[Federal Register Volume 86, Number 170 (Tuesday, September 7, 2021)]
[Proposed Rules]
[Pages 49989-50011]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-19091]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2021-0092; FF09E21000 FXES11110900000 212]
RIN 1018-BF43


Endangered and Threatened Wildlife and Plants; Threatened Species 
Status With Section 4(d) Rule for Pyramid Pigtoe

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our 
12-month finding on a petition to list the pyramid pigtoe (Pleurobema 
rubrum), a freshwater mussel species from Alabama, Arkansas, Kentucky, 
Louisiana, Mississippi, Ohio, Oklahoma, Tennessee, and Virginia, as an 
endangered or threatened species under the Endangered Species Act of 
1973, as amended (Act). After a review of the best available scientific 
and commercial information, we find that listing the species is 
warranted. Accordingly, we propose to list the pyramid pigtoe as a 
threatened species with a rule issued under section 4(d) of the Act 
(``4(d) rule''). If we finalize this rule as proposed, it would add 
this species to the List of Endangered and Threatened Wildlife and 
extend the Act's protections to the species.

DATES: We will accept comments received or postmarked on or before 
November 8, 2021. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for a 
public hearing, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by October 22, 2021.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter the docket number or RIN 
for this rulemaking (presented above in the document headings). For 
best results, do not copy and paste either number; instead, type the 
docket number or RIN into the Search box using hyphens. Then, click on 
the Search button. On the resulting page, in the panel on the left side 
of the screen, under the Document Type heading, check the Proposed Rule 
box to locate this document. You may

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submit a comment by clicking on ``Comment.''
    (2) By hard copy: Submit by U.S. mail to: Public Comments 
Processing, Attn: FWS-R4-ES-2021-0092, U.S. Fish and Wildlife Service, 
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on http://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Information Requested, below, for more information).

FOR FURTHER INFORMATION CONTACT: Janet Mizzi, Field Supervisor, U.S. 
Fish and Wildlife Service, Asheville Ecological Services Field Office, 
160 Zillicoa St, Asheville, NC 28801; telephone 828-258-3939. Persons 
who use a telecommunications device for the deaf (TDD) may call the 
Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act of 
1973, as amended (Act; 16 U.S.C. 1531 et seq.), if we determine that a 
species is an endangered or threatened species throughout all or a 
significant portion of its range, we are required to promptly publish a 
proposal in the Federal Register and make a determination on our 
proposal within 1 year, unless, due to substantial disagreement 
regarding the sufficiency or accuracy of the available data, we extend 
the 1-year period for no more than 6 months to solicit additional data. 
To the maximum extent prudent and determinable, we must designate 
critical habitat for any species that we determine to be an endangered 
or threatened species under the Act. Listing a species as an endangered 
or threatened species can only be completed by issuing a rule.
    What this document does. We propose to list the pyramid pigtoe as a 
threatened species with a rule under section 4(d) of the Act. If made 
final, this action would add the species to the List of Endangered and 
Threatened Wildlife in title 50 of the Code of Federal Regulations 
(CFR) at 50 CFR 17.11(h) and add specific provisions pertaining to the 
pyramid pigtoe to 50 CFR 17.45.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species because of any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that threats to the pyramid 
pigtoe include habitat degradation or loss from a variety of sources 
(e.g., dams and other barriers, resource extraction); degraded water 
quality from chemical contamination and erosion from development, 
agriculture, and mining operations; direct mortality from dredging; 
residual impacts (reduced population size) from historical harvest; and 
the proliferation of invasive, nonnative species. These threats also 
compound the negative effects associated with the species' small 
population size.
    Section 4(a)(3) of the Act requires the Secretary of the Interior 
(Secretary) to designate critical habitat concurrent with listing to 
the maximum extent prudent and determinable. Section 3(5)(A) of the Act 
defines critical habitat as (i) the specific areas within the 
geographical area occupied by the species, at the time it is listed, on 
which are found those physical or biological features (I) essential to 
the conservation of the species and (II) which may require special 
management considerations or protections; and (ii) specific areas 
outside the geographical area occupied by the species at the time it is 
listed, upon a determination by the Secretary that such areas are 
essential for the conservation of the species. Section 4(b)(2) of the 
Act states that the Secretary must make the designation on the basis of 
the best scientific data available and after taking into consideration 
the economic impact, the impact on national security, and any other 
relevant impacts of specifying any particular area as critical habitat. 
Critical habitat is not currently determinable. However, critical 
habitat is prudent, and we intend to propose critical habitat for the 
species within 1 year of publishing this rule, after acquiring the 
information to determine the areas warranting critical habitat 
designation.

Information Requested

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other governmental agencies, Native 
American Tribes, the scientific community, industry, or any other 
interested parties concerning this proposed rule.
    We particularly seek comments concerning:
    (1) The species' biology, range, and population trends, including:
    (a) Biological or ecological requirements of the species, including 
habitat requirements for feeding, breeding, and sheltering;
    (b) Genetics and taxonomy;
    (c) Historical and current range, including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the species, its 
habitat, or both.
    (2) Factors that may affect the continued existence of the species, 
which may include habitat modification or destruction, overutilization, 
disease, predation, the inadequacy of existing regulatory mechanisms, 
or other natural or manmade factors.
    (3) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to this species and existing regulations 
that may be addressing those threats.
    (4) Additional information concerning the historical and current 
status, range, distribution, and population size of this species, 
including the locations of any additional populations of this species.
    (5) Information on regulations that are necessary and advisable to 
provide for the conservation of the pyramid pigtoe and that the Service 
can consider in developing a 4(d) rule for the species. In particular, 
information concerning the extent to which we should include any of the 
section 9 prohibitions in the 4(d) rule or whether we should consider 
any additional exceptions from the prohibitions in the 4(d) rule.
    (6) Which areas would be appropriate as critical habitat for the 
species and why areas should or should not be proposed for designation 
as critical habitat in the future.
    (7) Specific information on:
    (a) The amount and distribution of habitat for pyramid pigtoe that 
should be considered for proposed critical habitat;
    (b) What may constitute ``physical or biological features essential 
to the conservation of the species within the geographical range 
currently occupied by the species'';
    (c) Where these features are currently found;
    (d) Whether any of these features may require special management 
considerations or practices;
    (e) What areas that are currently occupied and contain features 
essential to the conservation of the species should be included in the 
designation and why; and

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    (f) What unoccupied areas are essential for the conservation of the 
species and why.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for, or 
opposition to, the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is an endangered or a 
threatened species must be made ``solely on the basis of the best 
scientific and commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in ADDRESSES. We request that you 
send comments only by the methods described in ADDRESSES.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the website. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on http://www.regulations.gov.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on http://www.regulations.gov.
    Because we will consider all comments and information we receive 
during the comment period, our final determinations may differ from 
this proposal. Based on the new information we receive (and any 
comments on that new information), we may conclude that the species is 
endangered instead of threatened, or we may conclude that the species 
does not warrant listing as either an endangered species or a 
threatened species. In addition, we may change the parameters of the 
prohibitions or the exceptions to those prohibitions in the 4(d) rule 
if we conclude it is appropriate in light of comments and new 
information received. For example, we may expand the prohibitions to 
include prohibiting take associated with additional activities if we 
conclude that those additional activities are not compatible with 
conservation of the species. Conversely, we may establish additional 
exceptions to the prohibitions in the final rule if we conclude that 
the activities would facilitate or are compatible with the conservation 
and recovery of the species.

Public Hearing

    Section 4(b)(5) of the Act provides for a public hearing on this 
proposal, if requested. Requests must be received by the date specified 
in DATES. Such requests must be sent to the address shown in FOR 
FURTHER INFORMATION CONTACT. We will schedule a public hearing on this 
proposal, if requested, and announce the date, time, and place of the 
hearing, as well as how to obtain reasonable accommodations, in the 
Federal Register and local newspapers at least 15 days before the 
hearing. For the immediate future, we will provide these public 
hearings using webinars that will be announced on the Service's 
website, in addition to the Federal Register. The use of these virtual 
public hearings is consistent with our regulations at 50 CFR 
424.16(c)(3).

Previous Federal Actions

    In our 1989 Animal Notice of Review (a notice identifying animal 
taxa that are native to the United States and being considered for 
addition to the List of Endangered and Threatened Wildlife), we 
categorized the pyramid pigtoe (which we referred to as ``pink 
pigtoe'') as a taxon not meeting the Act's legal definition of a 
species, based on our taxonomic understanding of information in 
published scientific literature at that time (54 FR 554, January 6, 
1989). While taxonomic uncertainty remains regarding some populations 
identified as pyramid pigtoe, the species is recognized as valid in 
current scientific literature (see Background, below). On April 20, 
2010, we received a petition from the Center for Biological Diversity 
(CBD), Alabama Rivers Alliance, Clinch Coalition, Dogwood Alliance, 
Gulf Restoration Network, Tennessee Forests Council, and West Virginia 
Highlands Conservancy to list 404 aquatic, riparian, and wetland 
species, including the pyramid pigtoe (referred to as ``pink pigtoe'' 
in our National Domestic Listing Workplan) as endangered or threatened 
species under the Act. On September 27, 2011, we published our 
determination that the petition contained substantial information 
indicating listing may be warranted (76 FR 59836). On April 17, 2019, 
CBD filed a complaint challenging the Service's failure to complete 12-
month findings for these species within the statutory deadline. The 
Service and CBD reached a stipulated settlement agreement whereby the 
Service agreed to deliver a 12-month finding for the pyramid pigtoe to 
the Office of the Federal Register by August 31, 2021.

Supporting Documents

    A species status assessment (SSA) team prepared an SSA report for 
the pyramid pigtoe. The SSA team was composed of Service biologists, in 
consultation with other species experts. The SSA report represents a 
compilation of the best scientific and commercial data available 
concerning the status of the species, including the impacts of past, 
present, and future factors (both negative and beneficial) affecting 
the species. In accordance with our joint policy on peer review 
published in the Federal Register on July 1, 1994 (59 FR 34270), and 
our August 22, 2016, memorandum updating and clarifying the role of 
peer review of listing actions under the Act, we sought the expert 
opinions of three appropriate specialists regarding the SSA. We 
received two responses. We also received SSA report reviews from one 
Federal agency and five State agency partners, including scientists 
with expertise in aquatic ecology, freshwater mussel biology, taxonomy, 
and conservation. In addition, more than 50 individuals at Federal or 
State agencies, colleges or universities, or consultants provided data 
used in the SSA report.

