uses. These threats to mussels in general (and Neosho mucket 
and rabbitsfoot where specifically known) are individually discussed 
below.
Impoundments
    Dams eliminate and alter river flow within impounded areas, trap 
silt leading to increased sediment deposition, alter water quality, 
change hydrology and channel geomorphology, decrease habitat 
heterogeneity, affect normal flood patterns, and block upstream and 
downstream movement of mussels and fish (Layzer et al. 1993, pp. 68-69; 
Neves et al. 1997, pp. 63-64; Watters 2000, pp. 261-264). Within 
impounded waters, decline of mussels has been attributed to direct loss 
of supporting habitat, sedimentation, decreased dissolved oxygen, 
temperature levels, and alteration in resident fish populations (Neves 
et al. 1997, pp. 63-64; Pringle et al. 2000, pp. 810-815; Watters 2000, 
pp. 261-264). Downstream of dams, mussel declines are associated with 
changes and fluctuation in flow regime, channel scouring and bank 
erosion, reduced dissolved oxygen levels and water temperatures, and 
changes in resident fish assemblages (Williams et al. 1992, p. 7; 
Layzer et al. 1993, p. 69; Neves et

[[Page 63456]]

al. 1997, pp. 63-64; Watters 2000, pp. 265-266; Pringle et al. 2000, 
pp. 810-815). Dams that are low to the water surface, or have water 
passing over them (small low head or mill dams) can have some of these 
same effects on mussels and their fish hosts, particularly reducing 
species richness and evenness and blocking fish host movements (Watters 
2000, pp. 261-264; Dean et al. 2002, pp. 235-238). The decline of 
mussels within the Arkansas, Red, White, Tennessee, Cumberland, 
Mississippi, and Ohio River basins has been directly attributed to 
construction of numerous impoundments (Miller et al. 1984, p. 109; 
Williams and Schuster 1989, pp. 7-10; Layzer et al. 1993, pp. 68-69; 
Neves et al. 1997, pp. 63-64; Obermeyer et al. 1997b, pp. 113-115; 
Watters 2000, pp. 262-263; Sickel et al. 2007, pp. 71-78; Hanlon et al. 
2009, pp. 11-12; Watters and Flaute 2010, pp. 3-7). Population losses 
due to impoundments have likely contributed more to the decline of the 
Neosho mucket and rabbitsfoot than any other factor. River habitat 
throughout the ranges of the Neosho mucket and rabbitsfoot has been 
impounded, leaving short, isolated patches of suitable habitat that 
sometimes lacks suitable fish hosts. Neither Neosho mucket nor 
rabbitsfoot occur in reservoirs lacking riverine characteristics. They 
are unable to successfully reproduce and recruit under these conditions 
(Obermeyer et al. 1997b, p. 114; Butler 2005, p. 96). On the other 
hand, rabbitsfoot may persist and even exhibit some level of 
recruitment in some large rivers with locks and dams where appropriate 
habitat quality and quantity remain (Ohio and Tennessee Rivers in 
riverine reaches between a few locks and dams) (Butler 2005, p. 96).
    The majority of the main stem Ohio, Cumberland, Tennessee, and 
White Rivers and many of their largest tributaries are impounded, in 
many cases resulting in tail water (downstream of dam) conditions 
unsuitable for rabbitsfoot (Butler 2005, p. 96). There are 36 major 
dams within the Tennessee River basin (Holston, Little Tennessee, 
Clinch, Elk, Flint, and Sequatchie Rivers, and Bear Creek) that have 
resulted in the impoundment of 3,680 rkm (2,300 rmi) of the Tennessee 
River and its largest tributaries (Butler 2005, p. 95). Only three of 
these rivers support viable populations--Tennessee, Paint Rock, and 
Duck Rivers. Ninety percent of the Cumberland River downstream of 
Cumberland Falls (rkm 866, rmi 550) as well as numerous tributaries are 
either directly impounded or otherwise adversely affected by cold tail 
water releases from dams. Rabbitsfoot and its fish hosts are warm water 
species and the change in temperature to cold water below the dams 
further reduces suitable habitat for the species and may eliminate fish 
hosts that cannot adapt to colder water temperatures (see the 
Temperature section below for more information). Other tributary 
impoundments that adversely affected rabbitsfoot and its fish hosts 
within the Ohio River basin include, but are not limited to, the 
Walhonding, Barren, Rough, and Eel Rivers and two rivers with viable 
populations, Green and Tippecanoe Rivers. The majority (7 of 11 
populations or 64 percent) of viable rabbitsfoot populations (Ohio, 
Green, Tippecanoe, Tennessee, Duck, White, and Little Rivers) occur 
downstream of main stem impoundments that make these populations more 
susceptible to altered habitat quality and quantity associated with the 
impoundment or dam operation, which may be exacerbated during 
stochastic events such as droughts and floods.
    Navigational improvements on the Ohio River began in 1830, and now 
include 21 lock and dam structures stretching from Pittsburgh, 
Pennsylvania, to Olmsted, Illinois, near its confluence with the 
Mississippi River. Lock and dam structures convert riverine habitat to 
unsuitable static habitat for the mussel and prevent movement of their 
fish hosts. Numerous Ohio River tributaries also have been altered by 
lock and dam structures. For example, a 116-rkm (72-rmi) stretch of the 
Allegheny River in Pennsylvania has been altered with nine locks and 
dams from Armstrong County to Pittsburgh. A series of six locks and 
dams were constructed on the lower half of the Green River decades ago 
that extend upstream to the western boundary of Mammoth Cave National 
Park, Kentucky. The declines of rabbitsfoot populations are 
attributable to navigational locks and dams on the Ohio, Allegheny, 
Monongahela, Muskingum, Kentucky, Green, Barren, and White Rivers, and 
are widespread throughout the species range.
    Impoundments have eliminated a large portion of the Neosho mucket 
population and habitat in the Arkansas River basin. For example, mussel 
habitat in the Neosho River in Kansas has been adversely affected by at 
least 15 city dams and 2 Federal dams, both with regulated flows. 
Almost the entire length of the river in Oklahoma is now impounded or 
adversely affected by tail water releases from three major dams 
(Matthews et al. 2005, p. 308). Several reservoirs and numerous small 
watershed lakes have eliminated suitable mussel habitat in several 
larger Neosho River tributaries in Kansas and Missouri (Spring, Elk and 
Cottonwood Rivers and Shoal Creek). The Verdigris River (Kansas and 
Oklahoma) has two large reservoirs with regulated flows, and the lower 
section has been channelized as part of the McClellan-Kerr Arkansas 
River Navigation System. All the major Verdigris River tributaries in 
Kansas and Oklahoma have been partially inundated by reservoirs with 
regulated flows and numerous flood control watershed lakes (Obermeyer 
et al. 1995, pp. 7-21). Construction of Lake Tenkiller eliminated 
Neosho mucket populations and habitat in the lower portion of the 
Illinois River, Oklahoma (Davidson 2011, pers. comm.).
    Dam construction has a secondary effect of fragmenting the ranges 
of mussel species by leaving relict habitats and populations isolated 
upstream or between structures as well as creating extensive areas of 
deep uninhabitable, impounded waters. These isolated populations are 
unable to naturally recolonize suitable habitat downstream and become 
more prone to further extirpation from stochastic events, such as 
severe drought, chemical spills, or unauthorized discharges (Layzer et 
al. 1993, pp. 68-69; Cope et al. 1997, pp. 235-237; Neves et al. 1997, 
pp. 63-75; Watters 2000, pp. 264-265, 268; Miller and Payne 2001, pp. 
14-15; Pringle et al. 2000, pp. 810-815; Watters and Flaute 2010, pp. 
3-7). We conclude that habitat effects due to impoundment are a 
significant and ongoing threat to the Neosho mucket and rabbitsfoot.
Channelization
    Dredging and channelization activities have profoundly altered 
riverine habitats nationwide. Hartfield (1993, pp. 131-139), Neves et 
al. (1997, pp. 71-72), and Watters (2000, pp. 268-269) reviewed the 
specific upstream and downstream effects of channelization on 
freshwater mussels. Channelization affects a stream physically 
(accelerates erosion, increases sediment bed load, reduces water depth, 
decreases habitat diversity, creates geomorphic (natural channel 
dimensions) instability, eliminates riparian canopy) and biologically 
(decreases fish and mussel diversity, changes species composition and 
abundance, decreases biomass, and reduces growth rates) (Hartfield 
1993, pp. 131-139). Channel modification for navigation has been shown 
to increase flood heights (Belt 1975, p. 684), partly as a result of an 
increase in stream bed slope (Hubbard et al. 1993, p. 137). Flood 
events are exacerbated, conveying large quantities of sediment, 
potentially

[[Page 63457]]

with adsorbed contaminants, into streams. Channel maintenance often 
results in increased turbidity and sedimentation that often smothers 
mussels (Stansbery 1970, p. 10).
    Channel maintenance operations for commercial navigation have 
affected habitat for the rabbitsfoot in many large rivers rangewide. 
Periodic navigation maintenance activities (such as dredging and snag 
removal) may continue to adversely affect this species in the lower 
portions of the Ohio, Tennessee, and White Rivers, which represent 44 
percent of the viable rabbitsfoot populations. In the Tennessee River, 
a plan to deepen the navigation channel has been proposed (Hubbs 2009, 
pers. comm.). Some rabbitsfoot streams were ``straightened'' to 
decrease distances traversed by barge traffic (for example, Verdigris 
River). Hundreds of miles of many midwestern (Eel, North Fork 
Vermilion, and Embarras Rivers) and southeastern (Paint Rock and St. 
Francis Rivers and Bear Creek) streams with rabbitsfoot populations 
were channelized decades ago to reduce the probability and frequency of 
flood events. Because mussels are relatively immobile they require a 
stable substrate to survive and reproduce and are particularly 
susceptible to channel instability (Neves et al. 1997, p. 23) and 
alteration. Channel and bank degradation have led to the loss of stable 
substrates in numerous rivers with commercial navigation throughout the 
range of rabbitsfoot. While dredging and channelization have had a 
greater effect on rabbitsfoot, the Neosho mucket has been affected by 
these activities in the Verdigris River. We conclude that habitat 
effects due to channelization are a significant and ongoing threat to 
the Neosho mucket and rabbitsfoot.
Sedimentation
    Excessive sediments are believed to adversely affect riverine 
mussel populations requiring clean, stable streams (Ellis 1936, pp. 39-
40; Brim Box and Mossa 1999, p. 99). Adverse effects resulting from 
sediments have been noted for many components of aquatic communities. 
Potential sediment sources within a watershed include virtually all 
activities that disturb the land surface. Most localities occupied by 
the Neosho mucket and rabbitsfoot, including viable populations, are 
currently being affected to varying degrees by sedimentation.
    Sedimentation has been implicated in the decline of mussel 
populations nationwide, and remains a threat to Neosho mucket and 
rabbitsfoot (Ellis 1936, pp. 39-40; Vannote and Minshall 1982, pp. 
4105-4106; Dennis 1984, p. 212; Brim Box and Mosa 1999, p. 99; Fraley 
and Ahlstedt 2000, pp. 193-194; Poole and Downing 2004, pp. 119-122). 
Specific biological effects include reduced feeding and respiratory 
efficiency from clogged gills, disrupted metabolic processes, reduced 
growth rates, limited burrowing activity, physical smothering, and 
disrupted host fish attraction mechanisms (Ellis 1936, pp. 39-40; 
Marking and Bills 1979, p. 210; Vannote and Minshall 1982, pp. 4105-
4106; Waters 1995, pp. 173-175; Hartfield and Hartfield 1996, p. 373). 
In addition, mussels may be indirectly affected if high turbidity 
levels significantly reduce the amount of light available for 
photosynthesis, and thus, the production of certain food items (Kanehl 
and Lyons 1992, p. 7).
    Studies tend to indicate that the primary effects of excess 
sediment levels on mussels are sublethal, with detrimental effects not 
immediately apparent (Brim Box and Mossa 1999, p. 101). The physical 
effects of sediment on mussel habitat appear to be multifold, and 
include changes in suspended and bed material load; bed sediment 
composition associated with increased sediment production and runoff in 
the watershed; channel changes in form, position, and degree of 
stability; changes in depth or the width and depth ratio that affects 
light penetration and flow regime; actively aggrading (filling) or 
degrading (scouring) channels; and changes in channel position. These 
effects to habitat may dislodge, transport downstream, or leave mussels 
stranded (Vannote and Minshall 1982, p. 4106; Kanehl and Lyons 1992, 
pp. 4-5; Brim Box and Mossa 1999, pp. 109-112). For example, many 
Kansas streams (such as Verdigris and Neosho Rivers) supporting mussels 
have become increasingly silted in over the past century, reducing 
habitat for the Neosho mucket and rabbitsfoot (Obermeyer et al. 1997a, 
pp. 113-114).
    Increased sedimentation and siltation may explain in part why 
Neosho mucket and rabbitsfoot are experiencing recruitment failure in 
some streams. Interstitial spaces in the substrate provide crucial 
habitat (shelter and nutrient uptake) for juvenile mussel survival. 
When interstitial spaces are clogged, interstitial flow rates and 
spaces are reduced (Brim Box and Mossa 1999, p. 100), and this 
decreases habitat for juvenile mussels. Furthermore, sediment may act 
as a vector for delivering contaminants, such as nutrients and 
pesticides, to streams, and juvenile mussels may ingest contaminants 
adsorbed to silt particles during normal feeding activities. Neosho 
mucket and rabbitsfoot reproductive strategies depend on clear water 
(enables fish hosts to see mussel lures) during critical reproductive 
periods.
    Agricultural activities are responsible for much of the sediment 
affecting rivers in the United States (Waters 1995, p. 170). 
Sedimentation associated with agricultural land use is cited as one of 
the primary threats to 7 of the 11 (64 percent) viable rabbitsfoot 
populations (French Creek, Tippecanoe, Paint Rock, Duck, White, Black, 
and Strawberry Rivers; Smith et al. 2009, Table 1; USACE 2011, pp. 21-
22; Indiana Department of Environmental Management (IDEM) 2001, pp. 11-
12; EPA 2001, p. 10; Brueggen 2010, pp. 1-2; MDC 2012, http://mdc.mo.gov/landwater-care/stream-and-watershed-management/; EPA Water 
Quality Assessment Tool, http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.control?p_report_type=T). In addition, numerous stream 
segments in the Duck, White, Black, Little, and Strawberry River 
watersheds are listed as impaired waters under section 303(d) of the 
Clean Water Act (CWA) by EPA due to sedimentation associated with 
agriculture (USACE 2011, p. 21; EPA Water Quality Assessment Tool, 
http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.control?p_report_type=T). An impaired water is a water body (i.e., stream 
reaches, lakes, water body segments) with chronic or recurring 
monitored violations of the applicable numeric or narrative water 
quality criteria. An impaired water cannot support one or more of its 
designated uses (e.g., swimming, the protection and propagation of 
aquatic life, drinking, industrial supply, etc.). Once a stream segment 
is listed as an impaired water, the State must complete a plan to 
address the issue causing the impairment; this plan is called a Total 
Maximum Daily Load (TMDL). A TMDL is a calculation of the maximum 
amount of a pollutant that a water body can receive and still safely 
meet water quality standards (WQS). Completion of the plan is generally 
all that is required to remove the stream segment from the 303(d) 
impaired water list and does not mean that water quality has changed. 
Once the TMDL is completed, the stream segment may be placed on the 
305(b) list of impaired streams with a completed TMDL (http://water.epa.gov/lawsregs/lawsguidance/cwa/tmdl/intro.cfm). For example, 
some stream segments within the White, Barren, Little River Mountain 
Fork, and Wabash Rivers, and French Creek have completed TMDL plans and 
have

[[Page 63458]]

attained WQS for low dissolved oxygen, pathogens, nutrients, 
polychlorinated biphenyls (PCBs), and siltation. However, some of these 
same stream segments still have not attained WQS for lead (Little River 
Mountain Fork) and mercury (Wabash River).
    Impaired streams in the Duck River watershed (approximately 483 rkm 
(300 rmi)) are losing 5 to 55 percent more soil per year than the 
natural streams (USACE 2011, pp. 21-22). Unrestricted livestock access 
occurs on many streams and potentially threatens associated mussel 
populations (Fraley and Ahlstedt 2000, pp. 193-194). Grazing may reduce 
water infiltration rates and increase runoff; trampling and vegetation 
removal increases the probability of erosion (Armour et al. 1991, pp. 
8-10; Brim Box and Mossa 1999, p. 103).
    As discussed above, specific impacts on mussels from sediments 
include reduced feeding and respiratory efficiency, disrupted metabolic 
processes, reduced growth rates, increased substrata instability, and 
the physical smothering of mussels. Increased turbidity levels due to 
siltation can be a limiting factor that impedes the ability of sight-
feeding fishes to forage. Turbidity within the rivers and streams 
during the times that the mussels attempt to attract host fishes may 
have contributed and may continue to contribute to the decline of the 
Neosho mucket and rabbitsfoot by reducing their efficiency at 
attracting the fish hosts necessary for reproduction. In addition, 
sediment can eliminate or reduce the recruitment of juvenile mussels, 
interfere with feeding activity, and act as a vector in delivering 
contaminants to streams. Because the Neosho mucket and rabbitsfoot are 
filter-feeders and may bury themselves in the substrate, they are 
exposed to these contaminants contained within suspended particles and 
deposited in bottom substrates. We conclude that biological and habitat 
effects due to sedimentation are a significant and ongoing threat to 
the Neosho mucket and rabbitsfoot.
Chemical Contaminants
    Chemical contaminants are ubiquitous in the environment and are 
considered a major threat in the decline of mussel species (Richter et 
al. 1997, p. 1081; Strayer et al. 2004, p. 436; Wang et al. 2007a, p. 
2029; Cope et al. 2008, p. 451). Chemicals enter the environment 
through point and nonpoint discharges including spills, industrial and 
municipal effluents, and residential and agricultural runoff. These 
sources contribute organic compounds, heavy metals, nutrients, 
pesticides, and a wide variety of newly emerging contaminants such as 
pharmaceuticals to the aquatic environment. As a result, water and 
sediment quality can be degraded to the extent that results in adverse 
effects to mussel populations.
    Cope et al. (2008, p. 451) evaluated the pathways of exposure to 
environmental pollutants for all four freshwater mollusk life stages 
(free glochidia, encysted glochidia, juveniles, adults) and found that 
each life stage has both common and unique characteristics that 
contribute to observed differences in exposure and sensitivity. Almost 
nothing is known of the potential mechanisms and consequences of 
waterborne toxicants on sperm viability. In the female mollusk, the 
marsupial region of the gill is thought to be physiologically isolated 
from respiratory functions, and this isolation may provide some level 
of protection from contaminant interference with a female's ability to 
achieve fertilization or brood glochidia (Cope et al. 2008, p. 454). A 
major exception to this assertion is with chemicals that act directly 
on the neuroendocrine pathways controlling reproduction (see discussion 
below). Nutritional and ionic exchange is possible between a brooding 
female and her glochidia, providing a route for chemicals (accumulated 
or waterborne) to disrupt biochemical and physiological pathways (such 
as maternal calcium transport for construction of the glochidial 
shell). Glochidia can be exposed to waterborne contaminants for up to 
36 hours until encystment occurs; between 2 and 36 hours, and then from 
fish host tissue burdens (for example, atrazine), that last from weeks 
to months and could affect transformation success of glochidia into 
juveniles (Ingersoll et al. 2007, pp. 101-104).
    Juvenile mussels typically remain burrowed beneath the sediment 
surface for 2 to 4 years. Residence beneath the sediment surface 
necessitates deposit (pedal) feeding and a reliance on interstitial 
water for dissolved oxygen (Watters 2007, p. 56). The relative 
importance of exposure of juvenile Neosho mucket and rabbitsfoot to 
contaminants in overlying surface water, interstitial water, whole 
sediment, or food has not been adequately assessed. Exposure to 
contaminants from each of these routes varies with certain periods and 
environmental conditions (Cope et al. 2008, pp. 453 and 457).
    The primary routes of exposure to contaminants for adult Neosho 
mucket and rabbitsfoot are surface water, sediment, interstitial (pore) 
water, and diet; adults can be exposed when either partially or 
completely burrowed in the substrate (Cope et al. 2008, p. 453). Adult 
mussels have the ability to detect toxicants in the water and close 
their valves to avoid exposure (Van Hassel and Farris 2007, p. 6). 
Adult mussel toxicity and relative sensitivity (exposure and uptake of 
toxicants) may be reduced at high rather than at low toxicant 
concentrations because uptake is affected by the prolonged or periodic 
toxicant avoidance responses (when the avoidance behavior of keeping 
their valves closed can no longer be sustained for physiological 
reasons (respiration and ability to feed) (Cope et al. 2008, p. 454). 
Toxicity results based on low-level exposure of adults are similar to 
estimates for glochidia and juveniles for some toxicants (for example, 
copper). The duration of any toxicant avoidance response by an adult 
mussel is likely to vary due to several variables, such as species, 
age, shell thickness and gape, properties of the toxicant, and water 
temperature. There is a lack of information on toxicant response(s) for 
Neosho mucket and rabbitsfoot, but results of tests using glochidia and 
juveniles may be valuable for protecting adults (Cope et al. 2008, p. 
454).
    Mussels are very intolerant of heavy metals (such as lead, zinc, 
cadmium, and copper) compared to commonly tested aquatic organisms. 
Metals occur in industrial and wastewater effluents and are often a 
result of atmospheric deposition from industrial processes and 
incinerators, but also are associated with mine water runoff (for 
example, Tri-State Mining Area in southwest Missouri) and have been 
attributed to mussel declines in streams such as Shoal, Center, and 
Turkey Creeks and Spring River in the Arkansas River basin (Angelo et 
al. 2007, pp. 485-489), which are streams with historical and extant 
Neosho mucket and rabbitsfoot populations. Heavy metals can cause 
mortality and affect biological processes, for instance, disrupting 
enzyme efficiency, altering filtration rates, reducing growth, and 
changing behavior of freshwater mussels (Keller and Zam 1991, p. 543; 
Naimo 1995, pp. 351-355; Jacobson et al. 1997, p. 2390; Valenti et al. 
2005, p. 1244; Wang et al. 2007b, pp. 2039-2046; Wang et al. 2007c, pp. 
2052-2055; Wang et al. 2010, p. 2053). Mussel recruitment may be 
reduced in habitats with low but chronic heavy metal and other toxicant 
inputs (Yeager et al. 1994, p. 217; Naimo 1995, pp. 347 and 351-352; 
Ahlstedt and Tuberville 1997, p. 75). Newly

[[Page 63459]]

transformed juveniles (age at 5 days) are more sensitive to acute 
toxicity than glochidia or older juveniles (age at 2 to 6 months) (Wang 
et al. 2010, p. 2062).
    Mercury is another heavy metal that has the potential to negatively 
affect mussel populations. Mercury has been detected throughout aquatic 
environments as a product of municipal and industrial waste and 
atmospheric deposition from coal-burning plants. One study on rainbow 
mussel (Villosa iris) concluded that glochidia were more sensitive to 
mercury than were juvenile mussels, with a median lethal concentration 
value of 14 ug/L for glochidia and 114 ug/L for juvenile mussels 
(Valenti et al. 2005, p. 1242). The chronic toxicity is a test which 
usually measures sublethal effects (e.g., reduced growth or 
reproduction) in addition to lethality. These tests are usually longer 
in duration or conducted during some sensitive period of an organism's 
life cycle. For this species, the chronic toxicity test showed that 
juveniles exposed to mercury greater than or equal to 8 ug/L exhibited 
reduced growth (Valenti et al. 2005, p. 1245). Mercury also affects 
oxygen consumption, byssal thread production, and filtration rates 
(Naimo 1995, Jacobsen et al. 1997, and Nelson and Calabrese 1988 in 
Valenti et al. 2005, p. 1245). Effects to mussels from mercury toxicity 
may be occurring in some streams due to illegal dumping, spills, and 
permit violations. For example, acute mercury toxicity was determined 
to be the cause of extirpation of diverse mussel fauna for a 112-rkm 
(70-rmi) reach of the North Fork Holston River (Brown et al. 2005, pp. 
1455-1457). Of the 11 viable rabbitsfoot populations, 4 populations 
(French Creek, Duck River, Green River, and Ohio River) currently 
inhabit river reaches that are impaired by mercury and are listed as 
impaired waters under section 303(d) of the CWA.
    One chemical that is particularly toxic to early life stages of 
mussels is ammonia. Sources of ammonia include agricultural wastes 
(animal feedlots and nitrogenous fertilizers), municipal wastewater 
treatment plants, and industrial waste (Augspurger et al. 2007, p. 
2026) as well as precipitation and natural processes (decomposition of 
organic nitrogen) (Goudreau et al. 1993, p. 212; Hickey and Martin 
1999, p. 44; Augspurger et al. 2003, p. 2569; Newton 2003, p. 1243). 
Therefore, ammonia is considered a limiting factor for survival and 
recovery of some mussel species due to its ubiquity in aquatic 
environments and high level of toxicity, and because the highest 
concentrations typically occur in mussel microhabitats (Augspurger et 
al. 2003, p. 2574). In addition, studies have shown that ammonia 
concentrations increase with increasing temperature, pH, and low flow 
conditions (Cherry et al. 2005, p. 378; Cooper et al. 2005, p. 381; 
Wang et al. 2007, p. 2045), which may be exacerbated by the effects of 
climate change, and may cause ammonia (un-ionized and ionized) to 
become more problematic for juvenile mussels (Wang et al. 2007, p. 
2045). Sublethal effects include, but may not be limited to, reduced 
time the valves are held open for respiration and feeding; impaired 
secretion of the byssal thread (used for substrate attachment), reduced 
ciliary action impairing feeding, depleted lipid, glycogen, and other 
carbohydrate stores, and altered metabolism (Goodreau et al. 1993, pp. 
216-227; Augspurger et al. 2003, pp. 2571-2574; Mummert et al. 2003, 
pp. 2548-2552).
    Polychlorinated biphenyls (PCBs) are ubiquitous contaminants in the 
environment due to their widespread use from the 1920s to 1970s as 
insulating material in electric equipment, such as transformers and 
capacitors, as well as in heat transfer fluids and in lubricants. PCBs 
have also been used in a wide range of products, such as plasticizers, 
surface coatings, inks, adhesives, flame retardants, paints, and 
carbonless duplicating paper. PCBs were still being introduced into the 
environment at many sites (such as landfills and incinerators) until 
the 1990s. The inherent stability and toxicity of PCBs have resulted in 
them being a persistent environmental problem (Safe 1994 in Lehmann et 
al. 2007, p. 356). PCBs are lipophilic (affinity to combine with fats 
or lipids), adsorb easily to soil and sediment, and are present in the 
sediment and water column in aquatic environments, making them 
available to bioaccumulate and induce negative effects in living 
organisms (Livingstone 2001 in Lehmann et al. 2007, p. 356). Studies 
have demonstrated increased PCB concentrations in native freshwater 
mussels (Ruessler et al. 2011, pp. 1, 7), marine bivalves (Krishnakumar 
et al. 1994, p. 249), and nonnative, invasive mollusks (zebra mussels 
and Asian clams) (Gossiaux et al. 1996, p. 379; Lehmann et al. 2007, p. 
363) in areas with high levels of PCBs. Oxidative stress (imbalance in 
the normal redox state of cells that causes toxic effects that damage 
all components of the cell, including proteins, lipids, and DNA) is a 
direct consequence of exposure to PCBs. Relevant changes, whether 
directly or indirectly due to oxidative stress, may occur at the organ 
and organism levels and will likely result in mussel population-wide 
effects, including reduced fecundity and chronic maladies due to PCB 
exposure (Lehmann et al. 2007, p. 363). Two of the 11 viable 
rabbitsfoot populations (18 percent) inhabit waters listed as impaired 
due to PCBs under section 303(d) of the CWA.
    Agriculture, timber harvest, and lawn management practices utilize 
nutrients and pesticides. These are two broad categories of chemical 
contaminants that have the potential to adversely impact mussel 
species. Nutrients, such as nitrogen and phosphorus, primarily occur in 
runoff from livestock farms, feedlots, heavily fertilized row crops and 
pastures (Peterjohn and Correll 1984, p. 1471), post timber management 
activities, and urban and suburban runoff, including leaking septic 
tanks, and residential lawns.
    Studies have shown that excessive nitrogen concentrations can be 
lethal to the adult freshwater pearl mussel (Margaritifera 
margaritifera) and reduce the lifespan and size of other mussel species 
(Bauer 1988, p. 244; Bauer 1992, p. 425). Nutrient enrichment can 
result in an increase in primary productivity, and the associated algae 
respiration depletes dissolved oxygen levels. This may be particularly 
detrimental to juvenile mussels that inhabit the interstitial spaces in 
the substrate where lower dissolved oxygen concentrations are more 
likely than on the sediment surface where adults tend to live (Sparks 
and Strayer 1998, pp. 132-133). For example, Galbraith et al. (2008, 
pp. 48-49) reported a massive die-off of greater than 160 rabbitsfoot 
specimens at a long-term monitoring site in the Little River, Oklahoma. 
While the exact cause for the die-off is unknown, the authors speculate 
that the 2005 Oklahoma drought coupled with high water temperature and 
extensive blooms of filamentous algae may have resulted in extreme 
physiological stress. Over-enriched conditions are exacerbated by low 
flow conditions, such as those experienced during a typical summer 
season and that may occur with greater frequency and severity as a 
result of climate change. Three of the 11 viable rabbitsfoot 
populations (French Creek, Duck River, and Tippecanoe River) are listed 
as impaired waters under section 303(d) of the CWA due to nutrient 
enrichment.
    Elevated concentrations of pesticide frequently occur in streams 
due to residential or commercial pesticide runoff, overspray 
application to row crops, and lack of adequate riparian buffers. 
Agricultural pesticide applications often coincide with the 
reproductive and early life stages of

