[Federal Register Volume 67, Number 109 (Thursday, June 6, 2002)]
[Proposed Rules]
[Pages 39206-39235]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-14141]



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Part IV





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; Designation of Critical 
Habitat for the Rio Grande Silvery Minnow; Proposed Rule

  Federal Register / Vol. 67, No. 109 / Thursday, June 6, 2002 / 
Proposed Rules  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AH91


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the Rio Grande Silvery Minnow

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; notice of availability.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
designate critical habitat for the Rio Grande silvery minnow 
(Hybognathus amarus) (silvery minnow), a species federally listed as 
endangered under the authority of the Endangered Species Act of 1973, 
as amended (Act). The silvery minnow presently occurs only in the Rio 
Grande from Cochiti Dam, Sandoval County, downstream to the headwaters 
of Elephant Butte Reservoir, Sierra County, New Mexico. We propose to 
designate critical habitat within this last remaining portion of the 
occupied range in the middle Rio Grande (Cochiti Dam to Elephant Butte 
Dam) in New Mexico. The proposed critical habitat designation defines 
the lateral extent (width) as those areas bounded by existing levees 
or, in areas without levees, 91.4 meters (300 feet) of riparian zone 
adjacent to each side of the middle Rio Grande. We request data and 
comments from the public and all interested parties on all aspects of 
this proposed rule, including data on economic and other relevant 
impacts of the designation and the two areas that are not proposed as 
critical habitat. A draft economic analysis, which examines primarily 
economic impacts of this proposed rule, has been prepared and is also 
available for review and comments. This publication also provides 
notice of the availability of the draft economic analysis and the draft 
EIS for this proposed rule. We invite all interested parties to submit 
comments on these draft documents and this proposed rule.

DATES: Comments. We will consider all comments on the proposed rule, 
draft economic analysis, and the draft EIS received from interested 
parties by September 4, 2002.
    Public Hearings. We will also hold two public hearings to receive 
comments from the public. The public hearings will be held in Socorro 
and Albuquerque, New Mexico, on June 25 and 26, respectively.

ADDRESSES: 1. Send your comments on this proposed rule, the draft 
economic analysis, and draft EIS to the New Mexico Ecological Services 
Field Office, 2105 Osuna Road NE, Albuquerque, NM, 87113. Written 
comments may also be sent by facsimile to (505) 346-2542 or through the 
Internet to [email protected]. You may also hand-deliver written 
comments to our New Mexico Ecological Services Field Office, at the 
above address. You may obtain copies of the proposed rule, the draft 
economic analysis, or the draft EIS from the above address or by 
calling 505/346-2525. All documents are also available from our website 
at http://ifw2es.fws.gov/Library/.
    2. Comments and materials received, as well as supporting 
documentation used in the preparation of this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the New Mexico Ecological Services Field Office (see address 
above).
    3. We will hold public hearings in Socorro, NM, on June 25, 2002; 
and in Albuquerque, NM, on June 26, 2002 at the following locations:
     Socorro, NM: New Mexico Institute for Mining and 
Technology, Macey Center, 801 Leroy Place, Socorro, New Mexico, on June 
25, 2002, from 6 to 9 p.m.
     Albuquerque, NM: Indian Pueblo Cultural Center, 2401 12th 
Street NW, Albuquerque, New Mexico, on June 26, 2002, from 6 to 9 p.m.

FOR FURTHER INFORMATION CONTACT: Joy Nicholopoulos, Field Supervisor, 
New Mexico Ecological Services Field Office (see ADDRESSES above); 
phone: 505-346-2525.

SUPPLEMENTARY INFORMATION:

Background

    The Rio Grande silvery minnow is one of seven species in the genus 
Hybognathus found in the United States (Pflieger 1980). The species was 
first described by Girard (1856) from specimens taken from the Rio 
Grande near Fort Brown, Cameron County, TX. It is a stout silvery 
minnow with moderately small eyes and a small, slightly oblique mouth. 
Adults may reach 90 millimeters (mm) (3.5 inches (in)) in total length 
(Sublette et al. 1990). Its dorsal fin is distinctly pointed with the 
front of it located slightly closer to the tip of the snout than to the 
base of the tail. The fish is silver with emerald reflections. Its 
belly is silvery white, fins are plain, and barbels are absent 
(Sublette et al. 1990).
    This species was historically one of the most abundant and 
widespread fishes in the Rio Grande Basin, occurring from 
Espa[ntilde]ola, NM, to the Gulf of Mexico (Bestgen and Platania 1991). 
It was also found in the Pecos River, a major tributary of the Rio 
Grande, from Santa Rosa, NM, downstream to its confluence with the Rio 
Grande (Pflieger 1980). The silvery minnow is completely extirpated 
from the Pecos River and from the Rio Grande downstream of Elephant 
Butte Reservoir and upstream of Cochiti Reservoir (Bestgen and Platania 
1991). The current distribution of the silvery minnow is limited to the 
Rio Grande between Cochiti Dam and Elephant Butte Reservoir. Throughout 
much of its historic range, decline of the silvery minnow has been 
attributed to modification of the flow regime (hydrological pattern of 
flows that vary seasonally in magnitude and duration, depending on 
annual precipitation patterns such as runoff from snowmelt) and channel 
drying because of impoundments, water diversion for agriculture, stream 
channelization, and perhaps both interactions with non-native fish and 
decreasing water quality (Cook et al. 1992; Bestgen and Platania 1991, 
Service 1999; Buhl 2001).
    It is important to note that much of the species' life history 
information detailed below comes from studies conducted within the 
middle Rio Grande, the current range of the minnow. Nevertheless, we 
believe that our determinations for other areas outside of the middle 
Rio Grande, but within the historical range of the silvery minnow, are 
consistent with the data collected to date on the species' ecological 
requirements (e.g., Service 1999).
    The role of the plains minnow (Hybognathus placitus) in the decline 
and extirpation of the silvery minnow from the Pecos River is 
uncertain; however, the establishment of the plains minnow coincided 
with the disappearance of the silvery minnow (Bestgen and Platania 
1991; Cook et al. 1992). It is believed the non-native plains minnow 
was introduced into the Pecos drainage prior to 1964 (Cook et al. 
1992), and was probably the result of the release of ``bait minnows'' 
that were collected from the Arkansas River drainage. It is unclear, 
however, if populations of the native silvery minnow were depleted 
prior to the introduction of the plains minnow, or if the reduction and 
extirpation of the silvery minnow was a consequence of the interactions 
of the two species (C. Hoagstrom, U.S. Fish and Wildlife Service, pers. 
comm. 2001). One theory is that the plains minnow may be more tolerant 
of modified habitats and,

[[Page 39207]]

therefore, was able to replace the silvery minnow in the degraded 
reaches of the Pecos River. Nevertheless, the plains minnow has 
experienced population declines within its native range from highly 
variable water levels, unstable streambeds, and fluctuating water 
temperatures (Cross et al. 1985 cited in Taylor and Miller 1990). 
Although the interactions (e.g., hybridization or competition) between 
the silvery minnow and the introduced plains minnow are believed by 
some to be one of the primary causes for the extirpation of the silvery 
minnow in the Pecos River, this hypothesis is unsubstantiated (Hatch et 
al. 1985; Bestgen et al. 1989; Cook et al. 1992). Currently, New Mexico 
State University is conducting research on the plains minnow and 
silvery minnow to determine if the two species hybridize. Preliminary 
results of this research should be available in summer 2002. It is 
important to note that, within its native range, the plains minnow is 
sympatric (occurs at the same localities) with other species of 
Hybognathus. However, they are segregated ecologically (i.e., the 
plains minnow is found in the main river channel where the substrate is 
predominantly sand, whereas the western silvery minnow (Hybognathus 
argyritis) predominates backwaters and protected areas with little to 
no current and sand or silt substrate) (Pflieger 1997). Consequently, 
if the silvery minnow and plains minnow do not hybridize, they may be 
ecologically segregated and able to co-exist.
    The plains minnow and silvery minnow appear to have little in the 
way of behavioral or physiological isolating mechanisms and may 
hybridize (Cook et al. 1992); yet the combined effects of habitat 
degradation (i.e., modification of the flow regime, channel drying, 
water diversion, and stream channelization) may be a more likely 
explanation for the silvery minnow's extirpation from the Pecos River 
(Bestgen and Platania 1991; C. Hoagstrom, pers. comm. 2001). We 
acknowledge that there are no conclusive data to substantiate any 
reasons for extirpation of the silvery minnow from the Pecos River.
    The silvery minnow has also been extirpated from the lower Rio 
Grande, including the Big Bend National Park area (Hubbs et al. 1977; 
Bestgen and Platania 1991). Reasons for the species' extirpation in the 
lower Rio Grande are also uncertain. The last documented collection of 
a silvery minnow in the Big Bend area was 1961, but reexamination of 
that specimen revealed it was a plains minnow (Bestgen and Propst 
1996). Therefore, the last silvery minnow from the lower Rio Grande was 
apparently collected in the late 1950s (Trevino-Robinson 1959; Hubbs et 
al. 1977; Edwards and Contreras-Balderas 1991).
    Decline of the species in the middle Rio Grande probably began in 
1916 when the gates at Elephant Butte Dam were closed. Construction of 
the dam signaled the beginning of an era of mainstem Rio Grande dam 
construction that resulted in five major mainstem dams within the 
silvery minnow's historic range (Shupe and Williams 1988). These dams 
allowed manipulation and diversion of the flow of the river. Often this 
manipulation severely altered the flow regime and likely precipitated 
the decline of the silvery minnow (Bestgen and Platania 1991). 
Concurrent with construction of the mainstem dams was an increase in 
the abundance of non-native fish as these species were stocked into the 
reservoirs created by the dams (e.g., Cochiti Reservoir) (Sublette et 
al. 1990). Once established, these species often completely replaced 
the native fish fauna (Propst et al. 1987; Propst 1999).
    Development of agriculture and the growth of cities within the 
historic range of the silvery minnow resulted in a decrease in the 
quality of river water through municipal and agricultural run-off 
(i.e., sewage and pesticides) that may have also adversely affected the 
range and distribution of the silvery minnow. Historically there were 
four other small native fish species (speckled chub (Macrohybopsis 
aestivalis); Rio Grande shiner (Notropis jemezanus); phantom shiner 
(Notropis orca); and Rio Grande bluntnose shiner (Notropis simus 
simus)) within the middle Rio Grande that had similar reproductive 
attributes, but these species are now either extinct or extirpated 
(Platania 1991). The silvery minnow is a pelagic spawning species; i.e. 
its eggs flow in the water column. The silvery minnow is the only 
surviving small native pelagic spawning minnow in the middle Rio Grande 
and its range has been reduced to only 5 percent of its historic 
extent. Although the silvery minnow is a hearty fish, capable of 
withstanding many of the natural stresses of the desert aquatic 
environment, the majority of the individual silvery minnows live only 
one year (Bestgen and Platania 1991). Thus, a successful annual spawn 
is key to the survival of the species (Platania and Hoagstrom 1996; 
Service 1999; Dudley and Platania 2001). The silvery minnow's range has 
been so greatly restricted, the species is extremely vulnerable to a 
single catastrophic event, such as a prolonged period of low or no flow 
(i.e., the loss of all surface water) (59 FR 36988; Dudley and Platania 
2001).
    The various life history stages of the silvery minnow require 
shallow waters with a sandy and silty substrate that is generally 
associated with a meandering river that includes sidebars, oxbows, and 
backwaters (C. Hoagstrom, pers. comm, 2001; Bestgen and Platania 1991; 
Platania 1991). However, physical modifications to the Rio Grande over 
the last century--including the construction of dams, levees, and 
channelization of the mainstem--have altered much of the habitat that 
is necessary for the species to persist (Service 1999). Channelization 
has straightened and shortened mainstem river reaches; increased the 
velocity of the current; and altered riparian vegetation, instream 
cover, and substrate composition (U.S. Bureau of Reclamation (BOR) 
2001a).
    In the middle Rio Grande, the spring runoff coincides with and may 
trigger the silvery minnow's spawn (Platania and Hoagstrom 1996; 
Service 1999; Dudley and Platania 2001). The semi-buoyant (floating) 
eggs that are produced drift downstream in the water column (Smith 
1999; Dudley and Platania 2001) (see ``Primary Constituent Elements'' 
section of this proposed rule for further information on spawning). 
However, it is believed that diversion dams act as instream barriers 
and prevent silvery minnows from movement upstream after hatching 
(Service 2001b; Dudley and Platania 2001; 2002). In fact, the continued 
downstream displacement and decline of the silvery minnow in the middle 
Rio Grande is well documented (Dudley and Platania 2001).
    During the irrigation season (approximately March 1 to October 31 
of each year) in the middle Rio Grande, silvery minnow often become 
stranded in the diversion channels (or irrigation ditches), where they 
are unlikely to survive (Smith 1999, Lang and Altenbach 1994). For 
example, when the irrigation water in the diversion channels is used on 
agricultural fields, the possibility for survival of silvery minnows in 
the irrigation return flows (excess irrigation water that flows from 
agricultural fields and is eventually returned to the river) is low, 
because they perish in canals due to unsuitable habitat, dewatering, or 
predation (Lang and Altenbach 1994). Unscreened diversion dams also 
entrain (trap) silvery minnow fry (fish that have recently emerged from 
eggs) and semi-buoyant eggs (Smith 1998; 1999). However, some 
irrigation water is returned to the river via irrigation wasteways in 
the reach of the middle Rio Grande from the Isleta Diversion

[[Page 39208]]

Dam to the San Acacia Diversion Dam (Isleta reach), which helps sustain 
flow in certain segments of this reach. Nevertheless, we do not believe 
these riverside drains offer suitable refugia or are useful for 
recovery of the silvery minnow.
    In the middle Rio Grande, perhaps even more problematic for the 
silvery minnow are drought years during the irrigation season when 
there may be little supplemental water (water that is used to augment 
river flows) available and when most or all of the water in the middle 
Rio Grande may be diverted into the irrigation channels (e.g., see 
Dudley and Platania 2001) or otherwise consumed. Compounding this 
problem is stream bed aggradation (i.e., the river bottom is rising due 
to sedimentation) below San Acacia, NM, where the bed of the river is 
now perched above the bed of the low flow conveyance channel (LFCC), 
which is immediately adjacent and parallel to the river channel. 
Because of this physical configuration, waters in the mainstem of the 
river are drained from the river bed into the LFCC. The LFCC parallels 
the Rio Grande for approximately 121 kilometers (km) (75 miles (mi)) 
and was designed to expedite delivery of water to Elephant Butte 
Reservoir, pursuant to the Rio Grande Compact of 1939. The LFCC 
diverted water from the Rio Grande from 1959 to 1985. The LFCC was 
built to more efficiently deliver water to Elephant Butte Reservoir 
during low-flow conditions and has the capacity to take approximately 
2,000 cubic feet per second (cfs) of the river's flow, via gravity. If 
natural river flow is 2,000 cfs or less, the LFCC can dewater the Rio 
Grande from its heading at the San Acacia Diversion Dam south to 
Elephant Butte Reservoir.
    However, the LFCC has not been fully operational since 1985 because 
of outfall problems (e.g., stream bed aggradation) at Elephant Butte 
Reservoir. Even without water diversion into the LFCC, seepage from the 
river to the LFCC is occurring and causing some loss of surface flows 
in the river channel (BOR 2001a). In effect, water is drained from the 
Rio Grande into the LFCC and conveyed to Elephant Butte Reservoir, 
thereby resulting in water losses in the reach from the San Acacia 
Diversion Dam to Elephant Butte Reservoir (San Acacia reach). During 
some years this can result in prolonged periods of low or no flow.
    It is believed that, historically, the silvery minnow was able to 
withstand periods of drought primarily by retreating to pools and 
backwater refugia, and swimming upstream to repopulate upstream 
habitats (e.g., Deacon and Minckley 1974, J. Smith, U.S. Fish and 
Wildlife Service, pers. comm. 2001). It is also believed that after 
prolonged periods of low or no flow the silvery minnow may have been 
able to repopulate downstream habitat the following year by the drift 
of eggs from upstream populations (Platania 1995). However, when the 
present-day middle Rio Grande dries and dams prevent upstream movement 
of the silvery minnow, they can become trapped in dewatered reaches and 
often die in isolated pools before the river becomes wetted again. The 
inability of the population to find adequate refugia during prolonged 
periods of low or no flow and to repopulate extirpated reaches creates 
a very unstable population (Service 2001b). In some isolated pools, 
Smith and Hoagstrom (1997) and Smith (1999) documented complete 
mortality of silvery minnows in the middle Rio Grande in both 1996 and 
1997 during prolonged periods of low or no flow. These studies 
documented both the relative size of the isolated pool (i.e., estimated 
surface area and maximum depth) in relation to pool longevity (i.e., 
number of days the isolated pool existed) and the fish community within 
isolated pools. For example, isolated pools found during these 
conditions typically only lasted for about 48 hours before drying up 
completely (Smith 1999). Those isolated pools that persisted longer 
than 48 hours lost greater than 81 percent of their estimated surface 
area and greater than 26 percent of their maximum depth within 48 
hours. Moreover, isolated pools receive no surface inflow; water 
temperatures increase; dissolved oxygen decreases; and depending on 
location, size, and duration of the prolonged periods of low or no 
flow, will usually result in the death of all fish (Tramer 1977; 
Mundahl 1990; Platania 1993b; Ostrand and Marks 2000; Ostrand and Wilde 
2001). Therefore, when periods of low or no flow are longlasting (over 
48 hours), complete mortality of silvery minnows in isolated pools can 
be expected.
    Formation of isolated pools also increases the risk of predation of 
silvery minnows in drying habitats. Predators; primarily fish and 
birds, have been observed in high numbers in the middle Rio Grande, 
consuming fish in drying, isolated pools, where the fish become 
concentrated and are more vulnerable to predation (J. Smith, pers. 
comm. 2001).
    The potential for prolonged periods of low or no flow on the middle 
Rio Grande becomes particularly significant for the silvery minnow 
below the San Acacia Diversion Dam, where approximately 95 percent of 
the only extant population lives. For example, in the river reach above 
(north of) the San Acacia Diversion Dam, return flows from irrigation 
and other activities are routed back into the mainstem of the river. At 
times, this can provide a fairly consistent flow in particular 
stretches of the Isleta reach. However, at the San Acacia Diversion 
Dam, once diversions are made (i.e., to irrigation canals, as well as 
seepage losses to the LFCC) the return flows continue in off-river 
channels (with a few exceptions at Brown's Arroyo and the 10-mile 
outfall of the LFCC) until they enter Elephant Butte Reservoir. Thus, 
unlike in the Isleta reach, the silvery minnow does not receive the 
benefit of irrigation return flows in the San Acacia reach.
    Although we determine that a river reach in the lower Rio Grande in 
Big Bend National Park downstream of the park boundary to the Terrell/
Val Verde County line, Texas, and a river reach in the middle Pecos 
River, from Sumner Dam to Brantley Dam in De Baca, Chaves, and Eddy 
Counties, New Mexico, are essential to the conservation of the silvery 
minnow, these areas are not proposed for critical habitat designation 
because of our preliminary analysis under section 4(b)(2) (see 
``Exclusions Under Section 4(b)(2) of the Act'' section of this rule). 
The current proposal only includes the middle Rio Grande (Cochiti Dam 
to Elephant Butte Dam) in New Mexico, and no other reaches within the 
historical range of the silvery minnow. Therefore, we are only 
proposing to designate the river reaches currently occupied by the 
silvery minnow. This proposal is analyzed as the preferred alternative 
in the draft Environmental Impact Statement (EIS), pursuant to the 
National Environmental Policy Act (NEPA), which the Service was 
required to prepare under the court order from the United States 
District Court for the District of New Mexico, in Middle Rio Grande 
Conservancy District v. Babbitt, Civ. Nos. 99-870, 99-872, 99-1445M/RLP 
(Consolidated). The two reaches referenced above (i.e., middle Pecos 
River and lower Rio Grande) are also analyzed in the draft EIS. The 
Service must follow the procedures required by the Act, NEPA, and the 
Administrative Procedure Act. Therefore, we seek public comment on all 
reaches identified in this proposed rule as essential, including 
whether any of these or other areas should be excluded from the final 
designation pursuant to Section 4(b)(2). As required by law, we will 
consider all comments received on this proposed rule, the draft EIS, 
and the

[[Page 39209]]

draft economic analysis before making a final determination.
    In accordance with the Recovery Plan, we have initiated a captive 
propagation program for the silvery minnow (Service 1999). We currently 
have silvery minnows housed at: (1) The Service's Dexter National Fish 
Hatchery and Technology Center; (2) the Service's Mora National Fish 
Hatchery and Technology Center; (3) the City of Albuquerque's 
Biological Park; (4) the U.S. Geological Survey Biological Resources 
Division's Yankton Laboratory; and (5) the New Mexico State University 
(J. Brooks, pers. comm., 2001). Progeny of these fish are being used to 
augment the middle Rio Grande silvery minnow population, but could also 
be used in future augmentation or reestablishment programs for the 
silvery minnow in other river reaches (J. Remshardt, New Mexico Fishery 
Resources Office, pers. comm. 2001). We have also salvaged and 
transplanted silvery minnows within the middle Rio Grande in recent 
years (Service 1996, 1998, 1999, 2000, 2001). For example, 
approximately 220,000 silvery minnow larvae and adults have been 
released (i.e., stockings from captive bred fish or translocated from 
downstream reaches) since May 1996 (J. Remshardt, U.S. Fish and 
Wildlife Service, pers. comm. 2001). Effectiveness of these releases is 
currently being investigated and will be useful for evaluating future 
efforts to repatriate the species.
    If this proposed rule is finalized, section 7(a)(2) of the Act 
would require that Federal agencies ensure that actions they fund, 
authorize, or carry out are not likely to result in the ``destruction 
or adverse modification'' of critical habitat. In our regulations at 50 
CFR 402.02, we define destruction or adverse modification as ``direct 
or indirect alteration that appreciably diminishes the value of 
critical habitat for both the survival and recovery of a listed 
species. Such alterations include, but are not limited to, alterations 
adversely modifying any of those physical or biological features that 
were the basis for determining the habitat to be critical.'' Section 4 
of the Act requires us to consider economic and other relevant impacts 
of specifying any particular area as critical habitat.
    Our practice is to make comments that we receive on this 
rulemaking, including names and home addresses of the respondents, 
available for public review during normal business hours. Individual 
respondents may request that we withhold their home address from the 
rulemaking record, which we will honor to the extent allowable by 
Federal law.