I. Proposed Listing Determination

Background

    A thorough review of the taxonomy, life history, and ecology of the 
pyramid pigtoe (Pleurobema rubrum) is presented in the SSA report 
(version 1.0; Service 2021, pp. 19-36).
    The pyramid pigtoe is a freshwater mussel, reddish to chestnut 
brown in color, with a smooth periostracum (outer shell surface) that 
darkens with age (Watters et al. 2009, p. 233). Juveniles may have 
green rays that typically disappear with age. The shell is thick, 
triangular, and medium-sized (up to 3.6 inches (in) (91 millimeters 
(mm)) (Williams et al. 2008, p. 564). It has a shallow sulcus 
(depressed channel) and high anteriorly directed beak that is elevated 
above the hinge line (Stansbery 1967, p. 3).
    The pyramid pigtoe is found in medium to large rivers, in a mixture 
of sand, gravel, and cobble substrates. It currently occurs in 
Kentucky, Tennessee, Virginia, Ohio, Alabama, Oklahoma, Arkansas, 
Mississippi, and Louisiana. It is considered extirpated from 
Pennsylvania, West Virginia, Indiana, Illinois, Wisconsin, Minnesota, 
Iowa, Kansas, and Missouri. Extant populations of pyramid pigtoe occur 
in

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the Arkansas-White-Red, Lower Mississippi, Missouri, and Ohio River 
regions (Hydrologic Unit Code 2 scale, Seaber et al. 1987, pp. 3-4), 
and it is extirpated from the Missouri and Upper Mississippi River 
regions (Figure 1).
    Relying on fish hosts for successful reproduction, the pyramid 
pigtoe has a complex life cycle similar to other mussels. In general, 
mussels are either male or female, but differences between sexes in 
shell shape are subtle (Haag 2012, p. 54). Males release sperm into the 
water column, which is taken in by the female through the incurrent 
aperture, where water enters the mantle cavity. The sperm fertilize 
eggs in the suprabranchial chamber (located above the gills) as ova are 
passed from the gonad to the marsupia (Yokley 1972, p. 357). Developing 
larvae remain in the gill chamber until they mature (called glochidia) 
and are ready for release. Once released, the glochidia draw nutrients 
from fish hosts and develop into juvenile mussels, dropping from the 
hosts weeks to months after initial attachment. Only a few glochidia 
reach the free-living juvenile stage, and mortality rates for the 
glochidial stage have been estimated at 99 percent, making this a 
critical phase in the life history of freshwater mussels (Jansen et al. 
2001, p. 211).
[GRAPHIC] [TIFF OMITTED] TP07SE21.021

    The pyramid pigtoe is a short-term brooder and has been recorded as 
gravid in the Cumberland River in May, June, and July (Gordon and 
Layzer 1989, p. 50). Host fish species are minnows of the family 
Cyprinidae and genera Cyprinella, Erimystax, Lythrurus, and Notropis 
(Culp et al. 2009, p. 19). Similar to other species in its tribe, 
Pleurobemini (taxonomic rank above genus and below family), the pyramid 
pigtoe targets drift-feeding minnow species by releasing glochidia 
contained in packets called conglutinates (Haag 2012, p. 163). 
Following release from the female mussel, the semi-buoyant 
conglutinates drift in the water column where they are targeted by 
sight-feeding minnows (Culp et al, 2009, p. 21).
    A relatively long-lived species, the pyramid pigtoe has a lifespan 
that likely averages 20 to 30 years, based on observations of the 
closely related Ohio pigtoe and round pigtoe (Slater 2018, p. 35; 
Watters et al. 2009, p. 299). Given the longevity of closely related 
species, it possibly lives up to 40-45 years in some locations (Ostby 
and Beaty 2016, p. 117).
    The pyramid pigtoe exhibits a preference for sand and gravel in 
rivers but also may be found in coarse sand in larger rivers (Gordon 
and Layzer 1989, p. 31). They can be found at depths less than 3 ft (1 
m) but in large rivers can be found commonly at depths of 13 to

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20 ft (4 to 6 m) or greater (Parmalee and Bogan 1998, p. 193; Williams 
et al. 2008, p. 566). Adult freshwater mussels within the genus 
Pleurobema are suspension-feeders that filter water and nutrients to 
eat. Mussels may shift to deposit feeding, though reasons for this are 
poorly known and may depend on flow conditions or temperature. Their 
diet consists of a mixture of algae, bacteria, detritus, and 
microscopic animals (Gatenby et al. 1996, p. 606; Strayer et al. 2004, 
p. 430). It has also been surmised that dissolved organic matter may be 
a significant source of nutrition (Strayer et al. 2004, p. 431).
    The pyramid pigtoe (Pleurobema rubrum) belongs to a complex of four 
morphologically similar species, which includes the Ohio pigtoe (P. 
cordatum), rough pigtoe (P. plenum) and round pigtoe (P. sintoxia). 
Since its original description as a species (Rafinesque 1820, p. 314), 
Pleurobema rubrum has undergone several scientific name changes, due to 
its widespread distribution, variability in shell shape and size 
throughout its range, and similarity in morphological characters to 
other closely related species. Additionally, based on shell characters 
alone, the pyramid pigtoe has been periodically considered a subspecies 
of the Ohio pigtoe (Ortmann 1911, p. 331). Since its initial 
description in 1820, the pyramid pigtoe has sometimes been referred to 
as pink pigtoe by commercial shell harvesters and biologists. However, 
the common name applied to the species in the scientific literature and 
in the Integrated Taxonomic Information System is pyramid pigtoe.
    Genetic studies to clarify the taxonomic relationships among 
Pleurobema indicate potential differences between pyramid pigtoe 
populations occupying separate river drainages. Mitochondrial DNA 
samples from two specimens of pyramid pigtoe indicated the Duck River, 
Tennessee, specimen was genetically distinct from the St. Francis 
River, Arkansas, specimen (Campbell et al. 2005, p. 143). These same 
data were included in subsequent phylogenetic studies focused on 
Fusconaia (Burdick and White 2007, p. 372) and Pleurobema (Campbell et 
al. 2008, p. 714; Campbell and Lydeard 2012b, p. 27) with similar 
results. Phylogeographic structuring has been observed between pyramid 
pigtoe from the Ouachita and St. Francis drainages in Arkansas that may 
represent species-level variation (Christian et al. 2008, p. 9; Harris 
et al. 2009, p. 74). Additionally, an analysis that included all 
previously published and new data representing a broad sampling across 
Pleurobemini revealed that pyramid pigtoe and round pigtoe may 
represent a single species, with two out of three species delineation 
models indicating one lineage present in specimens identified as round 
pigtoe and pyramid pigtoe (Inoue et al. 2018, p. 694). However, one of 
the three models indicated separate lineages of the two species. While 
there is some uncertainty in the taxonomic identity of populations 
referred to as pyramid pigtoe, especially those outside the Ohio, 
Cumberland, and Tennessee basins, our SSA report analyzed the status of 
the single species currently recognized by the scientific community 
(Williams et al. 2017, p. 42; Graf and Cummings 2021, p. 19).

Regulatory and Analytical Framework

Regulatory Framework
    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species is an endangered species or a threatened species. The 
Act defines an endangered species as a species that is ``in danger of 
extinction throughout all or a significant portion of its range'' and a 
threatened species as a species that is ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The Act requires that we determine 
whether any species is an endangered species or a threatened species 
because of any of the following factors:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the expected response by the species, 
and the effects of the threats--in light of those actions and 
conditions that will ameliorate the threats--on an individual, 
population, and species level. We evaluate each threat and its expected 
effects on the species, then analyze the cumulative effect of all of 
the threats on the species as a whole. We also consider the cumulative 
effect of the threats in light of those actions and conditions that 
will have positive effects on the species, such as any existing 
regulatory mechanisms or conservation efforts. The Secretary determines 
whether the species meets the definition of an ``endangered species'' 
or a ``threatened species'' only after conducting this cumulative 
analysis and describing the expected effect on the species now and in 
the foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as the 
Service can reasonably determine that both the future threats and the 
species' responses to those threats are likely. In other words, the 
foreseeable future is the period of time in which we can make reliable 
predictions. ``Reliable'' does not mean ``certain''; it means 
sufficient to provide a reasonable degree of confidence in the 
prediction. Thus, a prediction is reliable if it is reasonable to 
depend on it when making decisions.
    It is not always possible or necessary to define foreseeable future 
as a particular number of years. Analysis of the foreseeable future 
uses the best scientific and commercial data available and should 
consider the timeframes applicable to the relevant threats and to the 
species' likely responses to those threats in view of its life-history 
characteristics. Data that are typically relevant to assessing the 
species' biological response include species-