[[Page 63460]]

mussels, and effects to mussels may be increased during a critical time 
period (Bringolf et al. 2007a, p. 2094). Recent studies tested the 
toxicity of glyphosate, its formulations, and a surfactant (MON 0818) 
used in several glyphosate formulations, to early life stages of the 
fatmucket (Lampsilis siliquoidea), a U.S. native freshwater mussel 
(Bringolf et al. 2007a, p. 2094). Studies conducted with juvenile 
mussels and glochidia determined that the surfactant (MON 0818) was the 
most toxic of the compounds tested and that L. siliquoidea glochidia 
were the most sensitive organism tested to date (Bringolf et al. 2007a, 
p. 2094). Roundup[supreg], technical grade glyphosate isopropylamine 
salt, and isopropylamine were also acutely toxic to juveniles and 
glochidia (Bringolf et al. 2007a, p. 2097). The study of other 
pesticides, including atrazine, chlorpyrifos, and permethrin, on 
glochidia and juvenile life stages determined that chlorpyrifos was 
toxic to both L. siliquoidea glochidia and juveniles (Bringolf et al. 
2007b, pp. 2101 and 2104). The above results indicate the potential 
toxicity of commonly applied pesticides and the threat to mussel 
species as a result of the widespread use of these pesticides.
    There are instances where chemical spills have resulted in the loss 
of high numbers of mussels (Jones et al. 2001, p. 20; Brown et al. 
2005, p. 1457; Schmerfeld 2006, pp. 12-13), and are considered a 
serious threat to mussel species. The Neosho mucket and rabbitsfoot are 
especially threatened by chemical spills because these spills can occur 
anywhere that highways with tanker trucks, industries, or mines overlap 
with their distribution.
    Other examples of the influence of point and nonpoint-source 
pollutants on streams throughout the range of the Neosho mucket and 
rabbitsfoot include two documented mussel kills in Fish Creek (circa 
1988) as a result of manure runoff from a hog farm and a diesel spill 
(Watters 1988, p. 18). Twelve point-source discharges occur on the 
Green River (Kentucky State Nature Preserves Commission and The Nature 
Conservancy 1998, pp. 15-19). The Illinois River, a tributary of the 
Arkansas River, is subject to nonpoint-source organic runoff from 
poultry farming and municipal wastewater.
    Pharmaceutical chemicals used in commonly consumed drugs are 
increasingly found in surface waters. A recent nationwide study 
sampling 139 stream sites in 30 States detected the presence of 
numerous pharmaceuticals, hormones, and other organic wastewater 
contaminants downstream from urban development and livestock production 
areas (Kolpin et al. 2002, pp. 1208-1210). Another study in 
northwestern Arkansas found pharmaceuticals or other organic wastewater 
constituents at 16 of 17 sites in seven streams surveyed in 2004 
(Galloway et al. 2005, pp. 4-22). Toxic levels of exposure to chemicals 
that act directly on the neuroendocrine pathways controlling 
reproduction can cause premature release of viable or nonviable 
glochidia. For example, the active ingredient in many human 
prescription antidepressant drugs belonging to the class of selective 
serotonin reuptake inhibitors may exert negative reproductive effects 
on mussels because of the drug's action on serotonin and other 
neuroendocrine pathways (Cope et al. 2008, p. 455). Pharmaceuticals or 
organic wastewater constituents are generally greater downstream of 
wastewater treatment facilities (Galloway et al. 2005, p. 28). 
Pharmaceuticals that alter mussel behavior and influence successful 
attachment of glochidia on fish hosts may have population-level 
implications for the Neosho mucket and rabbitsfoot.
    The information presented in this section represents some of the 
threats from chemical contaminants that have been documented both in 
the laboratory and field and demonstrates that chemical contaminants 
pose a substantial threat to Neosho mucket and rabbitsfoot. A cursory 
examination of land use trends, non-point and point source discharges, 
and the list of impaired waters under section 303(d) of the CWA 
suggests that all 11 rabbitsfoot populations currently considered 
viable may be subjected to the subtle, pervasive effects of chronic, 
low-level contamination that is ubiquitous in these watersheds. For 
example, 8 of the 11 (73 percent) streams with viable rabbitsfoot 
populations are listed as impaired waters under section 303(d) of the 
CWA. Reasons for impairment include mercury, nutrients, organic 
enrichment and dissolved oxygen depletion, pathogens, turbidity 
(sediment), and PCBs. Potential effects from contaminant exposure may 
result in death, reduced growth, altered metabolic processes, or 
reduced reproduction. We conclude that biological and habitat effects 
due to chemical contaminants are a significant and ongoing threat 
contributing to the decline of Neosho mucket and rabbitsfoot 
populations.
Mining
    Gravel, coal, and metal mining are activities negatively affecting 
water quality in Neosho mucket and rabbitsfoot habitat. Instream and 
alluvial gravel mining has been implicated in the destruction of mussel 
populations (Hartfield 1993, pp. 136-138; Brim Box and Mossa 1999, pp. 
103-104). Negative effects associated with gravel mining include stream 
channel modifications (altered habitat, disrupted flow patterns, 
sediment transport), water quality modifications (increased turbidity, 
reduced light penetration, increased temperature), macroinvertebrate 
population changes (elimination), and changes in fish populations, 
resulting from adverse effects to spawning and nursery habitat and food 
web disruptions (Kanehl and Lyons 1992, pp. 4-10). Gravel mining 
activities continue to be a localized threat in several streams with 
viable rabbitsfoot populations (Ohio, Tennessee, White, Strawberry, and 
Little Rivers). In the lower Tennessee River, instream mining occurs in 
18 reaches totaling 77.1 rkm (47.9 rmi) between the Duck River 
confluence and Pickwick Landing Dam (Hubbs 2010, pers. comm.).
    Coal mining activities, resulting in heavy metal-rich drainage, and 
associated sedimentation has adversely affected many drainages with 
rabbitsfoot populations, including portions of the upper Ohio River 
system in Kentucky, Pennsylvania, and West Virginia; the lower Ohio 
River system in eastern Illinois; the Rough River drainage in western 
Kentucky; and the upper Cumberland River system in Kentucky and 
Tennessee (Ortmann 1909 in Butler 2005, p. 102; Gordon 1991, pp. 4 and 
5; Layzer and Anderson 1992 in Butler 2005, p. 102). Numerous mussel 
toxicants, such as polycyclic aromatic hydrocarbons and heavy metals 
(copper, manganese, and zinc) from coal mining contaminate sediments 
when released into streams (Ahlstedt and Tuberville 1997, p. 75). Low 
pH commonly associated with mine runoff can reduce glochidial 
attachment rates on host fish (Huebner and Pynnonen 1990, pp. 2350-
2353). Thus, acid mine runoff may have local effects on mussel 
recruitment and may lead to mortality due to improper shell development 
or erosion.
    Metal mining (lead, cadmium, and zinc) in the Tri-State Mining Area 
(15,000 km\2\; 5,800 mi\2\ in Kansas, Missouri, and Oklahoma) has 
adversely affected Center and Shoal Creeks and the Spring River. It has 
been implicated in the loss of Neosho mucket and rabbitsfoot from 
portions of these streams (Obermeyer et al. 1997b, p. 114). A study by 
Kansas Department of Health and Environment documented a strong 
negative correlation between the distribution and abundance of native 
mussels, including Neosho mucket, and sediment concentrations of lead, 
zinc

[[Page 63461]]

and cadmium in the Spring River system (Angelo et al. 2007, pp. 477-
493). Sediment and water quality samples exceeded EPA 2006 threshold 
effect concentrations for cadmium, lead, and zinc at numerous sampling 
locations within the Tri-State Mining Area (Gunter 2007, pers. comm.). 
These physical habitat threats combined with poor water quality and 
agricultural nonpoint-source pollution are serious threats to all 
existing mussel fauna in the basin.
    In the St. Francis River basin, past metal mining and smelting 
(early eighteenth century through the 1940s) have resulted in 
continuing heavy metal (lead, iron, nickel, copper, cobalt, zinc, 
cadmium, chromium) contamination of surface waters in the area upstream 
of the extant rabbitsfoot population. Recent and historical metals 
mining and smelting produced large volumes of contaminated wastes. Most 
of these mining wastes are stored behind poorly constructed dams and 
impoundments (Roberts 2008, pers. comm.). Wappapello Reservoir and the 
confluence with Big Creek (with habitat degradation primarily from 
mining activities) may effectively limit the distribution of the 
rabbitsfoot in the St. Francis River. We conclude that biological and 
habitat effects due to mining activities are a significant and ongoing 
threat contributing to declining Neosho mucket and rabbitsfoot 
populations.
Oil and Natural Gas Development
    Oil and natural gas resources are present in some of the watersheds 
that are known to support rabbitsfoot, including the Allegheny and 
Middle Fork Little Red Rivers and two watersheds with viable 
populations (White River and French Creek). Exploration and extraction 
of these energy resources can result in increased siltation, a changed 
hydrograph (graph showing changes in the discharge of a river over a 
period of time), and altered water quantity and quality even at 
considerable distances from the mine or well field because effects are 
carried downstream from the original source. Rabbitsfoot habitat in 
streams can be threatened by the cumulative effects of multiple mines 
and well fields (adapted from Service 2008, p. 11).
    Recently, oil and gas exploration has been able to expand in areas 
of shale due to new technologies (i.e., hydraulic fracturing and 
horizontal drilling), making access possible to oil and gas reserves in 
areas that were previously inaccessible. Extraction of these resources, 
particularly natural gas, has increased dramatically in recent years in 
Arkansas, Oklahoma, Pennsylvania, and West Virginia. Although oil and 
natural gas extraction generally occurs away from the river, extensive 
road and pipeline networks are required to construct and maintain wells 
and transport the extracted resources. These road and pipeline networks 
frequently cross or occur near tributaries, contributing sediment to 
the receiving waterway. In addition, the construction and operation of 
wells may result in the discharge of chemical contaminants and 
subsurface minerals. Several of the viable rabbitsfoot populations 
occur in active shale basins (areas of shale gas formations) (http://www.eia.gov/analysis/studies/worldshalegas/). In 2006, more than 3,700 
permits were issued for oil and gas wells by the Pennsylvania 
Department of Environmental Protection, which also issued 98 citations 
for permit violations at 54 wells (Hopey 2007; adapted from Service 
2008, p. 13). A natural gas pipeline company pled guilty to three 
violations of the Act in 2011 for unauthorized take of a federally 
endangered mussel in Arkansas as a result of a large amount of sediment 
being transported from pipeline right-of-ways to tributary streams in 
the affected watershed (Department of Justice 2011, pers. comm.). Where 
oil and natural gas development occurs within the range of extant 
Neosho mucket and rabbitsfoot populations, we conclude that the 
resulting biological and habitat effects are a significant and ongoing 
threat contributing to the decline of both species.
Summary of Factor A
    The decline of mussels in the eastern United States is primarily 
the result of long-lasting direct and secondary effects of habitat 
alterations such as impoundments, channelization, sedimentation, 
chemical contaminants, oil and gas development, and mining and it is 
reasonable to conclude that the changes in the river basins 
historically and currently occupied by the species are the cause of 
population level (river basin) effects. Historical population losses 
due to impoundments have probably contributed more to the decline and 
range reductions of the Neosho mucket and rabbitsfoot than any other 
single factor. Seven of the 11 (64 percent) viable rabbitsfoot 
populations (Ohio, Green, Tippecanoe, Tennessee, Duck, White, and 
Little Rivers) occur downstream of main stem impoundments that make 
these populations more susceptible to altered habitat quality and 
quantity associated with the impoundment and dam operation, which may 
be exacerbated during stochastic events such as droughts and floods. 
Sedimentation resulting from a variety of sources such as 
channelization, agricultural and silvicultural practices, and 
construction activities has degraded Neosho mucket and rabbitsfoot 
habitat and altered biological processes essential to their survival. 
For example, sedimentation associated with agricultural land use is 
cited as one of the primary threats to 7 of the 11 (64 percent) streams 
with viable rabbitsfoot populations. Land use conversion, particularly 
urbanization that increases impervious surfaces in watersheds 
(impervious surface increases flood intensity and duration), 
channelization, and instream gravel and sand mining alter natural 
hydrology and stream geomorphology characteristics that also degrade 
mussel habitat in streams that support the Neosho mucket and 
rabbitsfoot. Contaminants associated with industrial and municipal 
effluents, agricultural practices, and mining degrade water and 
sediment quality leading to environmental conditions that have lethal 
and sublethal effects to Neosho mucket and rabbitsfoot, particularly 
the highly sensitive early life stages. Eight of the 11 (73 percent) 
streams with viable rabbitsfoot populations are listed as impaired 
waters under section 303(d) of the CWA, which means that the 
rabbitsfoot may be subjected to the subtle, pervasive effects of 
chronic, low-level contamination that is ubiquitous in these 
watersheds. Chronic contamination can affect the mussels in a variety 
of ways including sublethal effects (such as suppressed immune systems 
and effects to reproduction and fecundity from neuroendocrine 
disrupters) and lethal effects (such as sediment smothers and 
disruption of other metabolic processes).
    In summary, we have determined that impoundments, channelization, 
sedimentation, chemical contaminants, mining, and oil and natural gas 
development are significant, ongoing threats to the Neosho mucket and 
rabbitsfoot that are expected to continue into the future. Although 
efforts have been made to restore habitat in some areas, these threats 
are still ongoing, as evidenced by population declines and range 
reduction. Thus, these changes in the species' historical or current 
range are not expected to be ameliorated in the future; therefore, we 
find it reasonably likely that the effects of these threats on both 
species will continue at current levels or potentially increase.

[[Page 63462]]

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    The Neosho mucket was valuable in the pearl button industry (1800s 
to early 1940s), and historical episodes of overharvest in the Neosho 
River may have contributed to its decline (Obermeyer et al. 1997b, p. 
115). The rabbitsfoot was never a valuable shell for the commercial 
pearl button industry (Meek and Clark 1912, p. 15; Murray and Leonard 
1962, p. 65), nor the cultured pearl industry (Williams and Schuster 
1989, p. 23), and hence these activities were probably not significant 
factors in its decline. However, it was noted occasionally in 
commercial harvests as evidenced from mussel cull piles (Isely 1924; 
Parmalee et al. 1980, p. 101). Currently, Neosho mucket and rabbitsfoot 
are not commercially valuable species but may be increasingly sought by 
collectors as they become rarer. Although scientific collecting is not 
thought to represent a significant threat, unregulated collecting could 
adversely affect localized Neosho mucket and rabbitsfoot populations.
    Commercial mussel harvest is illegal in some States (for example, 
Indiana and Ohio), but regulated in others (for example, Arkansas, 
Alabama, Kentucky, and Tennessee). These species may be inadvertently 
harvested by inexperienced commercial harvesters unfamiliar with 
species identification. Although illegal harvest of protected mussel 
beds occurs (Watters and Dunn 1995, pp. 225 and 247-250), commercial 
harvest is not known to have a significant effect on the Neosho mucket 
and rabbitsfoot.
Summary of Factor B
    Though it is possible that the intensity of inadvertent or illegal 
harvest may increase in the future, there is no evidence that this 
stressor is currently increasing in severity. On the basis of this 
analysis, we find that overutilization for commercial, recreational, 
scientific, or educational purposes is not a current threat to the 
Neosho mucket or rabbitsfoot in any portion of their range at this time 
nor is likely to become so in the future.

C. Disease or Predation

    Little is known about diseases in freshwater mussels (Grizzle and 
Brunner 2007, p. 6). However, mussel die-offs have been documented in 
streams inhabited by rabbitsfoot (Neves 1986, pp. 8-11), and some 
researchers believe that disease may be a factor contributing to the 
die-offs (Buchanan 1986, p. 53; Neves 1986, p. 11). Mussel parasites 
include water mites, trematodes, oligochaetes, leeches, copepods, 
bacteria, and protozoa (Grizzle and Brunner 2007, p. 4). Generally, 
parasites are not suspected of being a major limiting factor in the 
species' survival (Oesch 1984, p. 6). However, mite and trematode 
burdens can affect reproductive output and physiological condition, 
respectively, in mussels (Gangloff et al. 2008, pp. 28-30). Stressors 
that reduce fitness may make mussels more susceptible to parasites 
(Butler 2007, p. 90). Furthermore, nonnative mussels may carry diseases 
and parasites that are potentially devastating to the native mussel 
fauna on an individual or population level basis (river basin), 
including Neosho mucket and rabbitsfoot (Strayer 1999b, p. 88). 
However, while individual mussels or beds of mussels historically or 
currently may have been affected by disease or parasites, we have no 
evidence that the severity of disease or parasite infestations impact 
either mussel on a population level (river basin).
    The muskrat (Ondatra zibethicus) is cited as the most prevalent 
mussel predator (Kunz 1898, p. 328; Convey et al. 1989, p. 654-655; 
Hanson et al. 1989, pp. 15-16). Muskrat predation may limit the 
recovery potential of endangered or threatened mussels or contribute to 
local extirpations of previously stressed populations, according to 
Neves and Odom (1989, p. 940), who consider it, however, primarily a 
seasonal or localized threat. Galbraith et al. (2008, p. 49) 
hypothesized that predation may have exacerbated rabbitsfoot mortality 
in the Little River, Oklahoma, during the 2005 drought. Harris et al. 
(2007, p. 31) reported numerous dead rabbitsfoot from muskrat middens 
(mound or deposit containing shells) in the Spring River, Arkansas. 
Other mammals (for example, raccoon, mink, otter, hogs, and rats), 
turtles, and aquatic birds also occasionally feed on mussels (Kunz 
1898, p. 328; Neck 1986, pp. 64-65). Recently, predation of Neosho 
mucket by reintroduced otters has been documented in a mussel bed also 
supporting rabbitsfoot in the Spring River, Kansas (Barnhart 2003, pp. 
16-17), and likely occurs elsewhere. Muskrat predation has been 
documented for Neosho mucket and rabbitsfoot, but the overall threat is 
generally considered insignificant.
    Some species of fish feed on mussels (for example, common carp 
(Cyprinus carpio), freshwater drum (Aplodinotus grunniens), and redear 
sunfish (Lepomis microlophus)) and potentially on young Neosho mucket 
and rabbitsfoot. Various invertebrates, such as flatworms, hydra, 
nonbiting midge larvae, dragonfly larvae, and crayfish, feed on 
juvenile mussels (Zimmerman et al. 2003, p. 28). Although predation by 
naturally occurring predators is a normal aspect of the population 
dynamics of a healthy mussel population, predation may amplify declines 
in small populations of this species. In addition, the potential now 
exists for black carp (Mylopharyngodon piceus), a mollusk-eating Asian 
fish recently introduced into the waters of the United States (Strayer 
1999b, p. 89), to eventually disperse throughout the range of the 
Neosho mucket and rabbitsfoot. However, we have no evidence that the 
severity of predation has reached levels where populations (river 
basin) of either mussel have been historically or recently impacted or 
should be impacted in the future based on current information.
    The life cycle of freshwater mussels is intimately related to that 
of the freshwater fish they use as hosts for their parasitic glochidia. 
For this reason, diseases that affect populations of freshwater fishes 
also pose a significant threat to mussels in general. Viral hemorrhagic 
septicemia (VHS) disease has been confirmed from much of the Great 
Lakes and St. Lawrence River system. If the VHS virus successfully 
migrates out of Clearfork Reservoir or the Great Lakes and into the 
Ohio and Mississippi River basins, it could spread rapidly and cause 
fish kills throughout the river basins. Few Neosho mucket and 
rabbitsfoot populations are currently recruiting at sustainable levels, 
and fish kills, particularly if VHS infects suitable fish hosts, could 
further reduce glochidia encounters with fish hosts and exacerbate 
mussel recruitment reductions. However, we have no evidence that fish 
kills affecting potential fish hosts of these two mussel species have 
had population affects historically or recently.
Summary of Factor C
    Disease in mussels is poorly known and not currently considered a 
threat rising to a level such that it would have an effect on the 
Neosho mucket, nor the rabbitsfoot, as a whole. Studies indicate that, 
in some localized areas, disease and predation may have negative 
effects on mussel populations. Though it is possible that the intensity 
of disease or predation may increase in the future, there is no 
evidence that this stressor is currently increasing in severity. Based 
on our analysis of the best available scientific and commercial data 
available, we find that neither disease nor predation is a significant 
threat to the overall status of Neosho mucket and

[[Page 63463]]

rabbitsfoot, nor is either likely to become so in the future.

D. The Inadequacy of Existing Regulatory Mechanisms

    The objective of the Federal Water Pollution Control Act, commonly 
referred to as the Clean Water Act (CWA) (33 U.S.C. 1251 et seq.), is 
to restore and maintain the chemical, physical, and biological 
integrity of the nation's waters by preventing point and nonpoint 
pollution sources. The CWA has a stated goal that ``* * *wherever 
attainable, an interim goal of water quality which provides for the 
protection and propagation of fish, shellfish, and wildlife and 
provides for recreation in and on the water be achieved by July 1, 
1983.'' States are responsible for setting and implementing water 
quality standards that align with the requirements of the CWA. Overall, 
implementation of the CWA could benefit both mussel species through the 
point and nonpoint programs.
    Nonpoint source (NPS) pollution comes from many diffuse sources, 
unlike pollution from industrial and sewage treatment plants. NPS 
pollution is caused by rainfall or snowmelt moving over and through the 
ground. As the runoff moves, it transports natural and human-made 
pollutants. While some pollutants may be ``deposited'', some may remain 
in suspension (dissolved) as they are transported through various 
waterbodies. States report that nonpoint source pollution is the 
leading remaining cause of water quality problems. The effects of 
nonpoint source pollutants on specific waters vary and may not always 
be fully assessed. However, these pollutants have harmful effects on 
fisheries and wildlife (http://www.epa.gov/owow_keep/NPS/whatis.html.)
    Sources of NPS pollution within the watersheds occupied by both 
mussels include timber clearcutting, clearing of riparian vegetation, 
urbanization, road construction, and other practices that allow bare 
earth to enter streams (The Nature Conservancy 2004, p. 13). Numerous 
stream segments in the Duck, White, Black, Little, and Strawberry River 
watersheds are listed as impaired waters under section 303(d) of the 
CWA by EPA due to sedimentation associated with agriculture (USACE 
2011, p. 21; EPA Water Quality Assessment Tool, http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.control?p_report_type=T). For 
example, impaired streams in the Duck River watershed (483 rkm (300 
rmi)) are losing 5 to 55 percent more soil per year than streams not 
labeled as impaired (USACE 2011, pp. 21-22). Currently, the CWA may not 
adequately protect Neosho mucket and rabbitsfoot habitat from NPS 
pollution. The Service has no information concerning the implementation 
of the CWA regarding NPS pollution specific to protection of both 
mussels. However, insufficient implementation could become a threat to 
both mussel species if they continue to decline in numbers or if new 
information becomes available.
    Point-source discharges within the range of the Neosho mucket and 
rabbitsfoot have been reduced since the enactment of the CWA. Despite 
some reductions in point source discharges, adequate protection may not 
be provided by the CWA for filter-feeding organisms that can be 
affected by extremely low levels of contaminants (see Chemical 
Contaminants discussion under Factor A). The Neosho mucket and 
rabbitsfoot continue to decline due to the effects of habitat 
destruction, poor water quality, contaminants, and other factors. Eight 
of the 11 (73 percent) streams with viable rabbitsfoot populations are 
listed as impaired waters under section 303(d) of the CWA. Reasons for 
impairment include mercury, nutrients, organic enrichment, dissolved 
oxygen depletion, pathogens, turbidity (sediment), and PCBs. In 
addition, numerous tributaries within watersheds supporting viable 
Neosho mucket and rabbitsfoot populations also are listed as impaired 
waters under section 303(d) of the CWA, which means that both species 
may be subjected to greater, albeit subtle, pervasive effects of 
chronic, low-level contamination that is ubiquitous in these 
watersheds. However, there is no specific information known about the 
sensitivity of the Neosho mucket and rabbitsfoot to common point source 
pollutants like industrial and municipal pollutants and very little 
information on other freshwater mussels. Because there is very little 
information known about water quality parameters necessary to fully 
protect freshwater mussels, such as the Neosho mucket and rabbitsfoot, 
it is difficult to determine whether the CWA is adequately addressing 
the threats to these species. However, given that a goal of the CWA is 
to establish water quality standards that protect shellfish and given 
that documented declines of these mussel species still continue due to 
poor water quality and other factors, we take a conservative approach 
in favor of the species and conclude that the CWA has been insufficient 
to significantly reduce or remove the threats to the Neosho mucket and 
rabbitsfoot. We invite public comment on this matter, and solicit 
information especially regarding water quality data that may be helpful 
in determining the water quality parameters necessary for these 
species' survival (see Information Requested, item 4).
Summary of Factor D
    In summary, the CWA has a stated goal to establish water quality 
standards that protect aquatic species, including the Neosho mucket and 
rabbitsfoot. However, the CWA has generally been insufficient at 
protecting mussels, and adequate water quality criteria that are 
protective of all life stages, particularly glochidia and juveniles, 
may not be established. Little information is known about specific 
sensitivities of mussels to various pollutants, but both species 
continue to decline due to the effects of habitat destruction, poor 
water quality, contaminants, and other factors. Based on our analysis 
of the best available scientific and commercial data, we conclude that 
the CWA is inadequate to reduce or remove threats to the Neosho mucket 
and rabbitsfoot throughout all of their range.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

Population Fragmentation and Isolation
    Population fragmentation and isolation prohibit the natural 
interchange of genetic material between populations. Most of the 
remaining Neosho mucket and rabbitsfoot populations are small and 
geographically isolated, and, thus, are susceptible to genetic drift, 
inbreeding depression, and stochastic changes to the environment, such 
as toxic chemical spills (Smith 1990, pp. 311-321; Watters and Dunn 
1995, pp. 257-258; Avise and Hamrick 1996, pp. 463-466). For example, 
the Spring River (White River basin) and Muddy Creek (Ohio River basin) 
rabbitsfoot populations are the only small populations not isolated 
from a viable population. Three marginal populations (Alleghany River 
and LeBoeuf and Conneauttee Creeks), considered metapopulations with 
French Creek, also are not isolated from a viable rabbitsfoot 
population (French Creek). However, 41 of 51 extant rabbitsfoot 
populations (80 percent) are isolated from other extant populations, 
excluding those discussed above and the Strawberry, Tennessee, and Ohio 
Rivers, which are viable populations that are not isolated from another 
viable population (Black River) or each other (lower Tennessee and Ohio 
Rivers).
    Inbreeding depression can result in early mortality, decreased 
fertility, smaller body size, loss of vigor, reduced