Previous Federal Action

    We proposed to list the silvery minnow as an endangered species 
with critical habitat on March 1, 1993 (58 FR 11821). The comment 
period, originally scheduled to close on April 30, 1993, was extended 
to August 25, 1993 (58 FR 19220; April 13, 1993). This extension 
allowed us to conduct public hearings and to receive additional public 
comments. Public hearings were held in Albuquerque and Socorro, NM, on 
the evenings of June 2 and 3, 1993, respectively. After a review of all 
comments received in response to the proposed rule, we published the 
final rule to list the silvery minnow as endangered on July 20, 1994 
(59 FR 36988).
    Section 4(a)(3) of the Act requires that the Secretary, to the 
maximum extent prudent and determinable, designate critical habitat at 
the time a species is listed as endangered or threatened. Our 
regulations (50 CFR 424.12(a)(2)) state that critical habitat is not 
determinable if information sufficient to perform required analyses of 
the impacts of the designation is lacking or if the biological needs of 
the species are not sufficiently well known to permit identification of 
an area as critical habitat. At the time the silvery minnow was listed, 
we found that critical habitat was not determinable because there was 
insufficient information to perform the required analyses of the 
impacts of the designation.
    We contracted for an economic analysis of the proposed critical 
habitat designation in September 1994 and a draft analysis was prepared 
and provided to us on February 29, 1996. The draft document was then 
provided to all interested parties on April 26, 1996. That mailing 
included 164 individuals and agencies, all affected Pueblos in the 
valley, all county commissions within the occupied range of the 
species, and an additional 54 individuals who had attended the public 
hearings on the proposed listing and who had requested that they be 
included on our mailing list, particularly for the economic analysis. 
At that time, we notified the public that, because of a moratorium on 
final listing actions and determinations of critical habitat imposed by 
Public Law 104-6, no work would be conducted on the analysis or on the 
final decision concerning critical habitat. However, we solicited 
comments from the public and agencies on the document for use when such 
work resumed.
    On April 26, 1996, the moratorium was lifted. Following the waiver 
of the moratorium, we reactivated the listing program that had been 
shut down for over a year and faced a backlog of 243 proposed species 
listings. In order to address that workload, we published, on May 16, 
1996, our Listing Priority Guidance for the remainder of Fiscal Year 
1996 (61 FR 24722). That guidance identified the designation of 
critical habitat as the lowest priority upon which we could expend 
limited funding and staff resources. Subsequent revisions of the 
guidance for Fiscal Years 1997 (December 5, 1996; 61 FR 64475) and for 
1998/1999 (May 8, 1998; 63 FR 25502) retained critical habitat as the 
lowest priority for the listing program within the Service. Thus, no 
work resumed on the economic analysis due the low priority assigned to 
critical habitat designations.
    On February 22, 1999, in Forest Guardians v. Babbitt, Civ. No. 97-
0453 JC/DIS, the United States District Court for the District of New 
Mexico ordered us to publish a final determination with regard to 
critical habitat for the silvery minnow within 30 days. The deadline 
was subsequently extended by the court to June 23, 1999. On July 6, 
1999, we published a final designation of critical habitat for the 
silvery minnow (64 FR 36274), pursuant to the court order.
    On November 21, 2000, the United States District Court for the 
District of New Mexico, in Middle Rio Grande Conservancy District v. 
Babbitt, Civ. Nos. 99-870, 99-872, 99-1445M/RLP (Consolidated), set 
aside the July 9, 1999, critical habitat designation and ordered us to 
issue both an EIS and a new proposed rule designating critical habitat 
for the silvery minnow. This proposed rule and the draft EIS are being 
issued pursuant to that court order.
    On April 5, 2001, we mailed approximately 500 pre-proposal 
notification letters to the six Middle Rio Grande Indian Pueblos 
(Cochiti, Santo Domingo, San Felipe, Santa Ana, Sandia, and Isleta), 
various governmental agencies, interested individuals, and the New 
Mexico Congressional delegation. The letter informed them of our intent 
to prepare an EIS for the proposed designation of critical habitat for 
the silvery minnow and announced public scoping meetings pursuant to 
NEPA. On April 17, 23, 24, and 27, 2001, we held public scoping 
meetings in Albuquerque and Carlsbad, NM, Fort Stockton, TX, and 
Socorro, NM, respectively. We solicited oral and written comments and 
input. We were particularly interested in obtaining additional 
information on the status of the species or information concerning 
threats to the species. The comment period closed June 5, 2001. We 
received

[[Page 39210]]

approximately 40 comments during the EIS scoping process. During April 
2001, we contracted with Industrial Economics Incorporated for an 
economic analysis and the Institute of Public Law at the University of 
New Mexico School of Law for an EIS on the proposed critical habitat 
designation. Following the closing of the scoping comment period, we 
outlined possible alternatives for the EIS. We held a meeting on 
September 12, 2001, to solicit input on the possible alternatives from 
the Rio Grande Silvery Minnow Recovery Team (Recovery Team) and other 
invited participants including individuals from the Carlsbad Irrigation 
District, Fort Sumner Irrigation District, the States of New Mexico and 
Texas, and potentially affected Pueblos and Tribes. Following this 
meeting, we sent letters to the Recovery Team and other invited 
participants, including Tribal entities, and resource agencies in New 
Mexico and Texas, to solicit any additional information--particularly 
biological, cultural, social, or economic data--that may be pertinent 
to the economic analysis or EIS. We received 10 comments from our 
requests for additional information. The information provided in the 
comment letters was fully considered in developing the alternatives 
that were analyzed in the draft EIS, which contains this proposed rule 
as our preferred alternative. We made these comments part of the 
administrative record for this rulemaking.

Recovery Plan

    Restoring an endangered or threatened species to the point where it 
is recovered is a primary goal of the Service's endangered species 
program. To help guide the recovery effort, we prepare recovery plans 
for most of the listed species native to the United States. Recovery 
plans describe actions considered necessary for conservation of the 
species, establish criteria for downlisting or delisting them, and 
estimate time and cost for implementing the recovery measures needed. 
Although a recovery plan is not a regulatory document (i.e., recovery 
plans are advisory documents because there are no specific protections, 
prohibitions, or requirements afforded to a species based solely on a 
recovery plan), the information contained in the Rio Grande Silvery 
Minnow Recovery Plan (Recovery Plan) was considered in developing this 
proposed critical habitat designation.
    On July 1, 1994, the Recovery Team was established by the Service 
pursuant to section 4(f)(2) of the Act and our cooperative policy on 
recovery plan participation, a policy intended to involve stakeholders 
in recovery planning (July 1, 1994; 59 FR 34272). Stakeholder 
involvement in the development of recovery plans helps minimize the 
social and economic impacts that could be associated with recovery of 
endangered species. Numerous individuals, agencies, and affected 
parties were involved in the development of the Recovery Plan or 
otherwise provided assistance and review (Service 1999). On July 8, 
1999, we finalized the Recovery Plan (Service 1999), pursuant to 
section 4(f) of the Act.
    The Recovery Plan recommends recovery goals for the silvery minnow, 
as well as procedures to better understand the biology of the species. 
The primary goals of the Recovery Plan are to: (1) Stabilize and 
enhance populations of silvery minnow and its habitat in the middle Rio 
Grande valley; and (2) reestablish the silvery minnow in at least two 
other areas of its historical range (Service 1999). The reasons for 
determining that these areas were necessary for recovery include: (1) 
Consideration of the biology of the species (i.e., few silvery minnows 
live more than 12 to 14 months, indicating the age 1 fish (e.g., all 
fish born in 2000 that remain alive in 2001 would be age 1 fish) are 
almost entirely responsible for perpetuation of the species); (2) the 
factors in each reach that may inhibit or enhance reestablishment and 
security of the species vary among areas; and (3) it is unlikely that 
any single event would simultaneously eliminate the silvery minnow from 
three geographic areas (Service 1999).
    We have continued working with the Recovery Team since the Recovery 
Plan was finalized. We believe this proposed critical habitat 
designation and our conservation strategy (see ``Exclusions Under 
Section 4(b)(2) of the Act'' section below) are consistent with the 
Recovery Plan (Service 1999). The purpose of the Recovery Plan is to 
outline the research and data collection activities that will identify 
measures to ensure the conservation of the silvery minnow in the wild 
and to provide a roadmap that leads to the protection of habitat 
essential to its recovery. Therefore, we also believe this proposed 
critical habitat designation and our conservation strategy are 
consistent with the recommendations of Recovery Team members. 
Nevertheless, we will request that peer reviewers who are familiar with 
this species review the proposed rule.
    The term ``conservation,'' as defined in section 3(3) of the Act 
and in 50 CFR 424.02(c), means ``to use and the use of all methods and 
procedures which are necessary to bring any endangered species or 
threatened species to the point at which the measures provided pursuant 
to this Act are no longer necessary'' (i.e., the species is recovered 
and removed from the list of endangered and threatened species). It is 
important to note that we utilized the recommendations in the Recovery 
Plan, consistent with this definition of conservation, to conclude that 
the middle Rio Grande proposed critical habitat unit and the middle 
Pecos River from Sumner Dam to Brantley Dam, NM (middle Pecos River), 
and the lower Rio Grande from the upstream boundary of Big Bend 
National Park downstream through the area designated as a wild and 
scenic river to the Terrell/Val Verde County line, TX (lower Rio 
Grande) are ``essential to the conservation of'' the silvery minnow. 
Although the middle Pecos River and the lower Rio Grande are not 
proposed as critical habitat units, we believe they are important for 
the recovery of the silvery minnow. Thus, we concur with the Recovery 
Plan that reestablishment of the silvery minnow within additional 
geographically distinct areas is necessary to ensure the minnow's 
survival and recovery (Service 1999). However, recovery is not achieved 
by designating critical habitat. The Act provides for other mechanisms 
that will provide for reestablishment of the minnow outside of the 
middle Rio Grande and the eventual recovery of the silvery minnow. We 
are not proposing critical habitat designation for the area on the 
middle Pecos River or the lower Rio Grande; we are proposing to 
designate only the middle Rio Grande as critical habitat. Our 
conservation strategy for this species and our rationale is discussed 
in the ``Exclusions Under Section 4(b)(2) of the Act'' section of this 
rule below.

Exclusions Under Section 4(b)(2) of the Act

    Section 4(b)(2) of the Act requires us to base critical habitat 
designations on the best scientific and commercial data available, 
after taking into consideration the economic and any other relevant 
impact of specifying any particular area as critical habitat. We may 
exclude areas from a critical habitat designation when the benefits of 
exclusion outweigh the benefits of designation, provided the exclusion 
will not result in the extinction of the species. Our preliminary 
analysis of the following two areas: (1) The river reach in the middle 
Pecos River, NM, from Sumner Dam to Brantley Dam in De Baca, Chaves, 
and Eddy Counties, NM; and (2)

[[Page 39211]]

the river reach in the lower Rio Grande in Big Bend National Park 
downstream of the National Park boundary to the Terrell/Val Verde 
County line, TX, finds that the benefits of excluding these areas from 
the designation of critical habitat outweigh the benefits of including 
them. Therefore, we are not proposing these areas as critical habitat.
    As indicated in the ``Public Comments Solicited'' section of this 
rule, we are seeking comments on whether these areas should be 
designated as critical habitat. In making a final determination, we 
will consider all comments we receive on this proposed rule, the draft 
EIS, and the draft economic analysis.

(1) Benefits of Inclusion

    The benefits of inclusion of the river reach in the middle Pecos 
River, NM, from Sumner Dam to Brantley Dam in De Baca, Chaves, and Eddy 
Counties, NM, would result from the requirement under section 7 of the 
Act that Federal agencies consult with us to ensure that any proposed 
actions do not destroy or adversely modify critical habitat. 
Historically, no consultations have occurred on the Pecos River for the 
silvery minnow since the area is not occupied. However, while critical 
habitat designation could provide some benefit to the silvery minnow, 
in fact, consultations are already occurring for another listed fish 
with similar requirements. The Pecos bluntnose shiner (Notropis simus 
pecosensis) was federally listed in 1987 and portions of the Pecos 
River are designated as critical habitat for the Pecos bluntnose shiner 
(52 FR 5295). As stated in the ``Criteria for Identifying Proposed 
Critical Habitat Units'' section of this rule, these fish species 
belong to the same guild of broadcast spawners with semi-buoyant eggs 
and also spawn during high flow events with eggs and larvae being 
distributed downstream (Bestgen et al. 1989). Therefore, flow regime 
operations in this reach that benefit the Pecos bluntnose shiner also 
provide benefits to habitat of the silvery minnow. We also believe that 
the primary constituent elements for the Pecos bluntnose shiner 
critical habitat are compatible with the proposed primary constituent 
elements for the silvery minnow. Thus, we find that little additional 
benefit through section 7 would occur as a result of the overlap 
between habitat suitable for the silvery minnow and the Pecos bluntnose 
shiner listing and critical habitat designation.
    In Sierra Club v. Fish and Wildlife Service, 245 F.3d 434 (5th Cir. 
2001), the Fifth Circuit Court of Appeals stated that the 
identification of habitat essential to the conservation of the species 
can provide informational benefits to the public, State, and local 
governments; scientific organizations; and Federal agencies. The court 
also noted that heightened public awareness of the plight of listed 
species and its habitat may facilitate conservation efforts. We agree 
with these findings; however, we believe that there would be little 
additional informational benefit gained from including the middle Pecos 
River because the final rule will identify all areas that are essential 
to the conservation of the silvery minnow, regardless of whether all of 
these areas are included in the regulatory designation. Consequently, 
we believe that the informational benefits will be provided to the 
middle Pecos River, regardless of whether this reach is designated as 
critical habitat.
    The draft economic analysis recognizes that while consultations 
regarding the Pecos will occur without a silvery minnow critical 
habitat designation, those consultations would not consider the silvery 
minnow. However, due to the similar life history requirements of these 
species, we do not anticipate that the outcomes of such consultations 
would be altered. We recognize, as does the draft economic analysis, 
that the middle Pecos River area (as described above) covers about 
twice the length of the area designated for the Pecos bluntnose shiner. 
Historically, two formal consultations and two informal consultations 
occurred annually for the Pecos bluntnose shiner. The draft economic 
analysis assumes that twice as many consultations would occur if this 
area were designated as critical habitat for the silvery minnow, since 
the area would be doubled in size. However, the draft economic analysis 
also recognizes that this is likely an overstatement of the actual 
increase in consultations because consultations frequently occur on 
projects located outside of Pecos bluntnose shiner critical habitat, 
due to the interdependent nature of the river system and the presence 
of the species. Consequently, we do not believe that designating 
critical habitat within this river reach would provide additional 
benefits for the silvery minnow, because currently the activities that 
occur outside of critical habitat designated for the Pecos bluntnose 
shiner are also being consulted upon. We find little benefit to 
including this river reach in the proposed critical habitat for the 
silvery minnow due to the presence of the Pecos bluntnose shiner and 
its designated critical habitat, in the absence of the silvery minnow. 
Current and ongoing activities for the Pecos bluntnose shiner are 
compatible with those of the silvery minnow such that reestablishment 
of the silvery minnow in this stretch of river should not be precluded 
in the future. Thus, we determine that any additional benefit from a 
designation of critical habitat in this river reach does not outweigh 
the benefit of excluding this area, as discussed below in the 
``Benefits of Exclusion'' section.
    The benefits of inclusion of the river reach in the lower Rio 
Grande in Big Bend National Park downstream of the park boundary to the 
Terrell/Val Verde County line, TX, would also result from the 
requirement under section 7 that Federal agencies consult with us to 
ensure that any proposed actions do not destroy or adversely modify 
critical habitat. However, as indicated in the draft economic analysis, 
we anticipate very little consultation activity within this area. The 
draft economic analysis (section 6.3.3) estimates that over the next 20 
years there would be a total of 12 formal consultations and 6 informal 
consultations. The only Federal actions that we are aware of within the 
stream reach of the lower Rio Grande downstream of Big Bend National 
Park is the Big Bend National Park oversight and permitting authority 
for float trips, scientific research permits, environmental education, 
and law enforcement (R. Skiles, Big Bend National Park, pers. comm. 
2001). Therefore, unless there are other types of Federal permitting or 
authorization within this area, private and State-owned lands would not 
be affected. Additional activities that were used to estimate the 
numbers of consultations for this area include: National Park 
management activities (e.g., pesticide application and fishing 
regulations), U.S. International Boundary and Water Commission channel 
maintenance activities, U.S. Fish and Wildlife Service (e.g., fire 
management plans, fish stocking), and Environmental Protection Agency, 
National Pollution Discharge Elimination System permitting for the 
Predsidio or Lajitas wastewater treatment facility. We find sufficient 
regulatory and protective conservation measures in place and believe 
there would be little benefit to a designation in this reach since this 
area is protected and managed by the National Park Service and the 
number of consultations expected to occur in this area are relatively 
low.
    As above, we believe that heightened public awareness of a listed 
species and its habitat may facilitate conservation efforts. 
Nevertheless, we believe that there would be little additional

[[Page 39212]]

informational benefit gained from including the lower Rio Grande within 
designated critical habitat for the silvery minnow because we have 
identified in this proposed rule, and will identify in the final 
designation, those areas that we believe are essential to the 
conservation of the species. For these reasons, we determine that any 
additional benefit of designation of critical habitat in this river 
reach does not outweigh the benefit of excluding this area, as 
discussed below.

(2) Benefits of Exclusion

    As discussed in the ``Recovery Plan'' section of this rule, the 
primary goals of the silvery minnow Recovery Plan are to: (1) Stabilize 
and enhance populations of the silvery minnow and its habitat in the 
middle Rio Grande valley; and (2) reestablish the silvery minnow in at 
least two other areas of its historical range (Service 1999). We 
believe that the best way to achieve the second recovery goal will be 
to use the authorities under section 10(j) of the Act. Consequently, we 
have developed a conservation strategy that we believe is consistent 
with the species' Recovery Plan. The conservation strategy is to 
reestablish the silvery minnow, under section 10(j) of the Act, within 
areas of its historical range, possibly including the river reach in 
the middle Pecos River and the river reach in the lower Rio Grande 
(both are described above). Since the silvery minnow is extirpated from 
these areas and natural repopulation is not possible without human 
assistance, use of a 10(j) rule is the appropriate tool to achieve this 
recovery objective. Nevertheless, any future recovery efforts, 
including repatriation of the species to areas of its historical range 
must be conducted in accordance with NEPA and the Act. An overview of 
the process to establish an experimental population under section 10(j) 
of the Act is described below.
    Section 10(j) of the Act enables us to designate certain 
populations of federally listed species that are released into the wild 
as ``experimental.'' The circumstances under which this designation can 
be applied are: (1) The population is geographically separate from non-
experimental populations of the same species (e.g., the population is 
reintroduced outside the species' current range but within its probable 
historical range); and (2) we determine that the release will further 
the conservation of the species. Section 10(j) is designed to increase 
our flexibility in managing an experimental population by allowing us 
to treat the population as threatened, regardless of the species' 
status elsewhere in its range. Threatened status gives us more 
discretion in developing and implementing management programs and 
special regulations for a population and allows us to develop any 
regulations we consider necessary to provide for the conservation of a 
threatened species. In situations where we have experimental 
populations, certain section 9 prohibitions (e.g., harm, harass, 
capture) that apply to endangered and threatened species may no longer 
apply, and a special rule can be developed that contains the 
prohibitions and exceptions necessary and appropriate to conserve that 
species. This flexibility allows us to manage the experimental 
population in a manner that will ensure that current and future land, 
water, or air uses and activities will not be unnecessarily restricted 
and the population can be managed for recovery purposes.
    When we designate a population as experimental, section 10(j) of 
the Act requires that we determine whether that population is either 
essential or nonessential to the continued existence of the species, 
based on the best available information. Nonessential experimental 
populations located outside National Wildlife Refuge System or National 
Park System lands are treated, for the purposes of section 7 of the 
Act, as if they are proposed for listing. Thus, for nonessential 
experimental populations, only two provisions of section 7 would apply 
outside National Wildlife Refuge System and National Park System lands: 
section 7(a)(1), which requires all Federal agencies to use their 
authorities to conserve listed species, and section 7(a)(4), which 
requires Federal agencies to informally confer with the Service on 
actions that are likely to jeopardize the continued existence of a 
proposed species. Section 7(a)(2) of the Act, which requires Federal 
agencies to ensure that their activities are not likely to jeopardize 
the continued existence of a listed species, would not apply except on 
National Wildlife Refuge System and National Park System lands. 
Experimental populations determined to be ``essential'' to the survival 
of the species would remain subject to the consultation provisions of 
section 7(a)(2) of the Act.
    In order to establish an experimental population we must issue a 
proposed regulation and consider public comments on the proposed rule 
prior to publishing a final regulation. In addition, we must comply 
with NEPA. Also, our regulations require that, to the extent 
practicable, a regulation issued under section 10(j) of the Act 
represent an agreement between the Service, the affected State and 
Federal agencies, and persons holding any interest in land that may be 
affected by the establishment of the experimental population (see 50 
CFR 17.81(d)).
    The flexibility gained by establishment of a nonessential 
experimental population through section 10(j) would be of little value 
if there is a designation of critical habitat that overlaps it. This is 
because Federal agencies would still be required to consult with us on 
any actions that may adversely modify critical habitat. In effect, the 
flexibility gained from section 10(j) would be rendered useless by the 
designation of critical habitat. In fact, section 10(j)(2)(C)(ii)(B) of 
the Act states that critical habitat shall not be designated under the 
Act for any experimental population determined to be not essential to 
the continued existence of a species.
    The second goal of the Recovery Plan is to reestablish the silvery 
minnow in areas of its historic range. We strongly believe that in 
order to achieve recovery for the silvery minnow we would need the 
flexibility provided for in section 10(j) of the Act to help ensure the 
success of reestablishing the minnow in the middle Pecos River and 
lower Rio Grande areas. Use of section 10(j) is meant to encourage 
local cooperation through management flexibility. Critical habitat is 
often viewed negatively by the public since it is not well understood 
and there are many misconceptions about how it affects private 
landowners. It is important for recovery of this species that we have 
the support of the public when we move towards meeting the second 
recovery goal. It is critical to the recovery of the silvery minnow 
that we reestablish the species in areas outside of its current 
occupied range. The current population of silvery minnow in the middle 
Rio Grande is in an imperiled state making it extremely important that 
reestablishment into other portions of its historical range occur.
    Nonessential experimental populations located within the National 
Park System are treated, for purposes of section 7 of the Act, as if 
they are listed as threatened (50 CFR 17.83(b)). Moreover, a 
nonessential experimental population established in the river reach in 
the lower Rio Grande downstream of the Big Bend National Park boundary 
(i.e., within the reach designated as a wild and scenic river) to the 
Terrell/Val Verde County line, TX, would also be treated, for purposes 
of section 7, as a threatened species because this area is a component 
of the national wild and scenic rivers system that is administered by 
the Secretary of the Interior through