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specific factors such as lifespan, reproductive rates or productivity, 
certain behaviors, and other demographic factors.
Analytical Framework
    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the species, including an assessment of the potential 
threats to the species. The SSA report does not represent a decision by 
the Service on whether the species should be proposed for listing as an 
endangered or threatened species under the Act. However, it does 
provide the scientific basis that informs our regulatory decisions, 
which involve the further application of standards within the Act and 
its implementing regulations and policies. The following is a summary 
of the key results and conclusions from the SSA report; the full SSA 
report can be found at Docket FWS-R4-ES-2021-0092 on http://www.regulations.gov and at https://www.fws.gov/Asheville/.
    To assess pyramid pigtoe viability, we used the three conservation 
biology principles of resiliency, redundancy, and representation 
(Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency supports the 
ability of the species to withstand environmental and demographic 
stochasticity (for example, wet or dry, warm or cold years), redundancy 
supports the ability of the species to withstand catastrophic events 
(for example, droughts, large pollution events), and representation 
supports the ability of the species to adapt over time to long-term 
changes in the environment (for example, climate changes). In general, 
the more resilient and redundant a species is and the more 
representation it has, the more likely it is to sustain populations 
over time, even under changing environmental conditions. Using these 
principles, we identified the species' ecological requirements for 
survival and reproduction at the individual, population, and species 
levels, and described the beneficial and risk factors influencing the 
species' viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical 
and current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to sustain populations in the 
wild over time. We use this information to inform our regulatory 
decision.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability.
Species Needs
    We assessed the best available information to identify the physical 
and biological needs to support individual fitness at all life stages 
for the pyramid pigtoe. Full descriptions of all needs are available in 
chapter 4 of the SSA report (Service 2021, pp. 29-36), which can be 
found in docket number FWS-R4-ES-2021-0092 on http://www.regulations.gov, and on our internet site https://www.fws.gov/Asheville/. To maintain viability, individual pyramid pigtoes need 
clean flowing water, appropriate water quality and temperatures 
(parameters listed in Service 2021, p. 29), low levels of 
sedimentation, and food and nutrients. Pyramid pigtoe habitat is in 
rivers with natural flow regimes. Perturbations that disrupt natural 
flow patterns (e.g., dams) have a negative influence on pyramid pigtoe 
and host fish resilience. Pyramid pigtoe habitat must have adequate 
flow to deliver oxygen, enable passive reproduction, and deliver food.
    At the population and species (rangewide) level, the pyramid pigtoe 
needs habitat connectivity and positive demographic attributes 
(population density and growth rate, age class structure, recruitment) 
to maintain viability (Service 2021, pp. 32-33). Dendritic, or 
branched, orientation of stream systems can enhance metapopulation 
persistence compared to linear or two-dimensional systems (Fagan 2002, 
p. 3,243). Tributary connection to river mainstems allows movement of 
host fishes and helps facilitate dispersal and colonization of 
appropriate habitat patches by mussels. A high degree of connection 
between habitat patches and occupied reaches is necessary, because 
mussels are heavily dependent on gene exchange and host fish movement 
and dispersal within river corridors to maintain viable populations 
(Newton et al. 2008, p. 425).
    Fragmentation of stream habitat results in barriers to host fish 
movement, which in turn, influences mussel distributions, increasing 
the likelihood and compounding the significance of local extirpation 
events (Fagan 2002, p. 3,248). The pyramid pigtoe and other mussel 
species that use small host fishes, such as minnows and shiners (family 
Cyprinidae), are more susceptible to impacts from habitat 
fragmentation. This is due to increasing distance between suitable 
habitat patches and low likelihood of small host fish swimming over 
that distance as compared to large host fishes (Vaughn 2012, p. 7). 
Barriers to movement can cause isolated or patchy distributions of 
mussels, which may limit both genetic exchange and recolonization 
(Jones et al. 2006, p. 528).
    Mussel abundance in a given river reach is a product of the number 
of mussel beds (aggregations of freshwater mussels) and the density of 
mussels within those beds. Healthy pyramid pigtoe populations have 
numerous individuals, with multiple age classes, and exhibit regular 
recruitment of new age classes. For pyramid pigtoe populations to be 
resilient, there must be multiple mussel beds of sufficient density 
such that local stochastic events do not eliminate the bed(s), allowing 
the mussel bed and the overall local population within a river reach to 
recover from any one event. A dendritic distribution (branching, such 
that there is not a line connecting a single upstream and downstream 
aggregation) over a large area also helps buffer against stochastic 
events that may impact populations. Mussels do not actively seek mates; 
rather, males release sperm into the water column, where it drifts 
until a female takes it in (Moles and Layzer 2008, p. 212). Therefore, 
successful individual reproduction and population viability require 
sufficient numbers of female mussels downstream of sufficient numbers 
of male mussels; higher density (number of mussels per unit area) 
increases the likelihood of fertilization.
Threats
    We have determined that past and current threats to the pyramid 
pigtoe include habitat degradation or loss from a variety of sources 
(e.g., dams and other barriers, resource extraction); degraded water 
quality from chemical contamination and erosion from development, 
agriculture, and mining operations; direct mortality from dredging; 
residual impacts (reduced population size) from historical harvest; and 
the proliferation of invasive, nonnative species. Cumulatively, these 
threats also contribute to the negative

[[Page 49995]]

effects associated with the species' small population size in certain 
areas.
    The following discussions include evaluations of three current 
threats and associated sources that are affecting the pyramid pigtoe 
and its habitat: (1) Habitat (including water quality) degradation or 
loss, (2) invasive and nonnative species, and (3) negative effects 
associated with small population size (Service 2021, pp. 51-83). We 
also considered impacts from climate change, but found no evidence 
linking climate change impacts to the current status of the pyramid 
pigtoe. We note that overutilization (commercial mussel harvest) was a 
threat historically and likely reduced the size of many populations 
such that they have not recovered to historical abundance levels, but 
it is not currently a threat. In addition, potential impacts from 
disease, parasites, and predation, as well as potential impacts to host 
species, were evaluated but were found to have minimal effects on 
viability of the pyramid pigtoe based on current knowledge (Service 
2021, pp. 78-79). Although not a widespread threat, disease is likely 
affecting at least one population of pyramid pigtoe: The Clinch River 
mussel assemblage, which includes a pyramid pigtoe population, has 
recently undergone a die-off that is associated with a novel densovirus 
(Richard et al. 2020, entire). Finally, we also considered effects 
associated with enigmatic population declines (unexplained die-offs of 
large numbers of mussels over a short period of time), which have been 
documented in fresh water river mussel populations since the 1960s; 
despite speculation and repeated aquatic organism surveys and water 
quality monitoring, the causes of these events are largely unknown 
(Haag 2019, p. 43).
    Predominant threats affecting each pyramid pigtoe population are 
listed in Table 1. Based on threat information in the literature or 
State Wildlife Action Plans, we categorized the threat level as low, 
moderate, or high depending on their magnitude and immediacy:
     Low--Threats to aquatic fauna far enough removed in time 
or space that they are currently exerting minimal influence on mussel 
populations.
     Moderate--Multiple threats linked to negative effects on 
mussels are present. Some threats currently acting on mussel habitat, 
reducing resource needs, and limiting recruitment and population 
growth.
     High--Multiple threats linked to negative effects on 
mussels are present and have been acting cumulatively on mussel 
habitat, prohibiting sustained recruitment and population growth.

        Table 1--Current Threats and Level of Threat to the Pyramid Pigtoe by River Basin and Population
                        [Adapted and modified from SSA report, Service 2021, pp. 157-164]
----------------------------------------------------------------------------------------------------------------
               Population                    Threat level category                      Threats
----------------------------------------------------------------------------------------------------------------
                                                OHIO RIVER BASIN
----------------------------------------------------------------------------------------------------------------
Muskingum River.........................  High.......................  Hydropower development; impoundment;
                                                                        dredging; population isolation; past
                                                                        commercial harvest.
Upper Green River.......................  Low........................  Impoundment; habitat loss and water
                                                                        quality degradation; resource
                                                                        extraction; past commercial harvest.
Barren River............................  Moderate...................  Impoundment; habitat loss and water
                                                                        quality degradation; resource
                                                                        extraction; past commercial harvest.
Middle Green River......................  Moderate...................  Impoundment; habitat loss and water
                                                                        quality degradation; resource
                                                                        extraction; past commercial harvest.
Lower Green River.......................  Moderate...................  Impoundment; habitat loss and water
                                                                        quality degradation; resource
                                                                        extraction; past commercial harvest.
Cumberland River........................  High.......................  Habitat fragmentation, hypolimnetic
                                                                        discharges.
----------------------------------------------------------------------------------------------------------------
                                              TENNESSEE RIVER BASIN
----------------------------------------------------------------------------------------------------------------
Holston River...........................  High.......................  Habitat fragmentation, hypolimnetic
                                                                        discharges.
Clinch River............................  Moderate...................  Development; agricultural activities;
                                                                        dams; overharvest historically;
                                                                        contaminants; resource extraction;
                                                                        degraded water quality; enigmatic die-
                                                                        offs.
Paint Rock River........................  Low........................  Habitat loss through channel maintenance
                                                                        (snag removal); habitat fragmentation
                                                                        and population isolation due to
                                                                        impoundment; agriculture.
Tennessee River (Wheeler Reservoir).....  High.......................  Impoundment; habitat degradation from
                                                                        flow releases; past commercial harvest.
Tennessee River (Pickwick Reservoir)....  High.......................  Impoundment; dredging; navigation
                                                                        impacts; past commercial harvest.
Tennessee River (Kentucky Reservoir)....  High.......................  Impoundment; dredging and navigation
                                                                        impacts; agriculture.
Upper Duck River........................  Moderate...................  Development; agricultural activities;
                                                                        water quality degradation; impoundments;
                                                                        fragmented populations.
Lower Duck River........................  Moderate...................  Development and water quality
                                                                        degradation.
----------------------------------------------------------------------------------------------------------------
                                            ARKANSAS-WHITE-RED BASIN
----------------------------------------------------------------------------------------------------------------
Petit Jean River........................  Moderate...................  Agriculture; habitat loss and water
                                                                        quality degradation.
Eleven Point River......................  Low........................  Habitat loss and water quality
                                                                        degradation; agricultural effects.
Little River............................  Moderate...................  Impoundment, habitat loss, and water
                                                                        quality degradation.
----------------------------------------------------------------------------------------------------------------
                                             LOWER MISSISSIPPI BASIN
----------------------------------------------------------------------------------------------------------------
Lower Black River.......................  Moderate...................  Agriculture, habitat loss, and water
                                                                        quality degradation.
Lower St. Francis River.................  High.......................  Agriculture, habitat loss, and water
                                                                        quality degradation.
Tyronza River...........................  High.......................  Agriculture, habitat loss, and water
                                                                        quality degradation.
White River.............................  Moderate...................  Impoundment, resource extraction, habitat
                                                                        loss, and water quality degradation.

[[Page 49996]]

 
Upper Ouachita River....................  Moderate...................  Impoundment, navigation, habitat loss,
                                                                        and water quality degradation.
Little Missouri River...................  Moderate...................  Agriculture, habitat loss, and water
                                                                        quality degradation.
Ouachita River..........................  Moderate...................  Impoundment, navigation, habitat loss,
                                                                        and water quality degradation.
Upper Saline River......................  Moderate...................  Impoundment, navigation; agriculture;
                                                                        resource extraction; habitat loss and
                                                                        water quality degradation.
Lower Saline River......................  Moderate...................  Impoundment, navigation, agriculture,
                                                                        resource extraction, habitat loss, and
                                                                        water quality degradation.
Bayou Bartholomew.......................  High.......................  Agriculture, habitat loss and water
                                                                        quality degradation.
Lower Ouachita River....................  High.......................  Impoundment; navigation; habitat loss and
                                                                        water quality degradation.
Big Sunflower River.....................  High.......................  Agriculture; habitat loss and water
                                                                        quality degradation.
Hushpuckna River........................  High.......................  Impoundment; agriculture; navigation;
                                                                        habitat loss and water quality
                                                                        degradation.
Bogue Phalia............................  High.......................  Impoundment; agriculture; navigation;
                                                                        habitat loss and water quality
                                                                        degradation.
Little Sunflower River..................  High.......................  Impoundment; agriculture; navigation;
                                                                        habitat loss and water quality
                                                                        degradation.
Sunflower River.........................  High.......................  Impoundment; agriculture; navigation;
                                                                        habitat loss and water quality
                                                                        degradation.
Sandy Bayou.............................  High.......................  Impoundment; agriculture; navigation;
                                                                        habitat loss and water quality
                                                                        degradation.
Big Black River.........................  High.......................  Impoundment; agriculture, habitat loss
                                                                        and water quality degradation.
----------------------------------------------------------------------------------------------------------------