[[Page 63464]]

fitness, and various chromosome abnormalities (Smith 1990, pp. 311-
321). A species' vulnerability to extinction is increased when they are 
patchily distributed due to habitat loss and degradation (Noss and 
Cooperrider 1994, pp. 58-62; Thomas 1994, p. 373). Although changes in 
the environment may cause populations to fluctuate naturally, small and 
low-density populations are more likely to fluctuate below a minimum 
viable population size (the minimum or threshold number of individuals 
needed in a population to persist in a viable state for a given 
interval) (Shaffer 1981, p. 131; Shaffer and Samson 1985, pp. 148-150; 
Gilpin and Soul[eacute] 1986, pp. 25-33). Furthermore, this level of 
isolation makes natural repopulation of any extirpated population 
unlikely without human intervention. Population isolation prohibits the 
natural interchange of genetic material between populations, and small 
population size reduces the reservoir of genetic diversity within 
populations, which can lead to inbreeding depression (Avise and 
Hambrick 1996, p. 461).
    Neosho mucket and rabbitsfoot were once widespread throughout their 
respective ranges with few natural barriers to prevent migration (via 
fish host species) among suitable habitats. However, construction of 
dams extirpated many Neosho mucket and rabbitsfoot populations and 
isolated others. Recruitment reduction or failure is a potential 
problem for many small Neosho mucket and rabbitsfoot populations 
rangewide, a potential condition exacerbated by their reduced range, 
increasingly small populations, and increasingly isolated populations. 
If these trends continue, further significant declines in total 
population size and subsequent reduction in long-term survivability may 
be observed in the future.
    The likelihood is high that some rabbitsfoot and Neosho mucket 
populations are below the effective population size (EPS--the number of 
individuals in a population who contribute offspring to the next 
generation), based on restricted distribution and populations only 
represented by a few individuals, and achieving the EPS is necessary 
for a population to adapt to environmental change and maintain long-
term viability. Isolated populations eventually are extirpated when 
population size drops below the EPS or threshold level of 
sustainability (Soul[eacute] 1980, pp. 162-164). Evidence of 
recruitment in many populations of these two species is scant, making 
recruitment reduction or outright failure suspect. These populations 
may be experiencing the bottleneck effect of not attaining the EPS. 
Small, isolated, below the EPS-threshold populations of short-lived 
species (most fish hosts) theoretically die out within a decade or so, 
while below-threshold populations of long-lived species, such as the 
Neosho mucket and rabbitsfoot, might take decades to die out even given 
years of total recruitment failure. Without genetic interchange, small, 
isolated populations could be slowly expiring, a phenomenon termed the 
extinction debt (Tilman et al. 1994, pp. 65-66). Even given the absence 
of existing or new anthropogenic threats, disjunct populations may be 
lost as a result of current below-threshold effective population size. 
Additionally, evidence indicates that general habitat degradation 
continues to decrease habitat patch size, further contributing to the 
decline of Neosho mucket and rabbitsfoot populations.
    We find that fragmentation and isolation of small remaining 
populations of the Neosho mucket and rabbitsfoot are current and 
ongoing threats to both species throughout all of their ranges and will 
continue into the future. Further, stochastic events may play a 
magnified role in population extirpation when small, isolated 
populations are involved.
Invasive Nonindigenous Species
    Various invasive or nonnative species of aquatic organisms are 
firmly established in the range of the Neosho mucket and rabbitsfoot. 
The nonnative, invasive species that poses the most significant threat 
is the zebra mussel, Dreissena polymorpha, introduced from Europe. Its 
invasion poses a threat to mussel faunas in many regions, and species 
extinctions are expected as a result of its continued spread in the 
eastern United States (Ricciardi et al. 1998, p. 613). Strayer (1999b, 
pp. 75-80) reviewed in detail the mechanisms by which zebra mussels 
affect native mussels. Zebra mussels attach in large numbers to the 
shells of live native mussels and are implicated in the loss of entire 
native mussel beds. Fouling effects include impeding locomotion (both 
laterally and vertically), interfering with normal valve movements, 
deforming valve margins, and locally depleting food resources and 
increasing waste products. Heavy infestations of zebra mussels on 
native mussels may overly stress the animals by reducing their energy 
stores. They may also reduce food concentrations to levels too low to 
support reproduction, or even survival in extreme cases. Zebra mussels 
also may affect Neosho mucket and rabbitsfoot through filtering and 
removing their sperm and possibly glochidia from the water column, thus 
reducing reproductive potential. Habitat for native mussels also may be 
degraded by large deposits of zebra mussel pseudofeces (undigested 
waste material passed out of the incurrent siphon) (Vaughan 1997, p. 
11).
    Overlapping much of the current range of the Neosho mucket and 
rabbitsfoot, zebra mussels have been detected or are established in 
Neosho mucket (Neosho and Verdigris Rivers) and rabbitsfoot streams 
(Ohio, Allegheny, Green, Tennessee, White, and Verdigris Rivers, and 
French and Bear Creeks). Zebra mussel populations appear to be 
maintained primarily in streams with barge navigation (Stoeckel et al. 
2003, p. 334). As zebra mussels may maintain high densities in big 
rivers, large tributaries, and below infested reservoirs, rabbitsfoot 
populations in these affected areas have the potential to be 
significantly affected. In addition, there is long-term potential for 
zebra mussel invasions into other systems that currently harbor Neosho 
mucket and rabbitsfoot populations. However, evidence is mounting in 
some northern streams where there is no barge navigation (French Creek 
and Tippecanoe River) and southern ones with barge traffic (Tennessee 
River) that the zebra mussel threat to native mussels may be minimal 
because native freshwater mussel populations are able to survive when 
zebra mussel abundance is low (Butler 2005, p. 116; Fisher 2009, pers. 
comm.).
    The Asian clam (Corbicula fluminea) has spread throughout the range 
of Neosho mucket and rabbitsfoot since its introduction in the early 
twentieth century. It competes with native mussels, particularly 
juveniles, for resources such as food, nutrients, and space (Neves and 
Widlak 1987, p. 6; Leff et al. 1990, p. 414), and may ingest sperm, 
glochidia, and newly metamorphosed juveniles of native mussels (Strayer 
1999b, p. 82; Yeager et al. 2000, p. 255). Periodic die-offs of Asian 
clams may produce enough ammonia and consume enough dissolved oxygen to 
kill native mussels (Strayer 1999b, p. 82). Yeager et al. (2000, pp. 
257-258) determined that high densities of Asian clams negatively 
affect the survival and growth of newly metamorphosed juvenile mussels 
and thus reduced recruitment. Dense Asian clam populations actively 
disturb sediments that may reduce habitat for juveniles of native 
mussels (Strayer 1999b, p. 82).
    Asian clam densities vary widely in the absence of native mussels 
or in

[[Page 63465]]

patches with sparse mussel concentrations, but Asian clam density is 
never high in dense mussel beds, indicating that the clam is unable to 
successfully invade small-scale habitat patches with high unionid 
biomass (Vaughn and Spooner 2006, pp. 334-335). The invading clam 
therefore appears to preferentially invade sites where mussels are 
already in decline (Strayer 1999b, pp. 82-83; Vaughn and Spooner 2006, 
pp. 332-336) and does not appear to be a causative factor in the 
decline of mussels in dense beds. However, an Asian clam population 
that thrives in previously stressed, sparse mussel populations might 
exacerbate mussel decline through competition and by impeding mussel 
population expansion (Vaughn and Spooner 2006, pp. 335-336).
    A molluscivore (mollusk eater), the introduced black carp 
(Mylopharyngodon piceus), is a potential threat to Neosho mucket and 
rabbitsfoot (Strayer 1999b, p. 89). It has been proposed for widespread 
use by aquaculturists to control snails, the intermediate host of a 
trematode (flatworm) parasite affecting catfish in ponds in the 
southeast and lower midwest. They are known to feed on various 
mollusks, including mussels and snails, in China. They are the largest 
of the Asiatic carp species, reaching more than 1.2 m (4 ft) in length 
(Nico and Williams 1996, p. 6). Foraging rates for a 4-year-old fish 
average 1.4-1.8 kg (3 or 4 pounds) a day, indicating that a single 
individual could consume 9,072 kg (10 tons) of native mollusks during 
its lifetime (MICRA 2005, p. 1). In 1994, 30 black carp escaped from an 
aquaculture facility in Missouri during a flood. The escape of 
nonsterile black carp is considered imminent by conservation biologists 
(Butler 2007, pp. 95-96). The black carp was officially added to the 
Federal list of injurious wildlife species on October 18, 2007 (72 FR 
59019).
    The round goby (Neogobius melanostomus) is another nonnative, 
invasive fish species released in the 1980s that is well established 
and likely to spread through the Mississippi River system (Strayer 
1999b, pp. 87-88). This species is an aggressive competitor of similar-
sized benthic fishes (sculpins and darters), as well as a voracious 
carnivore, despite its size (less than 25.4 cm (10 in.) in length), 
preying on a variety of foods, including small mussels and fishes that 
could serve as glochidial hosts (Strayer 1999b, p. 88; Janssen and Jude 
2001, p. 325). Round gobies may, therefore, pose a threat to Neosho 
mucket and rabbitsfoot reproduction.
    Nonnative, invasive species, such as those described above, are an 
ongoing threat to the Neosho mucket and rabbitsfoot. This threat is 
likely to increase as these and potentially other invasive species 
expand their occupancy within the ranges of the Neosho mucket and 
rabbitsfoot through displacement, recruitment interference, and direct 
predation of the mussels and their fish hosts.
Temperature
    Natural temperature regimes can be altered by impoundments, tail 
water releases from dams, industrial and municipal effluents, and 
changes in riparian habitat. Exact critical thermal limits for survival 
and normal functioning of many freshwater mussel species are unknown. 
However, high temperatures can reduce dissolved oxygen concentrations 
in the water, which slows growth, reduces glycogen stores, impairs 
respiration, and may inhibit reproduction (Fuller 1974, pp. 240-241). 
Low temperatures can significantly delay or prevent metamorphosis 
(Watters and O'Dee 1999, pp. 454-455). Water temperature increases have 
been documented to shorten the period of glochidial encystment, reduce 
righting speed (various reflexes that tend to bring the body into 
normal position in space and resist forces acting to displace it out of 
normal position), increase oxygen consumption, and slow burrowing and 
movement responses (Fuller 1974, pp. 240-241; Bartsch et al. 2000, p. 
237; Watters et al. 2001, p. 546; Schwalb and Pusch 2007, pp. 264-265). 
Several studies have documented the influence of temperature on the 
timing aspects of mussel reproduction (Gray et al. 2002, p. 156; Allen 
et al. 2007, p. 85; Steingraeber et al. 2007, pp. 303-309). Peak 
glochidial releases are associated with water temperature thresholds 
that can be thermal minimums or maximums, depending on the species 
(Watters and O'Dee 2000, p. 136).
    Alterations in temperature regimes in streams, such as those 
described above, are an ongoing threat to the Neosho mucket and 
rabbitsfoot. This threat is likely to continue and increase in the 
future due to additional navigation or water supply projects and as 
land use conversion to urban uses increases within the entire ranges of 
the Neosho mucket and rabbitsfoot.
Climate Change
    Our analyses under the Endangered Species Act include consideration 
of ongoing and projected changes in climate. The terms ``climate'' and 
``climate change'' are defined by the Intergovernmental Panel on 
Climate Change (IPCC). ``Climate'' refers to the mean and variability 
of different types of weather conditions over time, with 30 years being 
a typical period for such measurements, although shorter or longer 
periods also may be used (IPCC 2007, p. 78). The term ``climate 
change'' thus refers to a change in the mean or variability of one or 
more measures of climate (e.g., temperature or precipitation) that 
persists for an extended period, typically decades or longer, whether 
the change is due to natural variability, human activity, or both (IPCC 
2007, p. 78). Various types of changes in climate can have direct or 
indirect effects on species. These effects may be positive, neutral, or 
negative and they may change over time, depending on the species and 
other relevant considerations, such as the effects of interactions of 
climate with other variables (e.g., habitat fragmentation) (IPCC 2007, 
pp. 8-14, 18-19). In our analyses, we use our expert judgment to weigh 
relevant information, including uncertainty, in our consideration of 
various aspects of climate change.
    Projected changes in climate and related effects can vary 
substantially across and within different regions of the world (e.g., 
IPCC 2007a, pp. 8-12). Thus, although global climate projections are 
informative and in some cases are the only or the best scientific 
information available, to the extent possible we use ``downscaled'' 
climate projections which provide higher resolution information that is 
more relevant to the spatial scales used to assess effects to a given 
species (see Glick et al. 2011, pp. 58-61 for a discussion of 
downscaling). With regard to our analysis for the Neosho mucket and the 
rabbitsfoot, downscaled projections of climate change are available, 
but projecting precise effects on these two species from downscaled 
models is difficult because of the large geographic areas inhabited by 
both species. However, projections for the change in annual air 
temperature by the year 2080 for the Neosho mucket ranges between an 
increase of 7 to 8 degrees F and, for the rabbitsfoot, an increase of 
4.5 to 8 degrees F in annual air temperature (Maura et al. 2007, as 
displayed on http://www.climatewizard.org/# 2012).
    Ficke et al. (2005, pp. 67-69; 2007, pp. 603-605) described the 
general potential effects of climate change on freshwater fish 
populations worldwide. Overall, the distribution of fish species is 
expected to change, including range shifts and local extirpations. 
Because freshwater mussels are entirely dependent upon a fish host for

[[Page 63466]]

successful reproduction and dispersal, any changes in local fish 
populations would also affect freshwater mussel populations. Therefore, 
mussel populations will reflect local extirpations or decreases in 
abundance of fish species.
Summary of Factor E
    In summary, a variety of natural and manmade factors threatens the 
continued existence of Neosho mucket and rabbitsfoot. Forty-one of the 
51 (80 percent) extant rabbitsfoot populations are isolated from viable 
populations. A lack of recruitment and genetic isolation pose a threat 
to the continued existence of these species. Invasive, nonindigenous 
species, such as zebra mussel, black carp, and Asian clam, have 
potentially adversely affected populations of the Neosho mucket and 
rabbitsfoot and their fish hosts, and these effects are expected to 
persist into the future. Based on the best available information, we 
are unable to predict the timing and scope of any changes to these 
mussel species that may occur as a result of climate change effects.

Cumulative Effects of Threats

    The life-history traits and habitat requirements of the Neosho 
mucket and rabbitsfoot, and other freshwater mussels in general, make 
them extremely susceptible to environmental change. Unlike other 
aquatic organisms (e.g., aquatic insects and fish), mussels have 
limited refugia from stream disturbances (e.g., droughts, 
sedimentation, chemical contaminants). Mechanisms leading to the 
decline of Neosho mucket and rabbitsfoot, as discussed above, range 
from local (e.g., riparian clearing, chemical contaminants, etc.), to 
regional influences (e.g., altered flow regimes, channelization, etc.), 
to global climate change. The synergistic (interaction of two or more 
components) effects of threats are often complex in aquatic 
environments, making it difficult to predict changes in mussel and fish 
host(s) distribution, abundance, and habitat availability that may 
result from these effects. While these stressors may act in isolation, 
it is more probable that many stressors are acting simultaneously (or 
in combination) (Galbraith et al. 2010, p. 1176) on Neosho mucket and 
rabbitsfoot populations.

Summary of Threats

    The decline of the Neosho mucket and rabbitsfoot (described by 
Butler 2005, entire; described by Service 2010, entire) is primarily 
the result of habitat loss and degradation (Neves 1991, p. 252). Chief 
among the causes of decline, but in no particular ranking order, are 
impoundments, sedimentation, channelization, chemical contaminants, oil 
and natural gas development, and mining (Neves 1991, p. 252; Neves 
1993, pp. 4-6; Williams et al. 1993, pp. 7-9; Neves et al. 1997, pp. 60 
and 63-75; Watters 2000, pp. 262-267). These stressors have had 
profound adverse effects on Neosho mucket and rabbitsfoot populations, 
their habitats, and fish hosts.
    Regulations at the Federal level may not be providing the 
protection needed for the Neosho mucket and rabbitsfoot. For example, 8 
of the 11 (73 percent) viable rabbitsfoot populations are located in 
waters listed as impaired under section 303(d) of the CWA. In addition, 
numerous tributaries within watersheds with viable Neosho mucket and 
rabbitsfoot populations also are listed as impaired waters under 
section 303(d) of the CWA. The CWA has a stated goal to establish water 
quality standards that protect aquatic species, including mussel 
species. However, the CWA has generally been insufficient at protecting 
mussels, and adequate water quality criteria that are protective of all 
mussel life stages, particularly glochidia and juveniles, may not be 
established. Little information is known about specific sensitivities 
of mussels to various pollutants, but both species continue to decline 
due to the effects of poor water quality, contaminants, and other 
factors.
    The majority of extant Neosho mucket populations are small and 
isolated, with only one viable population remaining. The majority of 
extant rabbitsfoot populations are marginal and small (78 percent) and 
isolated (80 percent), with only two small (5 percent) and 4 viable 
populations (36 percent) not isolated from another viable population 
(Butler 2005, p. 22; Service 2010, pp. 3-8). The patchy distributional 
pattern of populations in short river reaches makes them more 
susceptible to extirpation from single catastrophic events, such as 
toxic chemical spills (Watters and Dunn 1995, p. 257). Furthermore, 
this level of isolation makes natural recolonization of extirpated 
populations virtually impossible without human intervention. Various 
nonnative species of aquatic organisms are firmly established in the 
range of the Neosho mucket and rabbitsfoot. The nonnative species that 
poses the most significant threat to the Neosho mucket and rabbitsfoot 
is the zebra mussel. Although there are ongoing attempts to alleviate 
some of these threats at some locations, there appear to be no 
populations without threats that are significantly impacting the 
species.

Proposed Determination

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Neosho mucket and the rabbitsfoot. Section 3(6) of the Act 
defines an endangered species as ``any species that is in danger of 
extinction throughout all or a significant portion of its range'' and 
defines a threatened species as ``any species that is likely to become 
endangered throughout all or a significant portion of its range within 
the foreseeable future.'' As described in detail above, these two 
species are currently at risk throughout all of their respective ranges 
due to the immediacy, severity, and scope of threats from habitat 
destruction and modification (Factor A), inadequacy of existing 
regulatory mechanisms (Factor D), and other natural or manmade factors 
affecting their continued existence (Factor E). Although there are 
ongoing actions to alleviate some threats, there appear to be no 
populations without current threats. These isolated species have a 
limited ability to recolonize historically occupied stream and river 
reaches and are vulnerable to natural or human-caused changes in their 
stream and river habitats.
    Their range curtailment, small population size, and isolation make 
the Neosho mucket and rabbitsfoot more vulnerable to threats such as 
sedimentation, disturbance of riparian corridors, changes in channel 
morphology, point- and nonpoint-source contaminants, urbanization, 
invasive species, and to stochastic events (such as chemical spills).

Neosho mucket

    The Neosho mucket has been extirpated (no longer in existence) from 
approximately 62 percent of its historical range with only 9 of the 16 
historical populations remaining (extant). This mussel is declining 
rangewide (eight of the nine extant populations), with only one 
remaining large, viable population. Based on the best available 
scientific and commercial information, we have determined that the 
Neosho mucket is in danger of extinction throughout all of its range. 
Therefore, we are proposing to list it as an endangered species. In 
other words, we find that a threatened species status is not 
appropriate for the Neosho mucket due to its contracted range (nine 
extant river populations within three river basins) and only one 
remaining stable and viable population.

[[Page 63467]]

Rabbitsfoot

    The rabbitsfoot has been extirpated from approximately 64 percent 
of its historical range. While this species is declining rangewide, it 
sustains recruitment and population viability consistently in 11 (8 
percent of historical or 22 percent of extant distribution) large, 
extant river populations and, while reduced in numbers, it also 
sustains limited recruitment and distribution in another 17 river 
populations. Of the 17 river populations with limited recruitment and 
distribution, 15 of these populations (88 percent) are declining.
    All remaining rabbitsfoot populations continue to be reduced in 
size or quality by habitat degradation as a result of impoundments and 
dams, navigation projects, commercial and residential development, 
agriculture, chemical contaminants, mining, and oil and natural gas 
development. Climate change could affect in-stream water temperatures, 
seasonal water flows, and mussel and fish host reproductive activities, 
including the availability of mussel fish host species. Invasive 
species occupying rabbitsfoot habitat cause displacement and 
recruitment interference. Eight of the 11 (73 percent) viable 
rabbitsfoot populations are in waters and have numerous tributaries in 
their watersheds that are listed as impaired waters under section 
303(d) of the CWA. Regulatory mechanisms such as the CWA have been 
insufficient to significantly reduce or remove these types of threats 
to rabbitsfoot. The synergistic effects of threats such as these are 
often complex in aquatic environments and, while making it difficult to 
predict changes in mussel and fish host(s) distribution, abundance, and 
habitat availability, it is probable that these threats are acting 
simultaneously on the remaining rabbitsfoot populations with negative 
results and are expected to continue to do so. Thus, while rabbitsfoot 
sustains 11 viable populations, these populations continue to be at 
risk, and the rabbitsfoot's other extant populations are affected by 
isolation, fragmentation, limited recruitment and distribution, and 
population declines, which make the species particularly susceptible to 
extinction in the near future if threats continue or increase.
    While we have determined that the rabbitsfoot is not currently in 
danger of extinction, because of the threats facing the species and 
impacts to its life history, we find that the species is likely to 
become in danger of extinction in the foreseeable future throughout all 
of its range. Therefore, we are proposing to list it as a threatened 
species. In other words, we find that endangered status is not 
appropriate for the rabbitsfoot because 8 percent of the historical 
populations or 22 percent of extant populations remaining in its 
historical streams can be considered viable, but are facing subtle, 
pervasive threats that are ubiquitous in each watershed.
Significant Portion of Its Range
    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. The Act defines ``endangered 
species'' as any species which is ``in danger of extinction throughout 
all or a significant portion of its range,'' and ``threatened species'' 
as any species which is ``likely to become an endangered species within 
the foreseeable future throughout all or a significant portion of its 
range.'' The definition of ``species'' is also relevant to this 
discussion. The Act defines ``species'' as follows: ``The term 
`species' includes any subspecies of fish or wildlife or plants, and 
any distinct population segment [DPS] of any species of vertebrate fish 
or wildlife which interbreeds when mature.'' The phrase ``significant 
portion of its range'' (SPR) is not defined by the statute, and we have 
never addressed in our regulations: (1) The consequences of a 
determination that a species is either endangered or likely to become 
so throughout a significant portion of its range, but not throughout 
all of its range; or (2) what qualifies a portion of a range as 
``significant.''
    Two recent district court decisions have addressed whether the SPR 
language allows the Service to list or protect less than all members of 
a defined ``species'': Defenders of Wildlife v. Salazar, 729 F. Supp. 
2d 1207 (D. Mont. 2010), concerning the Service's delisting of the 
Northern Rocky Mountain gray wolf (74 FR 15123, April 2, 2009); and 
WildEarth Guardians v. Salazar, 2010 U.S. Dist. LEXIS 105253 (D. Ariz. 
September 30, 2010), concerning the Service's 2008 finding on a 
petition to list the Gunnison's prairie dog (73 FR 6660, February 5, 
2008). The Service had asserted in both of these determinations that it 
had authority, in effect, to protect only some members of a 
``species,'' as defined by the Act (i.e., species, subspecies, or DPS), 
under the Act. Both courts ruled that the determinations were arbitrary 
and capricious on the grounds that this approach violated the plain and 
unambiguous language of the Act. The courts concluded that reading the 
SPR language to allow protecting only a portion of a species' range is 
inconsistent with the Act's definition of ``species.'' The courts 
concluded that once a determination is made that a species (i.e., 
species, subspecies, or DPS) meets the definition of ``endangered 
species'' or ``threatened species,'' it must be placed on the list in 
its entirety and the Act's protections applied consistently to all 
members of that species (subject to modification of protections through 
special rules under sections 4(d) and 10(j) of the Act).
    Consistent with that interpretation, and for the purposes of this 
finding, we interpret the phrase ``significant portion of its range'' 
in the Act's definitions of ``endangered species'' and ``threatened 
species'' to provide an independent basis for listing; thus there are 
two situations (or factual bases) under which a species would qualify 
for listing: A species may be endangered or threatened throughout all 
of its range; or a species may be endangered or threatened in only a 
significant portion of its range. If a species is in danger of 
extinction throughout a significant portion of its range, the species 
is an ``endangered species.'' The same analysis applies to ``threatened 
species.'' Based on this interpretation and supported by existing case 
law, the consequence of finding that a species is endangered or 
threatened in only a significant portion of its range is that the 
entire species shall be listed as endangered or threatened, 
respectively, and the Act's protections shall be applied across the 
species' entire range.
    We conclude, for the purposes of this finding, that interpreting 
the significant portion of its range phrase as providing an independent 
basis for listing is the best interpretation of the Act because it is 
consistent with the purposes and the plain meaning of the key 
definitions of the Act; it does not conflict with established past 
agency practice (i.e., prior to the 2007 Solicitor's Opinion), as no 
consistent, long-term agency practice has been established; and it is 
consistent with the judicial opinions that have most closely examined 
this issue. Having concluded that the phrase ``significant portion of 
its range'' provides an independent basis for listing and protecting 
the entire species, we next turn to the meaning of ``significant'' to 
determine the threshold for when such an independent basis for listing 
exists.
    Although there are potentially many ways to determine whether a 
portion of a species' range is ``significant,'' we conclude, for the 
purposes of this finding, that the significance of the portion of the 
range should be determined based on its biological

[[Page 63468]]

contribution to the conservation of the species. For this reason, we 
describe the threshold for ``significant'' in terms of an increase in 
the risk of extinction for the species. We conclude that a biologically 
based definition of ``significant'' best conforms to the purposes of 
the Act, is consistent with judicial interpretations, and best ensures 
species' conservation. Thus, for the purposes of this finding, and as 
explained further below, a portion of the range of a species is 
``significant'' if its contribution to the viability of the species is 
so important that without that portion, the species would be in danger 
of extinction.
    We evaluate biological significance based on the principles of 
conservation biology using the concepts of redundancy, resiliency, and 
representation. Resiliency describes the characteristics of a species 
and its habitat that allow it to recover from periodic disturbance. 
Redundancy (having multiple populations distributed across the 
landscape) may be needed to provide a margin of safety for the species 
to withstand catastrophic events. Representation (the range of 
variation found in a species) ensures that the species' adaptive 
capabilities are conserved. Redundancy, resiliency, and representation 
are not independent of each other, and some characteristic of a species 
or area may contribute to all three. For example, distribution across a 
wide variety of habitat types is an indicator of representation, but it 
may also indicate a broad geographic distribution contributing to 
redundancy (decreasing the chance that any one event affects the entire 
species), and the likelihood that some habitat types are less 
susceptible to certain threats, contributing to resiliency (the ability 
of the species to recover from disturbance). None of these concepts is 
intended to be mutually exclusive, and a portion of a species' range 
may be determined to be ``significant'' due to its contributions under 
any one or more of these concepts.
    For the purposes of this finding, we determine if a portion's 
biological contribution is so important that the portion qualifies as 
``significant'' by asking whether without that portion, the 
representation, redundancy, or resiliency of the species would be so 
impaired that the species would have an increased vulnerability to 
threats to the point that the overall species would be in danger of 
extinction (i.e., would be ``endangered''). Conversely, we would not 
consider the portion of the range at issue to be ``significant'' if 
there is sufficient resiliency, redundancy, and representation 
elsewhere in the species' range that the species would not be in danger 
of extinction throughout its range if the population in that portion of 
the range in question became extirpated (extinct locally).
    We recognize that this definition of ``significant'' (a portion of 
the range of a species is ``significant'' if its contribution to the 
viability of the species is so important that, without that portion, 
the species would be in danger of extinction) establishes a threshold 
that is relatively high. On the one hand, given that the consequences 
of finding a species to be endangered or threatened in a significant 
portion of its range would be listing the species throughout its entire 
range, it is important to use a threshold for ``significant'' that is 
robust. It would not be meaningful or appropriate to establish a very 
low threshold whereby a portion of the range can be considered 
``significant'' even if only a negligible increase in extinction risk 
would result from its loss. Because nearly any portion of a species' 
range can be said to contribute some increment to a species' viability, 
use of such a low threshold would require us to impose restrictions and 
expend conservation resources disproportionately to conservation 
benefit: Listing would be rangewide, even if only a portion of the 
range of minor conservation importance to the species is imperiled. On 
the other hand, it would be inappropriate to establish a threshold for 
``significant'' that is too high. This would be the case if the 
standard were, for example, that a portion of the range can be 
considered ``significant'' only if threats in that portion result in 
the entire species' being currently endangered or threatened. Such a 
high bar would not give the significant portion of its range phrase 
independent meaning, as the Ninth Circuit held in Defenders of Wildlife 
v. Norton, 258 F.3d 1136 (9th Cir. 2001).
    The definition of ``significant'' used in this finding carefully 
balances these concerns. By setting a relatively high threshold, we 
minimize the degree to which restrictions will be imposed or resources 
expended that do not contribute substantially to species conservation. 
But we have not set the threshold so high that the phrase ``in a 
significant portion of its range'' loses independent meaning. 
Specifically, we have not set the threshold as high as it was under the 
interpretation presented by the Service in the Defenders litigation. 
Under that interpretation, the portion of the range would have to be so 
important that current imperilment there would mean that the species 
would be currently imperiled everywhere. Under the definition of 
``significant'' used in this finding, the portion of the range need not 
rise to such an exceptionally high level of biological significance. 
(We recognize that if the species is imperiled in a portion that rises 
to that level of biological significance, then we should conclude that 
the species is in fact imperiled throughout all of its range, and that 
we would not need to rely on the significant portion of its range 
language for such a listing.) Rather, under this interpretation we ask 
whether the species would be endangered everywhere without that 
portion, i.e., if that portion were completely extirpated. In other 
words, the portion of the range need not be so important that even the 
species being in danger of extinction in that portion would be 
sufficient to cause the species in the remainder of the range to be 
endangered; rather, the complete extirpation (in a hypothetical future) 
of the species in that portion would be required to cause the species 
in the remainder of the range to be endangered.
    The range of a species can theoretically be divided into portions 
in an infinite number of ways. However, there is no purpose to 
analyzing portions of the range that have no reasonable potential to be 
significant or to analyzing portions of the range in which there is no 
reasonable potential for the species to be endangered or threatened. To 
identify only those portions that warrant further consideration, we 
determine whether there is substantial information indicating that: (1) 
The portions may be ``significant,'' and (2) the species may be in 
danger of extinction there or likely to become so within the 
foreseeable future. Depending on the biology of the species, its range, 
and the threats it faces, it might be more efficient for us to address 
the significance question first or the status question first. Thus, if 
we determine that a portion of the range is not ``significant,'' we do 
not need to determine whether the species is endangered or threatened 
there; if we determine that the species is not endangered or threatened 
in a portion of its range, we do not need to determine if that portion 
is ``significant.'' In practice, a key part of the determination that a 
species is in danger of extinction in a significant portion of its 
range is whether the threats are geographically concentrated in some 
way. If the threats to the species are essentially uniform throughout 
its range, no portion is likely to warrant further consideration. 
Moreover, if any concentration of