[[Page 39213]]

the National Park Service and is considered part of the National Park 
System (16 USC 1281(c)). These lands downstream of Big Bend National 
Park are owned by the State of Texas (Black Gap Wildlife Management 
Area) and approximately 12 to 15 private landowners. The National Park 
Service's management authority in the wild and scenic river designation 
currently extends 0.25 mi from the ordinary high water mark. For the 
past two years, Big Bend National Park has been working on a management 
plan for the ``outstanding remarkable values of the Rio Grande wild and 
scenic river'' (F. Deckert, Big Bend National Park, pers. comm. 2002). 
The development of the river management plan has involved stakeholders, 
including private landowners and the State of Texas. Throughout the 
stakeholder-based planning process, the Park has built trust among 
diverse and competing interests by encouraging open dialogue regarding 
various river management issues. If critical habitat were designated in 
this river reach, the introduction of additional Federal influence 
could jeopardize the trust and spirit of cooperation that has been 
established over the last several years (F. Deckert, pers. comm., 
2002). The designation of critical habitat would be expected to 
adversely impact our, and possibly the Park's, working relationship 
with the State of Texas and private landowners, and we believe that 
Federal regulation through critical habitat designation would be viewed 
as an unwarranted and unwanted intrusion. Based on recent conversations 
with the National Park Service, their plan and draft EIS are expected 
to be completed in 2002, and finalized in 2003. We do not want to 
impede the development of a river management plan, which will likely 
provide for the management of this river reach consistent with the 
recovery needs of the silvery minnow. We believe this area has the 
greatest potential for repatriating the species within an area of its 
historical range and believe this river reach also has the greatest 
potential for developing an experimental population under section 10(j) 
of the Act. In order for an experimental population to be successful, 
the support of local stakeholders--including the National Park Service, 
the State of Texas, private landowners, and other potentially affected 
entities--is crucial. In light of this and the fact that the river 
management plan will soon be completed, we find that there would be 
significant benefits to excluding this river reach from designation of 
critical habitat.
    On the middle Pecos River, we acknowledge that the New Mexico 
Interstate Stream Commission (NMISC) has been actively acquiring and 
leasing water rights to meet the State's delivery obligations to Texas 
as specified in the Pecos River Compact and pursuant to an Amended 
Decree entered by the U.S. Supreme Court. For example, between 1991 and 
1999, $27.8 million was spent on the Pecos River water rights 
acquisition program. New Mexico faced a shortfall in its Pecos River 
Compact delivery obligations for the year 2001 and the possibility of 
priority administration, in which the State Engineer would order junior 
water rights holders not to use water. Given the tight water situation 
and the Compact delivery obligations, we believe that the flexibility 
of section 10(j) would be especially appropriate in the middle Pecos. 
Economic costs associated with endangered species management and 
critical habitat designation for the silvery minnow are discussed in 
the draft economic analysis. There are a variety of current and 
potential future costs associated with the ongoing water management and 
water reallocation on the middle Pecos River. The draft economic 
analysis and DEIS discuss and analyze these costs. We used the draft 
economic analysis and DEIS to make our preliminary determinations on 
the benefits of including or excluding areas from the proposed 
designation of critical habitat. Consequently, we invite comments on 
the economic and other relevant impacts of all of the areas we have 
determined are essential for the conservation of the silvery minnow.
    In summary, we believe that the benefits of excluding the middle 
Pecos River and lower Rio Grande outweighs the benefits of their 
inclusion as critical habitat. Including these areas may result in some 
benefit through additional consultations with Federal agencies whose 
activities may affect critical habitat. However, overall this benefit 
is minimal due to the presence of the Pecos bluntnose shiner and its 
critical habitat in the middle Pecos River and the minimal number of 
estimated future consultations that are expected to occur within Big 
Bend National Park and the wild and scenic river designation that 
extends beyond the Park's boundaries. On the other hand, an exclusion 
will greatly benefit the overall recovery of the minnow by allowing us 
to move forward using the flexibility and greater public acceptance of 
section 10(j) of the Act to reestablish minnows in other portions of 
its historical range where it no longer occurs. This is likely the most 
important step in reaching recovery of this species and we believe that 
section 10(j), as opposed to a critical habitat designation, is the 
best tool to achieve this objective. Thus, we believe that an exclusion 
of these two areas outweighs any benefits that could be realized 
through a designation of critical habitat and we have not proposed 
these two areas for critical habitat designation.
    The Pecos River and lower Rio Grande reaches were historically 
occupied but are currently unoccupied by the silvery minnow (Hubbs 
1940; Trevino-Robinson 1959; Hubbs et al. 1977; Bestgen and Platania 
1991). The silvery minnow occupies less than five percent of its 
historic range and the likelihood of extinction from a catastrophic 
event is high because of its limited range (Hoagstrom and Brooks 2000, 
Service 1999). However, if critical habitat were designated in the 
middle Pecos River or lower Rio Grande, the likelihood of extinction of 
the species from the occupied reach of the middle Rio Grande would not 
decrease because critical habitat designation is not a process to 
reestablish additional populations within areas outside of the current 
known distribution. We believe that the exclusion of the river reaches 
of the middle Pecos River and the lower Rio Grande will not lead to the 
extinction of the species.

Exclusions Under Section 3(5)(A) Definition

    Section 3(5) of the Act defines critical habitat, in part, as areas 
within the geographical area occupied by the species ``on which are 
found those physical and biological features (I) essential to the 
conservation of the species and (II) which may require special 
management considerations and protection.'' As noted above, special 
management considerations or protection is a term that originates in 
the definition of critical habitat. Additional special management is 
not required if adequate management or protection is already in place. 
Adequate special management considerations or protection is provided by 
a legally operative plan or agreement that addresses the maintenance 
and improvement of the primary constituent elements important to the 
species and manages for the long-term conservation of the species. We 
use the following three criteria to determine if a plan provides 
adequate special management or protection: (1) A current plan or 
agreement must be complete and provide sufficient conservation benefit 
to the species; (2) the plan or agreement must provide assurances that 
the

[[Page 39214]]

conservation management strategies will be implemented; and (3) the 
plan or agreement must provide assurances that the conservation 
management strategies will be effective (i.e., provide for periodic 
monitoring and revisions as necessary). If all of these criteria are 
met, then the area covered under the plan would no longer meet the 
definition of critical habitat. If any management plans are submitted 
during the open comment period, we will consider whether these plans 
provide adequate special management or protection for the species. We 
will use this information in determining which, if any, river reaches 
or portions of river reaches within the middle Rio Grande should not be 
included in the final designation of critical habitat for the silvery 
minnow.

Proposed Critical Habitat

    Critical habitat is defined in section 3(5)(A) of the Act as--(i) 
the specific areas within the geographic area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographic area occupied by a species at the time it is listed, upon a 
determination that such areas are essential for the conservation of the 
species. ``Conservation,'' as defined by the Act, means the use of all 
methods and procedures that are necessary to bring an endangered or a 
threatened species to the point at which listing under the Act is no 
longer necessary.
    Section 4(b)(2) of the Act requires that we base critical habitat 
designation on the best scientific and commercial data available, 
taking into consideration the economic impact, and any other relevant 
impact, of specifying any particular area as critical habitat. We may 
exclude areas from critical habitat designation if we determine that 
the benefits of exclusion outweigh the benefits of including the areas 
as critical habitat, provided the exclusion will not result in the 
extinction of the species.
    Designation of critical habitat helps focus conservation activities 
by identifying areas that are essential to the conservation of the 
species and alerting the public and land management agencies to the 
importance of an area to conservation. Within areas currently occupied 
by the species, critical habitat also identifies areas that may require 
special management or protection. Critical habitat receives protection 
from destruction or adverse modification through required consultation 
under section 7 of the Act with regard to actions carried out, funded, 
or authorized by a Federal agency. Where no such Federal agency action 
is involved, critical habitat designation has no bearing on private 
landowners, State, or Tribal activities. Aside from the added 
protection provided under section 7, the Act does not provide other 
forms of protection to lands designated as critical habitat.
    Designating critical habitat does not, in itself, lead to recovery 
of a listed species. Designation does not create a management plan, 
establish numerical population goals, prescribe specific management 
actions (inside or outside of critical habitat), or directly affect 
areas not designated as critical habitat. Specific management 
recommendations for areas designated as critical habitat are most 
appropriately addressed in recovery, conservation, and management 
plans, and through section 7 consultations and section 10 permits. We 
recognize that designation of critical habitat may not include all of 
the habitat areas that may eventually be determined to be necessary for 
the recovery of the species. For these reasons, critical habitat 
designations do not signal that habitat outside the designation is 
unimportant or may not be required for recovery.
    Areas outside the critical habitat designation will continue to be 
subject to conservation actions that may be implemented under section 
7(a)(1), the regulatory protections afforded by the section 7(a)(2) 
jeopardy standard, and the section 9 take prohibition. Federally funded 
or assisted projects affecting listed species outside their designated 
critical habitat areas may still result in jeopardy findings in some 
cases. 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 under section 10 of the Act, or other species 
conservation planning efforts if new information available to these 
planning efforts calls for a different outcome.

Methods

    In determining areas that are essential to conserve the silvery 
minnow, we used the best scientific and commercial data available. This 
included data from research and survey observations published in peer-
reviewed articles, recovery criteria outlined in the Recovery Plan 
(Service 1999), data collected from reports submitted by biologists 
holding section 10(a)(1)(A) recovery permits, and comments received on 
the previous proposed and final rule, draft economic analysis, and 
environmental assessment. This proposed rule constitutes our best 
assessment of areas needed for the conservation of the silvery minnow. 
We must make this determination based on the information available at 
this time, and we are not allowed to delay our decision until all 
information about the species and its habitat are known, nor are we 
required to conduct further surveys or scientific studies on our own. 
Southwest Center for Biological Diversity v. Babbitt, 215 F.3d 58 (D.C. 
Cir. 2000). We have emphasized areas known to be occupied by the 
silvery minnow and described other stream reaches that were identified 
in the Recovery Plan and we believe are important for possible 
repatriation and recovery (Service 1999).

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas to propose as critical 
habitat, we are required to base critical habitat designations on the 
best scientific and commercial data available and to consider those 
physical and biological features (primary constituent elements) that 
are essential to the conservation of the species and, within areas 
currently occupied by the species, that may require special management 
considerations or protection. These include, but are not limited to: 
space for individual and population growth, and for normal behavior; 
food, water, or other nutritional or physiological requirements; cover 
or shelter; sites for breeding, reproduction, or rearing of offspring; 
and habitats that are protected from disturbance or are representative 
of the historical geographical and ecological distributions of a 
species.
    Diverse habitats are used by the various life-history stages of the 
silvery minnow. The following discussion summarizes the biological 
requirements of the silvery minnow relevant to identifying the primary 
constituent elements of its critical habitat.
    The silvery minnow historically inhabited the portions of the wide, 
shallow rivers and larger streams of the Rio Grande basin, 
predominantly the Rio Grande and the Pecos River (Bestgen and Platania 
1991). Adults were common in shallow and braided runs over sand 
substrate, and almost never occurred in habitats with bottoms of gravel 
or cobble, while young-of-year fish (less than 1 year old) occupy 
shallow, low-velocity backwaters with sand-silt substrates (Dudley and 
Platania 1997; Platania and Dudley

[[Page 39215]]

1997; Platania 1991; Remshardt et al. 2001). Young-of-year silvery 
minnows are infrequently found at the same time in the same habitat as 
adults. Stream reaches dominated by straight, narrow, incised (deep) 
channels with rapid flows are not typically occupied by the silvery 
minnow (Bestgen and Platania 1991).
    The habitats most often occupied by silvery minnow were 
characterized by low (<20 cm) to moderate depths (31 to 40 cm), little 
(<10 cm/s) to moderate (11 to 30 cm/s) water velocity, and silt and 
sand substrata (Dudley and Platania 1997; Remshardt et al. 2001). It is 
believed that silvery minnow select debris piles, pools, and 
backwaters, as habitat with main channel runs generally being avoided 
(Dudley and Platania 1997).
    The silvery minnow is believed to be a generalized forager, feeding 
upon items suspended in the water column and items lying on the 
substrate (e.g., plankton, algae, diatoms) (Sublette et al. 1990; 
Dudley and Platania 1997; Service 1999). The silvery minnow's elongated 
and coiled gastrointestinal tract suggests that detritus (partially 
decomposed plant or animal matter), including sand and silt, is scraped 
from the river bottom (Sublette et al. 1990). Other species of 
Hybognathus have similar food habits, consuming rich organic ooze and 
detritus found in silt or mud substrates (Pflieger 1997).
    The silvery minnow is a pelagic spawner, with each female capable 
of producing an average of 3,000 semi-buoyant, non-adhesive eggs during 
a spawning event (Platania 1995; Platania and Altenbach 1998). The 
collection of eggs in the middle of May, late May, early June, and late 
June suggest a contracted spawning period in response to a spring 
runoff or spike (increase in flow that occurs when winter snows melt) 
(Service 1999; BOR 2001a). However, the peak of egg production appears 
to occur in mid-May (Smith 1998, 1999). If the spring spike occurs at 
the wrong time or is reduced, then silvery minnow reproduction could be 
impacted. It is unknown if the silvery minnow spawns multiple times 
during the summer, although this behavior has been documented in other 
species of Hybognathus in other drainages (Lehtinen and Layzer 1988, 
Taylor and Miller 1990).
    Platania (1995, 2000) found that early development and hatching of 
eggs is correlated with water temperature. Silvery minnow eggs raised 
in 30 deg.C water hatched in about 24 hours, while eggs reared in 
20 deg.C water hatched within 50 hours. Eggs were 1.6 mm (0.06 in) in 
size upon fertilization, but quickly swelled to 3 mm (0.12 in). 
Recently hatched larval fish are about 3.7 mm (0.15 in) in standard 
length and grow about 0.15 mm (0.005 in) in size per day during the 
larval stages. Eggs and larvae remain in the drift for 3 to 5 days, and 
may be transported from 216 to 359 km (134 to 223 mi) downstream 
depending on river flows and habitat conditions (e.g., debris piles, 
low velocity backwaters, etc.) (Platania and Altenbach 1998). About 
three days after hatching, the larvae begin moving to low velocity 
habitats where food (mainly phytoplankton and zooplankton) is abundant 
and predators are scarce. Because eggs and larvae can be swept 
downstream, where recruitment (individuals added to the breeding 
population) of fish may be poor in the current degraded condition of 
the middle Rio Grande (e.g., channelization, banks stabilization, levee 
construction, disruption of natural processes throughout the 
floodplain, etc.), adequate stream length appears to be an important 
determinant of reproductive success.
    Platania (1995) indicated that the downstream transport of eggs and 
larvae of the silvery minnow over long distances may have been, 
historically, beneficial to the survival of their populations. This 
behavior could have promoted recolonization of reaches impacted during 
periods of natural drought (Platania 1995). Alternatively, in a natural 
functioning river system (e.g., a natural, unregulated flow regime), a 
variety of low-velocity refugia (e.g., oxbows, backwaters, etc.) would 
have been available for silvery minnow and lengthy downstream drift of 
eggs and larvae may not have been common (J. Brooks, U.S. Fish and 
Wildlife Service pers. comm., 2001). Currently, the release of floating 
silvery minnow eggs may replenish downstream reaches, but the presence 
of the diversion dams (Angostura, Isleta, and San Acacia Diversion 
Dams) prevents recolonization of upstream habitats (Platania 1995). As 
reaches are depleted upstream, and diversion structures prevent 
upstream movements, population decline of the species within stream 
reaches may occur through loss of connectivity (i.e., preventing 
upstream movement of fish). Silvery minnow, eggs, and larvae are also 
transported downstream to Elephant Butte Reservoir, where it is 
believed that survival of these fish is highly unlikely because of poor 
habitat, and, even more important, because of predation from reservoir 
fishes (Service 2001b). The population center (i.e., the stream reach 
that contains the majority of adult silvery minnows) is believed to 
have moved farther downstream over the last several years (Dudley and 
Platania 2001; 2002). For example, in 1997, it was estimated that 70 
percent of the silvery minnow population was found in the reach below 
San Acacia Diversion Dam (Dudley and Platania 1997). Moreover, during 
surveys in 1999, over 95 percent of the silvery minnows captured 
occurred downstream of San Acacia Diversion Dam (Dudley and Platania 
1999a, Smith and Jackson 2000). Probable reasons for this distribution 
include: (1) The spawning of buoyant eggs during the spring and early 
summer high flows, resulting in downstream transport of eggs and larval 
fish; (2) diversion dams that restrict or preclude the movement of fish 
into upstream reaches; and (3) reduction in the amount of available 
habitat due to the current degraded condition of some areas within the 
middle Rio Grande (e.g., channelization, streambed degradation, 
reduction in off-channel habitat, and the general narrowing and 
incising of the stream channel) (Platania 1998; Lagassee 1981; BOR 
2001).
    Most Great Plains streams are highly variable environments. Fish in 
these systems (e.g., the Rio Grande) are subjected to extremes in water 
temperatures, flow regimes, and overall water quality conditions (e.g., 
quantity of dissolved oxygen). Native fish in these streams often 
exhibit life history strategies and microhabitat preferences that 
enabled them to cope with these natural conditions. For example, 
Matthews and Maness (1979) reported that the synergistic (combined) 
effects of high temperature, low oxygen, and other stressors probably 
limit fishes in streams of the Great Plains.
    The silvery minnow evolved in a highly variable ecosystem, and is 
likely more tolerant of elevated temperatures and low dissolved oxygen 
concentrations for short periods than other non-native species. 
Although little is known about the upper tolerance limits of the 
silvery minnow, when water quality conditions degrade, stress 
increases, and fish generally die (e.g., see Matthews and Maness 1979; 
Ostrand and Wilde 2001). Generally, it is believed that during periods 
of low flow or no flow, Great Plains fishes seek refugia in large 
isolated pools, backwater areas, or adjoining tributaries (Deacon and 
Minckley 1974; Matthews and Maness 1979). Fish in these refugia strive 
to survive until suitable flow conditions return and these areas 
reconnect with the main river channel. This pattern of retraction and 
recolonization of occupied areas in response to flow and other habitat

[[Page 39216]]

conditions is typical of fishes that endure harsh conditions of Great 
Plains rivers and streams (Deacon and Minckley 1974; Matthews and 
Maness 1979).
    Localized reductions in abundance are not typically a concern where 
sufficient numbers of the species survive, because stream reaches can 
be recolonized when conditions improve. However, habitat conditions 
such as oxbows, backwaters, or other refugia that were historically 
present on the Rio Grande and Pecos River and were a component of 
natural population fluctuations (e.g., extirpation and recolonization) 
have been dramatically altered or lost (e.g., Bestgen and Platania 
1991; Hoagstrom 2000; BOR 2001a, 2001b). Over the past several decades, 
the extent of areas in the Rio Grande and Pecos River that periodically 
lost flow has increased due to human alterations of the watersheds and 
stream channels and diversion of the streamflows (Service 1994).
    Variation in stream flow (i.e., flow regime) strongly affects some 
stream fish (Schlosser 1985). For example, juvenile recruitment (that 
portion of the young-of-the-year fish that survive to adults and 
reproduce) of some stream fish is highly influenced by stable flow 
regimes (Schlosser 1985; Hoagstrom 2000). When sufficient flows persist 
and other habitat needs are met, then recruitment into the population 
is high. Silvery minnows and other Great Plains or desert fishes cannot 
currently survive when conditions lead to prolonged periods of low or 
no flow of long stretches of river (Hubbs 1974; Hoagstrom 2000). Fish 
mortality likely begins from degraded water quality (e.g., increasing 
temperatures, p.H., and decreasing dissolved oxygen) and loss of refuge 
habitat prior to prolonged periods of low or no flow (J. Brooks, pers. 
comm 2001; Ostrand and Wilde 2001). For instance, a reduction of stream 
flow reduces the amount of water available to protect against 
temperature oscillations, and high temperatures from reduced water flow 
frequently kill fish before prolonged periods of no flow occurs (Hubbs 
1990).
    It is also possible that fish may subsequently die from living 
under sub-optimal conditions or that their spawning activities may be 
significantly disrupted (Hubbs 1974; Platania 1993b). Such conditions 
are in part responsible for the current, precarious status of the 
silvery minnow. For example, management of water releases from 
reservoirs, evaporation, diversion dams, and irrigation water 
deliveries have resulted in dewatered habitat--causing direct mortality 
and isolated pools that cause silvery minnow mortality due to poor 
water quality (low dissolved oxygen, high water temperatures) and 
predation from other fish and predators (e.g., birds, raccoons etc.). 
Portions of the middle Rio Grande were dewatered in 1996 to 2001 
(Service 2001b; J. Smith, pers. comm. 2001). In 1996, about 58 km (34 
mi) out of the 90 km (56 mi) from the San Acacia Diversion Dam to 
Elephant Butte Reservoir was dewatered. In 1997, water flows ceased at 
the south boundary of the Bosque del Apache National Wildlife Refuge, 
resulting in dewatering 22.5 km (14 mi) of silvery minnow habitat. In 
1998, the Rio Grande was discontinuous within the Bosque del Apache 
National Wildlife Refuge, dewatering about 32 km (20 mi) of habitat. In 
1999, flows ceased about one mile upstream of the Bosque del Apache 
National Wildlife Refuge northern boundary, dewatering about 39 km (24 
mi) of habitat. A similar event occurred in 2000, only not to the 
extent of the 1999 drying. In 2001, approximately 14 combined km (9 mi) 
of river dried, within the Bosque del Apache National Wildlife Refuge 
and south of San Marcial (Smith 2001). Because of recurring prolonged 
periods of low or no flow through multiple years, the status of the 
silvery minnow has declined (Dudley and Platania 2001; 2002).
    We believe it is possible to manage the middle Rio Grande and Pecos 
River to avoid prolonged periods of low or no flow and provide 
sufficient flowing water during critical time periods, such as from May 
to October (Service 2001a, 2001b). For example, in a recent biological 
opinion we issued on the effects of actions associated with the U.S. 
Bureau of Reclamation's, U.S. Army Corps of Engineers'', and Non-
Federal Entities' discretionary actions related to water management on 
the middle Rio Grande, NM, provided, among other elements of a 
reasonable and prudent alternative:

river flow from Cochiti Dam to Elephant Butte Reservoir from October 
31 to April 30 of each year, with a target flow of 50 cfs at the San 
Marcial Floodway gage. Flows will not drop below 40 cfs. From May 1 
to June 15 of each year, provide a minimum flow of 50 cfs at the San 
Marcial Floodway gage. From June 16 to July 1 of each year, ramp 
down the flow to achieve 50 cfs over San Acacia Diversion Dam 
(Service 2001b).