Habitat Degradation or Loss

Development and Urbanization
    Development and urbanization activities that may contribute to 
pyramid pigtoe habitat degradation or loss, including reduced water 
quality, occur throughout the species' range. The term ``development'' 
refers to urbanization of the landscape, including (but not limited to) 
land conversion for residential, commercial, and industrial uses and 
the accompanying infrastructure. The effects of urbanization may 
include alterations to water quality, water quantity, and habitat (both 
in-stream and streamside) (Ren et al. 2003, p. 649; Wilson 2015, p. 
424). Urban development can lead to increased variability in 
streamflow, typically increasing the extent and volume of water 
entering a stream after a storm and decreasing the time it takes for 
the water to travel over the land before entering the stream (Giddings 
et al. 2009, p. 1). Deleterious effects on streams (i.e., water 
collection on impervious surfaces that rapidly flows into storm drains 
and local streams), including those that may be occupied by the pyramid 
pigtoe, include:
     Water Quantity: Storm drains deliver large volumes of 
water to streams much faster than would naturally occur, often 
resulting in flooding and bank erosion that reshapes the channel and 
causes substrate instability, resulting in destabilization of bottom 
sediments. Increased, high-velocity discharges can cause pyramid pigtoe 
to become stressed, displaced, or killed by fast-moving water and the 
debris and sediment carried in it.
     Water Quality: Pollutants (e.g., gasoline, oil drips, 
fertilizers) that accumulate on impervious surfaces may be washed 
directly into streams during storm events thereby directing killing 
pyramid pigtoe individuals.
     Water Temperature: During warm weather, rain that falls on 
impervious surfaces becomes superheated and can stress or kill pyramid 
pigtoe individuals when it enters streams.
    Water infrastructure to support development, including water 
supply, reclamation, and wastewater treatment, results in pollution or 
contaminant discharges to streams. Right of way (ROW) crossings for 
waterlines and other utility lines also affect stream habitats. Direct 
impacts from utility crossings include direct exposure or crushing of 
individuals, sedimentation, and flow disturbance. The most significant 
cumulative impact involves cleared ROWs that result in direct runoff 
and increased stream temperature at the crossing locations. Maintenance 
or clearing of ROWs may entail herbicide applications that subsequently 
enter streams via stream runoff.
    Most populations of pyramid pigtoe in urban areas with large human 
populations have been diminished or lost. Secondary impacts resulting 
from development, such as the increased contaminant introduction, 
stream disturbance caused by impervious surfaces, barrier construction, 
and forest conversion to other land use types such as agriculture or 
urban uses are likely acting cumulatively on the species. Increased 
human population growth projections indicate urban sprawl (a current 
process) will affect pyramid pigtoe populations in the Tennessee and 
Ohio basins (Terando et al. 2014, p. 7; Tayyebi et al. 2015, p. 110). 
In the Upper and Lower Duck River MUs, the species is currently 
impacted by rapid development encroaching from the city of Nashville 
and nearby smaller urban areas such as Columbia, TN (TWRA 2016, p. 15). 
The pyramid pigtoe population in the Muskingum River is downstream of 
the Tuscarawas River, which has been severely degraded by industrial 
development that continues to affect water quality (Hoggarth 1994, p. 
3; Haefner and Simonson 2018, p. 1).
    Threats to the pyramid pigtoe from development are partly mitigated 
by Federal lands. Several locations where the pyramid pigtoe occurs in 
water bodies located on or immediately adjacent to Federal lands 
receive some indirect benefits to viability such as lack of 
urbanization and land development pressure. These include the Pond 
Creek Refuge in Arkansas (Arkansas-White-Red basin) as well as Upper 
Ouachita, Felsenthal, and White River Refuges (Lower Mississippi 
basin), and Wheeler Refuge (Tennessee Basin) that are adjacent to large 
rivers where the pyramid pigtoe occurs. Mammoth Cave National Park also 
provides a level of localized protection against development pressures 
for the pyramid pigtoe population in the upper Green River, Kentucky 
(Ohio Basin).
    On private lands, the Saline-Caddo-Ouachita Programmatic Safe 
Harbor Agreement and Candidate Conservation Agreement with Assurances 
programs are voluntary conservation programs that support ongoing 
stewardship for imperiled species, including the pyramid pigtoe. Large 
tracts of private land in the upper Saline and Ouachita River systems 
adjacent to streams and upland areas are covered under these programs. 
These lands are mostly upstream of pyramid pigtoe sites

[[Page 49997]]

(Service 2015, p. 6) but could have a positive indirect long-term 
benefit to the species by reducing sediment and pollutant runoff and 
improving water quality downstream. Some private lands in pyramid 
pigtoe MUs also are managed for conservation through The Nature 
Conservancy (TNC) programs in the upper Green River in Kentucky, the 
upper Clinch/Powell River, Tennessee and Virginia, the Saline River in 
Arkansas, and the Paint Rock River in Alabama. In these watersheds, TNC 
has a few riparian inholdings that are protected from developments. In 
addition, within these watersheds, TNC implements community-based and 
partner-oriented projects to address aquatic species and instream 
habitat conservation by restoring and protecting streambanks and 
riparian zones.
    Various small, isolated parcels of State land (e.g., State parks, 
State forests, wildlife management areas) along MUs where the pyramid 
pigtoe occurs also provide a conservation benefit as a buffer to 
development. However, vast tracks of riparian lands in the range of the 
pyramid pigtoe are privately owned, without conservation programs, and 
the prevalence of privately owned lands along rivers is comparatively 
much larger than the species' occurrence on public lands. Limited 
overlap of the species' range with public lands and private lands with 
conservation programs diminishes their ability to protect the species, 
because the habitat protection benefits these lands provide are at 
significant risk of being negated by detrimental activities upstream or 
immediately downstream.
Transportation
    Transportation-related impacts include both road development and 
river navigation. Road development increases impervious surfaces as 
well as land clearing and habitat fragmentation. Roads are generally 
associated with negative effects on the biotic integrity of aquatic 
ecosystems, including changes in surface water temperatures and 
patterns of runoff, sedimentation, adding heavy metals (especially 
lead), salts, organics, and nutrients to stream systems (Trombulak and 
Frissell 2000, p. 18).
    With regard to river navigation, dredging and channelization 
activities (as a means of maintaining waterways) have altered riverine 
habitats nationwide (Ebert 1993, p. 157). Channelization affects many 
physical characteristics of streams through accelerated erosion, 
increased bedload, reduced depth, decreased habitat diversity, 
geomorphic instability, and riparian canopy loss (Hartfield 1993, p. 
139). All of these impacts contribute to loss of habitat for the 
pyramid pigtoe and host fishes. Increases in turbulence, suspended and 
deposited sediments, and turbidity resulting from river transportation 
and associated activities may affect mussel feeding and respiration 
(Aldridge et al. 1987, p. 25). In addition to dredging and channel 
maintenance, impacts associated with barge traffic, which includes 
construction of fleeting areas, mooring cells, docking facilities, and 
propeller wash, also destroy and disrupt mussel habitat (see Miller et 
al. (1989, pp. 48-49) as an example for disturbance from barges).
    Transportation-related impacts across the range of the pyramid 
pigtoe include (but are not limited to) the following examples:
     Extensive stream channelization and snag removal has 
severely affected the freshwater mussel fauna and habitat in the Paint 
Rock River system, including the lower reaches of Estill Fork and 
Hurricane Creek (Ahlstedt 1995-96, p. 65). Even if active 
channelization activities are not currently occurring in rivers and 
streams occupied by the pyramid pigtoe, impacts of past actions can 
have permanent effects (Haag and Cicerello 2016, p. 60; Hubbard et al. 
1993, p. 142; Watters 2000, p. 274).
     Commercial navigation previously took place in the lower 
Green and Barren Rivers, where navigation dams remain but are not in 
operation. Past dredging and navigation affected mussel beds in the 
mainstem Cumberland River, which has the last remaining population of 
pyramid pigtoe in the Cumberland River system (Hubbs 2012, p. 9).
     Currently, all three of the Tennessee River mainstem 
pyramid pigtoe MUs are likely affected to some extent by channel 
maintenance and navigation operations, due to their clustered 
distribution and proximity to navigation dams.
     Two navigation dams are operated on the Ouachita River, 
which is maintained by the Corps as a waterway, and affect three MUs.
Contaminants
    Contaminants contained in point and non-point discharges can 
degrade water and substrate quality and adversely impact mussel 
populations. The effects of contaminants such as metals, chlorine, and 
ammonia are profound on juvenile mussels (Bartsch et al. 2003, p. 
2,566; Augspurger et al. 2003, p. 2,571). Juvenile mussels may readily 
ingest contaminants bound to sediment particles (Newton and Cope 2007, 
p. 276). These contaminants also affect mussel glochidia, which are 
very sensitive to some toxicants (Goudreau et al. 1993, p. 221; 
Jacobson et al. 1997, p. 2,386; Valenti et al. 2005, p. 1,243). High 
levels of suspended solids alone (without bound contaminants) can 
result in mussel reproductive failure or low fertilization rates of 
long-term brooders, such as species of the genus Pleurobema (Gascho-
Landis and Stoeckel 2015, p. 229).
    Current State regulations regarding pollutants are designed to be 
protective of aquatic organisms; however, freshwater mussels may be 
more susceptible to some pollutants than the test organisms commonly 
used in bioassays. Additionally, water quality criteria may not 
incorporate data available for freshwater mussels (March et al. 2007, 
pp. 2,066-2,067). A multitude of bioassays conducted on 16 mussel 
species (summarized by Augspurger et al. 2007, pp. 2,025-2,028) show 
that freshwater mollusks are more sensitive than previously believed to 
some chemical pollutants, including chlorine, ammonia, copper, 
fungicides, and herbicide surfactants. Nickel and chloride were toxic 
to federally threatened mussel species at levels below the current 
criteria and are sensitive to sodium dodecyl sulfate (SDS), a 
surfactant commonly used in household detergents, for which water 
quality criteria do not currently exist (Gibson 2015, p. 80, p. 90; 
Gibson et al. 2018, pp. 247-250). None of the States in the range of 
the pyramid pigtoe have fully adopted the Environmental Protection 
Agency's 2013 recommended ammonia criteria for freshwater mollusks (78 
FR 52192, August 22, 2013).
    Contaminant inputs (including sediments) to pyramid pigtoe habitat 
stem from multiple threats, including urbanization, resource 
extraction, agriculture, and channel maintenance for navigation, 
diminishing water quality in many areas of the four basins where the 
species occurs. Examples of contaminant-related impacts in the range of 
the pyramid pigtoe include (but are not limited to) the following:
     Long-term declines and extirpation of mussels from reaches 
of the Upper Clinch MU in Virginia attributed, in part, to copper and 
zinc contamination originating from wastewater discharges at coal-fired 
power plants (Price et al. 2014, p. 12; Zipper et al. 2014, p. 9). Coal 
plants also are located on the Lower Green and Cumberland-Old Hickory 
MUs.
     Heavy metals toxicity to mussels has been documented in 
the