[[Page 63469]]

threats to the species occurs only in portions of the species' range 
that clearly would not meet the biologically based definition of 
``significant,'' such portions will not warrant further consideration.
    We evaluated the current range of the Neosho mucket and rabbitsfoot 
to determine if there is any apparent geographic concentration of 
potential threats for either species. The Neosho mucket and rabbitsfoot 
are highly restricted in their ranges, and the threats occur throughout 
their ranges. We considered the potential threats due to impoundments, 
sedimentation, channelization, chemical contaminants, oil and gas 
development, mining, and climate change. We found no concentration of 
threats because of the species limited and curtailed ranges, and 
uniformity of the threats throughout its entire range. Having 
determined that the Neosho mucket is endangered throughout its entire 
range, it is not necessary to evaluate whether there are any 
significant portions of its range. Having determined that the 
rabbitsfoot is threatened throughout its entire range, we must next 
consider whether there are any significant portions of the range where 
the rabbitsfoot is in danger of extinction or is likely to become 
endangered in the foreseeable future.
    We found no portion of the rabbitsfoot's range where potential 
threats are significantly concentrated or substantially greater than in 
other portions of their range. Therefore, we find that factors 
affecting the species are essentially uniform throughout its range, 
indicating no portion of the range of the species warrants further 
consideration of possible endangered or threatened status under the 
Act. Therefore, we find there is no significant portion of the 
rabbitsfoot range that may warrant a different status.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing encourages and results in public 
awareness and conservation by Federal, State, and local agencies, 
private organizations, and individuals. The Act encourages cooperation 
with the States and requires that recovery actions be carried out for 
all listed species. The protection required of Federal agencies and the 
prohibitions against take and harm are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Subsection 4(f) of the Act requires the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species, unless such a plan will not promote the 
conservation of the species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed and after preparation of a draft and 
final recovery plan. The recovery outline guides the immediate 
implementation of urgent recovery actions and describes the process to 
be used to develop a recovery plan. Revisions of the plan may be done 
to address continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan identifies site-
specific management actions that set a trigger for review of the five 
factors that control whether a species remains endangered or may be 
downlisted or delisted, and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (comprising species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) are often established to develop recovery plans. When 
completed, the recovery outline, draft recovery plan, and the final 
recovery plan will be available on our Web site (http://www.fws.gov/endangered), or from our Arkansas Ecological Services Field Office (see 
FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. Achieving recovery of these species requires cooperative 
conservation efforts on private, State, and Tribal lands.
    If these species are listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the States of Alabama, Arkansas, 
Indiana, Illinois, Kansas, Kentucky, Louisiana, Mississippi, Missouri, 
Ohio, Oklahoma, Pennsylvania, and Tennessee would be eligible for 
Federal funds to implement management actions that promote the 
protection or recovery of the Neosho mucket and rabbitsfoot. 
Information on our grant programs that are available to aid species 
recovery can be found at: http://www.fws.gov/grants.
    Although the Neosho mucket and rabbitsfoot are only proposed for 
listing under the Act at this time, please let us know if you are 
interested in participating in recovery efforts for these species. 
Additionally, we invite you to submit any new information on these 
species whenever it becomes available and any information you may have 
for recovery planning purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened and with respect to its critical 
habitat, if any is designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Federal agencies are required to confer with us informally on 
any action that is likely to jeopardize the continued existence of a 
proposed species. Section 7(a)(4) requires Federal agencies to confer 
with the Service on any action that is likely to jeopardize the 
continued existence of a species proposed for listing or result in 
destruction or adverse modification of proposed critical habitat. If a 
species is listed subsequently, section 7(a)(2) requires Federal 
agencies to ensure that activities they authorize, fund, or carry out 
are not likely to jeopardize the continued existence of the species or 
destroy or adversely modify its critical habitat. If a Federal action 
may adversely affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with the 
Service.
    Federal agency actions within these species' habitat that may 
require

[[Page 63470]]

conference or consultation or both as described in the preceding 
paragraph include, but are not limited to, the funding of, carrying 
out, or the issuance of permits for reservoir construction, navigation, 
natural gas extraction, stream alterations, discharges, wastewater 
facility development, water withdrawal projects, pesticide 
registration, mining, and road and bridge construction. This may 
include, but is not limited to, management and any other landscape-
altering activities on Federal lands administered by the Department of 
Defense, and USDA Forest Service; issuance of Clean Water Act permits 
by the Army Corps of Engineers and Environmental Protection Agency; 
construction and maintenance of interstate power and natural gas 
transmission line right-of-ways by the Federal Energy Regulatory 
Commission; and construction and maintenance of roads or highways by 
the Federal Highway Administration.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all endangered 
wildlife. The prohibitions of section 9(a)(2) of the Act, codified at 
50 CFR 17.21 for endangered wildlife, in part, make it illegal for any 
person subject to the jurisdiction of the United States to take 
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect, or to attempt any of these), import, export, ship 
in interstate commerce in the course of commercial activity, or sell or 
offer for sale in interstate or foreign commerce any listed species. 
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also 
illegal to possess, sell, deliver, carry, transport, or ship any such 
wildlife that has been taken illegally. Certain exceptions apply to 
agents of the Service and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered and threatened wildlife species under certain 
circumstances. Regulations governing permits are codified at 50 CFR 
17.22 for endangered species, and at 17.32 for threatened species. With 
regard to endangered wildlife, a permit must be issued for the 
following purposes: for scientific purposes, to enhance the propagation 
or survival of the species, and for incidental take in connection with 
otherwise lawful activities.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a proposed 
listing on proposed and ongoing activities within the range of species 
proposed for listing. The following activities could potentially result 
in a violation of section 9 of the Act; this list is not comprehensive:
    (1) Collecting, handling, possessing, selling, delivering, 
carrying, or transporting of the species, including import or export 
across State lines and international boundaries that are unauthorized, 
except for properly documented antique specimens of these taxa at least 
100 years old, as defined by section 10(h)(1) of the Act;
    (2) Introduction of nonnative species that compete with or prey 
upon the Neosho mucket and rabbitsfoot, such as the introduction of a 
predator of mussels, the nonnative black carp to a water body (White 
River) in the State of Arkansas;
    (3) The release of biological control agents that attack any life 
stage of Neosho mucket and rabbitsfoot that is unauthorized;
    (4) Modification of the channel or water flow of any stream in 
which the Neosho mucket and rabbitsfoot are known to occur that are 
unauthorized or not covered under the Act for impacts to these species; 
and
    (5) Discharge of chemicals or fill material into any waters 
supporting the Neosho mucket and rabbitsfoot that are unauthorized or 
not covered under the Act for impacts to these species.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Service's 
Field Office in the State where the proposed activities will occur. 
Requests for copies of the regulations concerning listed animals and 
general inquiries regarding prohibitions and permits may be addressed 
to the U.S. Fish and Wildlife Service, Endangered Species Permits, 1875 
Century Boulevard, Suite 200, Atlanta, GA 30345; telephone: 404-679-
7140; facsimile: 404-679-7081.
    If the Neosho mucket and rabbitsfoot are listed under the Act, the 
States of Kansas and Oklahoma's Endangered Species Act (Kansas Nongame 
and Endangered Species Conservation Act of 1975, Chapter 32. Wildlife, 
Parks and Recreation and Oklahoma Wildlife Conservation Code, Title 29, 
Game and Fish, Chapter 1, Article V. Game, Part 4, Protected Game, 
respectively) are automatically invoked, which would also prohibit take 
of these species and encourage conservation by State government 
agencies. Further, the State may enter into agreements with Federal 
agencies to administer and manage any area required for the 
conservation, management, enhancement, or protection of endangered 
species. Funds for these activities could be made available under 
section 6 of the Act (Cooperation with the States). Thus, the Federal 
protection afforded to these species by listing them as endangered and 
threatened species will be reinforced and supplemented by protection 
under State law.

Critical Habitat Designation for Neosho Mucket and Rabbitsfoot

Background

    It is our intent to discuss below only those topics directly 
relevant to the designation of critical habitat for Neosho mucket and 
rabbitsfoot in this section of the proposed rule.
    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features:
    (a) Essential to the conservation of the species and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the requirement that Federal agencies ensure, in consultation 
with the Service, that any action they authorize, fund, or carry out is 
not likely to result in the destruction or adverse modification of 
critical habitat. The designation of critical habitat does not affect 
land ownership or establish a refuge, wilderness, reserve, preserve, or 
other

[[Page 63471]]

conservation area. Such designation does not allow the government or 
public to access private lands. Such designation does not require 
implementation of restoration, recovery, or enhancement measures by 
non-Federal landowners. Where a landowner requests Federal agency 
funding or authorization for an action that may affect a listed species 
or critical habitat, the consultation requirements of section 7(a)(2) 
of the Act would apply, but even in the event of a destruction or 
adverse modification finding, the obligation of the Federal action 
agency and the landowner is not to restore or recover the species, but 
to implement reasonable and prudent alternatives to avoid destruction 
or adverse modification of critical habitat.
    Under the first prong of the Act's definition of critical habitat, 
areas within the geographic area occupied by the species at the time it 
was listed are included in a critical habitat designation if they 
contain physical or biological features (1) which are essential to the 
conservation of the species and (2) which may require special 
management considerations or protection. For these areas, critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, those physical or biological 
features that are essential to the conservation of the species (such as 
space, food, cover, and protected habitat). In identifying those 
physical and biological features within an area, we focus on the 
principal biological or physical constituent elements (primary 
constituent elements such as roost sites, nesting grounds, seasonal 
wetlands, water quality, tide, soil type) that are essential to the 
conservation of the species. Primary constituent elements are the 
elements of physical or biological features that, when laid out in the 
appropriate quantity and spatial arrangement to provide for a species' 
life-history processes, are essential to the conservation of the 
species.
    Under the second prong of the Act's definition of critical habitat, 
we can designate critical habitat in areas outside the geographic area 
occupied by the species at the time it is listed, upon a determination 
that such areas are essential for the conservation of the species. For 
example, an area currently occupied by the species but that was not 
occupied at the time of listing may be essential to the conservation of 
the species and may be included in the critical habitat designation. We 
designate critical habitat in areas outside the geographic area 
occupied by a species only when a designation limited to its range 
would be inadequate to ensure the conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines, provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, other unpublished materials, or 
experts' opinions or personal knowledge.
    Habitat is dynamic, and species may move from one area to another 
over time. Climate change will be a particular challenge for 
biodiversity because the interaction of additional stressors associated 
with climate change and current stressors may push species beyond their 
ability to survive (Lovejoy 2005, pp. 325-326). The synergistic 
implications of climate change and habitat fragmentation are the most 
threatening facet of climate change for biodiversity (Hannah and 
Lovejoy 2005, p. 4). Current climate change predictions for terrestrial 
areas in the Northern Hemisphere indicate warmer air temperatures, more 
intense precipitation events, and increased summer continental drying 
(Field et al. 1999, pp. 1-3; Hayhoe et al. 2004, p. 12422; Cayan et al. 
2005, p. 6; Intergovernmental Panel on Climate Change (IPCC) 2007, p. 
1181). Climate change may lead to increased frequency and duration of 
severe storms and droughts (Golladay et al. 2004, p. 504; McLaughlin et 
al. 2002, p. 6074; Cook et al. 2004, p. 1015). We recognize that 
critical habitat designated at a particular point in time may not 
include all of the habitat areas that we may later determine are 
necessary for the recovery of the species. For these reasons, a 
critical habitat designation does not signal that habitat outside the 
designated area is unimportant or may not be needed for recovery of the 
species. Areas that are important to the conservation of the species, 
both inside and outside the critical habitat designation, will continue 
to be subject to: (1) Conservation actions implemented under section 
7(a)(1) of the Act, (2) regulatory protections afforded by the 
requirement in section 7(a)(2) of the Act for Federal agencies to 
ensure their actions are not likely to jeopardize the continued 
existence of any endangered or threatened species, and (3) section 9 of 
the Act's prohibitions on taking any individual of the species, 
including taking caused by actions that affect habitat. Federally 
funded or permitted projects affecting listed species outside their 
designated critical habitat areas may still result in jeopardy findings 
in some cases. These protections and conservation tools will continue 
to contribute to recovery of these species. Similarly, critical habitat 
designations made on the basis of the best available information at the 
time of designation will not control the direction and substance of 
future recovery plans, habitat conservation plans (HCPs), or other 
species conservation planning efforts if new information available at 
the time of these planning efforts calls for a different outcome.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary designate critical habitat at 
the time the species is determined to be endangered or threatened. Our 
regulations (50 CFR 424.12(a)(1)) state that the designation of 
critical habitat is not prudent when one or both of the following 
situations exist: (1) The species is threatened by taking or other 
human activity, and identification of critical habitat can be expected 
to increase the degree of threat to the species, or (2) such 
designation of critical habitat would not be beneficial to the species.
    There is currently no impending threat of take attributed to 
collection or vandalism under Factor B for either of these species, and 
identification and mapping of critical habitat is not expected to 
initiate any such threat. In the absence of finding that the 
designation of critical habitat would increase threats to a species, if 
there are

[[Page 63472]]

any benefits to a critical habitat designation, then a prudent finding 
is warranted. Here, the potential benefits of designation include: (1) 
Triggering consultation under section 7 of the Act in new areas for 
actions in which there may be a Federal nexus where it would not 
otherwise occur because, for example, it is or has become unoccupied or 
the occupancy is in question; (2) focusing conservation activities on 
the most essential features and areas; (3) providing educational 
benefits to State or county governments or private entities; and (4) 
preventing people from causing inadvertent harm to the species. 
Therefore, because we have determined that the designation of critical 
habitat will not likely increase the degree of threat to the species 
and may provide some measure of benefit, we find that designation of 
critical habitat is prudent for the Neosho mucket and rabbitsfoot.

Critical Habitat Determinability

    Having determined that designation of critical habitat is prudent, 
under section 4(a)(3) of the Act, we must find whether critical habitat 
is determinable for the two species. Our regulations at 50 CFR 
424.12(a)(2) state that critical habitat is not determinable when one 
or both of the following situations exist:
    (i) Information sufficient to perform required analyses of the 
impacts of the designation is lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to permit identification of an area as critical habitat.
    When critical habitat is not determinable, the Act allows the 
Service an additional year to publish a critical habitat designation 
(16 U.S.C. 1533(b)(6)(C)(ii)).
    We reviewed the available information pertaining to the biological 
needs of the species and habitat characteristics where these species 
are located. This and other information represent the best scientific 
data available and led us to conclude that the designation of critical 
habitat is determinable for the Neosho mucket and rabbitsfoot.

Physical or Biological Features

    In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and 
regulations at 50 CFR 424.12, in determining which areas within the 
geographic area occupied by the species at the time of listing to 
designate as critical habitat, we consider the physical or biological 
features that are essential to the conservation of the species and 
which may require special management considerations or protection. 
These include, but are not limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, or rearing (or development) 
of offspring; and
    (5) Habitats that are protected from disturbance or are 
representative of the historical, geographic, and ecological 
distributions of a species.
    We derive the specific physical or biological features required for 
Neosho mucket and rabbitsfoot from studies of these species' habitat, 
ecology, and life history as described below. Additional information 
can be found in the STATUS ASSESSMENT FOR NEOSHO MUCKET AND RABBITSFOOT 
section of this proposed rule. We have determined that the following 
physical or biological features are essential for Neosho mucket and 
rabbitsfoot.
Space for Individual and Population Growth and for Normal Behavior
    The Neosho mucket is historically associated with the Illinois, 
Neosho, and Verdigris Rivers and their larger tributaries (Arkansas 
River basin). Generally, the Neosho mucket is found embedded in stable 
substrates associated with shallow riffles (areas where shallow, 
generally less than 1 m (3.3 ft) in depth, turbulent water passes 
through and over stones or gravel of somewhat similar size) and runs 
(intermediate areas between pools and riffles with moderate current) 
with gravel and sand substrate and moderate to swift currents (Oesch 
1984, p. 221; Harris 1998, p. 5; Obermeyer 2000, pp. 15-16). However, 
in Shoal Creek and the Illinois River, the Neosho mucket prefers near-
shore areas or areas out of the main current (Harris 1998, p. 5). These 
habitats are formed and maintained by water quantity, channel slope, 
and normal sediment input to the system.
    The rabbitsfoot is historically associated with small- to medium-
sized streams and some larger rivers in the Lower Great Lakes and Lower 
Mississippi River sub-basins and Ohio, Cumberland, Tennessee, White, 
Arkansas, and Red River basins. The rabbitsfoot usually occurs in 
shallow areas along the bank and adjacent runs and riffles with gravel 
and sand substrates where the water velocity is reduced, but it also 
may occur in deep runs (Parmalee and Bogan 1998, pp. 211-212). Unlike 
the Neosho mucket (Barnhart 2003, p. 17), the rabbitsfoot seldom 
burrows in the substrate, but lies on its side (Watters 1988, p. 13; 
Fobian 2007, p. 24).
    Neosho mucket and rabbitsfoot, similar to other mussels, are 
dependent on areas with flow refuges where shear stress (the stream's 
ability to entrain and transport bed material created by the flow 
acting on the bed material) is low and sediments remain stable during 
flood events (Layzer and Madison 1995, p. 341; Strayer 1999a, pp. 468 
and 472; Hastie et al. 2001, pp. 111-114). Flow refuges conceivably 
allow relatively immobile mussels such as the Neosho mucket and 
rabbitsfoot to remain in the same general location throughout their 
entire lives. These patches of stable habitat may be highly important 
for the rabbitsfoot since it typically does not burrow, making it more 
susceptible to displacement into unsuitable habitat. However, flow 
refuges are not created equally and there are likely other habitat 
variables that are important, but poorly understood (Roberts 2008, 
pers. comm.).
    Natural river and creek channel stability are achieved by allowing 
the river or creek to develop a stable dimension, pattern, and profile, 
such that, over time, channel features are maintained and the river or 
creek system neither aggrades nor degrades. Channel instability occurs 
when the scouring (flushing) process leads to degradation or excessive 
sediment deposition results in aggradation. Stable rivers and creeks 
consistently transport their sediment load, both in size and type, 
associated with local deposition and scour (Rosgen 1996, pp. 1-3).
    Habitat conditions described above provide space, cover, shelter, 
and sites for breeding, reproduction, and growth of offspring for the 
Neosho mucket and rabbitsfoot. These habitats are formed and maintained 
by water quantity, channel features (dimension, pattern, and profile), 
and sediment input to the system through periodic flooding, which 
maintains connectivity and interaction with the flood plain, and are 
dynamic. Changes in one or more of these parameters can result in 
channel degradation or aggradation, with serious effects to mussels. 
Therefore, we identify adequate water quantity, stream channel 
stability, and floodplain connectivity to be physical and biological 
features for Neosho mucket and rabbitsfoot that are essential in 
accommodating feeding, breeding, growth, and other normal behaviors of 
these species and in promoting gene flow within each species' 
populations and movement of their fish hosts.

[[Page 63473]]

Food, Water, Air, Light, Minerals, or Other Nutritional or 
Physiological Requirements
    The Neosho mucket and rabbitsfoot are riverine-adapted species that 
depend upon adequate water flow and are not found in ponds or lakes. 
Continuously flowing water is a habitat feature associated with all 
surviving populations of these species. Flowing water maintains the 
river and creek bottoms and flow refuge habitats in riffles and runs 
where these species are found, transports food items to the sedentary 
juvenile and adult life stages, removes wastes, and provides oxygen for 
respiration of the Neosho mucket and rabbitsfoot. A natural flow regime 
that includes periodic flooding and maintains connectivity and 
interaction with the floodplain is critical for the exchange of 
nutrients, movement of and spawning activities for potential fish 
hosts, and maintenance of flow refuges in riffle and run habitats.
    Mussels, such as the Neosho mucket and rabbitsfoot, filter algae, 
detritus, microscopic animals, and bacteria from the water column 
(Fuller 1974, p. 221; Silverman et al. 1997, pp. 1862-1865; Nichols and 
Garling 2000, pp. 874-876; Strayer et al. 2004, pp. 430-431). Encysted 
glochidia are nourished by their fish hosts and feed for a period of 
one week to several months. Nutrient uptake by glochidia is not well 
understood, but probably occurs through the microvillae of the mantle 
(Watters 2007, p. 55). For the first several months, juvenile mussels 
partially employ pedal (foot) feeding, extracting bacteria, algae, and 
detritus from the sediment, although they also may filter interstitial 
(pore) water (Yeager et al. 1994, pp. 217-221). However, their gills 
are rudimentary and generally incapable of filtering particles (Watters 
2007, p. 56). Adult mussels also can obtain their food by deposit 
feeding, siphoning in food from the sediment and its interstitial 
(pore) water and pedal feeding directly from the sediment (Yeager et 
al. 1994, pp. 217-221; Vaughn and Hakenkamp 2001, pp. 1432-1438). Food 
availability and quality for the Neosho mucket and rabbitsfoot in their 
habitats are affected by habitat stability, floodplain connectivity, 
flow, and water and sediment quality.
    The ranges of many water quality parameters that define suitable 
habitat conditions for the Neosho mucket and rabbitsfoot have not been 
investigated or are poorly understood. The pathways of exposure to a 
variety of environmental pollutants for all four mussel life stages 
(free and encysted glochidia, juveniles, and adults) and differences in 
exposure and sensitivity were previously discussed (Factor A). 
Environmental contamination is a causal (contributing) factor in the 
decline of mussel populations. We estimate that most numeric standards 
for pollutants and water quality parameters (for example, dissolved 
oxygen, pH, heavy metals) that have been adopted by the States under 
the Clean Water Act represent levels that are essential to the 
conservation of these mussels. However, some regulatory mechanisms may 
not adequately protect mollusks in some reaches (see Factor D). The 
Service is currently in consultation with the EPA to evaluate the 
protectiveness of criteria approved in EPA's water quality standards 
for endangered and threatened species and their critical habitat as 
described in the Memorandum of Agreement that our agencies signed in 
2001 (66 FR 11201, February 22, 2001). Other factors that can 
potentially alter water quality are droughts and periods of low flow, 
nonpoint-source runoff from adjacent land surfaces (excessive amounts 
of sediments, nutrients, and pesticides), point-source discharges from 
municipal and industrial wastewater treatment facilities (excessive 
amounts of ammonia, chlorine, and metals), and random spills or 
unregulated discharge events. This could be particularly harmful during 
drought conditions when flows are depressed and pollutants are more 
concentrated.
    As relatively sedentary animals, mussels must tolerate the full 
range of environmental stressors that occur within the streams where 
they persist. Both the amount (flow) and the physical and chemical 
conditions (sediment and water quality) where these species currently 
exist vary widely according to season, precipitation events, and 
seasonal human activities within the various watersheds. Conditions 
across their historical ranges vary even more due to geology, 
geography, and differences in human population densities and land uses. 
In general, these species survive in areas where the severity, 
frequency, duration, and seasonality of water flow is adequate to 
maintain stable flow refuges in riffle and run habitats (sufficient 
flow to remove fine particles and sediments without causing 
degradation), and where sediment and water quality is adequate for 
year-round survival (moderate to high levels of dissolved oxygen; low 
to moderate exposure to environmental pollutants such as nutrients, 
dissolved metals, and pharmaceuticals; and relatively unpolluted water 
and sediments). Adequate water flow, water quality, and sediment 
quality (as defined above) are essential for normal behavior, growth, 
and viability during all life stages of the Neosho mucket and 
rabbitsfoot and their potential larva fish hosts. Therefore, based on 
the information above, we identify water flow, water quality, and 
sediment quality to be physical or biological features for both these 
species.
Sites for Breeding, Reproduction, or Rearing
    Mussels require a fish host for transformation of larval mussels 
(glochidia) to juvenile mussels (Williams et al. 2008, p. 68); 
therefore, presence of the appropriate fish host(s) is essential to the 
conservation of the Neosho mucket and rabbitsfoot (see STATUS 
ASSESSMENT FOR NEOSHO MUCKET AND RABBITSFOOT). Neosho mucket and 
rabbitsfoot juveniles require stable habitats with adequate water 
quantity and quality as previously described for growth and survival. 
Excessive sediments or dense growth of filamentous algae can expose 
juvenile mussels to entrainment or predation and be detrimental to the 
survival of juvenile mussels (Hartfield and Hartfield 1996, pp. 372-
374). Geomorphic instability can result in the loss of interstitial 
habitats and juvenile mussels due to scouring or deposition (Hartfield 
1993, pp. 372-373). Water quality, sediment quality, stable habitat, 
health of fish hosts, and diet (of all life stages) all influence 
survival of each life stage and subsequent reproduction and recruitment 
(Cope et al. 2008, p. 452).
    Connections between the rivers and adjacent flood plains occur 
periodically during wet years and provide habitat for spawning and 
foraging fish hosts that require flood plain habitats for successful 
reproduction and recruitment to adulthood. Barko et al. (2006, pp. 252-
256) found that several fish host or potential host species benefited 
from exploiting the resources of flood plain habitats that were not 
typically available for use during normal hydrology years. Furthermore, 
Kwak (1988, pp. 243-247) and Slipke et al. (2005, p. 289) indicated 
that periodic inundation of floodplain habitats increased successful 
fish reproduction, which leads to increased availability of native host 
fishes for mussel reproduction. However, Rypel et al. (2009, p. 502) 
indicated that mussels tended to exhibit minimal growth during high 
flow years. Therefore, optimal flooding of these habitats would not be 
too frequent and should occur at similar frequencies to that of the 
natural hydrologic regime of the rivers and creeks inhabited by the 
Neosho mucket

[[Page 63474]]

and rabbitsfoot. Based on the information above, we identify water 
quality, sediment quality, stable habitat, health of fish hosts, diet 
(of all life stages), and periodic flooding of floodplain habitat to be 
physical or biological features for these species.
Primary Constituent Elements (PCEs) for the Neosho Mucket and 
Rabbitsfoot
    Under the Act and its implementing regulations, we are required to 
identify the physical or biological features (PBFs) essential to the 
conservation of Neosho mucket and the rabbitsfoot in areas occupied at 
the time of listing, focusing on the features' primary constituent 
elements. We consider primary constituent elements (PCEs) to be the 
elements of physical or biological features that, when laid out in the 
appropriate quantity and spatial arrangement to provide for a species' 
life-history processes, are essential to the conservation of the 
species.
    In addition to the physical and biological features just described, 
we derive the PCEs from the biological needs of these species as 
described in the STATUS ASSESSMENT FOR NEOSHO MUCKET AND RABBITSFOOT 
section of this proposed rule. Little is known of the specific habitat 
requirements for the Neosho mucket and rabbitsfoot other than that they 
require flowing water, stable river channels, adequate food, suitable 
substrate, and adequate water and sediment quality. Neosho mucket and 
rabbitsfoot mussel larvae also require fish hosts for development to 
juvenile mussels (see STATUS ASSESSMENT FOR NEOSHO MUCKET AND 
RABBITSFOOT section). To identify the physical and biological needs of 
these species, we have relied on current conditions at locations where 
the species survive, the limited information available on these species 
and their close relatives, and factors associated with the decline and 
extirpation of these and other aquatic mollusks from extensive portions 
of the Lower Great Lakes and Lower Mississippi River subbasins and 
Ohio, Cumberland, Tennessee, White, Arkansas, and Red River Basins.
    Based on the above needs and our current knowledge of the physical 
and biological features and habitat characteristics required to sustain 
the species' life-history processes, we determine that the PCEs 
specific to the Neosho mucket and rabbitsfoot are:
    (1) Geomorphically stable river channels and banks (channels that 
maintain lateral dimensions, longitudinal profiles, and sinuosity 
patterns over time without an aggrading or degrading bed elevation) 
with habitats that support a diversity of freshwater mussel and native 
fish (such as, stable riffles, sometimes with runs, and mid-channel 
island habitats that provide flow refuges consisting of gravel and sand 
substrates with low to moderate amounts of fine sediment and attached 
filamentous algae).
    (2) A hydrologic flow regime (the severity, frequency, duration, 
and seasonality of discharge over time) necessary to maintain benthic 
habitats where the species are found and to maintain connectivity of 
rivers with the floodplain, allowing the exchange of nutrients and 
sediment for maintenance of the mussel's and fish host's habitat, food 
availability, spawning habitat for native fishes, and the ability for 
newly transformed juveniles to settle and become established in their 
habitats.
    (3) Water and sediment quality (including, but not limited to, 
conductivity, hardness, turbidity, temperature, pH, ammonia, heavy 
metals, and chemical constituents) necessary to sustain natural 
physiological processes for normal behavior, growth, and viability of 
all life stages.
    (4) The presence and abundance (currently unknown) of fish hosts 
necessary for recruitment of the Neosho mucket and rabbitsfoot. The 
occurrence of natural fish assemblages, reflected by fish species 
richness, relative abundance, and community composition, for each 
inhabited river or creek will serve as an indication of appropriate 
presence and abundance of fish hosts until appropriate host fish can be 
identified.
    (5) Either no competitive or predaceous invasive (nonnative) 
species, or such species in quantities low enough to have minimal 
effect on survival of freshwater mussels.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the specific 
areas within the geographic area occupied by the species at the time of 
listing contain features which are essential to the conservation of the 
species and which may require special management considerations or 
protection.
    Various activities in or adjacent to each critical habitat unit 
described in this proposed rule may affect one or more of the physical 
or biological features and may require special management 
considerations or protection. Some of these activities include, but are 
not limited to, those previously discussed in the ``Summary of Factors 
Affecting the Species.'' The PBFs in all the proposed critical habitat 
units may require special management due to threats posed by 
channelization and other navigation related projects, dams, 
impoundments, land use runoff, and point or nonpoint-source water 
pollution, or both (see Factors A and D). Other activities that may 
affect the features and their component PCEs in the proposed critical 
habitat units include those listed in the ``Effects of Critical Habitat 
Designation'' section below.
    In summary, we find that the areas we are proposing as critical 
habitat that are occupied at the time of listing contain the features 
essential to the conservation of the Neosho mucket and rabbitsfoot, and 
that these features may require special management considerations or 
protections. Special management considerations or protections may be 
required to eliminate, or to reduce to negligible levels, the threats 
affecting each unit and to preserve and maintain the essential physical 
and biological features that the proposed critical habitat units 
provide to the Neosho mucket and rabbitsfoot. Additional discussions of 
threats facing individual sites are provided in the individual unit 
descriptions.