    A similar biological opinion on the effects on the Pecos bluntnose 
shiner of actions associated with the U.S. Bureau of Reclamation's 
discretionary actions related to water management on the Pecos River, 
in New Mexico, provided for target flows of 35 cfs at the Acme Gage 
(Service 2001a). We believe that by providing target flows, it may be 
possible to intensively manage and closely monitor the water in middle 
Rio Grande and Pecos River. For example, this was the case during the 
2001 irrigation season on the middle Rio Grande in which the continued 
existence of the silvery minnow was not jeopardized (i.e., the 
implementation of the elements of the reasonable and prudent 
alternative) (Service 2001b).
    The primary constituent elements identified below provide a 
qualitative description of those physical and biological features 
necessary to ensure the conservation of the silvery minnow. We did not 
identify quantitative estimates of specific minimum thresholds (e.g., 
minimum flows or depths), because we believe these estimates vary 
seasonally and annually, and by stream reach within the proposed 
critical habitat unit. Thus, we believe these thresholds are 
appropriately enumerated through section 7 consultations (e.g., see 
Service 2001b), which can be more easily changed if new information 
reveals effects to critical habitat in a manner or extent not 
previously considered (see 50 CFR 402.16(b)). We acknowledge that if 
thresholds were established as part of a critical habitat designation, 
they could be revised if new data became available (50 CFR 424.12(g)); 
however, the process of new rulemaking can take years (see 50 CFR 
424.17), as opposed to months to reinitiate and complete a formal 
consultation (see 50 CFR 402.14). Formal consultation provides an up-
to-date biological status of the species or critical habitat (i.e., 
environmental baseline) which is used to evaluate a proposed action 
during formal consultations. Consequently, we believe it is more 
prudent to pursue the establishment of specific thresholds through 
formal consultation.
    This proposed rule does not explicitly state what might be included 
as special management for a particular river reach within the middle 
Rio Grande. We anticipate that special management actions will likely 
be developed as part of the section 7 consultation process. Special 
management might entail a suite of actions including: re-establishment 
of hydrologic connectivity within the floodplain, widening the river 
channel, or placement of woody debris or boulders within the river 
channel (J. Smith, pers. comm., 2001).
    It is important to note that some areas within the middle Rio 
Grande proposed critical habitat unit have the potential for periods of 
low or no flow under certain conditions (e.g., see discussion above on 
middle Rio Grande). We recognize that the proposed critical

[[Page 39217]]

habitat designation specifically includes some areas that have lost 
flow periodically (Middle Rio Grande Conservancy District 1999; 
Scurlock and Johnson 2001; D. Coleman, U.S. Fish and Wildlife Service, 
pers. comm., 2001). It is difficult to describe the existing conditions 
for the river reach below San Acacia Diversion Dam on the middle Rio 
Grande. It is our belief that this stretch of river is likely to 
experience periods of low or no flow under certain conditions. However, 
it is important to note that we are not able to predict with certainty 
which areas within the middle Rio Grande will experience these 
conditions. We nevertheless believe this area is essential to the 
conservation of the silvery minnow because it likely serves as 
connecting corridors for fish movements between areas of sufficient 
flowing water (e.g., see Deacon and Minckley 1974; Eberle et al. 1993). 
Additionally, we believe this area is essential for the natural channel 
geomorphology (the topography of the river channel) to maintain or re-
create habitat, such as pools, by removing or redistributing sediment 
during high flow events (e.g., see Simpson et al. 1982; Middle Rio 
Grande Biological Interagency Team 1993). Therefore, we believe that 
the inclusion of an area that has the potential for periods of low or 
no flow as proposed critical habitat will ensure the long-term survival 
and recovery of silvery minnow. As such, we believe that the primary 
constituent elements as described in this proposed rule provide for a 
flow regime that allows for short periods of low or no flow. However, 
it is difficult to describe the existing conditions of this area (see 
above) and to define the primary constituent elements to reflect such a 
flow regime. Thus, we are soliciting comments or information related to 
the proposed designation of critical habitat in this area that may 
experience periods of no or low flow, and in particular the primary 
constituent elements and how they relate to the existing conditions 
(e.g., flow regime).
    If this proposed rule is finalized, Federal agencies with 
discretion over actions related to water management that affect 
critical habitat will be required to consider critical habitat and 
possibly enter into consultation under section 7 of the Act. These 
consultations will evaluate whether any Federal discretionary actions 
destroy or adversely modify critical habitat to the extent that the 
action appreciably diminishes the value of the critical habitat for the 
survival and recovery of the species. The adverse modification analysis 
will likely evaluate whether the adverse effect of prolonged periods of 
low or no flow is of sufficient magnitude (e.g., length of river) and 
duration that it would appreciably diminish the value of the critical 
habitat unit for the survival and recovery of the silvery minnow. For 
example, the effect of prolonged periods of low or no flow on the 
habitat quality (e.g., depth of pools, water temperature, pool size, 
etc.) and the extent of fish mortality is related to the duration of 
the event (Bestgen and Platania 1991). All of these factors will be 
analyzed under section 7 of the Act, if they are part of an action 
proposed by a Federal agency. Additionally, any Federal agency whose 
actions influence water quantity or quality in a way that may affect 
proposed critical habitat or the silvery minnow must enter into section 
7 consultation with us. Still, these consultations cannot result in 
biological opinions that require actions that are outside an action 
agency's legal authority and jurisdiction (50 CFR 402.02).
    We determined the primary constituent elements of critical habitat 
for the silvery minnow based on studies on their habitat and population 
biology including, but not limited to: Bestgen and Platania 1991; 
Service 1999; Dudley and Platania 1997; 2001; 2002; Platania and 
Altenbach 1998; Platania 1991, 2000; Service 2001; Smith 1998, 1999; 
Hoagstrom 2000; Remshardt et al. 2001. These primary constituent 
elements include:
    1. A hydrologic regime that provides sufficient flowing water with 
low to moderate currents capable of forming and maintaining a diversity 
of aquatic habitats, such as, but not limited to: backwaters (a body of 
water connected to the main channel, but with no appreciable flow), 
shallow side channels, pools (that portion of the river that is deep 
with relatively little velocity compared to the rest of the channel), 
eddies (a pool with water moving opposite to that in the river 
channel), and runs (flowing water in the river channel without 
obstructions) of varying depth and velocity which are necessary for 
each of the particular silvery minnow life-history stages; e.g., the 
silvery minnow requires habitat with sufficient flows from early spring 
(March) to early summer (June) to trigger spawning, flows in the summer 
(June) and fall (October) that do not increase prolonged periods of low 
or no flow; and a relatively constant winter flow (November to 
February), in appropriate seasons;
    2. The presence of low velocity habitat (including eddies created 
by debris piles, pools, or backwaters, or other refuge habitat (e.g., 
connected oxbows or braided channels)) within unimpounded stretches of 
flowing water of sufficient length (i.e., river miles) that provide a 
variation of habitats with a wide range of depth and velocities;
    3. Substrates of predominantly sand or silt; and
    4. Water of sufficient quality to maintain natural, daily, and 
seasonally variable water temperatures in the approximate range of 
greater than 1 deg.C (35 deg.F) and less than 30 deg.C (85 deg.F) and 
reduce degraded water quality conditions (decreased dissolved oxygen, 
increased pH, etc.).
    We determined that these proposed primary constituent elements of 
critical habitat provide for the physiological, behavioral, and 
ecological requirements of the silvery minnow. The first primary 
constituent element provides water of sufficient flows to reduce the 
formation of isolated pools. We conclude this element is essential to 
the conservation of the silvery minnow because the species cannot 
withstand permanent drying (loss of surface flow) of long stretches of 
river. Water is a necessary component for all silvery minnow life-
history stages and provides for hydrologic connectivity to facilitate 
fish movement. The second primary constituent element provides habitat 
necessary for development and hatching of eggs and the survival of the 
silvery minnow from larvae to adult. Low velocity habitat provides 
food, shelter, and sites for reproduction, and are essential for the 
survival and reproduction of silvery minnow. The third primary 
constituent element provides appropriate silt and sand substrates 
(Dudley and Platania 1997; Remshardt et al. 2001), which we and other 
scientists conclude are important in creating and maintaining 
appropriate habitat and life requisites (e.g., food and cover). The 
final primary constituent element provides protection from degraded 
water quality conditions. We conclude that when water quality 
conditions degrade (e.g., increasing water temperatures, pH, decreasing 
dissolved oxygen, etc.), silvery minnows will likely be injured or die.

Criteria for Identifying Proposed Critical Habitat

    The primary objective in designating critical habitat is to 
identify areas that are considered essential for the conservation of 
the species, and to highlight specific areas where management 
considerations should be given highest priority. In proposing critical 
habitat for the silvery minnow, we have reviewed the overall approach

[[Page 39218]]

to the conservation of the silvery minnow undertaken by the local, 
State, Tribal, and Federal agencies operating within the species' 
historical range since the species' listing in 1994, and the previous 
proposed (58 FR 11821) and final critical habitat rules (64 FR 36274). 
We have also outlined our conservation strategy to eventually recover 
the species (see ``Exclusions Under Section 4(b)(2) of the Act'' 
section above).
    We also considered the features and steps necessary for recovery 
and habitat requirements described in the Recovery Plan (Service 1999), 
and information provided by our Fishery Resources Office in New Mexico, 
and other biologists, as well as utilized our own expertise. We also 
reviewed the biological opinion issued June 29, 2001, to the BOR and 
U.S. Army Corps of Engineers (Corps) for impacts to the silvery minnow 
from water operations in the middle Rio Grande (Service 2001b), the 
biological opinion issued to the BOR for discretionary actions related 
to water management on the Pecos River, in New Mexico (Service 2001a), 
and reviewed available information that pertains to the habitat 
requirements of this species, including material received during the 
initial public comment period on the proposed listing and designation, 
the information received following the provision of the draft economic 
analysis to the public on April 26, 1996, the comments and information 
provided during the 30-day comment period opened on April 7, 1999, 
including the public hearing, and the comments and information received 
during the 60-day comment period opened on April 5, 2001, for the 
notice of intent to prepare an EIS and public scoping meetings held on 
April 17, 23, 24, and 27, 2001 (April 7, 1999; 64 FR 16890).
    Since the listing of the silvery minnow in 1994 (59 FR 36988), no 
progress has been made toward reestablishing this species within 
unoccupied areas (e.g., stream reaches on the middle Pecos, lower Rio 
Grande, etc.). Because the silvery minnow has been extirpated from 
these areas, Federal agencies have not consulted with us on how their 
discretionary actions may affect the silvery minnow. We conclude these 
areas (e.g., stream reaches on the middle Pecos and the lower Rio 
Grande) are essential to the conservation of the minnow, but we have 
not proposed them for designation of critical habitat (see discussion 
above).
    For these reasons, this proposed critical habitat designation 
differs from the final critical habitat designation we made in 1999 (64 
FR 36274), and which was subsequently set aside by court order. The 
differences also reflect the best scientific and commercial information 
analyzed in the context of the final Recovery Plan (see ``Recovery 
Plan'' discussion above) and our conservation strategy for this 
species. Although we could have proposed two additional critical 
habitat units to respond to the Recovery Plan's recommendation that 
additional areas are required to achieve recovery (Service 1999) (see 
``Recovery Plan'' discussion above), we believe that the inclusion of 
these areas could hinder our future conservation strategy (see 
``Exclusions Under Section 4(b)(2) of the Act'' section above) and 
actually impede recovery of the silvery minnow.
    Recovery requires protection and enhancement of existing 
populations and reestablishment of populations in suitable areas of 
historical range. The Recovery Plan identifies, ``the necessity of 
reestablishing silvery minnow in portions of its historical range 
outside of the middle Rio Grande in New Mexico.'' The Recovery Plan 
identified potential areas for reestablishment of silvery minnow in 
certain stream reaches of the Rio Grande and Pecos River. The Recovery 
Plan also recommended a thorough analysis of the reestablishment 
potential of specific river reaches within the historical range of the 
silvery minnow.
    Therefore, we have determined that one of the most important goals 
to be achieved toward the conservation of this species is the 
establishment of secure, self-reproducing populations in areas outside 
of the middle Rio Grande, but within the species' historical range 
(Service 1999). Thus, we have outlined our conservation strategy for 
the silvery minnow (see ``Exclusions Under Section 4(b)(2) of the Act'' 
section above). Because the species occupies less than five percent of 
its historical range and the likelihood of extinction from a 
catastrophic event is greatly increased (Hoagstrom and Brooks 2000, 
Service 1999), we believe that additional populations should be 
established within certain unoccupied reaches (i.e., areas outside of 
the current known distribution). Nevertheless, any future recovery 
efforts, including repatriation of the species to areas of its 
historical range must be conducted in accordance with NEPA and the Act.
    The recent trend in the status of the silvery minnow has been 
characterized by dramatic declines in numbers and range despite the 
fact that this species evolved in rapidly fluctuating, harsh 
environments. Moreover, none of the threats affecting the silvery 
minnow have been eliminated since the fish was listed (59 FR 36988), 
and through the summer of 2000, its status declined (Dudley and 
Platania 2001). Although the 2001 population levels of silvery minnow 
in the middle Rio Grande were higher than those recorded in 2000, the 
known silvery minnow population within the middle Rio Grande has become 
fragmented and isolated and is vulnerable to those natural or manmade 
factors that might further reduce population size (Dudley and Platania 
2001; 2002). Because there have been low spring peak flows in the Rio 
Grande in some recent years (e.g., such as in 2000), and a related 
decrease in spawning success of the silvery minnow, the population size 
of silvery minnow declined through the summer of 2000, but catch rates 
in June 2001 were higher than those observed in 2000 (Dudley and 
Platania 2001; 2002). We conclude the species' vulnerability to 
catastrophic events, such as prolonged periods of low or no flow, have 
increased since the species was listed as endangered in 1994 (59 FR 
36988).
    It is widely recognized that major efforts to repatriate the 
silvery minnow to large reaches of its historical habitat in the Rio 
Grande and Pecos River will not likely occur without either natural or 
induced changes in the river, including changes affecting the existing 
fish community, habitat restoration, and coordinated water management 
(e.g., see Service 1999). Nevertheless, we conclude that conservation 
and recovery of the silvery minnow requires habitat conditions that 
will facilitate population expansion or repatriation. As an example, we 
are currently involved in developing several efforts to assist in the 
conservation and recovery of the silvery minnow and other imperiled 
species (e.g., Federal and non-Federal efforts to create a middle Rio 
Grande Endangered Species Act Collaborative Program). Any future 
habitat restoration efforts conducted by us or other Federal agencies 
within the species' historical habitat will be analyzed through NEPA 
and will be conducted in accordance with the pertinent sections of the 
Act and Federal rulemaking procedures.
    Habitat alteration and loss, and non-native competition, predation, 
and other effects are inextricably intertwined and have contributed 
substantially to the endangered status of the silvery minnow (Service 
1999; Dudley and Platania 2001). Furthermore, habitat alteration has 
been a significant contributor to non-native fish invasion, 
competition, and adverse effects. In turn, non-native species have 
likely contributed significantly to the inability of native fish, such 
as the silvery minnow, to persist in altered environments (Hubbs

[[Page 39219]]

1990; Propst 1999). However, non-native fish species may have the 
potential to be removed or reduced to acceptable levels using a variety 
of control or management techniques. For example, the New Mexico State 
Game Commission recently passed a regulation limiting the species that 
can be used as baitfish in the Pecos River (New Mexico Department of 
Game and Fish 2000). As part of this proposed rule (see ``Public 
Comments Solicited'' section below) we are seeking further information 
regarding the role of unoccupied stream reaches within the historical 
range of the silvery minnow, including those reaches with non-native 
fish species (e.g., plains minnow) present or those reaches that have 
the potential for low or no flow events. We are particularly interested 
in assistance on how to describe the existing habitat (e.g., flow) 
conditions for the river reach below San Acacia Diversion Dam on the 
middle Rio Grande.
    It is important to note that the mere presence of non-native 
aquatic species does not eliminate an area from being considered for 
designation as critical habitat. For example, the relationship between 
the introduction of the plains minnow and extirpation of the silvery 
minnow is unclear (see discussion above). Although the Recovery Plan 
suggested that the plains minnow would be the primary limiting factor 
precluding successful reestablishment of the silvery minnow to the 
Pecos River (Service 1999), we have little data from which to draw firm 
conclusions for the extirpation of the silvery minnow from the Pecos 
River. We recognize that any efforts to reestablish the silvery minnow 
to unoccupied stream reaches must fully analyze and consider a variety 
of habitat management techniques, including the control or management 
of non-native fish. Consequently, we invite comments or information 
relating to the status of the plains minnow in the Pecos River and this 
area not being proposed as critical habitat. We are especially 
interested in observations of related species of Hybognathus and any 
behavioral or reproductive mechanisms that might provide for ecological 
separation in areas where two or more species of Hybognathus co-occur.
    Portions of the Pecos River include designated critical habitat for 
the Pecos bluntnose shiner (52 FR 5295). The Pecos bluntnose shiner 
critical habitat includes a 103 km (64 mi) reach of the Pecos River 
extending from a point 16 km (10 mi) south of Fort Sumner, NM 
downstream to the De Baca and Chaves County line and a 60 km (37 mi) 
reach from near Hagerman, NM, to near Artesia, NM (52 FR 5295). There 
are current protections in place for the Pecos bluntnose shiner in the 
river reach from Sumner to Brantley Reservoirs on the Pecos river; 
consequently, we believe that the designation of critical habitat would 
provide little additional benefit for the silvery minnow above the 
current jeopardy and adverse modifications standards for the Pecos 
bluntnose shiner (see ``Exclusions Under Section 4(b)(2) of the Act'' 
section above).
    The Pecos bluntnose shiner inhabits main-channel habitats with 
sandy substrates, low velocity flows, and at depths from 17 to 41 cm (7 
to 16 in) (Hatch et al. 1985). Adult Pecos bluntnose shiners use main-
channel habitats, with larger individuals found mainly in more rapidly 
flowing water (greater than 40 cm/sec, 1.25 ft/sec), but preferences 
for particular depths were not found (Hoagstrom et al. 1995). Young of 
the year use the upstream reaches between Sumner and Brantley 
Reservoirs, which provide shallow, low velocity habitat. These reaches 
also maintain such habitat at high (bankfull) discharge, providing 
refugia from swift, deep water. Pecos bluntnose shiner and related 
mainstream cyprinids (e.g., silvery minnow) are adapted to exploit 
features of Great Plains rivers (Hoagstrom 2000). These fish species 
belong to the same guild of broadcast spawners with semi-buoyant eggs 
and also spawn during high flow events in the Pecos River, with eggs 
and larvae being distributed downstream to colonize new areas (Bestgen 
et al. 1989). The habitat features used by the Pecos bluntnose shiner 
are largely affected by ongoing Sumner Dam operations (e.g., block 
releases). Nevertheless, any flow regime operations in this reach that 
benefit the Pecos bluntnose shiner, would also benefit the silvery 
minnow. We believe they could both occupy the same river reach in the 
future with little to no interspecific competition, in part, because 
these species historically co-existed (Bestgen and Platania 1991), and 
microhabitat partitioning has been documented for related species of 
southwestern fish (Matthews and Hill 1980). Therefore, we believe that 
the primary constituent elements for the Pecos bluntnose shiner 
critical habitat (e.g., clean permanent water; a main river channel 
habitat with sandy substrate; and a low velocity flow (52 FR 5295)) are 
compatible with our conservation strategy for repatriating the silvery 
minnow. We invite comments or information relating to the current 
protections under the Act for the Pecos bluntnose shiner and our 
exclusion of this area from the designation of critical habitat for the 
silvery minnow.