[[Page 49998]]

Muskingum, Upper Clinch, and all Tennessee River MUs (Havlik and 
Marking 1987, pp. 4-9).
     A chemical spill from a tanker truck accident flowed into 
the Upper Clinch MU in Virginia and eliminated approximately 18,000 
individuals of several mussel species (Jones et al. 2001, p. 20; 
Schmerfeld 2006, p. 12), including approximately 750 individuals of 
three federally listed species (Schmerfeld 2006, p. 12). A catastrophic 
chemical spill in 1999 affected approximately 10 miles of the Ohio 
River and resulted in the loss of an estimated 1 million mussels, 
including two federally listed species (Butler 2005, p. 24).
    State and Federal water quality programs provide a level of 
protection to the pyramid pigtoe from development, agriculture, and 
river navigation activities by regulating storm water and point source 
(end of pipe) discharges to streams. Section 401 of the Federal Clean 
Water Act (CWA; 33 U.S.C. 1251 et seq.) requires that an applicant for 
a Federal license or permit provide a certification that any discharges 
from the facility will not degrade water quality or violate water-
quality standards, including those established by States. Section 404 
of the CWA establishes a program to regulate the discharge of dredged 
and fill material into waters of the United States. Under the CWA, 
permits to fill wetlands and culvert, bridge, or realign streams or 
water features are issued by the U.S. Army Corps of Engineers. Current 
State regulations regarding pollutants are designed to be protective of 
aquatic organisms; however, as discussed above, freshwater mussels may 
be more susceptible to some pollutants than the aquatic biota for which 
water quality criteria are currently established.
    Despite existing authorities such as the CWA, pollutants continue 
to impair the water quality in areas of the pyramid pigtoe's range. 
State and Federal regulatory mechanisms have helped reduce the negative 
effects of point source discharges since the 1970s, yet these 
regulations are difficult to implement and enforce. Although new water 
quality criteria are under development that will take into account more 
sensitive aquatic species, most current criteria do not. It is expected 
that several years will be needed to implement new water quality 
criteria throughout the species' range.
Agriculture
    Agricultural activities occur across the range of the pyramid 
pigtoe and are a factor in its historical decline and localized 
extirpations. The advent of intensive row crop agricultural practices 
corresponds with freshwater mussel declines, and species extirpations, 
in the eastern United States (Peacock et al. 2005, p. 550). Nutrient 
enrichment and water withdrawals, threats commonly associated with 
agricultural activities, may be localized and limited in scope, and 
have the potential to affect individual pyramid pigtoe mussels. 
However, chemical control using pesticides may have broader impacts. 
Pesticides, including herbicides, fungicides, and insecticides as well 
as their surfactants and adjuvants, are highly toxic to juvenile and 
adult freshwater mussels (Bringolf et al. 2007, p. 2,092) and 
deleterious if not properly applied to agricultural operations. Waste 
from confined animal feeding and commercial livestock operations is 
another potential source of contaminants that come from agricultural 
runoff. The concentrations of these contaminants from fields or 
pastures may be at levels that can affect an entire population, 
especially given the highly fragmented distribution of the pyramid 
pigtoe.
    Agencies such as the Natural Resources Conservation Service (NRCS) 
and the Soil and Water Conservation Districts provide technical and 
financial assistance to farmers and private landowners. Additionally, 
county resource development councils and university agricultural 
extension services disseminate information on the importance of 
minimizing land use impacts, specifically agriculture, on aquatic 
resources. These programs help identify opportunities for conservation 
through projects such as exclusion fencing and alternate water supply 
sources, which help decrease nutrient inputs and water withdrawals and 
help keep livestock off stream banks and shorelines, reducing erosion. 
However, the overall effectiveness of these programs over a large scale 
is unknown given the pyramid pigtoe's wide distribution and varying 
agricultural intensities in its range.
Dams and Barriers
    Whether for flood control, hydropower, river navigation, or as 
abandoned mill structures, dams and their impoundments are one of the 
most pervasive threats to pyramid pigtoe rangewide: 26 of 35 
populations and all 4 major basins in the species' range are affected 
(Table 1). Dams have many impacts on stream ecosystems, and the effects 
of impoundments and barriers on aquatic habitats and freshwater mussels 
are relatively well-documented (Watters 2000, p. 261). Extinction and 
extirpation of many North American freshwater mussels can be traced to 
impoundment and inundation of riffle habitats in all major river basins 
of the central and eastern United States (Haag 2009, p. 107). 
Reductions in the diversity and abundance of mussels are primarily 
attributed to habitat shifts, alteration and disruption of 
connectivity, and diminished water quality as a result of reservoir 
construction (Neves et al. 1997, p. 63). The survival and reproductive 
success of mussels are influenced upstream of dams as flowing waters 
change to impounded waters, with increased depths and buildup of 
sediments, decreased dissolved oxygen, and drastic alteration of 
resident fish assemblages. Downstream of dams, biotic and physical 
habitat conditions provided by natural flow regimes are altered by 
minimal releases or scouring flows, seasonal dissolved oxygen 
depletion, and reduced or increased water temperatures. The number of 
fish species is greatly reduced where coldwater flow (hypolimnetic 
discharge) is released. Additionally, dams fragment habitat, limiting 
dispersal of mussels on their fish hosts, which leads to genetic 
isolation of mussel populations.
Resource Extraction
    Predominant resource extraction threats in the range of the pyramid 
pigtoe stem from mining (primarily coal but including other mineral 
resources) and oil and gas exploration. Activities associated with coal 
mining and oil and gas drilling can contribute chemical pollutants to 
streams. Acid mine drainage is created from the oxidation of iron-
sulfide minerals such as pyrite, forming sulfuric acid (Sams and Beer 
2000, p. 3). This acid mine drainage may be associated with high 
concentrations of aluminum, manganese, zinc, and other constituents 
(Tennessee Department of Environment and Conservation (TDEC) 2014, p. 
72). The metals, and the high acidity typically associated with acid 
mine drainage, can be acutely and chronically toxic to aquatic life 
(Jones 1964, p. 96). Implementation of the Surface Mining Control and 
Reclamation Act of 1977 (SMCRA; 30 U.S.C. 1201 et seq.) has 
significantly reduced acid mine drainage from new coal mines; however, 
un-reclaimed areas mined prior to the SMCRA continue to generate acid 
mine drainage in portions of the pyramid pigtoe's range. Direct impacts 
to the pyramid pigtoe from acid mine drainage in most occupied river 
reaches are unlikely because coal mining sites tend to be adjacent to 
smaller headwater streams, but mining pollutants can be

[[Page 49999]]

transferred downstream to pyramid pigtoe habitats.
    Surface mining has been identified as a source of impairment for 
approximately 775 mi (1,247 km) of streams in Kentucky (Kentucky 
Department for Environmental Protection 2014, p. 66). Weathering of 
soils and rock broken apart to access coal seams typically increases 
alkalinity, total dissolved solids, salinity, and sedimentation and 
alters hydrology and physical habitat of streams receiving surface mine 
drainage, impacting fish and aquatic invertebrate communities (e.g., 
Bernhardt and Palmer 2011, pp. 42-49; Linberg et al. 2011, entire; 
Hopkins and Roush 2013, pp. 585-586; Hitt and Chambers 2014, p. 923; 
Hitt et al. 2016, pp. 47-53). Mining continues to impair water quality 
in streams in the Cumberland Plateau and Central Appalachian regions of 
Tennessee and Kentucky (TDEC 2014, p. 62), which contain portions of 
the Tennessee and Cumberland River basins, and is the primary source of 
low pH impairment of 376 mi (605 km) of rivers in Tennessee (TDEC 2014, 
p. 53). Coal mining has resulted in discharges of industrial and mine 
wastes from coal mines and coal processing facilities in the Clinch and 
Powell Rivers (Ahlstedt et al. 2016, p. 8). Direct impacts to the 
pyramid pigtoe from acid mine drainage or total dissolved solids in 
most occupied river reaches are unlikely because coal mining sites tend 
to be adjacent to smaller headwater streams, but associated mining 
pollutants (fine sediments, metals, and salts) can be transferred 
downstream to medium and large river pyramid pigtoe habitats (Bernhardt 
and Palmer, 2011 p. 46).
    Natural gas extraction in the Appalachians, including the 
Cumberland River basin, has negatively affected water quality through 
accidental spills and discharges, as well as increased sedimentation 
due to development of road construction, pipeline, drill pad 
construction, as well as tree removal required to clear the 
construction areas (Vidic et al. 2013, p. 6). Disposal of 
insufficiently treated brine wastewater, more saline than seawater, has 
specifically been found to adversely affect freshwater mussels (Patnode 
et al. 2015, p. 62). Potential threats from natural gas and oil 
exploration are also a concern in the White River basin.
    Instream sand and alluvial gravel mining has been implicated in the 
destruction of mussel populations (Hartfield 1993, p. 138). Negative 
impacts associated with gravel mining include stream channel 
modifications such as altered habitat, disrupted flow patterns, and 
sediment transport (Hubbs et al. 2006, p. 170). Additionally, water 
quality modifications including increased turbidity, reduced light 
penetration, increased temperature, and increased sedimentation result 
from gravel mining. Commercial sand and gravel mining and dredging 
directly affects the pyramid pigtoe in the Tennessee River, 
specifically within the Lower Tennessee-Beech MU (Hubbs et al. 2006, p. 
170). The Lower Cumberland Old Hickory MU has also been affected by 
gravel mining and dredging in the past (Sickel 1982, p. 4) that has 
resulted in permanent alteration of substrates and hydraulic patterns, 
contributing to habitat loss for freshwater mussels.