Criteria Used To Identify Proposed Critical Habitat

    As required by section 4(b)(2) of the Act, we use the best 
scientific data available to designate critical habitat. We review 
available information pertaining to the habitat requirements of the 
Neosho mucket and rabbitsfoot. In accordance with the Act and its 
implementing regulation at 50 CFR 424.12(e), we consider whether 
designating additional areas--outside those currently occupied as well 
as those occupied at the time of listing--are necessary to ensure the 
conservation of the species. We are not currently proposing to 
designate any areas outside the geographic area occupied by the species 
because occupied areas are sufficient for the conservation of the 
species.
    When determining proposed critical habitat boundaries, we made 
every effort to avoid including developed areas such as lands covered 
by buildings, pavement, and other structures because such lands usually 
lack physical or biological features for the species. Areas proposed as 
critical habitat for the Neosho mucket and rabbitsfoot include only 
stream channels within the ordinary high-water line, and do not contain 
any developed areas, structures, or areas inundated by lakes and 
reservoirs. The ordinary high-water line defines the stream channel

[[Page 63475]]

and is the point on the stream bank where water is continuous and 
leaves some evidence, such as erosion or aquatic vegetation. The scale 
of the maps we prepared under the parameters for publication within the 
Code of Federal Regulations may not reflect the exclusion of structures 
or other developed areas. Any such areas inadvertently left inside 
critical habitat boundaries shown on the maps of this proposed rule 
have been excluded by text in the proposed rule and are not proposed 
for designation as critical habitat. Therefore, if the critical habitat 
is finalized as proposed, a Federal action involving these areas would 
not trigger section 7 consultation with respect to critical habitat and 
the requirement of no adverse modification unless the specific action 
would affect the physical or biological features in the adjacent 
critical habitat.
    We are proposing for designation of critical habitat areas that we 
have determined are occupied at the time of listing, as defined in this 
proposed rule, and contain sufficient elements of physical or 
biological features to support life-history processes essential for the 
conservation of the Neosho mucket and the rabbitsfoot. The Neosho 
mucket and rabbitsfoot persist in scattered portions of 38 rivers and 
creeks. Distribution and status information pertaining to the Neosho 
mucket and rabbitsfoot was previously discussed in the STATUS 
ASSESSMENT FOR NEOSHO MUCKET AND RABBITSFOOT section. River habitats 
are highly dependent upon upstream and downstream channel habitat 
conditions for their maintenance. Therefore, where one occurrence 
record was known from a river reach, we considered the entire reach 
between the uppermost and lowermost locations as occupied habitat, 
except lakes and reservoirs. We have defined occupied habitat for the 
Neosho mucket as those stream reaches known to be currently extant. For 
the rabbitsfoot, we have defined occupied habitat as those stream 
reaches that are sizeable and small populations as defined by Butler 
(2005), and the marginal populations of Fish Creek, Red River and 
Allegheny River that are the last extant populations in their 
respective basins (Great Lakes and Cumberland) and a metapopulation.
    No unoccupied stream, as defined in this proposed rule, is proposed 
as critical habitat for Neosho mucket and rabbitsfoot. We find that 
unoccupied stream reaches are not essential for the conservation of 
either species for one or more of the following reasons:
    (1) Unoccupied habitats are isolated from occupied habitats due to 
reservoir construction and dam operations (dam water releases have 
altered natural stream hydrology, geomorphology, water temperature, and 
native mollusk and fish communities);
    (2) Unoccupied areas exhibit limited habitat availability, degraded 
habitat, or low potential value for management (Muskingum, Elk, Scioto, 
Little Miami, Licking, East Fork White, Cumberland, Holston, Clinch, 
Sequatchie, and Buffalo (Duck River system) Rivers);
    (3) Collection records for these species indicate that these 
species have been extirpated from unoccupied areas for several decades 
or more; or
    (4) There are no historical records of occurrence within the stream 
reach for Neosho mucket, rabbitsfoot, or both.
    Our analysis concludes that inclusion of unoccupied habitats is not 
essential to conserve these species. While we recognize the importance 
to recovery of unoccupied habitat, in this case, unoccupied habitat 
also does not provide habitat for reintroduction, reduce the level of 
stochastic and human-induced threats, or decrease the risk of 
extinction:
    (1) Unoccupied habitat does not currently contain sufficient 
physical and biological features or have the ability to be restored to 
support life-history functions of the Neosho mucket and rabbitsfoot 
(such characteristics as geomorphically stable channels, perennial 
water flows, adequate water quality, and appropriate benthic 
substrates);
    (2) Unoccupied habitat does not support the once diverse mollusk 
communities, including the presence of closely related species 
requiring physical or biological features similar to the Neosho mucket 
and rabbitsfoot; or
    (3) Unoccupied habitat is not adjacent to currently occupied areas 
where there is potential for natural dispersal and reoccupation by the 
Neosho mucket and rabbitsfoot. A total of 43 units are proposed for 
designation based on sufficient elements of physical or biological 
features being present to support Neosho mucket (8 units) and 
rabbitsfoot (35 units) life-history processes. Some units contained all 
of the identified elements of physical or biological features and 
supported multiple life-history processes. Some units contained only 
some elements of the physical or biological features necessary to 
support the Neosho mucket and rabbitsfoot particular use of that 
habitat.

Proposed Critical Habitat Designation

    When designating critical habitat, we assess whether the areas 
within the geographical area occupied by the species at the time of 
listing contain features that are essential to the conservation of the 
species and whether those features may require special management 
considerations or protection. Three critical habitat units proposed for 
the Neosho mucket and rabbitsfoot are currently designated under the 
Act for the oyster mussel (Epioblasma capsaeformis) and Cumberlandian 
combshell (Epioblasma brevidens) encompassing the Duck River, Tennessee 
(74 rkm, 46 rmi) and Bear Creek, Alabama and Mississippi (40 rkm, 25 
rmi) (50 CFR 17.95(f)) or proposed as critical habitat under the Act 
for the yellowcheek darter (Etheostoma moorei) in the Middle Fork 
Little Red River, Arkansas (23.2 rkm, 14.5 rmi; 76 FR 63360, October 
12, 2011; Table 3). The existing critical habitat for the oyster mussel 
and Cumberlandian combshell completely overlaps Unit RF16 (Bear Creek), 
but the exact unit descriptions (length) differ due to mapping 
refinement since the earlier designation. In addition, five critical 
habitat units proposed for the Neosho mucket and rabbitsfoot are 
currently designated by the State of Kansas as critical habitat for 
both species in the Fall, Spring, Neosho, Cottonwood River, and 
Verdigris Rivers and Neosho mucket in Shoal Creek (K.S.A. 32-959; Table 
3) and are afforded similar state-level protections as those provided 
under the Act. No other critical habitat units proposed for these 
species have been designated or proposed as critical habitat for other 
species under the Act.

[[Page 63476]]



 Table 3--Critical Habitat Areas Proposed for the Neosho Mucket and Rabbitsfoot That Are Currently Designated or
                    Proposed as Critical Habitat for Other Federally and State Listed Species
----------------------------------------------------------------------------------------------------------------
                                                                                                     Length of
      Unit (Unit )         Species present in     Federal reference    State reference    overlap (rkm/
                                           unit                                                        rmi)
----------------------------------------------------------------------------------------------------------------
Shoal Creek (NM3)................  Neosho mucket,        ....................      K.S.A. 32-959         9.7/6.0
                                    fluted shell,
                                    Ouachita
                                    kidneyshell,
                                    Western fanshell,
                                    redspot chub.
Spring River (NM4 and RF1).......  Neosho mucket,        ....................      K.S.A. 32-959        11.6/7.2
                                    rabbitsfoot,
                                    elktoe, ellipse
                                    shell, Neosho
                                    madtom, fluted
                                    shell, Ouachita
                                    kidneyshell,
                                    Western fanshell,
                                    redspot chub.
Fall River (NM6).................  Neosho mucket,        ....................      K.S.A. 32-959       90.4/56.2
                                    Western fanshell.
Verdigris River (NM6 and RF2)....  Neosho mucket,        ....................      K.S.A. 32-959       80.6/50.1
                                    rabbitsfoot,
                                    Ouachita
                                    kidneyshell,
                                    western fanshell,
                                    butterfly.
Neosho River (NM7 and RF3).......  Neosho mucket,        ....................      K.S.A. 32-959     245.9/152.8
                                    rabbitsfoot,
                                    butterfly, Neosho
                                    madtom, Ouachita
                                    kidneyshell,
                                    western fanshell.
Cottonwood River (NM8)...........  Neosho mucket,        ....................      K.S.A. 32-959         2.6/1.6
                                    rabbitsfoot,
                                    butterfly, Ouachita
                                    kidneyshell,
                                    western fanshell.
Middle Fork Little Red River       Yellowcheek darter..  76 FR 63360, October  .................       23.3/14.5
 (RF7).                                                   12, 2011.
Bear Creek (RF16)................  Oyster mussel,        50 CFR 17.95(f).....  .................       49.7/30.9
                                    Cumberland
                                    combshell.
Duck River (RF19)................  Oyster mussel,        50 CFR 17.95(f).....  .................       74.0/46.0
                                    Cumberland
                                    Combshell.
                                                                                                 ---------------
    Total........................  ....................  ....................  .................     587.9/365.3
----------------------------------------------------------------------------------------------------------------

    We are proposing eight units, totaling approximately 779 rkm (484 
rmi), in four states (Arkansas, Kansas, Missouri, and Oklahoma) as 
critical habitat for the Neosho mucket (Table 4). We are proposing 35 
units, totaling approximately 2,662 rkm (1,653.8 rmi), in 12 states 
(Alabama, Arkansas, Illinois, Indiana, Kansas, Kentucky, Missouri, 
Mississippi, Oklahoma, Ohio, Pennsylvania, and Tennessee) as critical 
habitat for the rabbitsfoot (Table 4). Four of the 43 units, Units NM4, 
NM7, RF1, and RF3 are occupied by both Neosho mucket and rabbitsfoot. 
Table 5 summarizes primary adjacent riparian landowners in each of the 
proposed Neosho mucket and rabbitsfoot critical habitat units by 
private, State, Tribal (jurisdictional not ownership), or Federal 
ownership. One Neosho mucket and two rabbitsfoot proposed critical 
habitat units, respectively, are located within Tribal jurisdictional 
areas, Unit NM1 (Illinois River, Oklahoma; 103.0 rkm (64.0 rmi)), Unit 
RF2 (Verdigris River; 45.5 rkm (28.3 rmi)), and Unit RF6 (Little River, 
Oklahoma; 41.4 rkm (25.7 rmi)).
    Public lands adjacent to Neosho mucket and rabbitsfoot critical 
habitat units consist of approximately 505.3 rkm (314.0 rmi) of 
riparian lands in the following units.
     Unit NM1: Ozark National Forest, 20.3 rkm (12.7 rmi) 
Corps' Lake Tenkiller Project, 9.0 rkm (5.6 rmi), and Sparrowhawk 
Wildlife Management Area (WMA), 2.2 rkm (1.4 rmi);
     Units NM4 and RF1: Spring River Wildlife Area, 1.4 rkm 
(0.9 rmi);
     Unit RF2: Corps' Oologah Lake Project, 0.6 rkm (0.4 rmi) 
and Corps' McClellan-Kerr Arkansas River Navigation System Project, 3.4 
rkm (2.1 rmi);
     Unit NM7: Neosho Wildlife Area 6.1 rkm (3.8 rmi);
     Unit RF4a: Ouachita National Forest, 21.8 rkm (13.6 rmi);
     Unit RF5: Jenkins' Ferry State Park, 22.2 rkm (13.9 rmi);
     Unit RF6: Little River NWR, 37.6 rkm (23.5 rmi), Ouachita 
National Forest 16.0 rkm (10.0 rmi), and Cossatot NWR, 11.5 rkm (7.2 
rmi);
     Unit RF8a: Jacksonport State Park, 2.9 rkm (1.8 rmi) and 
Henry Gray-Hurricane Lake WMA, 7.8 rkm (4.9 rmi);
     Unit RF8b: White River NWR, 57.6 rkm (36.0 rmi);
     Unit RF9: Shirey Bay Rainey Brake WMA, 10.1 rkm (6.3 rmi);
     Unit RF10: Harold Alexander WMA, 1.1 rkm (0.7 rmi);
     Unit RF13: Buffalo National River, 113.6 rkm (70.6 rmi);
     Unit RF14: Sam A. Baker State Park 1.0 rkm (0.6 rmi) and 
Corps' Wappapello Lake Project 25.1 rkm (15.7 rmi);
     Unit RF16: Tishomingo State Park, 6.1 rkm (3.8 rmi), NPS 
Natchez Trace Parkway, 4.5 rkm (2.8 rmi), and TVA Pickwick Lake 
Project, 7.4 rkm (4.6 rmi);
     Unit RF18: Fern Cave NWR, 0.5 rkm (0.3 rmi);
     Unit RF19: Yanahli WMA, 38.9 rkm (24.3 rmi) and Santa Fe 
County Park, 1.4 rkm (0.9 rmi);
     Unit RF20a: Shiloh National Military Park, 2.6 rkm (1.6 
rmi);
     Unit RF20b: Kentucky Dam Village State Resort Park, 0.6 
rkm (0.4 rmi) and unnamed TVA land downstream of Kentucky Lake Dam, 2.4 
rkm (1.5 rmi);
     Unit RF21: Massac Forest Nature Preserve, 2.2 rkm (1.4 
rmi), West Kentucky WMA, 5.6 rkm (3.5 rmi), Ballard WMA, 2.6 rkm (1.6 
rmi) and Chestnut Hills Nature Preserve, 2.4 rkm (1.5 rmi);
     Unit RF22: Mammoth Cave National Park, 17.0 rkm (10.6 
rmi);
     Unit RF23: Pennsylvania State Game Land 277, 2.9 rkm (1.8 
rmi) and Pennsylvania State Game Land 85, 0.6 rkm (0.4 rmi);
     Unit RF24: Clear Creek State Forest, 9.9 rkm (6.2 rmi);
     Unit RF25: Erie NWR, 16.2 rkm (10.1 rmi) in;
     Unit RF26: Prophetstown State Park, 2.1 rkm (1.3 rmi);
     Unit RF27: Muskingum Watershed Conservancy Land, 5.0 rkm 
(3.1 rmi);
     Unit RF28: Little Darby State Scenic Waterway-River Lands, 
8.7 rkm (5.4 rmi);
     Unit RF30: Fish Creek Wildlife Area, 1.6 rkm (1.0 rmi); 
and
     Unit RF32: Corps' Shenango River Lake Project, 8.8 rkm 
(5.5 rmi).

[[Page 63477]]



Table 4--Occupancy of Neosho Mucket and Rabbitsfoot by Proposed Critical
                              Habitat Units
------------------------------------------------------------------------
                                            Approximate river distances
                                             currently occupied by the
                 Species                              species
                                         -------------------------------
                                             River km       River miles
------------------------------------------------------------------------
Neosho mucket...........................           779.1           484.1
Rabbitsfoot.............................         2,661.5         1,653.8
                                         -------------------------------
    Total...............................         3,440.6         2,137.9
------------------------------------------------------------------------
    Species, stream (unit), and State           Currently occupied
------------------------------------------------------------------------
Neosho mucket:
    Unit NM1, Illinois River AR, OK.....           146.1            90.8
    Unit NM2, Elk River, MO, OK.........            20.3            12.6
    Unit NM3, Shoal Creek, KS, MO.......            75.8            47.1
    Unit NM4, Spring River, KS, MO......           102.3            63.6
    Unit NM5, North Fork Spring River,              16.4            10.2
     MO.................................
    Unit NM6, Fall and Verdigris Rivers,           171.1           106.3
     KS.................................
    Unit NM7, Neosho River, KS..........           244.5           151.9
    Unit NM8, Cottonwood River, KS......             2.6             1.6
                                         -------------------------------
        Total...........................           779.1           484.1
                                         -------------------------------
Rabbitsfoot:
    Unit RF1, Spring River, MO, KS......            56.5            35.1
    Unit RF2, Verdigris River, OK.......            45.5            28.3
    Unit RF3, Neosho River, KS..........            26.6            16.5
    Unit RF4a, Ouachita River, AR.......            21.9            13.6
    Unit RF4b, Ouachita River, AR.......           157.9            98.1
    Unit RF5, Saline River, AR..........           288.4           179.2
    Unit RF6, Little River, OK, AR......           139.7            86.8
    Unit RF7, Middle Fork Little Red                23.3            14.5
     River, AR..........................
    Unit RF8a, White River, AR..........           188.3           117.0
    Unit RF8b, White River, AR..........            68.9            42.8
    Unit RF9, Black River, AR...........            92.2            57.3
    Unit RF10, Spring River, AR.........            62.8            39.0
    Unit RF11, South Fork Spring River,             16.4            10.2
     AR.................................
    Unit RF12, Strawberry River, AR.....           123.8            76.9
    Unit RF13, Buffalo River, AR........           113.6            70.6
    Unit RF14, St. Francis River, MO....            64.3            40.0
    Unit RF15, Big Sunflower River, MS..            51.5            32.0
    Unit RF16, Bear Creek, AL, MS.......            49.7            30.9
    Unit RF17, Big Black River, MS......            43.3            26.9
    Unit RF18, Paint Rock River, AL.....            81.0            50.3
    Unit RF19, Duck River, TN...........           235.3           146.2
    Unit RF20a, Tennessee River, TN.....            26.7            16.6
    Unit RF20b, Tennessee River, KY.....            35.6            22.1
    Unit RF21, Ohio River, KY, IL.......            45.9            28.5
    Unit RF22, Green River, KY..........           175.6           109.1
    Unit RF23, French Creek, PA.........           120.4            74.8
    Unit RF24, Allegheny River, PA......            57.3            35.6
    Unit RF25, Muddy Creek, PA..........            20.1            12.5
    Unit RF26, Tippecanoe River, IN.....            75.6            47.0
    Unit RF27, Walhonding River, OH.....            17.5            10.9
    Unit RF28, Little Darby Creek, OH...            33.3            20.7
    Unit RF29, North Fork Vermilion                 28.5            17.7
     River and Middle Branch North Fork
     Vermilion River, IL................
    Unit RF30, Fish Creek, OH...........             7.7             4.8
    Unit RF31, Red River, KY, TN........            50.2            31.2
    Unit RF32, Shenango River, PA.......            16.3            10.1
                                         -------------------------------
         Total..........................         2,661.5         1,653.8
------------------------------------------------------------------------

    States were granted ownership of lands beneath navigable waters up 
to the ordinary high-water line upon achieving statehood (Pollard v. 
Hagan, 44 U.S. (3 How.) 212 (1845)). Prior to statehood, the American 
colonies may have made grants to private parties that included lands 
below the ordinary high-water mark of some navigable waters that are 
included in this proposal. However, most, if not all, lands beneath the 
navigable waters included in this proposed rule are owned by the 
States. Riparian lands along the waters are either in private 
ownership, or owned by municipalities, States, or Federal entities 
(Table 5).

[[Page 63478]]



   Table 5--Proposed Critical Habitat Units for Neosho Mucket and Rabbitsfoot and Ownership of Riparian Lands
----------------------------------------------------------------------------------------------------------------
                                                                                                    Tribal *
                                                              State & local                        (subset of
         Critical habitat units           Federal rkm; rmi   government rkm;  Private rkm; rmi    private) rkm;
                                                                   rmi                                 rmi
----------------------------------------------------------------------------------------------------------------
                                                  Neosho Mucket
----------------------------------------------------------------------------------------------------------------
Unit NM1: Illinois River................        29.4; 18.3          2.3; 1.4       114.4; 71.1       103.0; 64.0
Unit NM2: Elk River.....................                 0                 0        20.3; 12.6                 0
Unit NM3: Shoal Creek...................                 0                 0        75.8; 47.1                 0
Unit NM4: Spring River..................                 0          1.4; 0.9       100.9; 62.7                 0
Unit NM5: North Fork Spring River.......                 0                 0        16.4; 10.2                 0
Unit NM6: Fall River....................                 0                 0        90.4; 56.2                 0
Unit NM6: Verdigris River...............                 0                 0        80.6; 50.1                 0
Unit NM7: Neosho River..................                 0          6.1; 3.8      238.3; 148.1                 0
Unit NM8: Cottonwood River..............                 0                 0          2.6; 1.6                 0
                                         -----------------------------------------------------------------------
    Total...............................        29.4; 18.3          9.8; 6.1      739.8; 459.7       103.0; 64.0
----------------------------------------------------------------------------------------------------------------
                                                   Rabbitsfoot
----------------------------------------------------------------------------------------------------------------
Unit RF1: Spring River..................                 0          1.4; 0.9        55.0; 34.2                 0
Unit RF2: Verdigris River...............          4.0; 2.5                 0        41.5; 25.8        41.5; 25.8
Unit RF3: Neosho River..................                 0                 0        26.6; 16.5                 0
Unit RF4a: Ouachita River...............          3.9; 2.4                 0        18.0; 11.2                 0
Unit RF4b: Ouachita River...............                 0                 0       157.9; 98.1                 0
Unit RF5: Saline River..................                 0        22.3; 13.9      266.0; 165.3                 0
Unit RF6: Little River..................        63.9; 39.7                 0        75.8; 47.1        41.4; 25.7
Unit RF7: Middle Fork Little Red River..                 0                 0        23.3; 14.5                 0
Unit RF8a: White River..................                 0         10.8; 6.7      177.5; 110.3                 0
Unit RF8b: White River..................        57.9; 36.0                 0         10.9; 6.8                 0
Unit RF9: Black River...................                 0         10.1; 6.3        82.1; 51.0                 0
Unit RF10: Spring River.................                 0          1.1; 0.7        61.6; 38.3                 0
Unit RF11: South Fork Spring River......                 0                 0        16.4; 10.2                 0
Unit RF12: Strawberry River.............                 0                 0       123.8; 76.9                 0
Unit RF13: Buffalo River................       113.6; 70.6                 0                 0                 0
Unit RF14: St. Francis River............        25.2; 15.7          1.0; 0.6        38.1; 23.7                 0
Unit RF15: Big Sunflower River..........                 0                 0        51.5; 32.0                 0
Unit RF16: Bear Creek...................         11.9; 7.4          6.1; 3.8        31.7; 19.7                 0
Unit RF17: Big Black River..............                 0                 0        43.3; 26.9                 0
Unit RF18: Paint Rock River.............          0.5; 0.3                 0        80.5; 50.0                 0
Unit RF19: Duck River...................                 0        40.5; 25.2      194.7; 121.0                 0
Unit RF20a: Tennessee River.............          2.6; 1.6                 0        24.1; 15.0                 0
Unit RF20b: Tennessee River.............          2.4; 1.5          0.6; 0.4        32.5; 20.2                 0
Unit RF21: Ohio River...................                 0         12.9; 8.0        33.0; 20.5                 0
Unit RF22: Green River..................        17.0; 10.6                 0       158.5; 98.5                 0
Unit RF23: French Creek.................                 0          3.5; 2.2       116.8; 72.6                 0
Unit RF24: Allegheny River..............                 0         10.0; 6.2        47.3; 29.4                 0
Unit RF25: Muddy Creek..................        16.3; 10.1                 0          3.9; 2.4                 0
Unit RF26: Tippecanoe River.............                 0          2.1; 1.3        73.5; 45.7                 0
Unit RF27: Walhonding River.............                 0          5.0; 3.1         12.6; 7.8                 0
Unit RF28: Little Darby Creek...........                 0          8.7; 5.4        24.6; 15.3                 0
Unit RF29: North Fork Vermilion River                    0                 0        28.5; 17.7                 0
 and Middle Branch North Fork Vermilion
 River..................................
Unit RF30: Fish Creek...................                 0          1.6; 1.0          6.1; 3.8                 0
Unit RF31: Red River....................                 0                 0        50.2; 31.2                 0
Unit RF32: Shenango River...............          8.8; 5.5                 0          7.4; 4.6                 0
                                         -----------------------------------------------------------------------
    Total...............................      328.1; 203.9       137.9; 85.7  2,195.7; 1,364.4        86.9; 54.0
                                         -----------------------------------------------------------------------
        Total for both species..........      357.6; 222.2       147.7; 91.8  2,935.6; 1,824.1      189.9; 118.0
----------------------------------------------------------------------------------------------------------------
Note: Distances may not sum due to rounding.
* Tribal Jurisdictional Area only, does not represent riparian land ownership by any tribe and is a subset of
  the private lands category.

    We present brief descriptions of all units and reasons why they 
meet the definition of critical habitat for the Neosho mucket and 
rabbitsfoot. River-kilometer totals presented in the Unit descriptions 
below are the sums of Federal; State and local government; and private 
lands (Tribal lands are a subset of private lands). Proposed critical 
habitat units include the river channels within the ordinary high-water 
line. As defined in 33 CFR 329.11, the ordinary high-water mark on 
nontidal rivers is the line on the shore established by the 
fluctuations of water and indicated by physical characteristics, such 
as a clear, natural line impressed on the bank; shelving;

[[Page 63479]]

changes in the character of soil; destruction of terrestrial 
vegetation; the presence of litter and debris; or other appropriate 
means that consider the characteristics of the surrounding areas. For 
each stream reach proposed as a critical habitat unit, the upstream and 
downstream boundaries are described generally below.
Neosho Mucket
    Neosho mucket status and distribution for each critical habitat 
unit was previously described in the STATUS ASSESSMENT FOR NEOSHO 
MUCKET AND RABBITSFOOT section.

Unit NM1: Illinois River--Benton and Washington Counties, Arkansas; and 
Adair, Cherokee, and Delaware Counties, Oklahoma

    Unit NM1 includes 146.1 rkm (90.8 rmi) of the Illinois River from 
the Muddy Fork Illinois River confluence with the Illinois River south 
of Savoy, Washington County, Arkansas, downstream to the Baron Creek 
confluence southeast of Tahlequah, Cherokee County, Oklahoma. This unit 
was occupied at the time of listing and contains all or some components 
of all four PBFs and contains PCEs 2, 3, 4, and 5. The PBFs in this 
unit may require special management considerations or protection to 
address changes in stream channel stability associated with urban 
development and clearing of riparian areas due to land use conversion 
in the watershed; alteration of water chemistry or water and sediment 
quality; and changes in stream bed material composition and quality 
from activities that would release sediments or nutrients into the 
water, such as urban development and associated construction projects, 
livestock grazing, confined animal operations, and timber harvesting 
(see Factor A). The majority of the adjacent riparian lands in this 
unit are in private ownership or private lands under tribal 
jurisdiction (Table 5).

Unit NM2: Elk River--McDonald County, Missouri; and Delaware County, 
Oklahoma

    Unit NM2 includes a total of 20.3 rkm (12.6 rmi) of the Elk River 
from Missouri Highway 59 at Noel, McDonald County, Missouri, to the 
confluence of Buffalo Creek immediately downstream of the Oklahoma and 
Missouri State line, Delaware County, Oklahoma. This unit was occupied 
at the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes in 
the existing flow regime due to such activities as impoundment, water 
diversion, or water withdrawal; alteration of water chemistry or water 
quality; and changes in stream bed material composition and sediment 
quality from activities that would release sediments or nutrients into 
the water, such as urban development and associated construction 
projects, livestock grazing, confined animal operations (turkey and 
chicken), timber harvesting, and mining (see Factor A). All the 
adjacent riparian lands in this unit are in private ownership (Table 
5).

Unit NM3: Shoal Creek--Cherokee County, Kansas; and Newton County, 
Missouri

    Unit NM3 includes approximately 75.8 rkm (47.1 rmi) of Shoal Creek 
from Missouri Highway W near Ritchey, Newton County, Missouri, to 
Empire Lake where inundation begins in Cherokee County, Kansas. This 
unit was occupied at the time of listing and contains all or some 
components of all four PBFs and contains all five PCEs. The PBFs in 
this unit may require special management considerations or protections 
to address changes to the same activities as discussed in Unit NM2 
above and releases of chemical contaminants from industrial and 
municipal effluents (see Factor A). All adjacent riparian lands in this 
unit are in private ownership (Table 5).

Unit NM4: Spring River--Jasper and Lawrence Counties, Missouri; and 
Cherokee County, Kansas

    Unit NM4 includes 102.3 rkm (63.6 rmi) of the Spring River from 
Missouri Highway 97 north of Stotts City, Lawrence County, Missouri, 
downstream to the confluence of Turkey Creek north of Empire, Cherokee 
County, Kansas. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and contains all five 
PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes to the same activities 
as discussed in Unit NM2 above and releases of chemical contaminants 
from industrial and municipal effluents. Almost all (99 percent) of the 
adjacent riparian lands in this unit are in private ownership (Table 
5).

Unit NM5: North Fork Spring River--Jasper County, Missouri

    Unit NM5 includes 16.4 rkm (10.2 rmi) of the North Fork Spring 
River from the confluence of Buck Branch southwest of Jasper, Missouri, 
downstream to its confluence with the Spring River near Purcell, Jasper 
County, Missouri. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and contains all five 
PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes to the same activities 
as discussed in Unit NM2 above. All adjacent riparian lands in this 
unit are in private ownership (Table 5).

Unit NM6: Fall River--Elk, Greenwood, and Wilson Counties, Kansas; 
Verdigris River--Montgomery and Wilson Counties, Kansas

    Unit NM6 includes a total of 171.1 rkm (106.3 rmi) including 90.4 
rkm (56.2 rmi) of the Fall River from Fall River Lake dam northwest of 
Fall River, Greenwood County, Kansas, downstream to its confluence with 
the Verdigris River near Neodesha, Wilson County, Kansas. Unit NM6 also 
includes 80.6 rkm (50.1 rmi) of the Verdigris River from Kansas Highway 
39 near Benedict, Wilson County, Kansas downstream to the Elk River 
confluence near Independence, Montgomery County, Kansas. This unit was 
occupied at the time of listing and contains all or some components of 
all four PBFs and contains all five PCEs. The PBFs in this unit may 
require special management considerations or protections to address 
changes to the same activities as discussed in Unit NM2 above. All 
adjacent riparian lands in this unit are in private ownership (Table 
5).