Lateral Extent of Critical Habitat

    The proposed critical habitat designation defines the lateral 
extent as those areas bounded by existing levees or in areas without 
levees the lateral extent of critical habitat is proposed to be defined 
as 91.4 meters (300 feet) of riparian zone adjacent to each side of the 
middle Rio Grande. Thus, the lateral extent of proposed critical 
habitat does not include areas adjacent to the existing levees but 
within the 300-foot lateral width outside the existing levees (i.e., 
these areas are not proposed as critical habitat, even though they may 
be within the 300-foot lateral width). If this proposed rule is 
finalized, critical habitat will not remove existing levees. We 
recognize that these areas can be important for the overall health of 
river ecosystems, but these areas have almost no potential for 
containing the primary constituent elements because they are protected 
from the levees and are rarely inundated by water. Therefore, they are 
not included in the proposed designation because we conclude they are 
not essential to the conservation of the silvery minnow. Nevertheless, 
these and other areas outside the critical habitat designation will 
continue to be subject to conservation actions that may be implemented 
under section 7(a)(1) of the Act and to the regulatory protections 
afforded by the section 7(a)(2) of the Act jeopardy standard and the 
section 9 of the Act take prohibition.
    For each stream reach within the middle Rio Grande, the up- and 
downstream-boundaries are described below. Proposed critical habitat 
includes the stream channels within the identified stream reaches and 
areas within these reaches potentially inundated during high flow 
events. Critical habitat includes the area of bankfull width plus 300 
feet on either side of the banks. The bankfull width is the width of 
the stream or river at bankfull discharge, i.e., the flow at which 
water begins to leave the channel and move into the floodplain (Rosgen 
1996). Bankfull discharge, while a function of the size of the stream, 
is a fairly consistent feature related to the formation, maintenance, 
and dimensions of the stream channel (Rosgen 1996). This 300-foot width 
defines the lateral extent of those areas we believe are essential to 
the species' conservation. Although the silvery minnow cannot be found 
in these areas when they are dry, they likely provided backwater 
habitat and were sometimes flooded (Middle Rio Grande Biological 
Interagency Team 1993), suggesting

[[Page 39220]]

these areas may provide habitat during high-water periods. As discussed 
in this section, we determined that the areas within the 300-foot 
lateral width are essential to the conservation of the silvery minnow.
    We determined the 300-foot lateral extent for several reasons. 
First, the implementing regulations of the Act require that critical 
habitat be defined by reference points and lines as found on standard 
topographic maps of the area (50 CFR 424.12). Although we considered 
using the 100-year floodplain, as defined by the Federal Emergency 
Management Agency (FEMA), we found that it was not included on standard 
topographic maps, and the information was not readily available from 
FEMA or from the Corps for the areas we are proposing to designate. We 
suspect this is related to the remoteness of various stream reaches. We 
could not find specific aerial photos, maps, or geographic information 
systems coverages that accurately delineated vegetation type along the 
proposed critical habitat unit. If this information were available, we 
could have refined the extent of the lateral width, specific to various 
river reaches. Therefore, we selected the 300-foot lateral extent, 
rather than some other delineation, for three biological reasons: (1) 
The biological integrity and natural dynamics of the river system are 
maintained within this area (i.e., the floodplain and its riparian 
vegetation provide space for natural flooding patterns and latitude for 
necessary natural channel adjustments to maintain appropriate channel 
morphology and geometry, store water for slow release to maintain base 
flows, provide protected side channels and other protected areas for 
larval and juvenile silvery minnow, allow the river to meander within 
its main channel in response to large flow events, and recreate the 
mosaic of habitats necessary for the survival and recovery of the 
silvery minnow); (2) conservation of the adjacent riparian area also 
helps provide essential nutrient recharge and protection from sediment 
and pollutants, which contributes to successful spawning and 
recruitment of silvery minnows; and (3) vegetated lateral zones are 
widely recognized as providing a variety of aquatic habitat functions 
and values (e.g., aquatic habitat for fish and other aquatic organisms, 
moderation of water temperature changes, and detritus for aquatic food 
webs) and help improve or maintain local water quality (65 FR 12897; 
Middle Rio Grande Biological Interagency Team 1993). We invite comments 
or information relating to the 300-foot lateral width of this proposed 
designation of critical habitat.
    This proposed critical habitat designation takes into account the 
naturally dynamic nature of riverine systems and recognizes that 
floodplains (including riparian areas) are an integral part of the 
stream ecosystem. For example, riparian areas are seasonally flooded 
habitats (i.e., wetlands) that are major contributors to a variety of 
vital functions within the associated stream channel (Federal 
Interagency Stream Restoration Working Group 1998, Brinson et al. 
1981). They are responsible for energy and nutrient cycling, filtering 
runoff, absorbing and gradually releasing floodwaters, recharging 
groundwater, maintaining streamflows, protecting stream banks from 
erosion, and providing shade and cover for fish and other aquatic 
species. Healthy riparian areas help ensure water courses maintain the 
habitat components essential to aquatic species (e.g., see U.S.D.A. 
Forest Service 1979; Middle Rio Grande Biological Interagency Team 
1993; Briggs 1996), including the silvery minnow. Habitat quality 
within the mainstem river channels in the historical range of the 
silvery minnow is intrinsically related to the character of the 
floodplain and the associated tributaries, side channels, and backwater 
habitats that contribute to the key habitat features (e.g., substrate, 
water quality, and water quantity) in the middle Rio Grande (Middle Rio 
Grande Biological Interagency Team 1993). Among other things, the 
floodplain provides space for natural flooding patterns and latitude 
for necessary natural channel adjustments to maintain channel 
morphology and geometry. We believe a relatively intact riparian area, 
along with periodic flooding in a relatively natural pattern, is 
important in maintaining the stream conditions necessary for long-term 
survival and recovery of the silvery minnow.
    Human activities that occur outside the river channel can have a 
demonstrable effect on physical and biological features of aquatic 
habitats. However, not all of the activities that occur within a 
floodplain will have an adverse impact on the silvery minnow or its 
habitat. Thus, in determining the lateral extent of critical habitat 
along riverine systems, we must consider the definition of critical 
habitat under the Act. That is, critical habitat must be determined to 
be essential to a species' conservation and, within areas currently 
occupied by the species, must be in need of special management 
considerations or protection.
    We do not believe that the entire floodplain is essential to the 
conservation of the species, and we are not proposing to designate the 
entire floodplain as critical habitat. However, conservation of the 
river channel alone is not sufficient to ensure the survival and 
recovery of the silvery minnow. For the reasons discussed above, we 
believe the riparian corridors adjacent to the river channel provide an 
important function for the protection and maintenance of the primary 
constituent elements and are essential to the conservation of the 
species.
    The lateral extent (width) of riparian corridors fluctuates 
considerably on the Rio Grande. The appropriate width for riparian 
protection has been the subject of several studies (Castelle et al. 
1994). Most Federal and State agencies generally consider a zone 23 to 
46 meters (m) (75.4 to 150.9 feet (ft)) wide on each side of a stream 
to be adequate to help improve or maintain local water quality (Natural 
Resource Conservation Service 1998, Moring et al. 1993, Lynch et al. 
1985), although lateral widths as wide as 152 m (500 ft) have been 
recommended for achieving flood attenuation benefits (Corps 1999). In 
most instances, however, these riparian areas are primarily intended to 
reduce (i.e. protect) detrimental impacts to the stream from sources 
outside the river channel (e.g., agricultural runoff). Generally, we 
believe a lateral distance of 91.4 m (300 ft) on each side of the 
stream beyond the bankfull width to be appropriate for the protection 
of riparian and wetland habitat and the natural processes involved in 
the maintenance and improvement of water quality (e.g., see Middle Rio 
Grande Biological Interagency Team 1993). We believe this lateral width 
will help ensure the protection of one or more primary constituent 
elements (e.g., water quality) of the critical habitat. Thus, within 
the area proposed for critical habitat designation on the middle Rio 
Grande, we conclude that the 300-foot lateral width is essential to the 
conservation of the species.
    We did not map critical habitat in sufficient detail to exclude all 
developed areas and other lands unlikely to contain primary constituent 
elements essential for silvery minnow conservation. Some developed 
lands within the 300-foot lateral extent are not considered critical 
habitat because they either do not contain the primary constituent 
elements or they are not essential to the conservation of the silvery 
minnow. Lands located within the exterior boundaries of the proposed 
critical habitat designation, but not considered critical habitat 
include:

[[Page 39221]]

existing paved roads, bridges, parking lots, dikes, levees, diversion 
structures, railroad tracks, railroad trestles, water diversion canals 
outside of natural stream channels, active gravel pits, cultivated 
agricultural land, and residential, commercial, and industrial 
developments. These developed areas do not contain any of the primary 
constituent elements and do not provide habitat or biological features 
essential to the conservation of the silvery minnow, and generally will 
not contribute to the species' recovery. However, some activities in 
these areas like activities in other areas not included within the 
designation (if Federally funded, authorized, or carried out) may 
affect the primary constituent elements of the proposed critical 
habitat and, therefore, may be affected by the critical habitat 
designation, as discussed later in this proposed rule.

Reach-by-Reach Analysis

    We conducted a reach-by-reach analysis of the entire known 
historical range of the silvery minnow to evaluate and select stream 
reaches that require special management or protection, or are essential 
to the conservation of the species. As identified in the Recovery Plan 
(see ``Recovery Plan'' discussion above), important factors we 
considered in determining whether areas were essential to the 
conservation of the species include presence of other members of the 
reproductive guild (e.g. pelagic spawners, species with semibuoyant 
eggs, etc.), habitat suitability (e.g., appropriate substrate), water 
quality, and presence of non-natives (competitors, predators, other 
species of Hybognathus, etc.). These important factors were evaluated 
in conjunction with the variable flow regime of each reach. Each of the 
stream reaches, to some extent, has a varying flow regime. However, the 
fact that a river reach may at times experience a prolonged period of 
low or no flow as a result of a varying flow regime does not preclude 
the area from being considered essential to the conservation of the 
species and, further, being proposed as critical habitat. Based on our 
reach-by-reach analysis, we have determined which reaches are essential 
for the conservation of the species.
    We are proposing to designate the middle Rio Grande as a critical 
habitat unit. This unit contains all of the primary constituent 
elements during some or all of the year (see the ``Regulation 
Promulgation'' section of this rule for exact descriptions of 
boundaries of the proposed critical habitat unit). We conclude that the 
proposed critical habitat unit can provide for the physiological, 
behavioral, and ecological requirements of the silvery minnow. The 
proposed critical habitat unit is within the middle Rio Grande from 
immediately downstream of Cochiti Reservoir to the Elephant Butte 
Reservoir Dam, including the tributary Jemez River from Jemez Canyon 
Reservoir to its confluence with the Rio Grande. Although we determined 
that other areas are essential to the conservation of the silvery 
minnow (i.e., the middle Pecos River from immediately downstream of 
Sumner Dam to Brantley Dam, NM; and the lower Rio Grande from the 
upstream boundary of Big Bend National Park to Terrell/Val Verde County 
line, TX), these areas are not proposed as critical habitat. A 
description of each stream reach within the silvery minnow's historical 
range is provided below. We also provide our reasons for determining 
whether each reach is essential to the conservation of the species and 
whether we are proposing or not proposing critical habitat for each of 
the identified reaches. We conclude that we can secure the long-term 
survival and recovery of this species with the establishment of future 
experimental populations under section 10(j) of the Act, along with the 
proposed critical habitat unit in the middle Rio Grande.
    The historical range of the species in the Rio Grande is from 
Espa[ntilde]ola, NM, to the Gulf of Mexico, and, in the Pecos River (a 
major tributary of the Rio Grande) from Santa Rosa, NM, downstream to 
its confluence with the Rio Grande (Pflieger 1980; Bestgen and Platania 
1991). We separated the historical range of the silvery minnow into 12 
stream reaches that include: (1) Upstream of Cochiti Reservoir to the 
confluence of the Rio Chama and Rio Grande, New Mexico; (2) Middle Rio 
Grande from Cochiti Reservoir downstream to the Elephant Butte Dam, 
including the Jemez River immediately downstream of Jemez Canyon 
Reservoir to the confluence of the Rio Grande; (3) Downstream of 
Elephant Butte Dam to the Caballo Dam, New Mexico; (4) downstream of 
Caballo Dam, New Mexico, to the American Dam, Texas; (5) downstream of 
American Reservoir, to the upstream boundary of Big Bend National Park, 
Texas; (6) the upstream boundary of Big Bend National Park to the 
southern boundary of the wild and scenic river designation at Terrell/
Val Verde County line, Texas; (7) the Terrell/Val Verde County line, 
Texas to the Amistad Dam, Texas; (8) downstream of Amistad Dam to the 
Falcon Dam, Texas; (9) downstream of the Falcon Dam to the Gulf of 
Mexico, Texas, (10) Pecos river from Santa Rosa Reservoir to Sumner 
Dam, Guadalupe County, New Mexico, (11) Sumner Dam to the Brantley Dam, 
NM; (12) Brantley Dam, NM to the Red Bluff Dam, TX; and (13) Red Bluff 
Dam to the confluence of the Rio Grande, TX. Each of these reaches are 
analyzed below.
    1. Upstream of Cochiti Reservoir to the confluence of the Rio Chama 
and Rio Grande, Rio Arriba, Sante Fe, and Sandoval Counties, NM. 
Currently, this reach is dominated by cool water, which is not 
considered suitable for the silvery minnow (Platania and Altenbach 
1998). The majority of this reach is bounded by canyons, with substrate 
dominated by gravel, cobble, and boulder (Service 1999). The flow 
regime is also highly variable seasonally because of irrigation and 
other agricultural needs, and recreational and municipal uses. This 
river reach is highly manipulated by releases from El Vado and Abiquiu 
Reservoirs (J. Smith, pers. comm. 2001). Furthermore, silvery minnow 
populations may have been historically low for some areas of this 
reach, supporting only small outlier populations (Bestgen and Platania 
1991). Currently, this reach is dominated by cool or cold water 
species, which have almost completely replaced the native fish species 
(Service 1999). For these reasons, we conclude that habitat for silvery 
minnow within this stream reach is generally degraded and unsuitable, 
and is not essential to the conservation of the silvery minnow. 
Therefore, this stream reach is not proposed as critical habitat.
    2. Middle Rio Grande from Cochiti Reservoir downstream to the 
Elephant Butte Dam, including the Jemez River immediately downstream of 
Jemez Canyon Reservoir to the confluence of the Rio Grande, Sandoval, 
Bernalillo, Valencia, and Socorro Counties, NM. The middle Rio Grande 
is currently occupied, and the status of the silvery minnow within this 
segment is unstable (Bestgen and Platania 1991; Dudley and Platania 
1999; Platania and Dudley 2001; 2002). This area currently contains the 
primary constituent elements (described above) during all or a part of 
the year and is considered suitable habitat for the silvery minnow, as 
shown by the presence of the silvery minnow within this reach. The 
river reaches in the proposed critical habitat unit are degraded from 
lack of floodplain connectivity, non-native vegetation, stabilized 
banks (e.g., jetty jacks), streambed aggradation, and decreasing 
channel width, increasing depths, and increasing velocities (BOR 2001a; 
Service 2001b). Thus,

[[Page 39222]]

conservation of the silvery minnow requires stabilizing populations 
within the middle Rio Grande, including special management 
considerations or protections (e.g., habitat management and/or 
restoration).
    The middle Rio Grande is essential to the conservation of the 
silvery minnow (see discussion below), and therefore we propose the 
following reaches as a critical habitat unit. This proposed critical 
habitat unit does not include the ephemeral or perennial irrigation 
canals and ditches, including the LFCC (i.e., downstream of the 
southern boundary of Bosque del Apache National Wildlife Refuge to the 
headwaters of Elephant Butte Reservoir) that are adjacent to a portion 
of the stream reach within the middle Rio Grande because these areas do 
not offer suitable refugia and are not useful for recovery of the 
silvery minnow. The stream reaches in the proposed middle Rio Grande 
critical habitat unit include (see the Regulation Promulgation section 
of this rule for exact descriptions of boundaries of this proposed 
critical habitat unit):
    a. Jemez Canyon Reach--8 km ( 5 mile) of river immediately 
downstream of Jemez Canyon Reservoir to the confluence of the Rio 
Grande. This reach of river is manipulated by releases from Jemez 
Canyon Reservoir. Releases from this reservoir are determined by 
downstream needs and flood events occurring in the Jemez River. Silvery 
minnows historically occupied this reach of the Jemez River and have 
recently been collected there (Sublette et al. 1990; Corps 2001). The 
water within this reach is continuous to the confluence with Rio Grande 
and currently contains the primary constituent elements (described 
above) during all or a part of the year. Although this reach currently 
provides suitable habitat for the silvery minnow, we believe that it is 
important to ensure that special management actions are implemented 
within this stream reach. We also conclude that this area is essential 
to the conservation and contains the primary constituent elements for 
the silvery minnow. This area is essential because the additional loss 
of any habitat that is currently occupied could increase the likelihood 
of extinction (Hoagstrom and Brooks 2000, Service 1999). Moreover, if 
the species or habitat were severely impacted within this reach, the 
continued existence of silvery minnows in downstream reaches would be 
affected (i.e., the extirpation of fish within this reach would create 
a very unstable population within the downstream reaches). Thus, we 
propose this section of the Jemez River as critical habitat for the 
silvery minnow.
    b. Cochiti Reservoir Dam to Angostura Diversion Dam (Cochiti 
Reach)--34 km (21 mile) of river immediately downstream of Cochiti 
Reservoir to the Angostura Diversion Dam. This reach is somewhat 
braided and is dominated by clear water releases from Cochiti 
Reservoir. Since Cochiti Reservoir was filled, the downstream substrate 
has changed from a course sand to a gravel substrate (Baird 2001). 
Silvery minnows were collected immediately downstream of Cochiti Dam in 
1988 (Platania 1993). Although the Cochiti reach has not been monitored 
since the mid-1990s (Platania 1995), it is believed that silvery minnow 
may still be present within this reach, but reduced in abundance. For 
example, silvery minnows were documented near the Angostura Diversion 
Dam in 2001 (Platania and Dudley 2001; 2002; Service 2001c). In this 
reach, water releases from Cochiti Reservoir have scoured sand from the 
stream channel and reduced the downstream temperatures (Bestgen and 
Platania 1991; Platania 1991; 59 FR 36988; Service 1999; Hoagstrom 
2000). These effects (e.g., low water temperatures) may inhibit or 
prevent reproduction among Rio Grande Basin Cyprinids (Platania and 
Altenbach 1998), but it is unknown if water temperatures have affected 
silvery minnow reproduction within this reach. Although reservoirs can 
modify river flows and habitat (e.g., the downstream river reaches have 
increased in depth and water velocity) (Hoagstrom 2000), we believe 
this river reach is essential to the conservation of the silvery minnow 
because we believe it is still occupied by the species and contributes 
to its survival in downstream reaches (i.e., the eggs and larvae of the 
silvery minnow drift in the water column and may be transported 
downstream depending on river flows and habitat conditions). We 
reviewed aerial photographs from 1997, and have determined that the 
river through this reach is braided in areas and contains many side 
channels. We also spoke with the Corps and conclude there is a high 
potential to increase the amount of suitable habitat (e.g., debris 
piles, low velocity backwaters, side channels, etc.) within the entire 
reach, but particularly in the proximity of the confluences of Galisteo 
Creek and the Rio Grande and the Sante Fe River and the Rio Grande (D. 
Kreiner, U.S. Army Corps of Engineers, pers. comm. 2001). Thus, we 
conclude special management in this reach is needed. We conclude that 
this area contains suitable habitat for the silvery minnow and contains 
the primary constituent elements (described above) during all or a part 
of the year. Therefore, this reach is proposed as critical habitat.
    c. Angostura Diversion Dam to Isleta Diversion Dam (Angostura 
Reach)--61 km (38 mile) of river immediately downstream of the 
Angostura Diversion Dam to the Isleta Diversion Dam. Silvery minnows 
and suitable habitat are still present throughout this reach of the 
river, although their abundance appears to be low (Dudley and Platania 
2001; 2002). This reach is relatively wide 183 m (600 ft) and the 
substrate is mostly course sand to gravel (Baird 2001). The river bank 
within this reach is dominated by bank stabilization (e.g., jetty 
jacks), which has led to the floodplain being predominantly 
disconnected from the river. Bank stabilization devices and other flood 
control operations (e.g., channelization) have led to flows that seldom 
exceed channel capacity, such that the river dynamics which likely 
provided backwater habitat for the silvery minnow no longer function 
naturally. These river processes historically shaped and reshaped the 
river, constantly redefining the physical habitat and complexity of the 
river. Historical large flow events allowed the river to meander, 
thereby creating and maintaining the mosaic of habitats necessary for 
the survival of the silvery minnow and other native fish (Middle Rio 
Grande Biological Interagency Team 1993). We conclude that the creation 
and maintenance of these habitats is essential to the conservation of 
the silvery minnow. We believe that special management is necessary in 
this and other downstream reaches within the middle Rio Grande to 
create and maintain the habitat complexity (e.g., backwater areas, 
braided channels, etc.) that was historically present, but may not 
currently present, in these river reaches. This reach currently 
contains the primary constituent elements (described above) during all 
or a part of the year. Thus, we propose this reach as critical habitat.
    d. Isleta Diversion Dam to San Acacia Diversion Dam (Isleta Reach)-
-90 km (56 mi) of river immediately downstream of the Isleta Diversion 
Dam to the San Acacia Diversion Dam. The river bank within this reach 
is also dominated by bank stabilization (e.g., jetty jacks), and the 
floodplain is predominantly disconnected from the river. The substrate 
is mostly sand and silt and there are many permanent islands within the 
river channel (J. Smith, pers. comm. 2001). This reach provides 
continuous water flow in most years with infrequent periods of low or