Invasive and Nonnative Species

    Invasive and nonnative species in the range of the pyramid pigtoe 
include the Asian clam, zebra mussel, black carp, and the plant 
species, hydrilla. These nonnative species impact the pyramid pigtoe 
through competitive interactions, water quality degradation, predation, 
and habitat alteration.
    The Asian clam, found throughout the range of the pyramid pigtoe, 
alters benthic substrates, may filter native mussel sperm or glochidia, 
competes with native species for limited resources, and causes ammonia 
spikes in surrounding water when dying off en masse (Scheller 1997, p. 
2). A typical settlement of the Asian clam occurs with a population 
density ranging from 100 to 200 clams per square meter, which may not 
be detrimental to native unionids; however, populations can grow as 
large as 3,000 clams per square meter, which would influence both food 
resources and competition for space for the pyramid pigtoe.
    Within the range of the pyramid pigtoe, the zebra mussel occurs in 
the Ohio, Tennessee, and Arkansas-White-Red River basins. Native 
mussels, such as the pyramid pigtoe, are negatively affected by zebra 
mussels through direct colonization, reduction of available habitat, 
changes in the biotic environment, or a reduction in food sources 
(MacIsaac 1996, p. 292). One of the direct consequences of the invasion 
of zebra mussels is the local extirpation of native freshwater mussel 
populations from (1) attachment to the shells of native mussels, which 
can kill them (zebra mussels are sessile, and cling to hard surfaces); 
(2) affecting vertical and lateral movements of native mussels, due to 
heavy infestations, which can prevent valve closure; and (3) 
outcompeting native mussels and other filter-feeding invertebrates for 
food. This problem has been particularly acute in the Ohio and 
Tennessee River systems. Densities of zebra mussels attained 17,000 per 
square meter in the Tennessee River below Wilson Dam in 2017, although 
recent survey efforts indicate a decline from that population explosion 
(Garner 2018, pers. comm.).
    The black carp, which feeds on mollusks, is listed as ``injurious'' 
under the Lacey Act and occurs in the Ohio, Tennessee, Lower 
Mississippi and Arkansas-White-Red basins where it overlaps populations 
of the pyramid pigtoe. It is highly likely that this nonnative fish 
will negatively impact native aquatic communities by direct predation, 
thus reducing populations of native mussels (Nico et al. 2005, p. 193). 
Because black carp attain a large size and have a lifespan reportedly 
over 15 years, they have the potential to cause significant harm to 
native mollusks by predation on multiple age classes (Nico et al. 2005, 
p. 77).
    In addition to negative impacts of nonnative animals, the invasive 
nonnative plant hydrilla can affect native mussels by covering spawning 
areas for native fish, which may be hosts for glochidia, and can cause 
significant reductions in stream oxygen levels (Colle et al. 1987, p. 
410). Hydrilla is widespread in the Ohio, Cumberland, and Tennessee 
River systems. In general, invasive aquatic plants grow uncontrolled 
and can cause habitat to fill in, affect flow dynamics, and increase 
water temperature, exacerbating drought impacts in stream habitats 
(Colle et al. 1987, p. 416).
    The Aquatic Nuisance Species (ANS) Task Force, co-chaired by the 
Service and the National Oceanic and Atmospheric Administration (NOAA), 
encourages State and interstate planning entities to develop management 
plans describing detection and monitoring efforts of aquatic nuisance 
and nonnative species, prevention efforts to stop their introduction 
and spread, and control efforts to reduce their impacts. Management 
plan approval by the ANS Task Force is required to obtain funding under 
Section 1204 of the ANS Prevention and Control Act. Each state within 
the range of the pyramid pigtoe has either a plan approved by or 
submitted to the ANS Task Force, or a plan under development. These 
plans have been effective in terms of raising awareness at the state 
level of the severity of ecological damage that non-native and nuisance 
species are capable of, but many are in early stages of implementation. 
Although laws and efforts are in place which may be effective in 
controlling or diminishing non-native and invasive species, these

[[Page 50000]]

organisms are a current and future threat to the pyramid pigtoe 
throughout its range.

Small Population Size

    Historically, an extensive, largely contiguous pyramid pigtoe 
population occurred through much of the eastern half of the United 
States, and there were limited barriers preventing genetic interchange 
among river systems. With the completion of hundreds of dams in the 
1900s, many large-river pyramid pigtoe populations were lost, resulting 
in isolation of tributary populations. The population size of a long-
lived species, such as the pyramid pigtoe, may take decades to decline 
to extirpation post-impoundment. At best, limited post-impoundment 
recruitment may be occurring in the isolated pyramid pigtoe 
populations, indicating that these small populations are not likely 
viable long term.
    Currently, the pyramid pigtoe exhibits several traits that reduce 
population viability, including small population size and low fecundity 
at many locations compared to other mussels. Smaller population size 
puts the species at greater risk of extirpation from stochastic events 
(e.g., drought) or anthropomorphic changes and management activities 
that affect habitat. In addition, smaller populations may have reduced 
genetic diversity, be less genetically fit, and more susceptible to 
disease during extreme environmental conditions (Frankham 1996, p. 
1,505). Moreover, small and isolated populations are at higher risk of 
further loss of genetic variation due to genetic drift, thereby 
lessening the affected species' ability to adapt to a continuously 
changing environment. Lastly, the relatively low fecundity, coupled 
with low juvenile survivorship, limit the pyramid pigtoe's ability to 
withstand and recover from population losses. While several populations 
of pyramid pigtoe are at risk of extirpation due to their small size, 
other populations are large enough and sufficiently connected within 
their MU that they are regularly recruiting new cohorts. Therefore, 
small population size is a population-level threat but not currently a 
species-level or rangewide threat.

Changing Climate Conditions

    Climate change threats for freshwater mussels include alteration of 
natural stream flow and water temperature regimes as drought, 
precipitation, and temperature patterns shift. Population discontinuity 
and isolation is possible due to the dynamics in range shifts of 
mussels and their host fishes as a result of warming climates, based on 
life-history traits (Archambault et al. 2018, p. 880). However, the 
mechanisms behind these shifts and how they alter population 
connectivity and gene flow are uncertain, and there is no evidence 
linking climate change impacts specifically to the current status of 
the pyramid pigtoe.

Cumulative/Synergistic Effects

    Collectively, threats to the pyramid pigtoe have acted on the 
species to reduce the number of historical populations and fragment and 
reduce the size of extant populations. Currently, 15 of the 35 extant 
populations are small in size, represented by fewer than 10 individuals 
observed over the past 20 years. Factors such as low effective 
population size, genetic isolation, relatively low levels of fecundity 
and recruitment, and limited juvenile survival could affect the ability 
of these species to maintain current population levels and to rebound 
if a reduction in population occurs (e.g., through predation, toxic 
releases or spills, or poor environmental conditions that inhibit 
successful reproduction). Additionally, fragmentation (i.e., the 
breaking apart of habitat segments, independent of habitat loss (Fahrig 
2003; p. 299)) and isolation contribute to the extinction risk that 
mussel populations face from stochastic events (see Haag 2012, pp. 336-
338). Throughout the range of the pyramid pigtoe, impoundments fragment 
and isolate populations from one another, prevent dispersal, which 
reduces gene flow (Vaughn 2012, p. 6; Service 2018, pp. 59-60; Service 
2019, p. 74), and compound other threats, such as the introduction of 
contaminants and pollution resulting from mining, oil and gas 
exploration, agricultural runoff, and untreated or poorly treated 
wastewater discharges.
Current Conditions
    Current (and future) conditions are described using the following 
categories that characterize the overall condition (resiliency) of the 
pyramid pigtoe populations:
     High--Population with more than 50 individuals reported 
since 2000, distributed over a more or less contiguous river or stream 
of at least 31 miles (mi) (50 kilometers (km)) in length, with evidence 
of recent recruitment. Water quality and habitat conditions remain 
optimal for recruitment, and multiple age classes are represented. 
Populations are not linearly distributed and occur in more than one 
stream within the river system.
     Medium--small restricted populations (10 to 50 individuals 
reported since 2000) generally distributed over a more or less 
contiguous length of river or stream of at least 6.2 mi (10 km) but 
less than 31 mi (50 km)), with some level of age class structure, but 
vulnerable to existing threats. Appropriate substrates are generally 
maintained with instream flows that mimic natural conditions. Water 
quality and habitat degradation may occur but not at a level that 
negatively affects both the density and extent of a population.
     Low--very small and highly restricted populations (fewer 
than 10 individuals reported since 2000), distributed over less than 
6.2 mi (10 km) of river or stream, with little to no evidence of age 
class structure (only older individuals observable). Loss of mussel 
habitat or water quality degradation within the formerly occupied river 
or stream reach has been measured or observed, and imminent threats are 
documented. Population is linearly distributed and geographically 
restricted and is not likely to withstand stochastic events.
    We assessed resiliency and redundancy based on management units 
(MUs) defined at the hydrologic unit code (HUC) scale (Seaber et al. 
1987, entire; U.S. Geological Survey 2018, entire). Management units 
consisted of HUC-8 regions, which are analogous to medium-sized river 
basins across the United States. An MU consisting of a linear reach of 
stream could harbor one population or, if it contained a large gap in 
the species' distribution as a result of an impoundment or 
physiographic boundary, more than one population. If multiple 
tributaries were occupied (dendritic distribution) each tributary 
within the MU was considered to represent a population. A majority of 
MUs contained one population, given that the pyramid pigtoe occurs only 
in large or medium-sized rivers and not smaller tributaries.
    Representation was assessed at the larger HUC-2 region (major 
basin) scale, and representation units were delineated to capture the 
variation in adaptive traits and genetic diversity. See chapter 2 in 
the SSA report for further explanation of the analysis methodology 
(Service 2021, pp. 20-22). Each major basin contains unique 
physiographic provinces and ecoregions. Therefore, the populations 
within each major basin may harbor basin-specific adaptive traits and 
as such species representation has been reduced from six basins to four 
basins. Historical connectivity between the major basins has been lost 
due habitat degradation and construction of

[[Page 50001]]

impoundments and there is no opportunity for exchange of beneficial, or 
adaptive, genes between the basins.
    The pyramid pigtoe's current range extends over nine States, 
including Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Ohio, 
Oklahoma, Tennessee, and Virginia. The species is considered extirpated 
in Indiana, Illinois, Iowa, Kansas, Minnesota, Missouri, Pennsylvania, 
West Virginia, and Wisconsin. Its current range is within four major 
HUC-2 regions (the Arkansas-White-Red, Lower Mississippi, Ohio, and 
Tennessee River regions, Figure 1). It is extirpated in the Missouri 
and Upper Mississippi River HUC-2 regions. Overall, the pyramid pigtoe 
formerly occupied at least 135 MUs but currently occurs in 28 MUs 
(Figure 2). Known populations have declined in number, from 151 
historically to 35 today. Currently, 15 MUs have low resiliency, 9 MUs 
have medium resiliency, and 4 MUs have high resiliency (Table 2, in 
Future Conditions).
BILLING CODE 4333-15-P

[[Page 50002]]

[GRAPHIC] [TIFF OMITTED] TP07SE21.022

BILLING CODE 4333-15-C
Future Conditions
    In the SSA report, we forecast the pyramid pigtoe's response to 
plausible future scenarios of environmental conditions. The future 
scenarios project the range in magnitude and scope of threats into the 
future. Uncertainty is inherent in any risk assessment, so we must 
consider plausible conditions to make our determinations. When 
assessing the future, viability is not a specific state, but rather a 
continuous measure of the likelihood that the species will sustain 
populations over time.
    The scenarios described in the SSA report represent two possible 
future conditions. Under scenario 1, the threat