Unit NM7: Neosho River--Allen, Cherokee, Coffey, Labette, Neosho, and 
Woodson Counties, Kansas

    Unit NM7 includes 244.5 rkm (151.9 rmi) of the Neosho River from 
Kansas Highway 58 west of LeRoy, Coffey County, Kansas, downstream to 
the Kansas and Oklahoma State line, Cherokee County, Kansas. This unit 
was occupied at the time of listing and contains all or some components 
of all four PBFs and contains all five PCEs. The PBFs in this unit may 
require special management considerations or protections to address 
changes previously to the same activities as discussed in Unit NM2 
above and releases of chemical contaminants from industrial and 
municipal effluents and tail water releases downstream of John Redmond 
Reservoir. All adjacent riparian lands in this unit are in private 
ownership (Table 5).

Unit NM8: Cottonwood River--Chase County, Kansas

    Unit NM8 includes 2.6 rkm (1.6 rmi) of the Cottonwood River from 
the South Fork Cottonwood River confluence downstream to the Kansas 
Road 140

[[Page 63480]]

(also known as Heins Road), east of Cottonwood Falls, Chase County, 
Kansas. This unit was occupied at the time of listing and contains all 
or some components of all four PBFs and contains all five PCEs. The 
PBFs in this unit may require special management considerations or 
protection to address changes in stream channel stability associated 
with clearing of riparian areas due to land use conversion in the 
watershed; alteration of water chemistry or water and sediment quality; 
and changes in stream bed material composition and quality from 
activities that would release sediments or nutrients into the water, 
such as urban development and associated construction projects, 
livestock grazing, and release of contaminants from municipal effluents 
(see Factor A). All adjacent riparian lands in this unit are in private 
ownership (Table 5).
Rabbitsfoot
    Rabbitsfoot status and distribution for each critical habitat unit 
was previously described in the STATUS ASSESSMENT FOR NEOSHO MUCKET AND 
RABBITSFOOT section.
    The PBFs in units RF1 through RF32 may require special management 
considerations to address changes in the existing flow regime due to 
such activities as impoundment, water diversion, or water withdrawal; 
alteration of water chemistry or water quality; and changes in stream 
bed material composition and sediment quality from activities that 
would release sediments or nutrients into the water, such as urban 
development and associated construction projects, livestock grazing, 
confined animal operations (turkey and chicken), timber harvesting, and 
mining, and releases of chemical contaminants from industrial and 
municipal effluents (see Factor A). Where there are other activities in 
individual units requiring special management considerations, they are 
set forth in the individual unit descriptions.

Unit RF1: Spring River--Jasper County, Missouri; and Cherokee County, 
Kansas

    Unit RF1 includes 56.5 rkm (35.1 rmi) of the Spring River from 
Missouri Highway 96 at Carthage, Jasper County, Missouri, downstream to 
the confluence of Turkey Creek north of Empire, Cherokee County, 
Kansas. This unit was occupied at the time of listing and contains all 
or some components of all four PBFs and contains all five PCEs. The 
PBFs in this unit may require special management considerations or 
protections described above. The majority of the adjacent riparian 
lands in this unit are in private ownership or private lands under 
tribal jurisdiction (Table 5).

Unit RF2: Verdigris River--Rogers County, Oklahoma

    Unit RF2 includes 45.5 rkm (28.3 rmi) of the Verdigris River from 
Oologah Lake dam north of Claremore, Oklahoma, downstream to Interstate 
44 (Will Rogers Turnpike) west of Catoosa, Rogers County, Oklahoma. 
This unit was occupied at the time of listing and contains all or some 
components of all four PBFs and in part, contains all five PCEs. It is 
possible that PCEs 1 and 2 are limiting factors for rabbitsfoot 
distribution and abundance from Oologah Lake dam downstream to the 
confluence of the Caney River; thus we are unable to determine at this 
time whether this reach contains PCEs 1 and 2. The PBFs in this unit 
may require special management considerations or protections as 
described above and changes in the existing flow regime due to such 
activities as impoundment, tail water releases from Oologah Lake dam, 
and channelization associated with the McClellan-Kerr Arkansas River 
Navigation System. The majority of the adjacent riparian lands in this 
unit are in private ownership or private lands under tribal 
jurisdiction (Table 5).

Unit RF3: Neosho River--Allen County, Kansas

    Unit RF3 includes 26.6 rkm (16.5 rmi) of the Neosho River from the 
Deer Creek confluence northwest of Iola, Kansas, downstream to the 
confluence of Owl Creek southwest of Humboldt, Allen County, Kansas. 
This unit was occupied at the time of listing and contains all or some 
components of all four PBFs and contains all five PCEs. The PBFs in 
this unit may require special management considerations or protections 
to address changes described above except for releases of chemical 
contaminants from industrial and municipal effluents. Approximately 97 
percent of the adjacent riparian lands in this unit are in private 
ownership and the remaining lands in State or local ownership (Table 
5).

Unit RF4a: Ouachita River--Montgomery County, Arkansas

    Unit RF4a includes 21.9 rkm (13.6 rmi) of the Ouachita River from 
Arkansas Highway 379 south of Oden, Montgomery County, Arkansas, 
downstream to Arkansas Highway 298 east of Pencil Bluff, Montgomery 
County, Arkansas. Units RF4a and RF4b are separated by three reservoirs 
(Lakes Ouachita, Hamilton, and Catherine). This unit was occupied at 
the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes 
described above. Approximately 82 percent of the adjacent riparian 
lands in this unit are in private ownership and the remaining 18 
percent are in Federal ownership (Table 5).

Unit RF4b: Ouachita River--Clark, Hot Spring, and Ouachita Counties, 
Arkansas

    Unit RF4b includes 157.9 rkm (98.1 rmi) of the Ouachita River from 
Interstate 30 at Malvern, Hot Spring County, Arkansas, downstream to 
U.S. Highway 79 at Camden, Ouachita County, Arkansas. This unit was 
occupied at the time of listing and contains all or some components of 
all four PBFs and contains all five PCEs. The PBFs in this unit may 
require special management considerations or protections to address 
changes described above. All the adjacent riparian lands in this unit 
are in private ownership (Table 5).

Unit RF5: Saline River--Ashley, Bradley, Cleveland, Dallas, Drew, 
Grant, and Saline Counties, Arkansas

    Unit RF5 includes 288.4 rkm (179.2 rmi) of the Saline River from 
Interstate 30 near Benton, Saline County, Arkansas, to the Snake Creek 
confluence north of the northern boundary of Felsenthal NWR northwest 
of Crossett, Ashley, and Bradley Counties, Arkansas. This unit was 
occupied at the time of listing and contains all or some components of 
all four PBFs and contains all five PCEs. The PBFs in this unit may 
require special management considerations or protections to address 
changes described above. Approximately 92 percent of the adjacent 
riparian lands in this unit are in private ownership and 8 percent are 
in State or local ownership (Table 5).

Unit RF6: Little River--McCurtain County, Oklahoma; and Little River 
and Sevier Counties, Arkansas

    Unit RF6 includes 139.7 rkm (86.8 rmi) of the Little River from the 
Glover River confluence northwest of Idabel, McCurtain County, 
Oklahoma, downstream to U.S. Highway 71 north of Wilton, Little River 
and Sevier Counties, Arkansas. This unit was occupied at the time of 
listing and contains all or some components of all four PBFs and 
contains all five PCEs. The PBFs in this unit may require special 
management considerations or protections to address changes described 
above. Adjacent riparian

[[Page 63481]]

lands in this unit are in private ownership (42 percent), Federal (35 
percent), and private land under tribal jurisdiction (23 percent) 
(Table 5).

Unit RF7: Middle Fork Little River--Van Buren County, Arkansas

    Unit RF7 includes 23.3 rkm (14.5 rmi) of the Middle Fork Little Red 
River from the confluence of Little Tick Creek north of Shirley, 
Arkansas, downstream to Greers Ferry Reservoir where inundation begins, 
Van Buren County, Arkansas. This unit was occupied at the time of 
listing and contains all or some components of all four PBFs and 
contains all five PCEs. The PBFs in this unit may require special 
management considerations or protections to address changes described 
above and natural gas development and hillside rock harvesting. All 
adjacent riparian lands in this unit are in private ownership (Table 
5).

Unit RF8a: White River--Independence, Jackson, White, and Woodruff 
Counties, Arkansas

    Unit RF8a includes 188.3 rkm (117.0 rmi) of the White River from 
the Batesville Dam at Batesville, Independence County, Arkansas, 
downstream to the Little Red River confluence north of Georgetown, 
White, and Woodruff Counties, Arkansas. There are no records of 
rabbitsfoot from the 160 rkm (100 rmi) reach separating Unit RF8a from 
Unit RF8b (Butler 2005, p. 66). This unit was occupied at the time of 
listing and contains all or some components of all four PBFs and 
contains PCEs 2, 3, 4, and 5. The U.S. Army Corps of Engineers 
maintains a navigation channel, which involves routine dredging and 
snag removal, from Newport, Arkansas to its confluence with the 
Mississippi River. The PBFs in this unit may require special management 
considerations or protections described above except for releases of 
chemical contaminants from industrial and municipal effluents and 
including tail water releases from a series of reservoirs on the upper 
White River, row crop agriculture, increasing demand for instream sand 
from the White River upstream of Newport, Arkansas, to support natural 
gas development needs, natural gas development, and channelization. 
Adjacent riparian lands in this unit are in private ownership (94 
percent) and State and local ownership (6 percent) (Table 5).

Unit RF8b: White River--Arkansas and Monroe Counties, Arkansas

    Unit RF8b includes 68.9 rkm (42.8 rmi) of the White River from U.S. 
Highway 79 at Clarendon, Monroe County, Arkansas, downstream to 
Arkansas Highway 1 near St. Charles, Arkansas County, Arkansas. This 
unit was occupied at the time of listing and contains all or some 
components of all four PBFs and contains PCEs 2, 3, 4, and 5. The U.S. 
Army Corps of Engineers maintains a navigation channel, which involves 
routine dredging and snag removal, from Newport, Arkansas, to its 
confluence with the Mississippi River. The PBFs in this unit may 
require special management considerations or protections described 
above except for releases of chemical contaminants from industrial and 
municipal effluents and including tail water releases from a series of 
reservoirs on the upper White River, row crop agriculture, increasing 
demand for instream sand from the White River upstream of Newport, 
Arkansas, to support natural gas development needs, natural gas 
development, and channelization. Approximately 84 percent of the 
adjacent riparian lands in this unit are in Federal ownership and 16 
percent are in private ownership (Table 5).

Unit RF9: Black River--Lawrence and Randolph Counties, Arkansas

    Unit RF9 includes 92.2 rkm (57.3 rmi) of the Black River from U.S. 
Highway 67 at Pocahontas, Randolph County, Arkansas, downstream to the 
Strawberry River confluence southeast of Strawberry, Lawrence County, 
Arkansas. This unit was occupied at the time of listing and contains 
all or some components of all four PBFs and contains all five PCEs. The 
PBFs in this unit may require special management considerations or 
protections to address changes described above and including row crop 
agriculture. Approximately 89 percent of the adjacent riparian lands in 
this unit are in private ownership and 11 percent are in State or local 
ownership (Table 5).

Unit RF10: Spring River--Lawrence, Randolph, and Sharp Counties, 
Arkansas

    Unit RF10 includes 62.8 rkm (39.0 rmi) of the Spring River from 
U.S. Highway 412 and 62 at Hardy in Sharp County, Arkansas, downstream 
to its confluence with the Black River east of Black Rock, Lawrence, 
and Randolph Counties, Arkansas. This unit was occupied at the time of 
listing and contains all or some components of all four PBFs and 
contains all five PCEs. The PBFs in this unit may require special 
management considerations or protections to address changes described 
above. Approximately 99 percent of the adjacent riparian lands in this 
unit are in private ownership and almost 1 percent is in State or local 
ownership (Table 5).

Unit RF11: South Fork Spring River--Fulton County, Arkansas

    Unit RF11 includes 16.4 rkm (10.2 rmi) of the South Fork Spring 
River from Fulton County Road 198 north of Heart, Arkansas, downstream 
to Arkansas Highway 289 at Saddle, Fulton County, Arkansas. This unit 
was occupied at the time of listing and contains all or some components 
of all four PBFs and contains all five PCEs. The PBFs in this unit may 
require special management considerations or protections to address 
changes described above. All of the adjacent riparian lands in this 
unit are in private ownership (Table 5).

Unit RF12: Strawberry River--Izard, Lawrence, and Sharp Counties, 
Arkansas

    Unit RF12 includes 123.8 rkm (76.9 rmi) of the Strawberry River 
from Arkansas Highway 56 south of Horseshoe Bend, Izard County, 
Arkansas, downstream to its confluence with the Black River southeast 
of Strawberry, Lawrence County, Arkansas. This unit was occupied at the 
time of listing and contains all or some components of all four PBFs 
and contains all five PCEs. The PBFs in this unit may require special 
management considerations or protections to address changes described 
above. All of the adjacent riparian lands in this unit are in private 
ownership (Table 5).

Unit RF13: Buffalo River--Newton and Searcy Counties, Arkansas

    Unit RF13 includes 113.6 rkm (70.6 rmi) of the Buffalo River from 
the Cove Creek confluence southeast of Erbie, Newton County, Arkansas, 
downstream to U.S. Highway 65 west of Gilbert, Searcy County, Arkansas, 
and Arkansas Highway 14 southeast of Mull, Arkansas, downstream to the 
Leatherwood Creek confluence in the Lower Buffalo Wilderness Area, 
Arkansas. This unit was occupied at the time of listing and contains 
all or some components of all four PBFs and contains all five PCEs. The 
PBFs in this unit may require special management considerations or 
protections to address changes described above. All of the adjacent 
riparian lands in this unit are in Federal ownership (Table 5).

Unit RF14: St. Francis River--Madison and Wayne Counties, Missouri

    Unit RF14 includes 64.3 rkm (40.0 rmi) of the St. Francis River 
from the Twelvemile Creek confluence west of

[[Page 63482]]

Saco, Madison County, Missouri, downstream to Lake Wappepello where 
inundation begins, Wayne County, Missouri. This unit was occupied at 
the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes 
described above. Adjacent riparian lands in this unit are in private 
(59 percent), Federal (39 percent), and less than 2 percent in State or 
local ownership (Table 5).

Unit RF15: Big Sunflower River--Sunflower County, Mississippi

    Unit RF15 includes 51.5 rkm (32.0 rmi) of the Big Sunflower River 
from Mississippi Highway 442 west of Doddsville, Mississippi, 
downstream to the Quiver River confluence east of Indianola, Sunflower 
County, Mississippi. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and contains all five 
PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes described above and 
row crop agriculture and channelization. All of the adjacent riparian 
lands in this unit are in private ownership (Table 5).

Unit RF16: Bear Creek--Tishomingo County, Mississippi; and Colbert 
County, Alabama

    Unit RF16 includes 49.7 rkm (30.9 rmi) of Bear Creek from the 
Alabama and Mississippi State line east of Golden, Tishomingo County, 
Mississippi, downstream to Alabama County Road 4 southwest of Sutton 
Hill, Colbert County, Alabama (just upstream of Pickwick Lake). Unit 
RF16 in its entirety is currently designated as critical habitat for 
the oyster mussel (Epioblasma capsaeformis) and Cumberlandian combshell 
(Epioblasma brevidens; 50 CFR 17.95(f)). This unit was occupied at the 
time of listing and contains all or some components of all four PBFs, 
except in the Bear Creek Floodway, which has been channelized for flood 
control and only contains components of PBF 2 and contains all five 
PCEs, except in the Bear Creek Floodway, which has been channelized for 
flood control and only contains PCEs 3, 4, and 5. The PBFs in this unit 
may require special management considerations or protections to address 
changes described above. Adjacent riparian lands in this unit are in 
private (64 percent), Federal (24 percent), and 12 percent in State or 
local ownership (Table 5).

Unit RF17: Big Black River--Hinds and Warren Counties, Mississippi

    Unit RF17 includes 43.3 rkm (26.9 rmi) of Big Black River from 
Porter Creek confluence west of Lynchburg, Hinds County, Mississippi, 
downstream to Mississippi Highway 27 west of Newman, Warren County, 
Mississippi. This unit was occupied at the time of listing and contains 
all or some components of all four PBFs and contains all five PCEs. The 
PBFs in this unit may require special management considerations or 
protections to address changes described above, as well as row crop 
agriculture and channelization. All riparian lands in this unit are in 
private ownership (Table 5).

Unit RF18: Paint Rock River--Jackson, Madison, and Marshall Counties, 
Alabama

    Unit RF18 includes 81.0 rkm (50.3 rmi) of the Paint Rock River from 
the convergence of Estill Fork and Hurricane Creek north of Skyline, 
Jackson County, Alabama, downstream to U.S. Highway 431 south of New 
Hope, Madison and Marshall Counties, Alabama. This unit was occupied at 
the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes 
described above as well as row crop agriculture and channelization. 
Approximately 99 percent of the adjacent riparian lands in this unit 
are in private ownership and one percent is in Federal ownership (Table 
5).

Unit RF19: Duck River--Hickman, Marshall, and Maury Counties, Tennessee

    Unit RF19 includes 235.3 rkm (146.2 rmi) of the Duck River from 
Lillard Mill (RKM 288; rmi 179) west of Tennessee Highway 272, Marshall 
County, Tennessee, downstream to Interstate 40 near Bucksnort, Hickman 
County, Tennessee. Seventy-four rkm (46 rmi) in Unit RF19 from rkm 214 
(rmi 133) upstream to Lillards Mill at rkm 288 (rmi 179) is currently 
designated as critical habitat for the oyster mussel and Cumberlandian 
combshell (50 CFR 17.95(f)).
    This unit was occupied at the time of listing and contains all or 
some components of all four PBFs and contains all five PCEs. The PBFs 
in this unit may require special management considerations or 
protections to address changes described above as well as row crop 
agriculture and channelization. Approximately 83 percent of the 
adjacent riparian lands in this unit are in private ownership and 17 
percent are in State or local ownership (Table 5).

Unit RF20a: Tennessee River--Hardin County, Tennessee

    Unit RF20a includes 26.7 rkm (16.6 rmi) of Tennessee River from 
Pickwick Lake Dam downstream to U.S. Highway 64 near Adamsville, Hardin 
County, Tennessee. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and contains PCEs 1, 
3, 4, and 5. The PBFs in this unit may require special management 
considerations or protections to address changes described above as 
well as row crop agriculture, channelization, and channel stability 
associated with tail water releases. Approximately 90 percent of the 
adjacent riparian lands in this unit are in private ownership and 10 
percent are in State or local ownership (Table 5).

Unit RF20b: Tennessee River--Livingston, Marshall, and McCracken 
Counties, Kentucky

    Unit RF20b includes 35.6 rkm (22.1 rmi) of Tennessee River from 
Kentucky Lake Dam downstream to its confluence with the Ohio River, 
McCracken and Livingston Counties, Kentucky. This unit was occupied at 
the time of listing and contains all or some components of all four 
PBFs and contains PCEs 1, 3, 4, and 5. The PBFs in this unit may 
require special management considerations or protection to address 
changes described above. Approximately 93 percent of the adjacent 
riparian lands in this unit are in private ownership, 7 percent are in 
Federal ownership, and less than 1 percent is in State or local 
ownership (Table 5).

Unit RF21: Ohio River--Ballard, Livingston, and McCracken Counties, 
Kentucky; Massac and Pulaski Counties, Illinois

    Unit RF21 includes 45.9 rkm (28.5 rmi) of the Ohio River from the 
Tennessee River confluence downstream to Lock and Dam 53 near Olmstead, 
Illinois. This unit was occupied at the time of listing and contains 
all or some components of all four PBFs and contains PCEs 1, 3, 4, and 
5. The PBFs in this unit may require special management considerations 
or protection to address changes described above, as well as row crop 
agriculture, channelization, and channel stability associated with tail 
water releases. Approximately 72 percent of the adjacent riparian lands 
in this unit are in private ownership and 28 percent are in State or 
local ownership (Table 5).

[[Page 63483]]

Unit RF22: Green River--Green, Hart, and Taylor Counties, Kentucky

    Unit RF22 includes 175.6 rkm (109.1 rmi) of the Green River from 
Green River Lake Dam south of Campbellsville, Taylor County, Kentucky, 
downstream to Maple Springs Ranger Station Road in Mammoth Cave 
National Park, Kentucky. This unit was occupied at the time of listing 
and contains all or some components of all four PBFs and contains PCEs 
1, 3, 4, and 5. Releases from Green River Lake dam have altered 
hydrologic flows and temperature regimes in the tail water reach 
(Butler 2005, p. 39). The PBFs in this unit may require special 
management considerations or protection to address changes described 
above and row crop agriculture, channelization, and channel stability 
associated with tail water releases. Approximately 90 percent of the 
adjacent riparian lands in this unit are in private ownership and 10 
percent are in Federal ownership (Table 5).

Unit RF23: French Creek--Crawford, Erie, Mercer, and Venango Counties, 
Pennsylvania

    Unit RF23 includes 120.4 rkm (74.8 rmi) of French Creek from Union 
City Reservoir Dam northeast of Union City, Erie County, Pennsylvania, 
downstream to its confluence with the Allegheny River near Franklin, 
Venango County, Pennsylvania. The Allegheny River rabbitsfoot 
population (Unit RF24) is likely a single metapopulation with the 
French Creek population (Butler 2005, p. 31). This unit was occupied at 
the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes 
described above as well as row crop agriculture and oil and gas 
development. Approximately 97 percent of the adjacent riparian lands in 
this unit are in private ownership and 3 percent are in Federal 
ownership (Table 5).

Unit RF24: Allegheny River--Venango County, Pennsylvania

    Unit RF24 includes 57.3 rkm (35.6 rmi) of the Allegheny River from 
the French Creek confluence near Franklin, Venango County, 
Pennsylvania, downstream to Interstate 80 near Emlenton, Venango 
County, Pennsylvania. The lower Allegheny River and French Creek (Unit 
RF23) populations likely represent a single metapopulation because no 
barriers exist between the streams (Butler 2005, p. 29). This unit 
contains all or some components of all four PBFs and likely functions 
as a metapopulation to French Creek (Unit RF23). This unit was occupied 
at the time of listing and contains PCEs 1, 3, 4, and 5 for the 
rabbitsfoot. A series of nine lock and dams and Kinzua Dam constructed 
over the past century has resulted in altered hydrologic flow regimes 
in the Allegheny River (Butler 2005, p. 29). The PBFS in this unit may 
require special management considerations or protections to address 
changes described above as well as row crop agriculture, oil and gas 
development, and channelization. Approximately 83 percent of the 
adjacent riparian lands in this unit are in private ownership and 17 
percent are in State or local ownership (Table 5).

Unit RF25: Muddy Creek--Crawford County, Pennsylvania

    Unit RF25 includes 20.1 rkm (12.5 rmi) of Muddy Creek from 
Pennsylvania Highway 77 near Little Cooley, Crawford County, 
Pennsylvania, downstream to its confluence with French Creek east of 
Cambridge Springs, Crawford County, Pennsylvania. This unit was 
occupied at the time of listing and contains all or some components of 
all four PBFs and contains all five PCEs. The PBFS in this unit may 
require special management considerations or protections to address 
changes described above and oil and gas development. Approximately 81 
percent of the adjacent riparian lands in this unit are in Federal 
ownership and 19 percent are in private ownership (Table 5).

Unit RF26: Tippecanoe River--Carroll, Pulaski, Tippecanoe, and White 
Counties, Indiana

    Unit RF26 includes 75.6 rkm (47.0 rmi) of the Tippecanoe River from 
Indiana Highway 14 near Winamac, Pulaski County, Indiana, downstream to 
its confluence with the Wabash River northeast of Battle Ground, 
Tippecanoe County, Indiana, excluding Lakes Schafer and Freeman and the 
stream reach between the two lakes. This unit was occupied at the time 
of listing and contains all or some components of all four PBFs and 
contains all five PCEs. The PBFs in this unit may require special 
management considerations or protections to address changes described 
above. Approximately 97 percent of the adjacent riparian lands in this 
unit are in private ownership and 3 percent are in State or local 
ownership (Table 5).

Unit RF27: Walhonding River--Coshocton County, Ohio

    Unit RF27 includes 17.5 rkm (10.9 rmi) of the Walhonding River from 
the convergence of the Kokosing and Mohican Rivers downstream to Ohio 
Highway 60 near Warsaw, Coshocton County, Ohio. This unit was occupied 
at the time of listing and contains all or some components of all four 
PBFs and contains all five PCEs. The PBFs in this unit may require 
special management considerations or protections to address changes 
described above. Approximately 83 percent of the adjacent riparian 
lands in this unit are in private ownership and 17 percent are in State 
or local ownership (Table 5).

Unit RF28: Little Darby Creek--Madison and Union Counties, Ohio

    Unit RF28 includes 33.3 rkm (20.7 rmi) of Little Darby Creek from 
Ohio Highway 161 near Chuckery, Madison County, Ohio, downstream to 
U.S. Highway 40 near West Jefferson, Madison County, Ohio. This unit 
was occupied at the time of listing and contains all or some components 
of all four PBFs and contains all five PCEs. The PBFS in this unti may 
require special management considerations or protections to address 
changes described above and row crop agriculture. All adjacent riparian 
lands in this unit are in private ownership (Table 5).

Unit RF29: North Fork Vermilion River and Middle Branch North Fork 
Vermilion River, respectively, Vermilion County, Illinois

    Unit RF29 includes 28.5 rkm (17.7 rmi) of the North Fork Vermilion 
River from the confluence of Middle Branch North Fork Vermilion River 
downstream to Illinois Highway 1 and U.S. Highway 136 upstream of Lake 
Vermilion, Vermilion County, Illinois. Unit RF29 also includes 7.2 rkm 
(4.5 rmi) of the Middle Branch North Fork Vermilion River from the 
Jordan Creek confluence northwest of Alvin, Illinois, downstream to its 
confluence with North Fork Vermilion River west of Alvin, Vermilion 
County, Illinois. The rabbitsfoot in the North Fork Vermilion River is 
considered a metapopulation with the Middle Branch North Fork Vermilion 
River population (Butler 2005, p. 47). This unit was occupied at the 
time of listing and contains all or some components of all four PBFs, 
including connectivity between North Fork Vermilion River and Middle 
Branch North Fork Vermilion River. This unit contains all five PCEs. 
The PBFs in this unit may require special

[[Page 63484]]

management considerations or protections to address changes described 
above and channelization and row crop agriculture. All adjacent 
riparian lands in this unit are in private ownership (Table 5).

Unit RF30: Fish Creek--Williams County, Ohio

    Unit RF30 includes 7.7 rkm (4.8 rmi) of Fish Creek from the Indiana 
and Ohio State line northwest of Edgerton, Ohio, downstream to its 
confluence with the St. Joseph's River north of Edgerton, Williams 
County, Ohio. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and sustains genetic 
diversity and historical distribution as the only remaining rabbitsfoot 
population in the Great Lakes subbasin. This unit contains all five 
PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes described above as 
well as row crop agriculture and confined animal operations (hogs). 
Approximately 90 percent of the adjacent riparian lands in this unit 
are in private ownership and 10 percent are in State or local ownership 
(Table 5).

Unit RF31: Red River--Logan County, Kentucky; and Robertson County, 
Tennessee

    Unit RF31 includes 50.2 rkm (31.2 rmi) of the Red River from the 
South Fork Red River confluence west of Adairville, Kentucky, 
downstream to the Sulphur Fork confluence southwest of Adams, 
Tennessee. This unit was occupied at the time of listing and contains 
all or some components of all four PBFs and sustains genetic diversity 
and historical distribution as the largest of two remaining rabbitsfoot 
populations within the Cumberland River basin. This unit contains all 
five PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes described above as 
well as row crop agriculture and channelization. All adjacent riparian 
lands in this unit are in private ownership (Table 5).

Unit RF32: Shenango River--Mercer County, Pennsylvania

    Unit RF32 includes 16.3 rkm (10.1 rmi) of the Shenango River from 
Kidds Mill Road near Greenville, Pennsylvania, downstream to the point 
of inundation by Shenango River Lake near Big Bend, Mercer County, 
Pennsylvania. This unit was occupied at the time of listing and 
contains all or some components of all four PBFs and contains all five 
PCEs. The PBFs in this unit may require special management 
considerations or protections to address changes described above. 
Approximately 54 percent of the adjacent riparian lands in this unit 
are in Federal ownership and 46 percent are in private ownership (Table 
5).