[[Page 39223]]

no flow (Service 2001b). Nevertheless, flows vary markedly in 
magnitude, from high spring to low summer flows. The variable flow 
regime is a result of irrigation demand, irrigation returns (e.g., 
augmented flow), precipitation, temperature, and sediment transport. 
This reach also contains numerous arroyos and small tributaries that 
provide water and sediment during rainstorm events, which may 
periodically augment river flows (Service 2001b; J. Smith, pers. comm. 
2001). Silvery minnows and suitable habitat are still present 
throughout this reach of the river; however, abundance appears to be 
low (Dudley and Platania 2001; 2002). Nevertheless, we conclude that 
this area is essential to the conservation of the silvery minnow 
because the additional loss of any habitat that is currently occupied 
could increase the likelihood of extinction (Hoagstrom and Brooks 2000, 
Service 1999). Similarly, if the species or habitat were severely 
impacted within this reach, the continued existence of silvery minnows 
in downstream reaches would be affected (i.e., the extirpation of fish 
within this reach would create a very unstable population within the 
downstream reaches). This reach currently contains the primary 
constituent elements (described above) during all or a part of the 
year. We believe that special management is necessary within this reach 
to create and maintain the habitat complexity (e.g., backwater areas, 
debris piles, meandering river, etc.) that was historically, but may 
not currently be associated with this reach. Thus, we propose this 
reach as critical habitat.
    e. San Acacia Diversion Dam to the Elephant Butte Dam (San Acacia 
Reach)--147 km (92 mi) of river immediately downstream of the San 
Acacia Diversion Dam to the Elephant Butte Dam. We selected Elephant 
Butte Dam as the boundary of the proposed critical habitat because it 
is a stationary structure. Nevertheless, the area inundated by the 
reservoir does not provide those physical or biological features 
essential to the conservation of the species and is specifically 
excluded from the proposed critical habitat. We define the reservoir as 
that part of the body of water impounded by Elephant Butte Dam where 
the storage waters are lentic (relatively still waters) and not part of 
the lotic (flowing water) river channel.
    The channel width within this reach varies from approximately 15 m 
(50 ft) to approximately 198 m (650 ft). The substrate is mostly sand 
and silt. The flow regime within this reach was historically, and is 
currently, highly variable. In fact, this stretch may not have provided 
continuous flow in some years prior to the 1900s (Middle Rio Grande 
Conservancy District 1999; Scurlock and Johnson 2001). As described 
above, we are soliciting comments or information relating to the 
proposed designation of critical habitat in this reach, which may 
experience periods of no or low flow.
    Currently, the river channel has been highly modified by water 
depletions from agricultural and municipal use, dams and water 
diversion structures, bank stabilization, and the infrastructure for 
water delivery (e.g., irrigation ditches). These modifications have led 
to the loss of sediment, channel drying, separation of the river from 
the floodplain, and changes in river dynamics and resulting channel 
morphology. Consequently, this reach requires special management 
considerations similar to those discussed above. This reach currently 
contains the primary constituent elements (described above) during all 
or a part of the year. Although the silvery minnow continues to be 
widespread within this reach with higher abundance than the Angostura 
or Isleta reaches (Dudley and Platania 2001; 2002), the variable flow 
regime and modifications to the river have increased the potential for 
short and long-term impacts not only to the silvery minnow, but also to 
its habitat. Thus, we determine that this area is essential to the 
conservation of the species and in need of special management 
considerations or protections; we propose this reach as critical 
habitat.
    3. Downstream of Elephant Butte Reservoir to the Caballo Dam, 
Sierra County, NM. This short 26-km (16-mile) reach is highly 
channelized with widely variable flow regimes. Construction of Elephant 
Butte and Caballo Reservoirs in 1916 and 1938, respectively, severely 
altered the flows and habitat within this reach (Bestgen and Platania 
1991). The silvery minnow has not been documented within this reach 
since 1944 (Service 1999). This river reach is currently highly 
channelized to expedite water deliveries and very few native fish 
remain (Propst et al. 1987; International Boundary and Water Commission 
2001). This reach is subject to prolonged periods of low or no flow and 
there is no spring runoff spike (Service 1999). Altered flow regimes 
will continue to affect habitat quality in this reach and it does not 
contain suitable habitat for the silvery minnow. The stream length in 
this reach is inadequate (e.g., less than 134 to 223 mi) to ensure the 
survival of downstream drift of eggs and larvae and recruitment of 
adults (Platania and Altenbach 1998). We conclude this area is not 
essential to the conservation of the species. Therefore, this river 
reach is not proposed as critical habitat.
    4. Downstream of Caballo Dam to American Reservoir Dam, Sierra and 
Do[ntilde]a Ana, Counties, NM and El Paso, County, TX. This 
approximately 176-km (110 mile) reach has a highly regulated flow 
regime from releases of water stored in Caballo Reservoir. This reach 
is also highly canalized with winter flows near zero in the upper 
portions and does not contain suitable habitat for the silvery minnow 
(Service 1999; IBWC 2001a). Silvery minnow have not been reported from 
this reach since 1944 (Bestgen and Platania 1991, Service 1999). The 
reach is currently inhabited by many non-native fish species (IBWC 
2001a). Due to lack of suitable habitat, diminished and highly 
regulated flow (IBWC 2001a), this reach of river no longer contains 
suitable habitat for the silvery minnow and is not essential to the 
conservation of the silvery minnow. Thus, this reach is not proposed as 
critical habitat.
    5. Downstream of American Reservoir to the upstream boundary of Big 
Bend National Park, El Paso, Hudspeth, and Presidio, Counties, TX. 
Portions of this reach, primarily upstream of Presido, TX, are 
continually dewatered, especially between Fort Quitman and Presidio 
(Hubbs et al. 1977; Department of Interior 1998). River flow is 
augmented downstream of Presido by waters flowing from the Rio Conchos. 
The near-continuous input of municipal waste has led to a deterioration 
of water quality, with corresponding changes to the ichthyofauna (fish 
species assemblage within a region) (Hubbs et al. 1977; Bestgen and 
Platania 1988; IBWC 1994; El-Hage and Moulton 1998a). Flows in this 
reach consist of a blend of raw river water; treated municipal waste 
from El Paso, TX; untreated municipal water from Juarez, Mexico; 
irrigation return flow; and the occasional floodwater (Texas Water 
Development Board 2001). For example, water temperature patterns can be 
elevated and oxygen levels decreased by the input of various pollutants 
(e.g., nitrogen, phosphorus) (Texas Water Development Board 2001; IBWC 
2001b). Water quality is believed to improve farther downstream of the 
confluence of the Rio Conchos and Rio Grande. The development of 
agriculture and population growth of this area has resulted in a 
decrease of water quantity and quality, which has had a significant 
impact on the range and distribution of many fish species within this 
reach

[[Page 39224]]

(IBWC 1994; El-Hage and Moulton 1998a). There are no current or museum 
records of silvery minnow from this reach (Service 1999). Because of 
dewatering upstream and the degraded water quality, we believe this 
reach of river would never provide suitable habitat for the silvery 
minnow. Thus, this river reach is not essential to the conservation of 
the silvery minnow and is not proposed as critical habitat.
    6. The upstream boundary of Big Bend National Park (3.2 km, 2 mi 
downstream of Lajitas), Brewster County, to the southern boundary of 
the wild and scenic river designation at Terrell/Val Verde County line, 
TX. This approximately 368-km (230-mile) reach of the lower Rio Grande 
was historically occupied but is currently unoccupied by the silvery 
minnow (Hubbs 1940; Trevino-Robinson 1959; Hubbs et al. 1977; Bestgen 
and Platania 1991). The continuing presence of members of the pelagic 
spawning guild (e.g., speckled chub and Rio Grande shiner) are evidence 
that the lower Rio Grande through Big Bend National Park area may 
support reestablishment of silvery minnow (Platania 1990; IBWC 1994). 
Moreover, water quality, compared to the reach upstream of the Park, is 
greatly improved in this reach from the many freshwater springs within 
Big Bend National Park (MacKay 1993; R. Skiles, pers. comm. 2001; IBWC 
1994). This area is protected and managed by the National Park Service 
and the river currently supports a relatively stable hydrologic regime 
(R. Skiles, pers. comm. 2001). The National Park Service's management 
authority in the wild and scenic river designation currently extends 
0.25 mi from the ordinary high water mark. Thus, the area designated as 
a wild and scenic river outside of Big Bend National Park is currently 
managed by the National Park Service under their authorities and is 
considered part of the National Park Service System. As discussed 
above, we have determined that recovery of the silvery minnow requires 
reestablishing populations outside of the middle Rio Grande (see 
``Recovery Plan'' discussion above), and should include areas within 
the lower Rio Grande. Because the silvery minnow has been extirpated 
from this reach, Federal agencies have determined their actions will 
not adversely affect the silvery minnow and therefore have not 
consulted with the Service under section 7(a)(2) on their actions 
related to this reach. We believe it is important to ensure that the 
assistance of Federal agencies, the State of Texas resource agencies, 
and non-Federal entities in future recovery actions (e.g., the 
establishment of an experimental population) are not compromised. 
Although Big Bend National Park expressed support for a critical 
habitat designation for the silvery minnow within the National Park, 
they also indicated that if areas outside the National Park, but within 
the wild and scenic river were included, their attempts at developing a 
river management plan could be compromised (F. Deckert, Big Bend 
National Park, pers. comm.).
    We have determined that this reach is essential to the conservation 
of the silvery minnow. However, our conservation strategy for the 
silvery minnow is to establish populations within its historical range 
under section 10(j) of the Act, and this could include all or portions 
of this stream reach. We believe that this area will contribute to the 
recovery of the silvery minnow, but have not proposed this stream reach 
for designation of critical habitat. As indicated in the ``Public 
Comments Solicited'' section of this rule we are seeking comments on 
whether this reach should or should not be designated as critical 
habitat based upon the factors discussed in this proposed rule and any 
other relevant information that you believe should be considered in our 
analysis. We are also soliciting comments on the applicability of an 
experimental population under section 10(j) of the Act to provide for 
conservation and recovery of the silvery minnow within this reach of 
its historical range.
    7. The Terrell/Val Verde County line, TX to the Amistad Dam, TX. 
This short reach is highly influenced by the Amistad Dam at its 
terminus. It is also believed that introduced fish played a role in the 
extirpation of silvery minnow in this reach (Bestgen and Platania 
1991). Water quality conditions within this reach are generally 
degraded, and are also a concern for this reach, particularly during 
low-flow conditions (Texas Water Development Board 2001; Texas Natural 
Resource Conservation Commission 1996). For all these reasons, we do 
not believe that this river reach is essential to the conservation of 
the silvery minnow; therefore, it is not proposed as critical habitat.
    8. Downstream of the Amistad Dam to the Falcon Dam, Val Verde, 
Kinney, Maverick, Web, Zapata, and Starr Counties, TX. This reach does 
provide continuous base flows ranging between 500 and 3000 cfs (Service 
1999), but the reach is highly urbanized and has many instream barriers 
(e.g., earthen dams) at Maverick, Eagle Pass, and Indio that would 
prevent movements of silvery minnow. Water quality is also a potential 
concern for this reach, particularly during low-flow conditions (Texas 
Water Development Board 2001; Texas Natural Resource Conservation 
Commission 1996). This reach is heavily channelized with little to no 
stream braiding and, in areas inappropriate substrate (e.g., cobble). 
There is no suitable habitat for the silvery minnow within this reach, 
and the species was last recorded here in the 1950s (Service 1999). The 
fish community within this reach is dominated by warm water non-native 
predators (Platania 1990; Service 1999). Because this reach does not 
have suitable habitat for the silvery minnow and water quality during 
variable flow conditions is a concern, this reach of river is not 
essential to the conservation of the silvery minnow and is not proposed 
as critical habitat.
    9. Downstream of Falcon Reservoir to the Gulf of Mexico, Starr, 
Hildago, and Cameron, Counties, TX. The silvery minnow historically 
occupied this reach of river (Service 1999). In fact, the type locality 
(the location from which the species was originally described) for the 
species is Brownsville, TX (Hubbs and Ortenburger 1929). However, the 
last collection of the silvery minnow occurred in 1961 just downstream 
of Falcon Reservoir (Bestgen and Platania 1991). This flow regime of 
this reach of the Rio Grande is highly influenced by releases from 
Falcon Reservoir. Most of the tributary inflow is controlled or 
influenced by small impoundments off the main channel of the river. The 
lower portion of this reach is often dewatered with the river flow 
stopping before the confluence with the Gulf of Mexico (IBWC 2001b). 
The fish community in this reach of the Rio Grande has had a 
significant shift toward estuarine (a mixture of fresh and salt water) 
type species (IBWC 1994; Contreras-B. and Lozano-V.1994). There has 
also been a significant loss of the native fish fauna in the Mexican 
tributaries in the last several decades (Hubbs et al. 1977 Almada-
Villela 1990; Platania 1990), apparently from poor water quality (e.g., 
see Texas Water Development Board 2001; Texas Natural Resource 
Conservation Commission 1996). Finally, invasive weeds (e.g., hydrilla 
and hyacinth) have clogged many areas of this reach and have reduced 
the amount of dissolved oxygen in the water (IBWC 2001b). Because this 
reach does not have suitable habitat, there appears to be little 
benefit in trying to intensively managing the flow regime in this reach 
of river. For these reasons, this reach is not considered essential to

[[Page 39225]]

the conservation of the silvery minnow and is not proposed as critical 
habitat.
    10. Pecos River from Santa Rosa Reservoir to Sumner Dam, Guadalupe 
County, NM. This reach is approximately 89 km (55 mi) and is typified 
by wide fluctuations in flow regimes from upstream releases from Santa 
Rosa Reservoir (Hoagstrom 2000). Within this reach there is one 
diversion at Puerto del Luna, NM. The silvery minnow has not been 
collected within this reach since 1939 (Bestgen and Platania 1991; 
Service 1999). The habitat in this reach is not suitable for the 
silvery minnow because much of the surrounding topography is composed 
of steep cliffs and canyons (Hoagstrom 2000). Canyon habitat does not 
provide suitable habitat (e.g., shallow, braided, streams with sandy 
substrates) for the silvery minnow (Bestgen and Platania 1991; Dudley 
and Platania 1997; Remshardt et al. 2001). Due to the short length of 
this reach, fluctuations in the flow regime, and the absence of 
suitable habitat for the silvery, this reach of river is not essential 
to the conservation of the silvery minnow and is not proposed as 
critical habitat.
    11. Middle Pecos Reach--approximately 345 km (214 mi) of river 
immediately downstream of Sumner Reservoir to the Brantley Reservoir 
Dam in De Baca, Chaves, and Eddy Counties, NM. The Pecos River was 
historically occupied but is currently unoccupied by the silvery minnow 
(Bestgen and Platania 1991). In fact, the silvery minnow was once one 
of the most common fish species present between Sumner and Avalon 
Reservoir (the area currently inundated by Brantley Reservoir) (Bestgen 
and Platania 1991). The Pecos River can support a relatively stable 
hydrologic regime between Sumner and Brantley Reservoirs, and, until 
summer 2001, this stretch maintained continuous flow for about the last 
10 years (D. Coleman, pers. comm. 2001). For example, groundwater 
seepage areas and base flow supplementation from Sumner Dam bypasses 
can offer a degree of stability for the river flow, especially during 
low flow periods (Hatch et al. 1985; Service 2001). Still, segments of 
this river reach were dewatered for at least 5 days during summer 2001 
(D. Coleman, pers. comm. 2001). Although springs and irrigation return 
flows maintain water flow in the lower portions of this river reach 
during times when no water is being released from Sumner Dam, periods 
of low discharge or intermittency have the potential to impact much of 
the suitable habitat within portions of this reach (Service 2001).
    After the construction of Sumner Dam, major channel incision 
occurred during the 1949 to 1980 period, accompanied by salt cedar 
proliferation along the river banks (Hoagstrom 2000). High velocity 
flows within the incised (deep) river channel have the ability to 
displace eggs from pelagic spawners such as the silvery minnow. This 
channel incision also reduced the areas of low velocity habitat within 
this river reach (Hoagstrom 2000). Recently lengthy reservoir releases 
such as those that occurred in 1988 (36 days) and in 1989 (56 days), 
have been shortened to about 10 days, which has benefitted species such 
as the Pecos bluntnose shiner (Service 2001). Nevertheless, historical 
block releases of water from Sumner Reservoir have modified river flows 
and habitat (e.g., the downstream river reaches have increased in depth 
and water velocity) (Hoagstrom 2000).
    The recovery of the silvery minnow requires reestablishing 
populations outside of the middle Rio Grande (Service 1999). We believe 
that repatriation is required outside of the area presently occupied by 
the species (i.e., the middle Rio Grande) to ensure the recovery of the 
silvery minnow (50 CFR 424.12(e)) (see ``Recovery Plan'' discussion 
above). We recognize that habitat within this river reach is degraded, 
but believe this reach within the middle Pecos River may provide one of 
the most promising areas for conducting recovery efforts because we 
believe it still contains habitat suitable for the silvery minnow 
(Hoagstrom 2000). For example, the continuing presence of members of 
the pelagic spawning guild (e.g., speckled chub, Rio Grande shiner, 
Pecos bluntnose shiner) is evidence that this reach of the Pecos River 
contains habitat suitable for the silvery minnow and may support 
reestablishment of the species (Hoagstrom 2000).
    Federal agencies have not consulted with us on how their actions 
will affect the silvery minnow, because the species no longer occurs 
within the Pecos River (D. Coleman, pers. comm. 2001). Because habitat 
suitable for the silvery minnow is still present within this river 
reach, we find that this stream reach is essential to the conservation 
of the species. Although we have determined that this reach is 
essential to the conservation of the silvery minnow, we have not 
proposed this area for designation of critical habitat (see 
``Exclusions Under Section 4(b)(2) of the Act'' section above). Our 
conservation strategy is to develop, through Federal rulemaking 
procedures, one or more experimental populations within the historical 
range of the silvery minnow. We believe this river reach may provide a 
suitable area for an experimental population. Consequently, we are 
soliciting comments on the applicability of an experimental population 
under section 10(j) of the Act to provide for conservation and recovery 
of the silvery minnow in areas of currently suitable habitat within its 
historical range.
    12. Downstream of Brantley Reservoir, Eddy County, NM to Red Bluff 
Reservoir, Loving and Reeves Counties, Texas. This reach is short, with 
a highly variable flow regime that is dependent on agricultural demand. 
This reach is also highly segmented with small closely placed 
impoundments (e.g., permanent and temporary diversion dams) that pond 
water, impede fish movements, and would not allow for adequate stream 
length (e.g., 134 to 223 mi) to ensure the survival of downstream drift 
of eggs and larvae and recruitment of adults (Platania and Altenbach 
1998). Additionally, agricultural and oil field pollution and permian 
salts (i.e., brine) are added to the river in this reach, decreasing 
the water quality to levels that likely would not support the silvery 
minnow (Campbell 1959; Larson 1994). Silvery minnow was historically 
uncommon within this reach; only 14 specimens from two collections are 
known (Bestgen and Platania 1991). Due to the short length of this 
reach, fluctuations in the flow regime, degraded water quality, and the 
absence of suitable habitat for the silvery minnow, it is not 
considered essential to the conservation of the silvery minnow and is 
not proposed as critical habitat.
    13. Downstream of Red Bluff Reservoir to the confluence with Rio 
Grande, Loving, Reeves, Pecos, Ward, Crane, Crockett, and Terrell 
Counties, TX. Historically silvery minnows occurred in this reach, 
though their exact distribution and abundance is unclear (Campell 
1958,Trevino-Robinson 1959, James and De La Cruz 1989, Linam and 
Kleinsasser 1996, Garrett 1997, Service 1999). For example, Bestgen and 
Platania (1991) suggest silvery minnows may have been uncommon within 
this reach because of pond habitat and high water salinity. However, 
this area may not have been well surveyed when the silvery minnow was 
still extant in the Pecos River (D. Propst, New Mexico Game and Fish, 
pers. comm. 2001). Still, sampling the middle and lower parts of this 
river reach has been historically difficult because of dense 
vegetation, steep canyon banks, and lack of public access (Campbell 
1959). The upper segment of this reach can be characterized as devoid 
of suitable habitat, and has a

[[Page 39226]]

highly variable flow regime from release of water from Red Bluff 
Reservoir for agricultural use. Indeed, many freshwater springs that 
historically augmented the Pecos River throughout this reach have 
recently been diminished or gone dry (Campbell 1959; Brune 1981 cited 
in Hoagstrom 2000; Barker et al. 1994; El-Hage and Moulton 1998b; ). 
The water quality in this upper portion is also poor and dominated by 
high salinity (generally exceeding 5 parts per thousand) (Hiss 1970; 
Hubbs 1990; Linam and Kleinsasser 1996; Miyamoto et al. 1995; El-Hage 
and Moulton 1998b). Additionally, algal blooms (Prymnesium parvum) have 
essentially eliminated all the fishes throughout from Malaga, NM, to 
Amistad Dam, TX (James and De la Cruz 1989; Hubbs 1990; Rhodes and 
Hubbs 1992). The river channel is also somewhat incised and dominated 
by non-native vegetation in parts (Koidin 2000; Harman 1999; IBWC 
2001b). Agricultural needs diminish south of Girvin, TX, and water 
quality conditions (e.g., salinity) generally begin to improve 
downstream from the confluence of Independence Creek to Amistad Dam 
(Hubbs 1990; Linam and Kleinsasser 1996). This improvement could result 
from the freshwater springs within the lower 160 km (100 mi) stretch of 
this reach. Nevertheless, gaging records from the lower segment 
indicate that there is virtually no flow during drought conditions 
(Texas Water Development Board 2001) and water quality (e.g., total 
dissolved solids) at Shumla Bend, just upstream of Amistad Reservoir, 
would be expected to have a deleterious effect on aquatic life (IBWC 
1994). We did not include this reach because the current or potential 
suitability for the silvery minnow is unknown; detailed habitat studies 
have not been conducted in this reach. Moreover, it is believed that 
this area contains a network of steep canyons, with rock and course 
gravel substrate (Campbell 1959; Texas Parks and Wildlife 1999). Canyon 
habitat reduces stream channel width, which decreases sinuosity and 
meandering, and creates deep channels that do not provide suitable 
habitat (e.g., shallow, braided, streams with sandy substrates) 
(Bestgen and Platania 1991; Dudley and Platania 1997; Remshardt et al. 
2001). Additionally, the presence of algal blooms will continue to 
affect water quality in this reach. For these reasons, we do not 
believe that this reach is essential to the conservation of the 
species. It is unknown whether this reach contains or has the potential 
to develop the primary constituent elements. Although portions of this 
river reach may contain fresh water (i.e., salinity less than 1 part 
per thousand), we suspect that much of this stream reach may never 
provide suitable habitat for the silvery minnow, and it is not proposed 
as critical habitat.