[[Page 50003]]

levels remain unchanged (threats continue to act on the species at the 
current rate), whereas under scenario 2 the threat levels increase. 
Both scenarios project existing regulatory mechanisms and voluntary 
conservation measures benefiting the species remaining in place. We did 
not analyze a scenario whereby threat levels lessen because the primary 
threats that have fragmented and isolated populations will persist. 
Developed areas, large dams, and most of the small and retired dams 
affecting the species will remain in place.
    We included climate change in our future scenarios as a factor that 
would add to the negative impacts of the primary threats on the 
species' habitat. Climate change is expected to alter the natural flow 
regime through increased drought and flooding worsening desiccation, 
scour, and sedimentation in each MU. However, in our analysis the 
influence of climate change, as a secondary threat, does not alter the 
projected future viability of any population or management unit. Those 
future outcomes are driven by the primary threats of habitat alteration 
or loss, nonnative invasive species, and the effects of small 
population size.
    Using the scenarios, we project the pyramid pigtoe's viability over 
20 to 30 years. We selected this duration because the species is slow 
growing and long-lived and has relatively low fecundity; long-term 
trend information on pyramid pigtoe abundance and threats is not 
available across the species' range to contribute to meaningful 
alternative timeframes.
    Future resiliency of pyramid pigtoe populations depends on the 
extent to which the species' needs are met for water quality, flow, 
substrate suitability, abundance and distribution of host fish species, 
and habitat connectivity. We projected the expected future resiliency 
of each population based on how events likely to occur under each 
scenario would affect the species' resource needs. Future resiliency of 
each population is classified as high, medium, low, or very low. Where 
multiple populations occur within an MU, the MU condition is the 
average of the population condition classifications; however, there are 
no management units where the population classifications vary (i.e., 
all populations within the MU have the same classification). These 
projections are informed by development planning documents, peer-
reviewed literature, vetting of initial condition ranking by mussel 
experts, and our best professional judgment. Very low condition 
populations will become extirpated; low condition populations will 
become functionally extirpated (no recruitment); medium condition 
populations will exhibit limited recruitment and be linearly 
distributed and thus will have impaired ability to recover from 
disturbances and will be vulnerable to catastrophic events; and high 
condition populations will consistently recruit and be distributed over 
long distances and in connected mainstem and tributary river reaches 
(see SSA report for detailed future condition category definitions, 
Service 2021, pp. 84-85).
    Our analysis shows that whether threats remain constant or increase 
into the future, all 35 populations are expected to experience negative 
changes to their important habitat requisites or resource needs, and 
the condition of many of the populations would decrease (Table 2). 
Under scenario 1, we expect 23 populations will be in low or very low 
condition and 9 in medium condition, with no to little resiliency, 
respectively. The remaining 3 populations occurring within the Saline 
or Upper Ouachita Rivers, where the impact of impoundments is not as 
severe as elsewhere in the species' range, are expected to maintain a 
high condition. Under scenario 2, we expect 31 populations to be either 
functionally extirpated (low condition) or extirpated (very low 
condition) and 4 to be in medium condition. With increasing threat 
levels, the population condition of the Saline and Upper Ouachita 
Rivers decline, and, thus, within 20 to 30 years no high condition 
populations remain.

   Table 2--Summary of Pyramid Pigtoe Current Mussel Population Size, Extent, Threat Level, and Projected Future Conditions. Only Overall Condition Is
                                                               Listed for Future Scenarios
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  Contiguous                                                                                    Future condition
       Management unit            population      Population size     Population       Threat level        Current     ---------------------------------
                               (occupied river)                         extent                            condition        Scenario 1       Scenario 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       OHIO BASIN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Muskingum....................  Muskingum River.  Small...........  Small...........  High............  Low............  Very Low.......  Very Low.
Upper Green..................  Upper Green       Large...........  Large...........  Low.............  High...........  Medium.........  Medium.
                                River.
Barren.......................  Barren River....  Small...........  Small...........  Mod.............  Med............  Medium.........  Low.
Middle Green.................  Middle Green      Medium..........  Medium..........  Mod.............  Med............  Medium.........  Low.
                                River.
Lower Green..................  Lower Green       Small...........  Small...........  Mod.............  Low............  Low............  Very Low.
                                River.
Lower Cumberland-Old Hickory   Cumberland River  Medium..........  Small...........  High............  Low............  Very Low.......  Very Low.
 Lake.                          (Old Hickory
                                Reservoir)
                                Cordell Hull
                                Tailwater.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     TENNESSEE BASIN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Holston......................  Holston River...  Small...........  Small...........  High............  Low............  Very Low.......  Very Low.
Upper Clinch.................  Clinch River....  Medium..........  Medium..........  Mod.............  Med............  Low............  Low.
Wheeler Lake.................  Paint Rock River  Small...........  Small...........  Mod.............  Low............  Low............  Very Low.
                               Tennessee River   Medium..........  Small...........  High............  Low............  Low............  Very Low.
                                (Wheeler
                                Reservoir)
                                Guntersville
                                Tailwater.
Pickwick Lake................  Tennessee River   Medium..........  Medium..........  High............  Low............  Low............  Low.
                                (Pickwick
                                Reservoir)
                                Wilson
                                Tailwater.
Lower Tennessee-Beech........  Tennessee River   Small...........  Small...........  High............  Low............  Low............  Low.
                                (Kentucky
                                Reservoir)
                                Pickwick
                                Tailwater.
Upper Duck...................  Upper Duck River  Large...........  Medium..........  Mod.............  Med............  Medium.........  Low.
Lower Duck...................  Lower Duck River  Large...........  Small...........  Mod.............  Med............  Low............  Very Low.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                ARKANSAS-WHITE-RED BASIN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Petit Jean...................  Petit Jean River  Small...........  Small...........  Mod.............  Low............  Low............  Very Low.
Eleven Point.................  Eleven Point      Small...........  Small...........  Low.............  Low............  Low............  Very Low.
                                River.

[[Page 50004]]

 
Lower Little.................  Little River....  Medium..........  Small...........  Mod.............  Low............  Low............  Very Low.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 LOWER MISSISSIPPI BASIN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lower Black..................  Lower Black       Small...........  Small...........  Mod.............  Low............  Low............  Very Low.
                                River.
Lower St. Francis............  St. Francis       Medium..........  Small...........  High............  Med............  Medium.........  Low.
                                River.
                               Tyronza River...  Medium..........  Large...........  High............  Med............  Medium.........  Low.
Middle White.................  Middle White      Small...........  Small...........  Mod.............  Low............  Low............  Very Low.
                                River.
Upper Ouachita...............  Upper Ouachita    Large...........  Large...........  Mod.............  High...........  High...........  Medium.
                                River.
Little Missouri..............  Little Missouri   Large...........  Medium..........  Mod.............  Med............  Medium.........  Low.
                                River.
Lower Ouachita-Smackover.....  Lower Ouachita    Medium..........  Medium..........  Mod.............  Med............  Medium.........  Low.
                                River
                                (Smackover).
Upper Saline.................  Upper Saline      Large...........  Large...........  Mod.............  High...........  High...........  Medium.
                                River.
Lower Saline.................  Lower Saline      Large...........  Large...........  High............  High...........  High...........  Medium.
                                River.
Bayou Bartholomew............  Bayou             Large...........  Large...........  High............  Med............  Medium.........  Low.
                                Bartholomew.
Lower Ouachita-Bayou De        Lower Ouachita    Medium..........  Medium..........  High............  Low............  Low............  Low.
 Loutre.                        River (Bayou De
                                Loutre).
Big Sunflower................  Hushpuckna River  Small...........  Small...........  High............  Med............  Low............  Very Low.
                               Bogue Phalia....  Small...........  Small...........  High............  Med............  Low............  Very Low.
                               Little Sunflower  Small...........  Small...........  High............  Med............  Low............  Very Low.
                                River.
                               Sunflower River.  Medium..........  Large...........  High............  Med............  Low............  Very Low.
                               Sandy Bayou.....  Small...........  Small...........  High............  Med............  Low............  Very Low.
                               Big Sunflower     Medium..........  Large...........  High............  Med............  Low............  Very Low.
                                River.
Lower Big Black..............  Big Black River.  Small...........  Small...........  High............  Low............  Very Low.......  Very Low.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The viability implications associated with the expected change in 
population conditions can be discerned at the MU and HUC-2 scales. 
Under scenario 1, we expect 3 MUs (11 percent) remain in high 
condition; 9 MUs (32 percent), in medium condition; 12 MUs (43 
percent), in low condition; and 4 (14 percent), in very low condition. 
Therefore, the species' ability to withstand natural environmental 
variation and threats will be greatly limited. Loss of the three MUs 
reduces the species' distribution, increasing its risk to catastrophic 
events. The pyramid pigtoe will continue to be represented in the Ohio, 
Tennessee, and Lower Mississippi basins, but reduced to six States (as 
compared to the current nine States) occupied by the species. 
Representation will be lost from the Arkansas-White-Red basin, as all 
of its MUs are expected to be in low condition. It will take many years 
(potentially beyond the 20- to 30-year timeframe analyzed), for full 
evaluation of the species' response to any current beneficial actions, 
such as removal of Lock and Dam 6 on the Green River, or the safe 
harbor agreements and candidate conservation agreements with assurances 
in the Upper Ouachita and Upper Saline Rivers.
    Under scenario 2, none of the MUs are expected to be in high 
condition, 4 (14 percent) are in medium condition, 11 (39 percent) are 
in low condition, and 13 (46 percent) are in very low condition. Given 
no MUs will be in high condition, the species' ability to withstand 
natural environmental variation and threats will be substantially 
limited. Redundancy will also be substantially reduced with no high 
condition MUs remaining and the expected loss of 13 (46 percent) MUs. 
Loss of the species from the Arkansas-White-Red basin, with no high 
condition MUs in any basin, and potential extirpation of the species 
from the States of Virginia, Ohio, Oklahoma, and Mississippi will 
substantially reduce the species' genetic diversity, thereby decreasing 
its ability to adapt to changing environmental conditions.
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the factors that may be 
influencing the species, including threats and conservation efforts. 
Because the SSA framework considers not just the presence of the 
factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.
Conservation Efforts and Regulatory Mechanisms
    As discussed under Threats, Federal and State lands and water 
quality regulations afford the pyramid pigtoe and its habitats some 
protection from land development, industrial, and transportation 
activities. Additionally, laws intended to reduce the threat of 
nonnative species are in place. Many populations of the pyramid pigtoe 
were extirpated or reduced prior to development of modern conservation 
programs and regulatory mechanisms. As such, historical threats no 
longer present on the landscape impart a legacy effect (small 
population size or degraded habitat) on some current populations. 
Further, some water quality regulations have not been fully adopted or 
consistently applied across the species' range. Therefore, despite the 
existing regulatory mechanisms in place, the combined threats and 
impacts of actions that occurred prior to the implementation of these 
regulatory mechanisms continue to negatively affect the pyramid pigtoe.