Effects of Critical Habitat Designation

Section 7 Consultation

    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they fund, authorize, or carry out 
is not likely to jeopardize the continued existence of any endangered 
species or threatened species or result in the destruction or adverse 
modification of designated critical habitat of such species. In 
addition, section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any agency action which is likely to 
jeopardize the continued existence of any species proposed to be listed 
under the Act or result in the destruction or adverse modification of 
proposed critical habitat.
    Decisions by the United States Courts of Appeal for the Fifth and 
Ninth Circuits have invalidated our regulatory definition of 
``destruction or adverse modification'' (50 CFR 402.02) (see Gifford 
Pinchot Task Force v. U.S. Fish and Wildlife Service, 378 F. 3d 1059 
(9th Cir. 2004) and Sierra Club v. U.S. Fish and Wildlife Service et 
al., 245 F.3d 434, 442 (5th Cir. 2001)), and we do not rely on this 
regulatory definition when analyzing whether an action is likely to 
destroy or adversely modify critical habitat. Under the provisions of 
the Act, we determine destruction or adverse modification on the basis 
of whether, with implementation of the proposed Federal action, the 
affected critical habitat would continue to serve its intended 
conservation role for the species.
    If a Federal action may affect a listed species or its critical 
habitat, the responsible Federal agency (action agency) must enter into 
consultation with us. Examples of actions that are subject to the 
section 7 consultation process are actions on State, tribal, local, or 
private lands that require a Federal permit (such as a permit from the 
U.S. Army Corps of Engineers under section 404 of the Clean Water Act 
or a permit from the Service under section 10 of the Act) or that 
involve some other Federal action (such as funding from the Federal 
Highway Administration, Federal Aviation Administration, or the Federal 
Emergency Management Agency). Federal actions not affecting listed 
species or critical habitat, and actions on State, tribal, local, or 
private lands that are not federally funded or authorized, do not 
require section 7 consultation.
    As a result of section 7 consultation, we document compliance with 
the requirements of section 7(a)(2) through our issuance of:
    (1) A concurrence letter for Federal actions that may affect, but 
are not likely to adversely affect, listed species or critical habitat; 
or
    (2) A biological opinion for Federal actions that may affect, or 
are likely to adversely affect, listed species or critical habitat.
    When we issue a biological opinion concluding that a project is 
likely to jeopardize the continued existence of a listed species and/or 
destroy or adversely modify critical habitat, we provide reasonable and 
prudent alternatives to the project, if any are identifiable, that 
would avoid the likelihood of jeopardy and/or destruction or adverse 
modification of critical habitat. We define ``reasonable and prudent 
alternatives'' (at 50 CFR 402.02) as alternative actions identified 
during consultation that:
    (1) Can be implemented in a manner consistent with the intended 
purpose of the action,
    (2) Can be implemented consistent with the scope of the Federal 
agency's legal authority and jurisdiction,
    (3) Are economically and technologically feasible, and
    (4) Would, in the Director's opinion, avoid the likelihood of 
jeopardizing the continued existence of the listed species and/or avoid 
the likelihood of destroying or adversely modifying critical habitat.
    Reasonable and prudent alternatives can vary from slight project 
modifications to extensive redesign or relocation of the project. Costs 
associated with implementing a reasonable and prudent alternative are 
similarly variable.
    Regulations at 50 CFR 402.16 require Federal agencies to reinitiate 
consultation on previously reviewed actions in instances where we have 
listed a new species or subsequently designated critical habitat that 
may be affected and the Federal agency has retained discretionary 
involvement or control over the action (or the agency's discretionary 
involvement or control is authorized by law). Consequently, Federal 
agencies sometimes may need to request reinitiation of consultation 
with us on actions for which formal consultation has been completed, if 
those actions with discretionary involvement or control may affect 
subsequently listed species or designated critical habitat.

[[Page 63485]]

Application of the ``Adverse Modification'' Standard

    The key factor related to the adverse modification determination is 
whether, with implementation of the proposed Federal action, the 
affected critical habitat would continue to serve its intended 
conservation role for the species. Activities that may destroy or 
adversely modify critical habitat are those that alter the physical or 
biological features to an extent that appreciably reduces the 
conservation value of critical habitat for Neosho mucket and the 
rabbitsfoot. As discussed above, the role of critical habitat is to 
support life-history needs of the species and provide for the 
conservation of the species.
    Section 4(b)(8) of the Act requires us to briefly evaluate and 
describe, in any proposed or final regulation that designates critical 
habitat, activities involving a Federal action that may destroy or 
adversely modify such habitat, or that may be affected by such 
designation.
    Activities that may affect critical habitat, when carried out, 
funded, or authorized by a Federal agency, should result in 
consultation for the Neosho mucket and rabbitsfoot. These activities 
include, but are not limited to:
    (1) Actions that would alter the geomorphology of their stream and 
river habitats. Such activities may include, but are not limited to, 
instream excavation or dredging, impoundment, channelization, sand and 
gravel mining, clearing riparian vegetation, and discharge of fill 
materials. These activities could cause aggradation or degradation of 
the channel bed elevation or significant bank erosion, result in 
entrainment or burial of these mollusks, and cause other direct or 
cumulative adverse effects to these species and their life cycles.
    (2) Actions that would significantly alter the existing flow regime 
where these species occur. Such activities may include, but are not 
limited to, impoundment, channelization, urban development, water 
diversion, water withdrawal, and tail water releases downstream of 
dams. These activities could eliminate or reduce the habitat necessary 
for growth and reproduction of these mollusks and their life cycles 
including fish hosts.
    (3) Actions that would significantly alter water chemistry or water 
quality (for example, temperature, pH, contaminants, conductivity, and 
excess nutrients). Such activities may include, but are not limited to, 
tail water releases downstream of dams, or the release of chemicals, 
biological pollutants, or heated effluents into surface water or 
connected groundwater at a point source or by dispersed release 
(nonpoint source). These activities could alter water conditions that 
are beyond the tolerances of these mussels or their fish hosts or both, 
and result in direct or cumulative adverse effects to the species and 
their life cycles.
    (4) Actions that would significantly alter stream bed material 
composition and quality by increasing sediment deposition or 
filamentous algal growth. Such activities may include, but are not 
limited to, construction projects, gravel and sand mining, oil and gas 
development, livestock grazing, timber harvest, off-road vehicle use, 
and other watershed and floodplain disturbances that release sediments 
or contaminants into the water. These activities could eliminate or 
reduce habitats necessary for the survival, growth and reproduction of 
these mollusks or their fish hosts or both by causing excessive 
sedimentation and burial of Neosho mucket and rabbitsfoot or their 
habitats, sublethal effects from sediment exposure that are not readily 
apparent, acute and chronic exposure to chemical contaminants resulting 
in sublethal and lethal effects, and nutrification leading to excessive 
filamentous algal growth. Excessive filamentous algal growth can cause 
reduced nighttime dissolved oxygen levels through respiration and 
prevent mussel glochidia from settling into stream sediments.

Exemptions

Application of Section 4(a)(3) of the Act

    The Sikes Act Improvement Act of 1997 (Sikes Act) (16 U.S.C. 670a) 
required each military installation that includes land and water 
suitable for the conservation and management of natural resources to 
complete an integrated natural resources management plan (INRMP) by 
November 17, 2001. An INRMP integrates implementation of the military 
mission of the installation with stewardship of the natural resources 
found on the base. Each INRMP includes:
    (1) An assessment of the ecological needs on the installation, 
including the need to provide for the conservation of listed species;
    (2) A statement of goals and priorities;
    (3) A detailed description of management actions to be implemented 
to provide for these ecological needs; and
    (4) A monitoring and adaptive management plan.
    Among other things, each INRMP must, to the extent appropriate and 
applicable, provide for fish and wildlife management; fish and wildlife 
habitat enhancement or modification; wetland protection, enhancement, 
and restoration where necessary to support fish and wildlife; and 
enforcement of applicable natural resource laws.
    The National Defense Authorization Act for Fiscal Year 2004 (Pub. 
L. 108-136) amended the Act to limit areas eligible for designation as 
critical habitat. Specifically, section 4(a)(3)(B)(i) of the Act (16 
U.S.C. 1533(a)(3)(B)(i)) now provides: ``The Secretary shall not 
designate as critical habitat any lands or other geographical areas 
owned or controlled by the Department of Defense, or designated for its 
use, that are subject to an integrated natural resources management 
plan prepared under section 101 of the Sikes Act (16 U.S.C. 670a), if 
the Secretary determines in writing that such plan provides a benefit 
to the species for which critical habitat is proposed for 
designation.'' There are no Department of Defense lands with a 
completed INRMP within the proposed critical habitat designation for 
the Neosho mucket and rabbitsfoot.

Exclusions

Application of Section 4(b)(2) of the Act

    Section 4(b)(2) of the Act states that the Secretary must designate 
and make revisions to critical habitat on the basis of the best 
available scientific data after taking into consideration the economic 
impact, national security impact, and any other relevant impact of 
specifying any particular area as critical habitat. The Secretary may 
exclude an area from critical habitat if he determines that the 
benefits of such exclusion outweigh the benefits of specifying such 
area as part of the critical habitat, unless he determines, based on 
the best scientific data available, that the failure to designate such 
area as critical habitat will result in the extinction of the species. 
In making that determination, the statute on its face, as well as the 
legislative history, are clear that the Secretary has broad discretion 
regarding which factor(s) to use and how much weight to give to any 
factor.
    Under section 4(b)(2) of the Act, we may exclude an area from 
designated critical habitat based on economic impacts, impacts on 
national security, or any other relevant impacts. In considering 
whether to exclude a particular area from the designation, we identify 
the benefits of including the area in the designation, identify the 
benefits of excluding the area from the designation, and evaluate 
whether the benefits of exclusion outweigh the benefits of inclusion. 
If the analysis

[[Page 63486]]

indicates that the benefits of exclusion outweigh the benefits of 
inclusion, the Secretary may exercise his discretion to exclude the 
area only if such exclusion would not result in the extinction of the 
species.
Exclusions Based on Economic Impacts
    Under section 4(b)(2) of the Act, we consider the economic impacts 
of specifying any particular area as critical habitat. In order to 
consider economic impacts, we are preparing an analysis of the economic 
impacts of the proposed critical habitat designation and related 
factors.
    We will announce the availability of our draft economic analysis as 
soon as it is completed, at which time we will seek public comment. 
During the development of a final designation, we will consider 
economic impacts, public comments, and other new information related to 
economic impacts, and areas may be excluded from the final critical 
habitat designation under section 4(b)(2) of the Act and our 
implementing regulations at 50 CFR 424.19.
Exclusions Based on National Security Impacts
    Under section 4(b)(2) of the Act, we consider whether there are 
lands owned or managed by the Department of Defense where a national 
security impact might exist. In preparing this proposal, we have 
determined that none of the lands within the proposed designation of 
critical habitat for the Neosho mucket and rabbitsfoot are owned or 
managed by the Department of Defense and, therefore, we anticipate no 
impact on national security. Consequently, the Secretary does not 
propose to exert his discretion to exclude any areas from the final 
designation based on impacts on national security.
Exclusions Based on Other Relevant Impacts
    Under section 4(b)(2) of the Act, we consider any other relevant 
impacts, in addition to economic impacts and impacts on national 
security. We consider a number of factors, including whether the 
landowners have developed any HCPs or other management plans for the 
area, or whether there are conservation partnerships that would be 
encouraged by designation of, or exclusion of lands from, critical 
habitat. In addition, we look at any tribal issues, and consider the 
government-to-government relationship of the United States with tribal 
entities. We also consider any social impacts that might occur because 
of the designation.
    In preparing this proposed rule, we have determined that there are 
currently no HCPs or other management plans for the Neosho mucket and 
rabbitsfoot. The proposed designation of critical habitat includes only 
tribal jurisdictional areas not lands managed by any Tribe. We 
anticipate no effect to tribal lands, partnerships, or HCPs from this 
proposed critical habitat designation. Accordingly, the Secretary does 
not propose to exert his discretion to exclude any areas from the final 
designation based on other relevant impacts.

Peer Review

    In accordance with our joint policy published in the Federal 
Register on July 1, 1994 (59 FR 34270), we will seek the expert 
opinions of at least three appropriate and independent specialists for 
each species regarding this proposed rule. The purpose of peer review 
is to ensure that our critical habitat designation is based on 
scientifically sound data, assumptions, and analyses. We have invited 
these peer reviewers to comment during this public comment period on 
our specific assumptions and conclusions in this proposed designation 
of critical habitat.
    We will consider all comments and information received during this 
comment period on this proposed rule during our preparation of a final 
determination. Accordingly, the final decision may differ from this 
proposal.

Public Hearings

    Section 4(b)(5) of the Act provides for one or more public hearings 
on this proposal, if requested. Requests must be received within 45 
days after the date of publication of this proposed rule in the Federal 
Register. Such requests must be sent to the address shown in FOR 
FURTHER INFORMATION CONTACT. We will schedule public hearings on this 
proposal, if any are requested, and announce the dates, times, and 
places of those hearings, as well as how to obtain reasonable 
accommodations, in the Federal Register and local newspapers at least 
15 days before the hearing.

Required Determinations

Regulatory Planning and Review (Executive Orders 12866 and 13563)

    Executive Order 12866 provides that the Office of Information and 
Regulatory Affairs (OIRA) will review all significant rules. The Office 
of Information and Regulatory Affairs has determined that this rule is 
not significant.
    Executive Order 13563 reaffirms the principles of E.O. 12866 while 
calling for improvements in the nation's regulatory system to promote 
predictability, to reduce uncertainty, and to use the best, most 
innovative, and least burdensome tools for achieving regulatory ends. 
The executive order directs agencies to consider regulatory approaches 
that reduce burdens and maintain flexibility and freedom of choice for 
the public where these approaches are relevant, feasible, and 
consistent with regulatory objectives. E.O. 13563 emphasizes further 
that regulations must be based on the best available science and that 
the rulemaking process must allow for public participation and an open 
exchange of ideas. We have developed this rule in a manner consistent 
with these requirements.

Regulatory Flexibility Act (5 U.S.C. 601 et seq.)

    Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.) as 
amended by the Small Business Regulatory Enforcement Fairness Act of 
1996 (SBREFA; 5 U.S.C. 801 et seq.), whenever an agency is required to 
publish a notice of rulemaking for any proposed or final rule, it must 
prepare and make available for public comment a regulatory flexibility 
analysis that describes the effects of the rule on small entities 
(small businesses, small organizations, and small government 
jurisdictions). However, no regulatory flexibility analysis is required 
if the head of the agency certifies the rule will not have a 
significant economic impact on a substantial number of small entities. 
The SBREFA amended the RFA to require Federal agencies to provide a 
certification statement of the factual basis for certifying that the 
rule will not have a significant economic impact on a substantial 
number of small entities.
    According to the Small Business Administration, small entities 
include small organizations such as independent nonprofit 
organizations; small governmental jurisdictions, including school 
boards and city and town governments that serve fewer than 50,000 
residents; and small businesses (13 CFR 121.201). Small businesses 
include such businesses as manufacturing and mining concerns with fewer 
than 500 employees, wholesale trade entities with fewer than 100 
employees, retail and service businesses with less than $5 million in 
annual sales, general and heavy construction businesses with less than 
$27.5 million in annual business, special trade contractors doing less 
than $11.5 million in annual business, and forestry and logging 
operations with fewer than 500 employees and annual business less than 
$7 million. To

[[Page 63487]]

determine whether small entities may be affected, we will consider the 
types of activities that might trigger regulatory impacts under this 
designation as well as types of project modifications that may result. 
In general, the term ``significant economic impact'' is meant to apply 
to a typical small business firm's business operations.
    Importantly, the incremental impacts of a rule must be both 
significant and substantial to prevent certification of the rule under 
the RFA and to require the preparation of an initial regulatory 
flexibility analysis. If a substantial number of small entities are 
affected by the proposed critical habitat designation, but the per-
entity economic impact is not significant, the Service may certify. 
Likewise, if the per-entity economic impact is likely to be 
significant, but the number of affected entities is not substantial, 
the Service may also certify.
    Under the RFA, as amended, and following recent court decisions, 
Federal agencies are only required to evaluate the potential 
incremental impacts of rulemaking on those entities directly regulated 
by the rulemaking itself, and not the potential impacts to indirectly 
affected entities. The regulatory mechanism through which critical 
habitat protections are realized is section 7 of the Act, which 
requires Federal agencies, in consultation with the Service, to ensure 
that any action authorized, funded, or carried by the Agency is not 
likely to adversely modify critical habitat. Therefore, only Federal 
action agencies are directly subject to the specific regulatory 
requirement (avoiding destruction and adverse modification) imposed by 
critical habitat designation. Under these circumstances, it is our 
position that only Federal action agencies will be directly regulated 
by this designation. Therefore, because Federal agencies are not small 
entities, the Service may certify that the proposed critical habitat 
rule will not have a significant economic impact on a substantial 
number of small entities.
    We acknowledge, however, that in some cases, third-party proponents 
of the action subject to permitting or funding may participate in a 
section 7 consultation, and thus may be indirectly affected. We believe 
it is good policy to assess these impacts if we have sufficient data 
before us to complete the necessary analysis, whether or not this 
analysis is strictly required by the RFA. While this regulation does 
not directly regulate these entities, in our draft economic analysis we 
will conduct a brief evaluation of the potential number of third 
parties participating in consultations on an annual basis in order to 
ensure a more complete examination of the incremental effects of this 
proposed rule in the context of the RFA.
    In conclusion, we believe that, based on our interpretation of 
directly regulated entities under the RFA and relevant case law, this 
designation of critical habitat will only directly regulate Federal 
agencies which are not by definition small business entities. And as 
such, certify that, if promulgated, this designation of critical 
habitat would not have a significant economic impact on a substantial 
number of small business entities. Therefore, an initial regulatory 
flexibility analysis is not required. However, though not necessarily 
required by the RFA, in our draft economic analysis for this proposal 
we will consider and evaluate the potential effects to third parties 
that may be involved with consultations with Federal action agencies 
related to this action.

Energy Supply, Distribution, or Use--Executive Order 13211

    Executive Order 13211 (Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use) requires 
agencies to prepare Statements of Energy Effects when undertaking 
certain actions. Although two of the proposed units are downstream of 
hydropower reservoirs, current and proposed operating regimes have been 
deemed adequate for the species, and therefore their hydropower 
operations are not anticipated to be affected by the proposed 
designation of critical habitat.
    Natural gas and oil exploration and development activities occur or 
could potentially occur in the rabbitsfoot proposed critical habitat (6 
of 35 critical habitat units). However, compliance with State 
regulatory requirements or voluntary BMPs would be expected to minimize 
impacts of natural gas and oil exploration and development in the areas 
of proposed critical habitat for both species. The measures for natural 
gas and oil exploration and development are generally not considered a 
substantial cost compared with overall project costs and are already 
being implemented by oil and gas companies. Coal mining occurs or could 
potentially occur in 5 of 35 proposed critical habitat units for the 
rabbitsfoot. Incidental take for listed species associated with surface 
coal mining activities is currently covered under a programmatic, no 
jeopardy biological opinion between the Office of Surface Mining and 
the Service completed in 1996 (Service 1996, entire). The biological 
opinion covers existing, proposed, and future endangered and threatened 
species that may be affected by the implementation and administration 
of surface coal mining programs under the Surface Mining Control and 
Reclamation Act of 1977. Through its analysis, the Service concluded 
that the proposed action (surface coal mining and reclamation 
activities) was not likely to jeopardize the continued existence of any 
endangered, threatened, or proposed species or result in adverse 
modification of designated or proposed critical habitat.
    All other proposed units are remote from energy supply, 
distribution, or use activities. We do not expect the designation of 
this proposed critical habitat to significantly affect energy supplies, 
distribution, or use. Therefore, this action is not a significant 
energy action, and no Statement of Energy Effects is required. However, 
we will further evaluate this issue as we conduct our economic 
analysis, and review and revise this assessment as warranted.

Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)

    In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501 
et seq.), we make the following findings:
    (1) This rule will not produce a Federal mandate. In general, a 
Federal mandate is a provision in legislation, statute, or regulation 
that would impose an enforceable duty upon State, local, or tribal 
governments, or the private sector, and includes both ``Federal 
intergovernmental mandates'' and ``Federal private sector mandates.'' 
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal 
intergovernmental mandate'' includes a regulation that ``would impose 
an enforceable duty upon State, local, or tribal governments'' with two 
exceptions. It excludes ``a condition of Federal assistance.'' It also 
excludes ``a duty arising from participation in a voluntary Federal 
program,'' unless the regulation ``relates to a then-existing Federal 
program under which $500,000,000 or more is provided annually to State, 
local, and tribal governments under entitlement authority,'' if the 
provision would ``increase the stringency of conditions of assistance'' 
or ``place caps upon, or otherwise decrease, the Federal Government's 
responsibility to provide funding,'' and the State, local, or tribal 
governments ``lack authority'' to adjust accordingly. At the time of 
enactment, these entitlement programs were: Medicaid; Aid to Families 
with

[[Page 63488]]

Dependent Children work programs; Child Nutrition; Food Stamps; Social 
Services Block Grants; Vocational Rehabilitation State Grants; Foster 
Care, Adoption Assistance, and Independent Living; Family Support 
Welfare Services; and Child Support Enforcement. ``Federal private 
sector mandate'' includes a regulation that ``would impose an 
enforceable duty upon the private sector, except (i) a condition of 
Federal assistance or (ii) a duty arising from participation in a 
voluntary Federal program.''
    The designation of critical habitat does not impose a legally 
binding duty on non-Federal Government entities or private parties. 
Under the Act, the only regulatory effect is that Federal agencies must 
ensure that their actions do not destroy or adversely modify critical 
habitat under section 7. While non-Federal entities that receive 
Federal funding, assistance, or permits, or that otherwise require 
approval or authorization from a Federal agency for an action, may be 
indirectly impacted by the designation of critical habitat, the legally 
binding duty to avoid destruction or adverse modification of critical 
habitat rests squarely on the Federal agency. Furthermore, to the 
extent that non-Federal entities are indirectly impacted because they 
receive Federal assistance or participate in a voluntary Federal aid 
program, the Unfunded Mandates Reform Act would not apply and neither 
would critical habitat shift the costs of the large entitlement 
programs listed above onto State governments.
    (2) We do not believe that this rule will significantly or uniquely 
affect small governments because the Neosho mucket and rabbitsfoot 
occur only in navigable waters in which the river bottom is generally 
owned by the State. However, the adjacent upland properties are owned 
by private, State, or Federal entities (see Table 5). As such, a Small 
Government Agency Plan is not required. We will, however, further 
evaluate this issue as we conduct our economic analysis and revise this 
assessment if appropriate.

Takings--Executive Order 12630

    In accordance with Executive Order 12630 (Government Actions and 
Interference with Constitutionally Protected Private Property Rights), 
we have analyzed the potential takings implications of designating 
critical habitat for Neosho mucket and rabbitsfoot in a takings 
implications assessment. Critical habitat designation does not affect 
landowner actions that do not require Federal funding or permits, nor 
does it preclude development of habitat conservation programs or 
issuance of incidental take permits to permit actions that do require 
Federal funding or permits to go forward. The takings implications 
assessment concludes that this designation of critical habitat for 
Neosho mucket and rabbitsfoot does not pose significant takings 
implications for lands within or affected by the designation.

Federalism--Executive Order 13132

    In accordance with Executive Order 13132 (Federalism), this 
proposed rule does not have significant Federalism effects. A 
Federalism assessment is not required. In keeping with Department of 
the Interior and Department of Commerce policy, we requested 
information from, and coordinated development of this proposed critical 
habitat designation with appropriate State resource agencies in 
Alabama, Arkansas, Illinois, Indiana, Kansas, Kentucky, Missouri, 
Mississippi, Oklahoma, Ohio, Pennsylvania, and Tennessee. The 
designation of critical habitat in areas currently occupied by the 
Neosho mucket and rabbitsfoot may impose nominal additional regulatory 
restrictions to those currently in place and, therefore, may have minor 
incremental impact on State and local governments and their activities. 
The designation may have some benefit to these governments because the 
areas that contain the physical or biological features essential to the 
conservation of the species are more clearly defined, and the elements 
of the features of the habitat necessary to the conservation of the 
species are specifically identified. This information does not alter 
where and what federally sponsored activities may occur. However, it 
may assist local governments in long-range planning (rather than having 
them wait for case-by-case section 7 consultations to occur).
    Where State and local governments require approval or authorization 
from a Federal agency for actions that may affect critical habitat, 
consultation under section 7(a)(2) would be required. While non-Federal 
entities that receive Federal funding, assistance, or permits, or that 
otherwise require approval or authorization from a Federal agency for 
an action, may be indirectly impacted by the designation of critical 
habitat, the legally binding duty to avoid destruction or adverse 
modification of critical habitat rests squarely on the Federal agency.

Civil Justice Reform--Executive Order 12988

    In accordance with Executive Order 12988 (Civil Justice Reform), 
the Office of the Solicitor has determined that the rule does not 
unduly burden the judicial system and that it meets the requirements of 
sections 3(a) and 3(b)(2) of the Order. We have proposed designating 
critical habitat in accordance with the provisions of the Act. This 
proposed rule uses standard property descriptions and identifies the 
elements of physical or biological features essential to the 
conservation of the Neosho mucket and rabbitsfoot within the designated 
areas to assist the public in understanding the habitat needs of the 
species.

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain any new collections of information that 
require approval by OMB under the Paperwork Reduction Act of 1995 (44 
U.S.C. 3501 et seq.). This rule will not impose recordkeeping or 
reporting requirements on State or local governments, individuals, 
businesses, or organizations. An agency may not conduct or sponsor, and 
a person is not required to respond to, a collection of information 
unless it displays a currently valid OMB control number.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with listing a species as endangered or 
threatened under the Endangered Species Act. We published a notice 
outlining our reasons for this determination in the Federal Register on 
October 25, 1983 (48 FR 49244).
    It is also our position that, outside the jurisdiction of the U.S. 
Court of Appeals for the Tenth Circuit, we do not need to prepare 
environmental analyses pursuant to NEPA in connection with designating 
critical habitat under the Endangered Species Act. We published a 
notice outlining our reasons for this determination in the Federal 
Register on October 25, 1983 (48 FR 49244). This position was upheld by 
the U.S. Court of Appeals for the Ninth Circuit (Douglas County v. 
Babbitt, 48 F.3d 1495 (9th Cir. 1995), cert. denied 516 U.S. 1042 
(1996)). However, when the range of the species includes States within 
the Tenth Circuit, such as that of

[[Page 63489]]

the Neosho mucket (Oklahoma) and rabbitsfoot (Oklahoma and Kansas), 
under the Tenth Circuit ruling in Catron County Board of Commissioners 
v. U.S. Fish and Wildlife Service, 75 F.3d 1429 (10th Cir. 1996), we 
will undertake a NEPA analysis for critical habitat designation. 
Accordingly, we will notify the public of the availability of the draft 
environmental assessment for this proposal when it is finished.

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in the ADDRESSES section. To 
better help us revise the rule, your comments should be as specific as 
possible. For example, you should tell us the numbers of the sections 
or paragraphs that are unclearly written, which sections or sentences 
are too long, the sections where you feel lists or tables would be 
useful, etc.

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
tribes in developing programs for healthy ecosystems, to acknowledge 
that tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to tribes.
    We have determined that there are tribal lands occupied at this 
time that contain the physical and biological features essential for 
the conservation of Neosho mucket and rabbitsfoot (1 of 8 Neosho mucket 
critical habitat units and 2 of 35 rabbitsfoot critical habitat units). 
However, these lands do not represent riparian land ownership by any 
Tribe, represent only tribal jurisdictional areas, are not manged by 
any Tribe, and are on otherwise privately owned lands. We contacted 
each Tribe in writing and considered their comments during preparation 
of this proposed rule. Their comments were limited to providing tribal 
land and jurisdictional area maps and biological data for the two 
mussels. At this time, we do not anticipate excluding any lands under 
tribal jurisdiction.

References Cited

    A complete list of references cited in this rulemaking is available 
on the Internet at http://www.regulations.gov at Docket No. FWS-R4-ES-
2012-0031 and upon request from the Arkansas Ecological Services Office 
(see FOR FURTHER INFORMATION CONTACT).

Authors

    The primary authors of this package are staff of the Arkansas 
Ecological Services Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

    1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.

    2. In Sec.  17.11(h) add entries for ``Mucket, Neosho'' and 
``Rabbitsfoot'' in alphabetical order under ``Clams'' to the List of 
Endangered and Threatened Wildlife to read as follows:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
              Clams
 
                                                                      * * * * * * *
Mucket, Neosho...................  Lampsilis             U.S.A. (AR, KS, MO,  NA.................  E               ...........     17.95(f)           NA
                                    rafinesqueana.        OK).
 
                                                                      * * * * * * *
Rabbitsfoot......................  Quadrula cylindrica   U.S.A. (AL, AR, GA,  NA.................  T               ...........     17.95(f)           NA
                                    cylindrica.           IL, IN, KS, KY,
                                                          LA, MS, MO, OH,
                                                          OK, PA, TN, WV).
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

    3. In Sec.  17.95, amend paragraph (f) by adding entries for 
``Neosho Mucket (Lampsilis rafinesqueana)'' and ``Rabbitsfoot (Quadrula 
cylindrica cylindrica)'' after the entry for ``Georgia Pigtoe 
(Pleurobema hanleyianum)'' to read as follows:

[[Page 63490]]

Sec.  17.95  Critical habitat--fish and wildlife.