Land Ownership

    The proposed critical habitat for the silvery minnow encompasses 
stream reaches where the species has been collected in the recent past 
and where it is currently known to exist. Proposed critical habitat for 
the silvery minnow includes both the active river channel and the area 
of bankfull width plus 300 feet on either side of the banks, except in 
areas narrowed by existing levees.
    Ownership of the river channel and the lateral width along the bank 
is unclear in the middle Rio Grande proposed critical habitat unit. 
However, most of the land in the middle Rio Grande valley that abuts 
critical habitat is within the administrative boundaries of the Middle 
Rio Grande Conservancy District. The Middle Rio Grande Conservancy 
District is a political subdivision of the State of New Mexico which 
provides for irrigation, flood control, and drainage of the Middle Rio 
Grande valley in New Mexico, from Cochiti Dam downstream 150 mi (285 
km) to the northern boundary of the Bosque del Apache National Wildlife 
Refuge. Within these 150 miles are also the lands of the communities of 
Algodones, Bernalillo, Rio Rancho, Corrales, Albuquerque, Los Lunas, 
Belen, Socorro, and a number of smaller incorporated and unincorporated 
communities. Other landowners, sovereign entities, and managers 
include: The Pueblos of Cochiti, Santo Domingo, San Felipe, Santa Ana, 
Sandia, and Isleta; the BOR; the Service; the U.S. Bureau of Land 
Management (BLM); New Mexico State Parks Division; New Mexico 
Department of Game and Fish; New Mexico State Lands Department; and the 
Corps. Approximately 86 river km (45 mi) of our proposed critical 
habitat run through Pueblo lands including: Cochiti, Santo Domingo, San 
Felipe, Santa Ana, Sandia, and Isleta.

Effect of Critical Habitat Designation

Section 7  Consultation

    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that actions they fund, authorize, or carry out do 
not destroy or adversely modify critical habitat to the extent that the 
action appreciably diminishes the value of the critical habitat for the 
survival and recovery of the species. Individuals, organizations, 
States, Indian Pueblos and Tribes, local governments, and other non-
Federal entities are affected by the designation of critical habitat 
only if their actions occur on Federal lands, require a Federal permit, 
license, or other authorization, or involve Federal funding.
    Activities on Federal lands that may affect the silvery minnow or 
its proposed critical habitat will require section 7 consultation. 
Actions on private, State, or Indian Pueblo and Tribal lands receiving 
funding or requiring a permit from a Federal agency also will be 
subject to the section 7 consultation process if the action may affect 
proposed critical habitat. Federal actions not affecting the species or 
its proposed critical habitat, as well as actions on non-Federal lands 
that are not federally funded or permitted, will not require section 7 
consultation. Regulations implementing this interagency cooperation 
provision of the Act are codified at 50 CFR part 402.
    Section 7(a)(4) of the Act require Federal agencies to confer with 
us on any action that is likely to jeopardize the continued existence 
of a proposed species or to result in destruction or adverse 
modification of proposed critical habitat. Conference reports provide 
conservation recommendations to assist the agency in eliminating 
conflicts that may be caused by the proposed action. The conservation 
recommendations in a conference report are advisory.
    We may issue a formal conference report if requested by a Federal 
agency. Formal conference reports on proposed critical habitat contain 
a biological opinion that is prepared according to 50 CFR 402.14, as if 
critical habitat were designated. We may adopt the formal conference 
report as a biological opinion if the critical habitat is designated, 
if no significant new information or changes in the action alter the 
content of the opinion (see 50 CFR 402.10(d)).
    Regulations at 50 CFR 402.16 also require Federal agencies to 
reinitiate consultation in instances where we have already reviewed an 
action for its effects on a listed species if critical habitat is 
subsequently designated. Consequently, some Federal agencies may 
request reinitiation of consultation or conferencing with us on actions 
for which formal consultation has been completed, if those actions may 
affect designated critical habitat or adversely modify or destroy 
proposed critical habitat.
    When we issue a biological opinion concluding that a project is 
likely to

[[Page 39227]]

result in jeopardy or the destruction or adverse modification of 
critical habitat, we also provide reasonable and prudent alternatives 
to the project, if any are identifiable. Reasonable and prudent 
alternatives are defined at 50 CFR 402.02 as alternative actions 
identified during consultation that can be implemented in a manner 
consistent with the intended purpose of the action, that are consistent 
with the scope of the Federal agency's legal authority and 
jurisdiction, that are economically and technologically feasible, and 
that the Director of the Service believes would avoid the likelihood of 
jeopardizing the continued existence of listed species or result in the 
destruction or adverse modification of 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.
    Section 4(b)(8) of the Act requires us to describe in any proposed 
or final regulation that designates critical habitat a description and 
evaluation of those activities involving a Federal action that may 
adversely modify such habitat or that may be affected by such 
designation. When determining whether any of these activities may 
adversely modify critical habitat, we will analyze the effects of the 
action in relation to the designated critical habitat unit (Service and 
National Marine Fisheries Service 1998). Therefore, the analysis (i.e., 
the determination whether an action destroys or adversely modifies 
critical habitat) conducted through consultation or conferencing should 
evaluate whether that loss, when added to the environmental baseline, 
is likely to appreciably diminish the capability of the critical 
habitat unit to satisfy essential requirements of the species. In other 
words, activities that may destroy or adversely modify critical habitat 
include those that alter the primary constituent elements (defined 
above) to an extent that the value of the critical habitat unit for 
both the survival and recovery of the silvery minnow is appreciably 
reduced (50 CFR 402.02).
    A number of Federal agencies or departments fund, authorize, or 
carry out actions that may affect the silvery minnow and proposed 
critical habitat. We have reviewed and continue to review numerous 
activities proposed within the range of the silvery minnow that are 
currently the subject of formal or informal section 7 consultations. A 
wide range of Federal activities have the potential to destroy or 
adversely modify critical habitat of the silvery minnow. These 
activities may include land and water management actions of Federal 
agencies (e.g., Corps, BOR, Service, and the Bureau of Indian Affairs) 
and related or similar actions of other federally regulated projects 
(e.g., road and bridge construction activities by the Federal Highway 
Administration; dredge and fill projects, sand and gravel mining, and 
bank stabilization activities conducted or authorized by the Corps; 
construction, maintenance, and operation of diversion structures; 
management of the conveyance channel; and levee and dike construction 
and maintenance by the BOR; and, National Pollutant Discharge 
Elimination System permits authorized by the Environmental Protection 
Agency). These types of activities have already been examined under 
consultation with us upon listing the species as endangered and in our 
previous designation of critical habitat. We expect that the same types 
of activities will be reviewed in section 7 consultation if critical 
habitat is again designated. However, there is some potential for an 
increase in the number of proposed actions we review under section 7 of 
the Act from actions proposed in areas that are contained within the 
300-foot lateral width. We believe that we currently review most 
actions (e.g., indirect effects) that could affect silvery minnow 
through section 7 that occur in this lateral width, but acknowledge 
that an explicit boundary could result in a slight increase in 
consultations.
    Activities that we are likely to review under section 7 of the Act 
include, but are not limited to:
    1. Significantly and detrimentally altering the river flow or the 
natural flow regime of any of the proposed river reaches in the middle 
Rio Grande. Possible actions would include groundwater pumping, 
impoundment, and water diversion with a Federal nexus (i.e., activities 
that are authorized, funded, or carried out by a Federal agency). We 
note that such flow reductions that result from actions affecting 
tributaries of the designated stream reaches may also destroy or 
adversely modify critical habitat.
    2. Significantly and detrimentally altering the characteristics of 
the 300-foot lateral width (e.g., parts of the floodplain) in the 
middle Rio Grande critical habitat unit. Possible actions would include 
vegetation manipulation, timber harvest, road construction and 
maintenance, prescribed fire, livestock grazing, off-road vehicle use, 
powerline or pipeline construction and repair, mining, and urban and 
suburban development with a Federal nexus.
    3. Significantly and detrimentally altering the channel morphology 
(e.g., depth, velocity, etc.) of any of the stream reaches within the 
proposed designation. Possible actions would include channelization, 
impoundment, road and bridge construction, deprivation of substrate 
source, reduction of available floodplain, removal of gravel or 
floodplain terrace materials, reduction in stream flow, and excessive 
sedimentation from mining, livestock grazing, road construction, timber 
harvest, off-road vehicle use, and other watershed and floodplain 
disturbances with a Federal nexus.
    4. Significantly and detrimentally altering the water quality 
within the proposed designation. Possible actions with a Federal nexus 
would include release of chemical or biological pollutants into the 
surface water or connected groundwater at a point source or by 
dispersed release (non-point).
    5. Introducing, spreading, or augmenting non-native aquatic species 
within the proposed designation. Possible actions with a Federal nexus 
would include fish stocking for sport, aesthetics, biological control, 
or other purposes; use of live bait fish; aquaculture; construction and 
operation of canals; and interbasin water transfers.
    Not all of the identified activities are necessarily of current 
concern within the middle Rio Grande; however, they do indicate the 
potential types of activities that will require consultation in the 
future and, therefore, that may be affected by the proposed designation 
of critical habitat. We do not expect that the proposed designation of 
critical habitat will result in a significant regulatory burden above 
that already in place due to the presence of the listed species. 
However, areas included within the 300-foot lateral width of the 
proposed designation that are not currently occupied by the species may 
result in an additional regulatory burden when there is a Federal nexus 
(Federal funding, authorization, or permit).
    As discussed previously, Federal actions that are found likely to 
destroy or adversely modify critical habitat may often be modified, 
through development of reasonable and prudent alternatives, in ways 
that will remove the likelihood of destruction or adverse modification 
of critical habitat. Such project modifications may include such things 
as adjustment in timing of projects to avoid sensitive periods for the 
species and its habitat; replanting of riparian vegetation; 
minimization of work and vehicle use in the main river channel or the 
300-foot lateral width; restriction of

[[Page 39228]]

riparian and upland vegetation clearing in the 300-foot lateral width; 
fencing to exclude livestock and limit recreational use; use of 
alternative livestock management techniques; avoidance of pollution; 
minimization of ground disturbance in the 300-foot lateral width; use 
of alternative material sources; storage of equipment and staging of 
operations outside the 300-foot lateral width; use of sediment 
barriers; access restrictions; and use of best management practices to 
minimize erosion.
    The silvery minnow does not need a large quantity of water to 
survive but it does need a sufficient amount of flowing water to reduce 
prolonged periods of low or no flow and minimize the formation of 
isolated pools. The identification of primary constituent elements for 
the silvery minnow is not intended to create a high-velocity, deep 
flowing river, with a bank-to-bank flow. The silvery minnow does not 
require such habitat characteristics. Instead, the silvery minnow 
requires habitat with sufficient flows through the irrigation season to 
avoid prolonged periods of low or no flow; additionally, a spike in 
flow in the late spring or early summer to trigger spawning, and a 
relatively constant winter flow are also required.
    If you have questions regarding whether specific activities will 
likely constitute destruction or adverse modification of proposed 
critical habitat, contact the Field Supervisor, New Mexico Ecological 
Services Field Office (see ADDRESSES section). If you would like copies 
of the regulations on listed wildlife or have questions about 
prohibitions and permits, contact the U.S. Fish and Wildlife Service, 
Division of Endangered Species, P.O. Box 1306, Albuquerque, New Mexico 
87103 (telephone 505-248-6920; facsimile 505-248-6788).

Economic Analysis

    Section 4(b)(2) of the Act requires that we designate critical 
habitat on the basis of the best scientific and commercial information 
available and consider the economic and other relevant impacts of 
designating a particular area as critical habitat. We based this 
proposed rule on the best available scientific information, including 
the recommendations in the Recovery Plan (Service 1999). We will 
further utilize the draft and final economic analyses and our analysis 
of other relevant impacts, and consider all comments and information 
submitted during the public hearing and comment period, to make a final 
critical habitat designation. We may exclude areas from the final 
designation upon a final determination that the benefits of such 
exclusions outweigh the benefits of specifying such areas as critical 
habitat. In accordance with section 4(b)(2) of the Act we cannot 
exclude areas from critical habitat when their exclusion will result in 
the extinction of the species. We have prepared a draft economic 
analysis that is available for public review and comment during the 
comment period for this proposed rule. Send your requests for copies of 
the draft economic analysis to the New Mexico Ecological Services Field 
Office (see ADDRESSES section).

American Indian Tribal Rights, Federal-Tribal Trust Responsibilities, 
and the Endangered Species Act

    In accordance with the Presidential Memorandum of April 29, 1994, 
we believe that, to the maximum extent possible, Indian Pueblos and 
Tribes should be the governmental entities to manage their lands and 
tribal trust resources. To this end, we support tribal measures that 
preclude the need for Federal conservation regulations. We provide 
technical assistance to Indian Pueblos and Tribes who ask for 
assistance in developing and expanding tribal programs for the 
management of healthy ecosystems so that Federal conservation 
regulations, such as designation of critical habitat, on tribal lands 
are unnecessary.
    The Presidential Memorandum of April 29, 1994, also requires us to 
consult with the Indian Pueblos and Tribes on matters that affect them, 
and section 4(b)(2) of the Act requires us to gather information 
regarding the designation of critical habitat and the effects thereof 
from all relevant sources, including Indian Pueblos and Tribes. 
Recognizing a government-to-government relationship with Indian Pueblos 
and Tribes and our Federal trust responsibility, we have and will 
continue to consult with the Indian Pueblos and Tribes that might be 
affected by the designation of critical habitat.
    We will make every effort to consult with the affected Indian 
Pueblos and Tribes during the comment period for this proposed rule to 
gain information on: (1) possible effects if critical habitat were 
designated on Tribal lands; and (2) possible effects on tribal 
resources resulting from the proposed designation of critical habitat 
on non-tribal lands. We will meet with each potentially affected Pueblo 
or Tribe to ensure that government-to-government consultation on 
proposed critical habitat issues occurs in a timely manner.

Designation of Critical Habitat on Tribal Lands

    Section 3(5) of the Act defines critical habitat, in part, as areas 
within the geographical area occupied by the species ``on which are 
found those physical and biological features (I) essential to the 
conservation of the species and (II) which may require special 
management considerations and protection.'' We included lands of the 
Indian Pueblos of Cochiti, Santo Domingo, San Felipe, Santa Ana, 
Sandia, and Isleta in this proposed designation of critical habitat for 
the silvery minnow.
    As provided under section 4(b)(2) of the Act, we are soliciting 
information on the possible economic and other impacts of critical 
habitat designation, and we will continue to work with the Indian 
Pueblos and Tribes in developing voluntary measures adequate to 
conserve silvery minnow on tribal lands. If any of these Indian Pueblos 
and Tribes submit management plans, we will consider whether these 
plans provide adequate special management or protection for the 
species, and we will further weigh the benefits of including these 
areas versus the benefits of excluding these areas under section 
4(b)(2) of the Act. We will use this information in determining which, 
if any, tribal lands should be excluded in the final designation of 
critical habitat for the silvery minnow.

Effects on Tribal Trust Resources From Critical Habitat Designation on 
Non-Tribal Lands

    We do not anticipate that the proposal of critical habitat on non-
tribal lands will result in any impact on tribal trust resources or the 
exercise of tribal rights. However, in complying with our tribal trust 
responsibilities, we must communicate with all Indian Pueblos and 
Tribes potentially affected by the designation. Therefore, we are 
soliciting information from the Indian Pueblos and Tribes and will 
arrange meetings with them during the comment period on potential 
effects to them or their resources that may result from critical 
habitat designation. We sent preproposal letters to all affected Indian 
Pueblos including Cochiti, Santo Domingo, San Felipe, Santa Ana, 
Sandia, Isleta, and San Juan, and solicited additional information from 
them regarding biological, cultural, social, or economic data that were 
pertinent to the EIS process. We will continue to provide assistance to 
and cooperate with Indian Pueblos and Tribes that potentially could be 
affected

[[Page 39229]]

by this proposed critical habitat designation at their request.

Public Comments Solicited

    We intend to make any final action resulting from this proposed 
rule to be as accurate and as effective as possible. Therefore, we are 
soliciting comments or suggestions from the public, other concerned 
governmental agencies, the scientific community, industry, or any other 
interested party concerning this proposed rule. We particularly seek 
comments concerning:
    1. The reasons why any habitat should or should not be determined 
to be critical habitat as provided by section 4 of the Act, including 
whether the benefits of excluding areas will outweigh the benefits of 
including areas as critical habitat. Specifically we ask if there is 
adequate special management and protection in place on any lands 
included in this proposed rule to allow us not to designate these lands 
as critical habitat. We also seek information concerning New Mexico or 
Texas State water rights issues (e.g., Rio Grande Compact delivery 
obligations) and how designation of critical habitat might affect these 
uses. We also request assistance in describing the existing conditions 
for the river reach below San Acacia Diversion Dam on the middle Rio 
Grande. For these and other areas that have the potential for low or no 
flow events, we are soliciting comments or information relating to the 
proposed designation of critical habitat that includes areas that may 
experience these conditions. In addition, we are seeking comments on 
the primary constituent elements and how they relate to the existing 
conditions (i.e., flow regime) in the middle Rio Grande.
    2. We ask whether areas or river reaches suggested in the Recovery 
Plan for potential reestablishment of the silvery minnow, which are not 
included in this proposed rule, should be designated as critical 
habitat. We are further soliciting information or comments concerning 
our conservation strategy for the silvery minnow. We believe that, in 
particular, the development of one or more experimental populations 
provides a conservation benefit for the silvery minnow that outweighs 
the conservation benefit of designating areas as critical habitat. 
Depending on public comments, information, or data received, we will 
evaluate whether the areas we have determined are essential for the 
conservation of the silvery minnow (i.e., the river reach of the middle 
Pecos and lower Rio Grande in Big Bend National Park and downstream to 
the Terrell/Val Verde County line) should be designated as critical 
habitat, and critical habitat could be revised as appropriate.
    3. Specific information on the amount and distribution of silvery 
minnow habitat, and what habitat is essential to the conservation of 
the species and why;
    4. Land use practices and current or planned activities in the 
subject areas, including comments or information relating to the 300-
foot lateral width, and their possible impacts on proposed critical 
habitat;
    5. Any foreseeable economic or other impacts resulting from the 
proposed designation of critical habitat including, in particular, any 
impacts on small entities or families; and
    6. Economic and other values associated with designating critical 
habitat for the silvery minnow, such as those derived from 
nonconsumptive uses (e.g., hiking, camping, birding, enhanced watershed 
protection, increased soil retention, ``existence values,'' and 
reductions in administrative costs).
    We are also seeking additional information about the silvery 
minnow's status and would like information on any of the following:
    1. The location of silvery minnow populations;
    2. Any additional information about the silvery minnow's range, 
distribution, and population sizes; and
    3. Any current or planned activities (i.e., threats or recovery 
actions) in or near areas occupied by the silvery minnow.

Clarity of the Rule

    Executive Order 12866 requires each agency to write regulations and 
notices that are easy to understand. We invite your comments on how to 
make this proposed rule easier to understand including answers to 
questions such as the following: (1) Are the requirements in the 
document clearly stated? (2) Does the proposed rule contain technical 
language or jargon that interferes with the clarity? (3) Does the 
format of the proposed rule (grouping and order of sections, use of 
headings, paragraphing, etc.) aid or reduce its clarity? (4) Is the 
description of the proposed rule in the ``Supplementary Information'' 
section of the preamble helpful in understanding the document? (5) What 
else could we do to make the proposed rule easier to understand? Send a 
copy of any written comments about how we could make this rule easier 
to understand to: Office of Regulatory Affairs, Department of the 
Interior, Room 7229, 1849 C Street NW., Washington, DC 20240.
    Our practice is to make comments that we receive on this 
rulemaking, including names and home addresses of respondents, 
available for public review during regular business hours. Individual 
respondents may request that we withhold their home address from the 
rulemaking record, which we will honor to the extent allowable by 
Federal law. In some circumstances, we would withhold from the 
rulemaking record a respondent's identity, as allowable by Federal law. 
If you wish for us to withhold your name and/or address, you must state 
this prominently at the beginning of your comment. However, we will not 
consider anonymous comments. We will make all submissions from 
organizations or businesses, including individuals identifying 
themselves as representatives or officials of organizations or 
businesses, available for public inspection in their entirety.

Peer Review

    In accordance with our policy published on July 1, 1994 (59 FR 
34270), we will seek the expert opinions of at least three appropriate 
and independent specialists regarding this proposed rule. The purpose 
of such review is to ensure listing decisions are based on 
scientifically sound data, assumptions, and analyses. We will send 
copies of this proposed rule immediately following publication in the 
Federal Register to these peer reviewers. We will invite these peer 
reviewers to comment, during the public comment period, on the specific 
assumptions and conclusions regarding the proposed designation of 
critical habitat.
    We will consider all comments and information received during the 
comment period on this proposed rule during preparation of a final 
rulemaking. Accordingly, the final decision may differ from this 
proposed rule. It is important to note that we have not proposed 
critical habitat designation for two areas that we have determined are 
essential for the conservation of the silvery minnow (i.e., the river 
reach of the middle Pecos and lower Rio Grande in Big Bend National 
Park and downstream to the Terrell/Val Verde County line). We believe 
that our conservation strategy of developing one or more experimental 
populations outweighs the benefits that would be provided to the 
silvery minnow by including these areas within a designation of 
critical habitat. However, depending on public comments, information, 
or data received, we will evaluate whether these areas within the 
silvery minnow's historical range should be designated as critical 
habitat,

[[Page 39230]]

and critical habitat could be revised as appropriate.

Public Hearings

    The Act provides for one or more public hearings on this proposed 
rule, if requested. Given the high likelihood of multiple requests we 
have scheduled two public hearings. We will hold public hearings in 
Socorro, New Mexico, on June 25, 2002; and in Albuquerque, NM, on June 
26, 2002 (see ADDRESSES section for times and locations). Announcements 
for the public hearings will be made in local newspapers.
    Written comments submitted during the comment period receive equal 
consideration with those comments presented at a public hearing.

Required Determinations

Regulatory Planning and Review

    In accordance with Executive Order 12866, this document is a 
significant rule and has been reviewed by the Office of Management and 
Budget (OMB), under Executive Order 12866.
    1. We have prepared a draft economic analysis to assist us in 
considering whether areas should be excluded pursuant to section 
4(b)(2) of the Act. The draft analysis indicates that this rule will 
not have an annual economic effect of $100 million or more or adversely 
affect an economic sector, productivity, jobs, the environment, or 
other units of government. Under the Act, critical habitat may not be 
destroyed or adversely modified by a Federal agency action; the Act 
does not impose any restrictions related to critical habitat on non-
Federal persons unless they are conducting activities funded or 
otherwise sponsored or permitted by a Federal agency.
    2. As discussed above, Federal agencies would be required to ensure 
that their actions do not destroy or adversely modify designated 
critical habitat of the silvery minnow. Because of the potential for 
impacts on other Federal agencies activities, we will review this 
proposed action for any inconsistencies with other Federal agency 
actions.
    3. We believe that this rule, if finalized, will not materially 
affect entitlements, grants, user fees, loan programs, or the rights 
and obligations of their recipients, except those involving Federal 
agencies which would be required to ensure that their activities do not 
destroy or adversely modify designated critical habitat. As discussed 
above, we do not anticipate that the adverse modification prohibition 
(from critical habitat designation) will have any significant economic 
effects such that it will have an annual economic effect of $100 
million or more.
    4. OMB has determined that the critical habitat portion of this 
rule will raise novel legal or policy issues and, as a result, this 
rule has undergone OMB review. The proposed rule follows the 
requirements for proposing critical habitat contained in the Act.

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

    Under the Regulatory Flexibility Act (as amended by the Small 
Business Regulatory Enforcement Fairness Act (SBREFA) of 1996; 5 U.S.C. 
804(2)), whenever a Federal 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 effect of the rule on small entities (i.e., small 
businesses, small organizations, and small government jurisdictions). 
However, no regulatory flexibility analysis is required if the head of 
an agency certifies that the rule will not have a significant economic 
impact on a substantial number of small entities. SBREFA amended the 
Regulatory Flexibility Act to require Federal agencies to provide a 
statement of the factual basis for certifying that a rule will not have 
a significant economic impact on a substantial number of small 
entities. We are certifying that the rule will not have a significant 
effect on a substantial number of small entities. The following 
discussion explains our rationale.
    The economic analysis determined whether this proposed critical 
habitat designation potentially affects a ``substantial number'' of 
small entities in counties supporting proposed critical habitat areas. 
It also quantifies the probable number of small businesses that 
experience a ``significant effect.'' While SBREFA does not explicitly 
define either ``substantial number'' or ``significant effect,'' the 
Small Business Administration (SBA) and other Federal agencies have 
interpreted these terms to represent an impact on 20 percent or more of 
the small entities in any industry and an effect equal to three percent 
or more of a business' annual sales.
    Based on the past consultation history for the silvery minnow, 
wastewater discharges from municipal treatment plants are the primary 
activities anticipated to be affected by the designation of critical 
habitat that could affect small businesses. To be conservative, (i.e., 
more likely to overstate impacts than understate them), the economic 
analysis assumes that a unique company will undertake each of the 
projected consultations in a given year, and so the number of 
businesses affected is equal to the total annual number of 
consultations (both formal and informal).
    First, the number of small businesses affected is estimated. As 
shown in Exhibit 1 below, the following calculations yield this 
estimate:
     Estimate the number of businesses within the study area 
affected by section 7 implementation annually (assumed to be equal to 
the number of annual consultations);
     Calculate the percent of businesses in the affected 
industry that are likely to be small;
     Calculate the number of affected small businesses in the 
affected industry;
     Calculate the percent of small businesses likely to be 
affected by critical habitat.

   Exhibit 1.--Estimated Annual Number of Small Businesses Affected by
         Critical Habitat Designation: The ``Substantial'' Test
------------------------------------------------------------------------
                                                   Sanitary services SIC
                  Industry name                             4959
------------------------------------------------------------------------
Annual number of affected businesses in industry:
    By formal consultation.......................  0.13
(Equal to number of annual consultations): 1
    By informal consultation.....................  0.75
Total number of all businesses in industry within  6
 study area.
Number of small businesses in industry within      6
 study area.
Percent of businesses that are small (Number of    100%
 small businesses)/(Total Number of businesses).

[[Page 39231]]

 
Annual number of small businesses affected         0.88
 (Number affected businesses) * (Percent of small
 businesses).
Annual percentage of small businesses affected     15%
 (Number of small businesses affected)/(Total
 number of small businesses); 20
 percent is substantial.
------------------------------------------------------------------------
1 Note that because these values represent the probability that small
  businesses will be affected during a one-year time period,
  calculations may result in fractions of businesses. This is an
  acceptable result, as these values represent the probability that
  small businesses will be affected.

    This calculation reflects conservative assumptions and nonetheless 
yields an estimate that is still far less than the 20 percent threshold 
that would be considered ``substantial.'' As a result, this analysis 
concludes that a significant economic impact on a substantial number of 
small entities will not result from the designation of critical habitat 
for the silvery minnow. Nevertheless, an estimate of the number of 
small businesses that will experience effects at a significant level is 
provided below.
    Costs of critical habitat designation to small businesses consist 
primarily of the cost of participating in section 7 consultations and 
the cost of project modifications. To calculate the likelihood that a 
small business will experience a significant effect from critical 
habitat designation for the silvery minnow, the following calculations 
were made:
     Calculate the per-business cost. This consists of the unit 
cost to a third party of participating in a section 7 consultation 
(formal or informal) and the unit cost of associated project 
modifications. To be conservative, the economic analysis uses the high-
end estimate for each cost.
     Determine the amount of annual sales that a company would 
need to have for this per-business cost to constitute a ``significant 
effect.'' This is calculated by dividing the per-business cost by the 
three percent ``significance'' threshold value.
     Estimate the likelihood that small businesses in the study 
area will have annual sales equal to or less than the threshold amount 
calculated above. This is estimated using national statistics on the 
distribution of sales within industries.
     Based on the probability that a single business may 
experience significant effects, calculate the expected value of the 
number of businesses likely to experience a significant effect.
     Calculate the percent of businesses in the study area 
within the affected industry that are likely to be affected 
significantly.
    Calculations for costs associated with designating critical habitat 
for the silvery minnow are provided in Exhibit 2 below.

      Exhibit 2.--Estimated Annual Effects on Small Businesses: The
                       ``Significant Effect'' Test
------------------------------------------------------------------------
                                        Sanitary services SIC 4959
                                ----------------------------------------
                                        Formal
            Industry              consultations with       Informal
                                       project           consultations
                                    modifications
------------------------------------------------------------------------
Annual Number of Small           0.13...............  0.75
 Businesses Affected (From
 Exhibit 8-1).
Per-Business Cost..............  $34,100............  $2,900
Level of Annual Sales Below      $1,136,667.........  $96,667
 Which Effects Would Be
 Significant (Per-Business Cost/
 3%).
Probability That Per-Business    48%................  3%
 Cost Is Greater Than 3% of
 Sales for Small Business \1\.
Probable Annual Number of Small  0.06...............  0.02
 Businesses Experiencing
 Significant Effects (Number
 Small Businesses)*
 (Probability of Significant
 Effect).
Total Annual Number of Small                       0.08
 Businesses Bearing Significant
 Costs in Industry.
Total Annual Percentage of                        1.4%
 Small Businesses Bearing
 Significant Costs in Industry.
------------------------------------------------------------------------
\1\ This probability is calculated based on national industry statistics
  obtained from the Robert Morris Associated Annual Statement of
  Studies: 2001-2002, which provides data on the distribution of annual
  sales in an industry within the following ranges: $0-1 million, $1-3
  million, $3-5 million, $5-10, $10-25 million, and $25+ million. This
  analysis uses the ranges that fall within the SBA definition of small
  businesses (i.e., for industries in which small businesses have sales
  of less than $5.0 million, it uses $0-1 million, $1-3 million, and $3-
  5 million) to estimate a distribution of sales for small businesses.
  It then calculates the probability that small businesses have sales
  below the threshold value using the following components: (1) All
  small businesses (expressed as a percentage of all small businesses)
  in ranges whose upper limits fall below the threshold value experience
  the costs as significant; (2) for the range in which the threshold
  value falls, the percentage of companies in the bin that fall below
  the threshold value is calculated as [(threshold value-range minimum)/
  (bin maximum-range minimum)] x percent of small businesses captured in
  range. This percentage is added to the percentage of small businesses
  captured in each of the lower ranges to reach the total probability
  that small businesses have sales below the threshold value. Note that
  in instances in which the threshold value exceeds the definition of
  small businesses (i.e., the threshold value is $10 million and the
  definition of small businesses is sales less than $5.0 million), all
  small businesses experience the effects as significant.

    Because the costs associated with designating critical habitat for 
the silvery minnow are likely to be significant for less than one small 
businesses per year (approximately one percent of the small businesses 
in the sanitary services industry) in the affected counties, the 
economic analysis concludes that a significant economic impact on a 
substantial number of small entities will not result from the 
designation of critical habitat for the silvery minnow. This would be 
true even if all of the effects of section 7 consultation on these 
activities were attributed solely to the critical habitat designation.

[[Page 39232]]

Executive Order 13211

    On May 18, 2001, the President issued an Executive Order (E.O. 
13211) on regulations that significantly affect energy supply, 
distribution, and use. Executive Order 13211 requires agencies to 
prepare Statements of Energy Effects when undertaking certain actions. 
We have a very good consultation history for silvery minnow; thus, we 
can describe the kinds of actions that have undergone consultations. 
Within the middle Rio Grande proposed critical habitat unit, the BLM 
has the highest likelihood of any Federal agency to undergo section 7 
consultation for actions relating to energy supply, distribution, or 
use. However, since 1994, the BLM has not conducted any consultations 
for resource management plans that related to energy supply, 
distribution, or use. We do not anticipate the development of oil and 
gas leases within the area we are proposing to designate as critical 
habitat (J. Smith, pers. comm. 2001). Nevertheless, if we were to 
consult on a proposed BLM energy-related action, the outcome of that 
consultation likely would not differ from the BLM's policy of not 
allowing oil and gas development within the 100-year floodplain. For 
these reasons, we do not anticipate, this rule will be a significant 
regulatory action under Executive Order 12866, and it is not expected 
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.

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.):
    1. This rule will not ``significantly or uniquely'' affect small 
governments. A Small Government Agency Plan is not required. Small 
governments will be affected only to the extent that any of their 
actions involving Federal funding or authorization must not destroy or 
adversely modify the critical habitat or take the species under section 
9.
    2. This rule will not produce a Federal mandate of $100 million or 
greater in any year (i.e., it is not a ``significant regulatory 
action'' under the Unfunded Mandates Reform Act).

Takings

    In accordance with Executive Order 12630 (``Government Actions and 
Interference with Constitutionally Protected Private Property 
Rights''), we have analyzed the potential takings implications of the 
proposed listing and designation of critical habitat for the silvery 
minnow. The takings implications assessment concludes that this 
proposed rule does not pose significant takings implications. A copy of 
this assessment is available by contacting the New Mexico Ecological 
Services Field Office (see ADDRESSES section).
    Based on the above assessment, the Service finds that this proposed 
rule designating critical habitat for the silvery minnow does not pose 
significant takings implications.

Federalism

    In accordance with Executive Order 13132, we have considered 
whether this rule has significant Federalism effects and have 
determined that a Federalism assessment is not required. In keeping 
with Department of the Interior policy, we requested information from 
and coordinated development of this proposed rule with appropriate 
resource agencies in New Mexico and Texas (i.e., during the EIS scoping 
period). We will continue to coordinate any future designation of 
critical habitat for the silvery minnow with the appropriate agencies.
    We do not anticipate that this regulation will intrude on State 
policy or administration, change the role of the Federal or State 
government, or affect fiscal capacity. For example, we have conducted 
one formal consultation with the Corps and BOR, and a non-Federal 
agency (e.g., Middle Rio Grande Conservancy District) over actions 
related to water operations on the middle Rio Grande (Service 2001b). 
Although this consultation was conducted after critical habitat 
designation for the silvery minnow was removed pursuant to court order, 
we do not believe that this designation of critical habitat will have 
significant Federalism effects. For example, in the recent formal 
section 7 consultation, the Middle Rio Grande Conservancy District's 
regulatory burden requirement was only affected to the extent that they 
were acting as the United States' agent over the operation and 
maintenance of facilities. If this critical habitat designation is 
finalized, Federal agencies also must ensure, through section 7 
consultation with us, that their activities do not destroy or adversely 
modify designated critical habitat. Nevertheless, we do not anticipate 
that the amount of supplemental instream flow, provided by past 
consultations (e.g., Service 2001b), will increase because an area is 
designated as critical habitat. This rule also will not change the 
appropriation of water rights within the area proposed to be designated 
as critical habitat. For these reasons, we do not anticipate that the 
designation of critical habitat will change State policy or 
administration, change the role of the Federal or State government, or 
affect fiscal capacity.
    Within the 300-foot lateral width, designation of critical habitat 
could trigger additional review of Federal activities under section 7 
of the Act, and may result in additional requirements on Federal 
activities to avoid destroying or adversely modifying critical habitat. 
Any action that lacked Federal involvement would not be affected by the 
critical habitat designation. Should a Federally funded, permitted, or 
implemented project be proposed that may affect designated critical 
habitat, we will work with the Federal action agency and any applicant, 
through section 7 consultation, to identify ways to implement the 
proposed project while minimizing or avoiding any adverse effect to the 
species or critical habitat. In our experience, the vast majority of 
such projects can be successfully implemented with at most minor 
changes that avoid significant economic impacts to project proponents.
    The designation may have some benefit to these governments in that 
the areas essential to the conservation of the species would be clearly 
defined, and the primary constituent elements of the habitat necessary 
to the survival of the species would be identified. While this 
definition and identification does not alter where and what Federally 
sponsored activities may occur, it may assist these local governments 
in long-range planning (rather than waiting for case-by-case section 7 
consultations to occur).

Civil Justice Reform

    In accordance with Executive Order 12988, the Office of the 
Solicitor has determined that this rule would not unduly burden the 
judicial system and would meet the requirements of sections 3(a) and 
3(b)(2) of the Order. We propose to designate critical habitat in 
accordance with the provisions of the Act. The rule uses standard 
property descriptions and identifies the primary constituent elements 
within the designated areas to assist the public in understanding the 
habitat needs of the silvery minnow.

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 the Office of Management and Budget (OMB) under 44 
U.S.C. 3501 et seq. This rule will not impose new

[[Page 39233]]

record-keeping 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 they display a currently valid OMB control number.

National Environmental Policy Act

    It is our position that, outside the Tenth Circuit, we do not need 
to prepare environmental analyses as defined by the NEPA in connection 
with designating critical habitat under the Endangered Species Act of 
1973, as amended. We published a notice outlining our reasons for this 
determination in the Federal Register on October 25, 1983 (48 FR 
49244). This assertion was upheld in the Ninth Circuit Douglas County 
v. Babbitt, 48 F.3d 1495 (9th Cir. 1995), cert. denied, 116 S. Ct. 698 
(1996). However, when the range of the species includes States within 
the Tenth Circuit, such as that of the silvery minnow, pursuant to 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. 
Additionally, on November 21, 2000, the United States District Court 
for the District of New Mexico, in Middle Rio Grande Conservancy 
District v. Babbitt, Civ. Nos. 99-870, 99-872 and 99-1445M/RLP 
(Consolidated) set aside the July 9, 1999, critical habitat designation 
and ordered us to issue within 120 days both an EIS and a new proposed 
rule designating critical habitat for the silvery minnow. We have 
prepared the draft EIS pursuant to that court order.

Government-to-Government Relationship With Indian Pueblos and Tribes

    In accordance with the Secretarial Order 3206, ``American Indian 
Tribal Rights, Federal-Tribal Trust Responsibilities, and the 
Endangered Species Act'' (June 5, 1997), the President's memorandum of 
April 29, 1994, ``Government-to-Government Relations with Native 
American Tribal Governments'' (59 FR 22951), Executive Order 13175, and 
the Department of the Interior's requirement at 512 DM 2, we understand 
that recognized Federal Indian Pueblos and Tribes must be related to on 
a Government-to-Government basis. Therefore, we are soliciting 
information from the Indian Pueblos and Tribes and will arrange 
meetings with them during the comment period on potential effects to 
them or their resources that may result from critical habitat 
designation.

References Cited

    A complete list of all references cited in this proposed rule is 
available upon request from the New Mexico Ecological Services Field 
Office (see ADDRESSES section).

Authors

    The primary authors of this notice are the New Mexico Field Office 
staff (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
record-keeping 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. Amend Sec. 17.95(e) by revising critical habitat for the Rio 
Grande silvery minnow (Hybognathus amarus), to read as follows.


Sec. 17.95  Critical habitat--fish and wildlife.

* * * * *
    (e) Fishes. * * *

Rio Grande Silvery Minnow (Hybognathus amarus)

    (1) Proposed critical habitat is depicted for Socorro, Valencia, 
Bernalillo, and Sandoval, Counties, New Mexico; on the map and as 
described below.
    (2) For each river reach proposed, the up- and downstream 
boundaries are described below. Proposed critical habitat includes 
the stream channels within the identified river reaches and areas 
within these reaches included within the existing levees, or if no 
levees are present, then within a lateral distance of 91.4 m (300 
ft) on each side of the river width at bankfull discharge. Bankfull 
discharge is the flow at which water begins to leave the channel and 
move into the floodplain.
    (3) Within these areas the primary constituent elements include, 
but are not limited to, those habitat components that are essential 
for the primary biological needs of foraging, sheltering, and 
reproduction. These elements include the following:
    (i) A hydrologic regime that provides sufficient flowing water 
with low to moderate currents capable of forming and maintaining a 
diversity of aquatic habitats, such as, but not limited to: 
backwaters (a body of water connected to the main channel, but with 
no appreciable flow), shallow side channels, pools (that portion of 
the river that is deep with relatively little velocity compared to 
the rest of the channel), eddies (a pool with water moving opposite 
to that in the river channel), and runs (flowing water in the river 
channel without obstructions) of varying depth and velocity 
necessary for each of the particular silvery minnow life-history 
stages in appropriate seasons (e.g., the silvery minnow requires 
habitat with sufficient flows from early spring (March) to early 
summer (June) to trigger spawning, flows in the summer (June) and 
fall (October) that do not increase prolonged periods of low or no 
flow, and a relatively constant winter flow (November to February));
    (ii) The presence of eddies created by debris piles, pools, or 
backwaters, or other refuge habitat (e.g., connected oxbows or 
braided channels) within unimpounded stretches of flowing water of 
sufficient length (i.e., river miles) that provide a variation of 
habitats with a wide range of depth and velocities;
    (iii) Substrates of predominantly sand or silt; and
    (iv) Water of sufficient quality to maintain natural, daily, and 
seasonally variable water temperatures in the approximate range of 
greater than 1  deg.C (35  deg.F) and less than 30  deg.C (85 
deg.F) and reduce degraded conditions (decreased dissolved oxygen, 
increased p.H., etc.).
    (4) Proposed critical habitat is depicted on the following map 
for the Middle Rio Grande, which includes the area from Cochiti 
Reservoir downstream to the Elephant Butte Dam, Sandoval, 
Bernalillo, Valencia, and Socorro Counties, New Mexico. The stream 
reaches in the middle Rio Grande include:
    (i) Jemez Canyon Reach--8 km ( 5 mile) of river immediately 
downstream of Jemez Canyon Reservoir to the confluence of the Rio 
Grande;
    (ii) Cochiti Diversion Dam to Angostura Diversion Dam (Cochiti 
Reach)--34 km (21 mile) of river immediately downstream of Cochiti 
Reservoir to the Angostura Diversion Dam;
    (iii) Angostura Diversion Dam to Isleta Diversion Dam (Angostura 
Reach)--61 km (38 mile) of river immediately downstream of the 
Angostura Diversion Dam to the Isleta Diversion Dam;
    (iv) Isleta Diversion Dam to San Acacia Diversion Dam (Isleta 
Reach)--90 km (56 mi) of river immediately downstream of the Isleta 
Diversion Dam to the San Acacia Diversion Dam; and
    (v) San Acacia Diversion Dam to the Elephant Butte Dam (San 
Acacia Reach)-147 km (92 mi) of river immediately downstream of the 
San Acacia Diversion Dam to the Elephant Butte Dam.
    (vi) Map Follows:

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    (5) This designation does not include the ephemeral or perennial 
irrigation canals and ditches outside of natural stream channels, 
including the low flow conveyance channel that is adjacent to a 
portion of the stream reach within the middle Rio Grande (i.e., 
downstream of the southern boundary of Bosque del Apache National 
Wildlife Refuge to the Elephant Butte Dam).
    (6) The area inundated by Elephant Butte Reservoir does not 
provide those physical or biological features essential to the 
conservation of the species and is specifically excluded by 
definition from the proposed critical habitat. We define the 
reservoir as that part of the body of water impounded by the dam 
where the storage waters are lentic (relatively still waters) and 
not part of the lotic (flowing water) river channel.
    (7) Lands located within the exterior boundaries of the proposed 
critical habitat designation (i.e., within the existing levees, or 
if no levees are present, then within a lateral distance of 91.4 m 
(300 ft) on each side of the stream width at bankfull discharge), 
but that are not considered critical habitat and are therefore 
excluded by definition, include existing paved roads; bridges; 
parking lots; dikes; levees; diversion structures; railroad tracks; 
railroad trestles; active gravel pits; cultivated agricultural land; 
and residential, commercial, and industrial developments.
* * * * *


    Dated: May 23, 2002
Craig Manson,
Assistant Secretary for Fish and Wildlife and Parks.
[FR Doc. 02-14141 Filed 6-5-02; 8:45 am]
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