* * * * *
    (f) Clams and Snails.
* * * * *

Neosho Mucket (Lampsilis rafinesqueana)

    (1) Critical habitat units for the Neosho mucket are depicted on 
the maps below in:
    (i) Arkansas: Benton and Washington Counties.
    (ii) Kansas: Allen, Chase, Cherokee, Coffey, Elk, Greenwood, 
Labette, Montgomery, Neosho, Wilson, and Woodson Counties.
    (iii) Missouri: Jasper, Lawrence, McDonald, and Newton Counties.
    (iv) Oklahoma: Adair, Cherokee, and Delaware Counties.
    (2) Within these areas, the primary constituent elements of the 
physical and biological features essential to the conservation of the 
Neosho mucket consist of five components:
    (i) Geomorphically stable river channels and banks (channels that 
maintain lateral dimensions, longitudinal profiles, and sinuosity 
patterns over time without an aggrading or degrading bed elevation) 
with habitats that support a diversity of freshwater mussel and native 
fish (such as stable riffles, sometimes with runs, and midchannel 
island habitats that provide flow refuges consisting of gravel and sand 
substrates with low to moderate amounts of fine sediment and attached 
filamentous algae).
    (ii) A hydrologic flow regime (the severity, frequency, duration, 
and seasonality of discharge over time) necessary to maintain benthic 
habitats where the species are found and to maintain connectivity of 
rivers with the floodplain, allowing the exchange of nutrients and 
sediment for maintenance of the mussel's and fish host's habitat, food 
availability, spawning habitat for native fishes, and the ability for 
newly transformed juveniles to settle and become established in their 
habitats.
    (iii) Water and sediment quality (including, but not limited to, 
conductivity, hardness, turbidity, temperature, pH, ammonia, heavy 
metals, and chemical constituents) necessary to sustain natural 
physiological processes for normal behavior, growth, and viability of 
all life stages.
    (iv) The presence and abundance (currently unknown) of fish hosts 
necessary for recruitment of the Neosho mucket. The occurrence of 
natural fish assemblages, reflected by fish species richness, relative 
abundance, and community composition, for each inhabited river or creek 
will serve as an indication of appropriate presence and abundance of 
fish hosts until appropriate host fish can be identified.
    (v) Either no competitive or predaceous invasive (nonnative) 
species, or such species in quantities low enough to have minimal 
effect on survival of freshwater mussels.
    (3) Critical habitat does not include manmade structures (such as 
buildings, bridges, aqueducts, airports, roads, and other paved areas) 
and the land on which they are located exists within the legal 
boundaries on the effective date of this rule.
    (4) Critical habitat map units. Unit maps were developed using ESRI 
ArcGIS mapping software along with various spatial data layers. 
Critical habitat unit upstream and downstream limits were delineated at 
the nearest road crossing or stream confluence of each occupied reach. 
Data layers defining map units were created with USGS National 
Hydrography Dataset (NHD) Medium Flowline data. ArcGIS was also used to 
calculate river kilometers and miles from the NHD dataset, and it was 
used to determine longitude and latitude coordinates in decimal 
degrees. The projection used in mapping and calculating distances and 
locations within the units was North American Albers Equal Area Conic, 
NAD 83.
    (5) Note: Index map of critical habitat units for the Neosho mucket 
follows:
BILLING CODE 4310-55-P

[[Page 63491]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.000

    (6) Unit NM1: Illinois River--Benton and Washington Counties, 
Arkansas; and Adair, Cherokee, and Delaware Counties, Oklahoma.
    (i) Unit NM1 includes 146.1 rkm (90.8 rmi) of the Illinois River 
from the Muddy Fork Illinois River confluence south of Savoy, 
Washington County, Arkansas, downstream to the Baron Creek confluence 
southeast of Tahlequah, Cherokee County, Oklahoma.
    (ii) Note: Map of Unit NM1 (Illinois River) of critical habitat for 
Neosho mucket follows:

[[Page 63492]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.001

    (7) Unit NM2: Elk River--McDonald County, Missouri; and Delaware 
County, Oklahoma.
    (i) Unit NM2 includes 20.3 rkm (12.6 rmi) of the Elk River from 
Missouri Highway 59 at Noel, McDonald County, Missouri, downstream to 
the confluence of Buffalo Creek, Delaware County, Oklahoma.
    (ii) Note: Map of Unit NM2 (Elk River) of critical habitat for 
Neosho mucket follows:

[[Page 63493]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.002

    (8) Unit NM3: Shoal Creek--Cherokee County, Kansas; and Newton 
County, Missouri.
    (i) Unit NM3 includes 75.8 rkm (47.1 rmi) of Shoal Creek from 
Missouri Highway W near Ritchey, Newton County, Missouri, downstream to 
the upstream point of inundation by Empire Lake, Cherokee County, 
Kansas.
    (ii) Note: Map of Unit NM3 (Shoal Creek) of critical habitat for 
Neosho mucket follows:

[[Page 63494]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.003

    (9) Unit NM4: Spring River--Jasper and Lawrence Counties, Missouri; 
and Cherokee County, Kansas.
    (i) Unit NM4 includes 102.3 rkm (63.6 rmi) of the Spring River from 
Missouri Highway 97 north of Stotts City, Lawrence County, Missouri, 
downstream to the confluence of Turkey Creek north of Empire, Cherokee 
County, Kansas.
    (ii) Note: Map of Unit NM4 (Spring River) of critical habitat for 
Neosho mucket follows:

[[Page 63495]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.004

    (10) Unit NM5: North Fork Spring River--Jasper County, Missouri.
    (i) Unit NM5 includes 16.4 rkm (10.2 rmi) of the North Fork Spring 
River from the confluence of Buck Branch southwest of Jasper, Missouri, 
downstream to its confluence with the Spring River near Purcell, Jasper 
County, Missouri.
    (ii) Note: Map of Unit NM5 (North Fork Spring River) of critical 
habitat for Neosho mucket follows:

[[Page 63496]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.005

    (11) Unit NM6: Fall River--Elk, Greenwood, and Wilson Counties, 
Kansas; Verdigris River--Montgomery and Wilson Counties, Kansas.
    (i) Unit NM6 includes a total of 171.1 rkm (106.3 rmi) including 
90.4 rkm (56.2 rmi) of the Fall River from Fall River Lake dam 
northwest of Fall River, Greenwood County, Kansas, downstream to its 
confluence with the Verdigris River near Neodesha, Wilson County, 
Kansas. Unit NM6 also includes 80.6 rkm (50.1 rmi) of the Verdigris 
River from Kansas Highway 39 near Benedict, Wilson County, Kansas, 
downstream to the Elk River confluence near Independence, Montgomery 
County, Kansas.
    (ii) Note: Map of Unit NM6 (Fall and Verdigris Rivers) of critical 
habitat for Neosho mucket follows:

[[Page 63497]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.006

    (12) Unit NM7: Neosho River--Allen, Cherokee, Coffey, Labette, 
Neosho, and Woodson Counties, Kansas.
    (i) Unit NM7 includes 244.5 rkm (151.9 rmi) of the Neosho River 
from Kansas Highway 58 west of LeRoy, Coffey County, Kansas, downstream 
to the Kansas and Oklahoma State line, Cherokee County, Kansas.
    (ii) Note: Map of Unit NM7 (Neosho River) of critical habitat for 
Neosho mucket follows:

[[Page 63498]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.007

    (13) Unit NM8: Cottonwood River--Chase County, Kansas.
    (i) Unit NM8 includes 2.6 rkm (1.6 rmi) of the Cottonwood River 
from the South Fork Cottonwood River confluence downstream to the 
Kansas Road 140 (also known as Heins Road), east of Cottonwood Falls, 
Chase County, Kansas.
    (ii) Note: Map of Unit NM8 (Cottonwood River) of critical habitat 
for Neosho mucket follows:

[[Page 63499]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.008

Rabbitsfoot (Quadrula cylindrica cylindrica)
    (1) Critical habitat units are depicted for the rabbitsfoot in:
    (i) Alabama: Colbert, Jackson, Madison, and Marshall Counties.
    (ii) Arkansas: Arkansas, Ashley, Bradley, Clark, Cleveland, Dallas, 
Drew, Fulton, Grant, Hot Spring, Independence, Izard, Jackson, 
Lawrence, Little River, Marion, Monroe, Montgomery, Newton, Ouachita, 
Randolph, Saline, Searcy, Sevier, Sharp, Van Buren, White, and Woodruff 
Counties.
    (iii) Kansas: Allen and Cherokee Counties.
    (iv) Kentucky: Ballard, Green, Hart, Livingston, Logan, Marshall, 
and McCracken Counties.
    (v) Illinois: Massac, Pulaski, and Vermilion Counties.
    (vi) Indiana: Carroll, Pulaski, Tippecanoe, and White Counties.
    (vii) Mississippi: Hinds, Sunflower, Toshimingo, and Warren 
Counties.
    (viii) Missouri: Jasper, Madison, and Wayne Counties.
    (ix) Ohio: Coshocton, Madison, Union, and Williams Counties.
    (x) Oklahoma: McCurtain and Rogers Counties.
    (xi) Pennsylvania: Crawford, Erie, Mercer, and Venango Counties.
    (xii) Tennessee: Hardin, Hickman, Marshall, Maury, and Robertson 
Counties.
    (2) Within these areas, the primary constituent elements of the 
physical and biological features essential to the conservation of the 
rabbitsfoot consist of five components:
    (i) Geomorphically stable river channels and banks (channels that 
maintain lateral dimensions, longitudinal profiles, and sinuosity

[[Page 63500]]

patterns over time without an aggrading or degrading bed elevation) 
with habitats that support a diversity of freshwater mussel and native 
fish (such as stable riffles, sometimes with runs, and midchannel 
island habitats that provide flow refuges consisting of gravel and sand 
substrates with low to moderate amounts of fine sediment and attached 
filamentous algae).
    (ii) A hydrologic flow regime (the severity, frequency, duration, 
and seasonality of discharge over time) necessary to maintain benthic 
habitats where the species are found and to maintain connectivity of 
rivers with the floodplain, allowing the exchange of nutrients and 
sediment for maintenance of the mussel's and fish host's habitat, food 
availability, spawning habitat for native fishes, and the ability for 
newly transformed juveniles to settle and become established in their 
habitats.
    (iii) Water and sediment quality (including, but not limited to, 
conductivity, hardness, turbidity, temperature, pH, ammonia, heavy 
metals, and chemical constituents) necessary to sustain natural 
physiological processes for normal behavior, growth, and viability of 
all life stages.
    (iv) The presence and abundance (currently unknown) of fish hosts 
necessary for recruitment of the rabbitsfoot. The occurrence of natural 
fish assemblages, reflected by fish species richness, relative 
abundance, and community composition, for each inhabited river or creek 
will serve as an indication of appropriate presence and abundance of 
fish hosts until appropriate host fish can be identified.
    (v) Either no competitive or predaceous invasive (nonnative) 
species, or such species in quantities low enough to have minimal 
effect on survival of freshwater mussels.
    (3) Critical habitat does not include manmade structures (such as 
buildings, bridges, aqueducts, airports, roads, and other paved areas) 
and the land on which they are located exists within the legal 
boundaries on the effective date of this rule.
    (4) Critical habitat map units. Unit maps were developed using ESRI 
ArcGIS mapping software along with various spatial data layers. 
Critical habitat unit upstream and downstream limits were delineated at 
the nearest road crossing or stream confluence of each occupied reach. 
Data layers defining map units were created with USGS National 
Hydrography Dataset (NHD) Medium Flowline data. ArcGIS was also used to 
calculate river kilometers and miles from the NHD dataset, and it was 
used to determine longitude and latitude coordinates in decimal 
degrees. The projection used in mapping and calculating distances and 
locations within the units was North American Albers Equal Area Conic, 
NAD 83.
    (5) Note: Index map of critical habitat units for the rabbitsfoot 
follows:

[[Page 63501]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.009

    (6) Unit RF1: Spring River--Jasper County, Missouri; and Cherokee 
County, Kansas.
    (i) Unit RF1 includes 56.5 rkm (35.1 rmi) of the Spring River from 
Missouri Highway 96 at Carthage, Jasper County, Missouri, downstream to 
the confluence of Turkey Creek north of Empire, Cherokee County, 
Kansas.
    (ii)  Note: Map of Unit RF1 (Spring River) of critical habitat for 
rabbitsfoot follows:

[[Page 63502]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.010

    (7) Unit RF2: Verdigris River--Rogers County, Oklahoma.
    (i) Unit RF2 includes 45.5 rkm (28.3 rmi) of the Verdigris River 
from Oologah Lake dam north of Claremore, Oklahoma, downstream to 
Interstate 44 (Will Rogers Turnpike) west of Catoosa, Rogers County, 
Oklahoma.
    (ii) Note: Map of Unit RF2 (Verdigris River) of critical habitat 
for rabbitsfoot follows:

[[Page 63503]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.011

    (8) Unit RF3: Neosho River--Allen County, Kansas.
    (i) Unit RF3 includes 26.6 rkm (16.5 rmi) of the Neosho River from 
the Deer Creek confluence northwest of Iola, Kansas, downstream to the 
confluence of Owl Creek southwest of Humboldt, Allen County, Kansas.
    (ii)  Note: Map of Unit RF3 (Neosho River) of critical habitat for 
rabbitsfoot follows:

[[Page 63504]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.012

    (9) Unit RF4a: Ouachita River--Montgomery County, Arkansas.
    (i) Unit RF4a includes 21.9 rkm (13.6 rmi) of the Ouachita River 
from Arkansas Highway 379 south of Oden, Montgomery County, Arkansas, 
downstream to Arkansas Highway 298 east of Pencil Bluff, Montgomery 
County, Arkansas.
    (ii) Note: Map of Unit RF4a (Ouachita River) of critical habitat 
for rabbitsfoot follows:

[[Page 63505]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.013

    (10) Unit RF4b: Ouachita River--Clark, Hot Spring, and Ouachita 
Counties, Arkansas.
    (i) Unit RF4b includes 157.9 rkm (98.1 rmi) of the Ouachita River 
from Interstate 30 at Malvern, Hot Spring County, Arkansas, downstream 
to U.S. Highway 79 at Camden, Ouachita County, Arkansas.
    (ii) Note: Map of Unit RF4b (Ouachita River) of critical habitat 
for rabbitsfoot follows:

[[Page 63506]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.014

    (11) Unit RF5: Saline River--Ashley, Bradley, Cleveland, Dallas, 
Drew, Grant, and Saline Counties, Arkansas.
    (i) Unit RF5 includes 288.4 rkm (179.2 rmi) of the Saline River 
from Interstate 30 near Benton, Saline County, Arkansas, downstream to 
Snake Creek confluence north of Felsenthal National Wildlife Refuge's 
northern border located northwest of Crossett, Ashley and Bradley 
Counties, Arkansas.
    (ii) Note: Map of Unit RF5 (Saline River) of critical habitat for 
rabbitsfoot follows:

[[Page 63507]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.015

    (12) Unit RF6: Little River--McCurtain County, Oklahoma; and Little 
River and Sevier Counties, Arkansas.
    (i) Unit RF6 includes 139.7 rkm (86.8 rmi) of the Little River from 
the Glover River confluence northwest of Idabel, McCurtain County, 
Oklahoma, downstream to U.S. Highway 71 north of Wilton, Little River 
and Sevier Counties, Arkansas.
    (ii)  Note: Map of Unit RF6 (Little River) of critical habitat for 
rabbitsfoot follows:

[[Page 63508]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.016

    (13) Unit RF7: Middle Fork Little River--Van Buren County, 
Arkansas.
    (i) Unit RF7 includes 23.3 rkm (14.5 rmi) of the Middle Fork Little 
Red River from the confluence of Little Tick Creek north of Shirley, 
Arkansas, downstream to the upstream point of inundation by Greers 
Ferry Reservoir, Van Buren County, Arkansas.
    (ii) Note: Map of Unit RF7 (Middle Fork Little Red River) of 
critical habitat for rabbitsfoot follows:

[[Page 63509]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.017

    (14) Unit RF8a: White River--Independence, Jackson, White, and 
Woodruff Counties, Arkansas.
    (i) Unit RF8a includes 188.3 rkm (117.0 rmi) of the White River 
from the Batesville Dam at Batesville, Independence County, Arkansas, 
downstream to the Little Red River confluence north of Georgetown, 
White, and Woodruff Counties, Arkansas.
    (ii) Note: Map of Unit RF8a (White River) of critical habitat for 
the rabbitsfoot follows:

[[Page 63510]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.018

    (15) Unit RF8b: White River--Arkansas and Monroe Counties, 
Arkansas.
    (i) Unit RF8b includes 68.9 rkm (42.8 rmi) of the White River from 
U.S. Highway 79 at Clarendon, Monroe County, Arkansas, downstream to 
Arkansas Highway 1 near St. Charles, Arkansas County, Arkansas.
    (ii) Note: Map of Unit RF8b (White River) of critical habitat for 
rabbitsfoot follows:

[[Page 63511]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.019

    (16) Unit RF9: Black River--Lawrence and Randolph Counties, 
Arkansas.
    (i) Unit RF9 includes 92.2 rkm (57.3 rmi) of the Black River from 
U.S. Highway 67 at Pocahontas, Randolph County, Arkansas, downstream to 
the Strawberry River confluence southeast of Strawberry, Lawrence 
County, Arkansas.
    (ii) Note: Map of Unit RF9 (Black River) of critical habitat for 
rabbitsfoot follows:

[[Page 63512]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.020

    (17) Unit RF10: Spring River--Lawrence, Randolph, and Sharp 
Counties, Arkansas.
    (i) Unit RF10 includes 62.8 rkm (39.0 rmi) of the Spring River from 
U.S. Highway 412 and 62 at Hardy in Sharp County, Arkansas, downstream 
to its confluence with the Black River east of Black Rock, Lawrence, 
and Randolph Counties, Arkansas.
    (ii)  Note: Map of Unit RF10 (Spring River) of critical habitat for 
rabbitsfoot follows:

[[Page 63513]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.021

    (18) Unit RF11: South Fork Spring River--Fulton County, Arkansas.
    (i) Unit RF11 includes 16.4 rkm (10.2 rmi) of the South Fork Spring 
River from Fulton County Road 198 north of Heart, Arkansas, downstream 
to Arkansas Highway 289 at Saddle, Fulton County, Arkansas.
    (ii) Note: Map of Unit RF11 (South Fork Spring River) of critical 
habitat for rabbitsfoot follows:

[[Page 63514]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.022

    (19) Unit RF12: Strawberry River--Izard, Lawrence, and Sharp 
Counties, Arkansas.
    (i) Unit RF12 includes 123.8 rkm (76.9 rmi) of the Strawberry River 
from Arkansas Highway 56 south of Horseshoe Bend, Izard County, 
Arkansas, downstream to its confluence with the Black River southeast 
of Strawberry, Lawrence County, Arkansas.
    (ii) Note: Map of Unit RF12 (Strawberry River) of critical habitat 
for rabbitsfoot follows:

[[Page 63515]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.023

    (20) Unit RF13: Buffalo River--Newton and Searcy Counties, 
Arkansas.
    (i) Unit RF13 includes 113.6 rkm (70.6 rmi) of the Buffalo River 
from the Cove Creek confluence southeast of Erbie, Newton County, 
Arkansas, downstream to U.S. Highway 65 west of Gilbert, Searcy County, 
Arkansas (western segment), and Arkansas Highway 14 downstream to the 
confluence of Leatherwood Creek in the Lower Buffalo Wilderness Area 
(eastern segment).
    (ii)  Note: Map of Unit RF13 (Buffalo River) of critical habitat 
for rabbitsfoot follows:

[[Page 63516]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.024

    (21) Unit RF14: St. Francis River--Madison and Wayne Counties, 
Missouri.
    (i) Unit RF14 includes 64.3 rkm (40.0 rmi) of the St. Francis River 
from the Twelvemile Creek confluence west of Saco, Madison County, 
Missouri, downstream to the upstream point of inundation by Lake 
Wappepello, Wayne County, Missouri.
    (ii) Note: Map of Unit RF14 (St. Francis River) of critical habitat 
for rabbitsfoot follows:

[[Page 63517]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.025

    (22) Unit RF15: Big Sunflower River--Sunflower County, Mississippi.
    (i) Unit RF15 includes 51.5 rkm (32.0 rmi) of the Big Sunflower 
River from Mississippi Highway 442 west of Doddsville, Mississippi, 
downstream to the Quiver River confluence east of Indianola, Sunflower 
County, Mississippi.
    (ii) Note: Map of Unit RF15 (Big Sunflower River) of critical 
habitat for rabbitsfoot follows:

[[Page 63518]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.026

    (23) Unit RF16: Bear Creek--Tishomingo County, Mississippi; and 
Colbert County, Alabama.
    (i) Unit RF16 includes 49.7 rkm (30.9 rmi) of Bear Creek from the 
Alabama and Mississippi State line east of Golden, Tishomingo County, 
Mississippi, downstream to Alabama County Road 4 southwest of Sutton 
Hill, Colbert County, Alabama (just upstream of Pickwick Lake).
    (ii) Note: Map of Unit RF16 (Bear Creek) of critical habitat for 
rabbitsfoot follows:

[[Page 63519]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.027

    (24) Unit RF17: Big Black River--Hinds and Warren Counties, 
Mississippi.
    (i) Unit RF17 includes 43.3 rkm (26.9 rmi) of the Big Black River 
from Porter Creek confluence west of Lynchburg, Hinds County, 
Mississippi, downstream to Mississippi Highway 27 west of Newman, 
Warren County, Mississippi.
    (ii) Note: Map of Unit RF17 (Big Black River) of critical habitat 
for rabbitsfoot follows:

[[Page 63520]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.028

    (25) Unit RF18: Paint Rock River--Jackson, Madison, and Marshall 
Counties, Alabama.
    (i) Unit RF18 includes 81.0 rkm (50.3 rmi) of the Paint Rock River 
from the convergence of Estill Fork and Hurricane Creek north of 
Skyline, Jackson County, Alabama, downstream to U.S. Highway 431 south 
of New Hope, Madison and Marshall Counties, Alabama.
    (ii) Note: Map of Unit RF18 (Paint Rock River) of critical habitat 
for rabbitsfoot follows:

[[Page 63521]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.029

    (26) Unit RF19: Duck River--Hickman, Marshall, and Maury Counties, 
Tennessee.
    (i) Unit RF19 includes 235.3 rkm (146.2 rmi) of the Duck River from 
Lillard Mill (RKM 288.1; RMI 179) west of Tennessee Highway 272, 
Marshall County, Tennessee, downstream to Interstate 40 near Bucksnort, 
Hickman County, Tennessee.
    (ii) Note: Map of Unit RF19 (Duck River) of critical habitat for 
rabbitsfoot follows:

[[Page 63522]]

[GRAPHIC] [TIFF OMITTED] TP16OC12.030

    (27) Unit RF20a: Tennessee River--Hardin County, Tennessee.
    (i) Unit RF20a includes 26.7 rkm (16.6 rmi) of the Tennessee River 
from Pickwick Lake Dam downstream to U.S. Highway 64 near Adamsville, 
Hardin County, Tennessee.
    (ii)  Note: Map of Unit RF20a (Tennessee River) of critical habitat 
for rabbitsfoot follows:

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    (28) Unit RF20b: Tennessee River--Livingston, Marshall, and 
McCracken Counties, Kentucky.
    (i) Unit RF20b includes 35.6 rkm (22.1 rmi) of the Tennessee River 
from Kentucky Lake Dam, Marshall and Livingston Counties, Kentucky, 
downstream to its confluence with the Ohio River, Livingston and 
McCracken Counties, Kentucky.
    (ii)  Note: Map of Unit RF20b (Tennessee River) of critical habitat 
for rabbitsfoot follows:

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    (29) Unit RF21: Ohio River--Ballard, Livingston, and McCracken 
Counties, Kentucky; Massac and Pulaski Counties, Illinois.
    (i) Unit RF21 includes 45.9 rkm (28.5 rmi) of the Ohio River from 
the Tennessee River confluence, Livingston and McCracken Counties, 
Kentucky, downstream to Lock and Dam 53 near Olmstead, Pulaski County, 
Illinois.
    (ii)  Note: Map of Unit RF21 (Ohio River) of critical habitat for 
rabbitsfoot follows:

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    (30) Unit RF22: Green River--Green, Hart, and Taylor Counties, 
Kentucky.
    (i) Unit RF22 includes 175.6 rkm (109.1 rmi) of the Green River 
from Green River Lake Dam south of Campbellsville, Taylor County, 
Kentucky, downstream to Maple Springs Ranger Station Road in Mammoth 
Cave National Park, Kentucky.
    (ii) Note: Map of Unit RF22 (Green River) of critical habitat for 
rabbitsfoot follows:

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    (31) Unit RF23: French Creek--Crawford, Erie, Mercer, and Venango 
Counties, Pennsylvania.
    (i) Unit RF23 includes 120.4 rkm (74.8 rmi) of French Creek from 
Union City Reservoir Dam northeast of Union City, Erie County, 
Pennsylvania, downstream to its confluence with the Allegheny River 
near Franklin, Venango County, Pennsylvania.
    (ii) Note: Map of Unit RF23 (French Creek) of critical habitat for 
rabbitsfoot follows:

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    (32) Unit RF24: Allegheny River--Venango County, Pennsylvania.
    (i) Unit RF24 includes 57.3 rkm (35.6 rmi) of the Allegheny River 
from the French Creek confluence near Franklin, Venango County, 
Pennsylvania, downstream to Interstate 80 near Emlenton, Venango 
County, Pennsylvania.
    (ii) Note: Map of Unit RF24 (Allegheny River) of critical habitat 
for rabbitsfoot follows:

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    (33) Unit RF25: Muddy Creek--Crawford County, Pennsylvania.
    (i) Unit RF25 includes 20.1 rkm (12.5 rmi) of Muddy Creek from 
Pennsylvania Highway 77 near Little Cooley, Crawford County, 
Pennsylvania, downstream to its confluence with French Creek east of 
Cambridge Springs, Crawford County, Pennsylvania.
    (ii) Note: Map of Unit RF25 (Muddy Creek) of critical habitat for 
rabbitsfoot follows:

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    (34) Unit RF26: Tippecanoe River--Carroll, Pulaski, Tippecanoe, and 
White Counties, Indiana.
    (i) Unit RF26 includes 75.6 rkm (47.0 rmi) of the Tippecanoe River 
from Indiana Highway 14 near Winamac, Pulaski County, Indiana, 
downstream to its confluence with the Wabash River northeast of Battle 
Ground, Tippecanoe County, Indiana, excluding Lakes Schafer and Freeman 
and the stream reach between the two lakes.
    (ii) Note: Map of Unit RF26 (Tippecanoe River) of critical habitat 
for rabbitsfoot follows:

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    (35) Unit RF27: Walhonding River--Coshocton County, Ohio.
    (i) Unit RF27 includes 17.5 rkm (10.9 rmi) of the Walhonding River 
from the convergence of the Kokosing and Mohican Rivers downstream to 
Ohio Highway 60 near Warsaw, Coshocton County, Ohio.
    (ii) Note: Map of Unit RF27 (Walhonding River) of critical habitat 
for rabbitsfoot follows:

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    (36) Unit RF28: Little Darby Creek--Madison and Union Counties, 
Ohio.
    (i) Unit RF28 includes 33.3 rkm (20.7 rmi) of Little Darby Creek 
from Ohio Highway 161 near Chuckery, Madison County, Ohio, downstream 
to U.S. Highway 40 near West Jefferson, Madison County, Ohio.
    (ii) Note: Map of Unit RF28 (Little Darby Creek) of critical 
habitat for rabbitsfoot follows:

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    (37) Unit RF29: North Fork Vermilion River and Middle Branch North 
Fork Vermilion River, respectively, Vermilion County, Illinois.
    (i) Unit RF29 includes 28.5 rkm (17.7 rmi) of the North Fork 
Vermilion River from the confluence of Middle Branch North Fork 
Vermilion River downstream to Illinois Highway 1 and U.S. Highway 136 
upstream of Lake Vermilion, Vermilion County, Illinois. Unit RF29 also 
includes 7.2 rkm (4.5 rmi) of the Middle Branch North Fork Vermilion 
River from the Jordan Creek confluence northwest of Alvin, Illinois, 
downstream to its confluence with North Fork Vermilion River west of 
Alvin, Vermilion County, Illinois.
    (ii) Note: Map of Unit RF29 (North Fork Vermilion River and Middle 
Branch North Fork Vermilion River) of critical habitat for rabbitsfoot 
follows:

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    (38) Unit RF30: Fish Creek--Williams County, Ohio.
    (i) Unit RF30 includes 7.7 rkm (4.8 rmi) of Fish Creek from the 
western (upstream) portion of Fish Creek Wildlife Area near the Indiana 
and Ohio State line northwest of Edgerton, Ohio, downstream to its 
confluence with the St. Joseph's River north of Edgerton, Williams 
County, Ohio.
    (ii) Note: Map of Unit RF30 (Fish Creek) of critical habitat for 
rabbitsfoot follows:

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    (39) Unit RF31: Red River--Logan County, Kentucky; and Robertson 
County, Tennessee.
    (i) Unit RF31 includes 50.2 rkm (31.2 rmi) of the Red River from 
the South Fork Red River confluence west of Adairville, Logan County, 
Kentucky, downstream to the Sulphur Fork confluence southwest of Adams, 
Robertson County, Tennessee.
    (ii) Note: Map of Unit RF31 (Red River) of critical habitat for 
rabbitsfoot follows:

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    (40) Unit RF32: Shenango River--Mercer County, Pennsylvania.
    (i) Unit RF32 includes 16.3 rkm (10.1 rmi) of the Shenango River 
from Kidds Mill Road near Greenville, Pennsylvania, downstream to the 
upstream point of inundation by Shenango River Lake near Big Bend, 
Mercer County, Pennsylvania.
    (ii) Note: Map of Unit RF32 (Shenango River) of critical habitat 
for rabbitsfoot follows:

[[Page 63536]]

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* * * * *

    Dated: August 22, 2012.
Rachel Jacobson,
Principal Deputy Assistant Secretary for Fish and Wildlife and Parks.
[FR Doc. 2012-24151 Filed 10-12-12; 8:45 am]
BILLING CODE 4310-55-c