Determination of Pyramid Pigtoe Status

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species meets the definition of an endangered species or a 
threatened species. The Act defines an endangered species as a species 
``in

[[Page 50005]]

danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as a species ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The Act requires that we determine 
whether a species meets the definition of an endangered species or a 
threatened species because of any of the following factors: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) the 
inadequacy of existing regulatory mechanisms; or (E) other natural or 
manmade factors affecting its continued existence.
Status Throughout All of Its Range
    Historically, the pyramid pigtoe occurred within 151 populations 
and 136 MUs, in 6 basins across 18 States (Figure 2). Currently, the 
species occurs within 35 populations and 28 MUs, in 4 basins across 9 
States, which represents a 77 percent reduction of its historically 
occupied populations. Of the extant MUs, 4 are highly resilient, while 
9 and 15 have medium and low resiliency, respectively. The threats 
leading to its current condition include past and ongoing habitat 
degradation or loss (Factor A), residual impacts from past harvest and 
overutilization (Factor B), and ongoing competition, predation, and 
habitat alteration from invasive, nonnative species (Factor E). 
Collectively, these threats reduce population abundance, thereby 
precipitating negative genetic and demographic effects associated with 
small population size (Factor E) within some of the smaller 
populations. Although downtrends from historical numbers are evident 
and declines are likely to continue, four high resilient MUs are 
distributed across two of the four occupied major river basins. These 
four MUs provide for current representation and redundancy of the 
species. Thus, after assessing the best available information, we 
conclude that the pyramid pigtoe is not in danger of extinction 
throughout all of its range. We, therefore, proceed with determining 
whether the pyramid pigtoe is likely to become endangered within the 
foreseeable future throughout all of its range.
    The best available information suggests that the threats currently 
acting upon the pyramid pigtoe will continue into the foreseeable 
future. In areas experiencing human population and land development 
growth, these threats (e.g., water quality and habitat degradation) are 
reasonably expected to increase over time, further reducing the 
species' resiliency, redundancy, and representation. Our foreseeable 
future (20 to 30 years) reflects the period of time over which we can 
reliably predict both the threats to the pyramid pigtoe and the pyramid 
pigtoe's response to those threats based on the best available 
information. Within the foreseeable future, even if threats were to 
remain at current levels and not increase, 23 of the 35 populations are 
projected to become extirpated or functionally extirpated (Table 2). 
Additionally, with no change in threat levels, the condition of one of 
the four high resilient populations will decline to medium resiliency 
and the remaining three high resilient populations would be confined to 
a single basin. At the MU scale, only 3 of the 28 extant MUs remain in 
high condition, with 17 MUs projected to become extirpated or 
functionally extirpated within 20 to 30 years. If threats increase, 19 
populations will likely be extirpated within 20 to 30 years, leading to 
only 4 MUs persisting. These MUs will have limited recruitment 
potential and restricted distribution, thus impairing the species' 
ability to recover from disturbances and increasing its vulnerability 
to catastrophic events. In summary, threats currently acting on the 
species are likely to persist or increase in the foreseeable future, 
resulting in zero to three high resilient populations in one of its six 
historical major basins and resulting in a high risk of impacts from a 
single catastrophe or stochastic events. Thus, after assessing the best 
available information, we conclude that the pyramid pigtoe is likely to 
become in danger of extinction within the foreseeable future throughout 
all of its range.
Status Throughout a Significant Portion of Its Range
    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. The court in Center for Biological Diversity v. Everson, 
2020 WL 437289 (D.D.C. Jan. 28, 2020) (Center for Biological 
Diversity), vacated the aspect of the Final Policy on Interpretation of 
the Phrase ``Significant Portion of Its Range'' in the Endangered 
Species Act's Definitions of ``Endangered Species'' and ``Threatened 
Species'' (79 FR 37578; July 1, 2014) that provided that the Service 
does not undertake an analysis of significant portions of a species' 
range if the species warrants listing as threatened throughout all of 
its range. Therefore, we proceed to evaluating whether the species is 
endangered in a significant portion of its range--that is, whether 
there is any portion of the species' range for which both (1) the 
portion is significant and (2) the species is in danger of extinction 
in that portion. Depending on the case, it might be more efficient for 
us to address the ``significance'' question or the ``status'' question 
first. We can choose to address either question first. Regardless of 
which question we address first, if we reach a negative answer with 
respect to the first question that we address, we do not need to 
evaluate the other question for that portion of the species' range.
    Following the court's holding in Center for Biological Diversity, 
we now consider whether there are any significant portions of the 
species' range where the species is in danger of extinction now (i.e., 
endangered). In undertaking this analysis for the pyramid pigtoe, we 
choose to address the status question first--we consider information 
pertaining to the geographic distribution of both the species and the 
threats that the species faces to identify any portions of the range 
where the species is endangered.
    For the pyramid pigtoe, we considered whether the threats are 
geographically concentrated in any portion of the species' range at a 
biologically meaningful scale. We examined the following threats: 
Habitat degradation or loss, invasive and nonnative species, and 
negative effects associated with small population size, including 
cumulative effects. Habitat degradation or loss, including diminished 
water quality, is a threat in all four basins occupied by the pyramid 
pigtoe, although the contribution by source (e.g., agriculture, 
urbanization, mining, dredging) varies. Invasive or nonnative species 
also is a threat in each occupied basin. Lastly, large populations 
(number of individuals) occur in three of the four basins, and medium 
populations occur in all four basins.
    We examined the Arkansas-White-Red basin (the only basin not 
containing any large populations) to determine if there is a 
concentration of threats because, of the three populations in the 
basin, two have a moderate threat level and one has a low threat level. 
All three of these populations are in a low current condition, and two 
of the three populations have small numbers of individuals. Thus, the 
cumulative effects of small population size with the other identified 
threats may be concentrated in this basin.

[[Page 50006]]

    We then evaluated whether the Arkansas-White-Red basin may be 
biologically important to the overall species' viability, i.e., 
significant. This basin contains 3 of the 35 (8.6 percent) pyramid 
pigtoe populations. By length of river, the populations combined occupy 
about 5 percent of the species' range. Therefore, the populations in 
the Arkansas-White-Red basin minimally contribute to the overall 
viability of the species.
    The pyramid pigtoe occurs in similar habitats across the four 
basins it occupies and does not use unique observable environmental 
characteristics attributable to any of the basins. The Arkansas-White-
Red basin populations occur in stream habitat with substrate types and 
water quality similar to the other basins where the pyramid pigtoe 
performs the important life-history functions of breeding, feeding, and 
sheltering. The basin does not act as a refugium for the species or as 
an important spawning ground. In addition, the water quality is similar 
throughout the species' range, with impaired water quality occurring in 
all four basins. Because the pyramid pigtoe occurs in similar aquatic 
habitats, the Arkansas-White-Red basin population exhibits similar 
habitat use as populations in the remainder of the range.
    Overall, we found no substantial information that would indicate 
the Arkansas-White-Red basin is a portion of the range that may be 
significant in terms of its overall contribution to the species' 
resiliency, redundancy, and representation, or that it is significant 
in terms of high-quality habitat or habitat that is otherwise important 
for the species' life history. Additionally, within each of the other 
three basins (or portions of the range) there was no concentration of 
threats that would indicate the species is facing elevated threats in 
those portions. As a result, we determined there is no portion of the 
pyramid pigtoe's range that constitutes a significant portion of the 
range where the species is currently endangered. Accordingly, we 
determine that the species is likely to become in danger of extinction 
within the foreseeable future throughout all of its range. This is 
consistent with the courts' holdings in Desert Survivors v. Department 
of the Interior, No. 16-cv-01165-JCS, 2018 WL 4053447 (N.D. Cal. Aug. 
24, 2018), and Center for Biological Diversity v. Jewell, 248 F. Supp. 
3d, 946, 959 (D. Ariz. 2017).
Determination of Status
    Our review of the best available scientific and commercial 
information indicates that the pyramid pigtoe meets the definition of a 
threatened species. Therefore, we propose to list the pyramid pigtoe as 
a threatened species in accordance with sections 3(20) and 4(a)(1) of 
the Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened species under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies and 
the prohibitions against certain activities are discussed, in part, 
below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Section 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning consists of preparing draft and final recovery 
plans, beginning with the development of a recovery outline and making 
it available to the public following a final listing determination. The 
recovery outline guides the immediate implementation of urgent recovery 
actions and describes the process to be used to develop a recovery 
plan. Revisions of the plan may be done to address continuing or new 
threats to the species, as new substantive information becomes 
available. The recovery plan also identifies recovery criteria for 
review of when a species may be ready for reclassification from 
endangered to threatened (``downlisting'') or removal from protected 
status (``delisting''), and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (composed of species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) are often established to develop recovery plans. When 
completed, the recovery outline, draft recovery plan, and the final 
recovery plan will be available on our website (http://www.fws.gov/endangered), or from our Asheville Field Office (see FOR FURTHER 
INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    If this species is listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost-share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the States of Alabama, Arkansas, 
Kentucky, Louisiana, Mississippi, Ohio, Oklahoma, Tennessee, and 
Virginia would be eligible for Federal funds to implement management 
actions that promote the protection or recovery of the pyramid pigtoe. 
Information on our grant programs that are available to aid species 
recovery can be found at: http://www.fws.gov/grants.
    Although the pyramid pigtoe is only proposed for listing under the 
Act at this time, please let us know if you are interested in 
participating in recovery efforts for this species. Additionally, we 
invite you to submit any new information on this species whenever it 
becomes available and any information you may have for recovery 
planning purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as an 
endangered or threatened species and with respect to its critical 
habitat, if any is designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part

[[Page 50007]]

402. Section 7(a)(4) of the Act requires Federal agencies to confer 
with the Service on any action that is likely to jeopardize the 
continued existence of a species proposed for listing or result in 
destruction or adverse modification of proposed critical habitat. If a 
species is listed subsequently, section 7(a)(2) of the Act requires 
Federal agencies to ensure that activities they authorize, fund, or 
carry out are not likely to jeopardize the continued existence of the 
species or destroy or adversely modify its critical habitat. If a 
Federal action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into consultation with the 
Service.
    Federal agency actions within the species' habitat that may require 
conference, consultation, or both as described in the preceding 
paragraph include management and any other landscape-altering 
activities on Federal lands administered by the following:
    (1) U.S. Army Corps of Engineers (channel dredging and maintenance; 
dam projects including flood control, navigation, hydropower, bridge 
projects, stream restoration, and Clean Water Act permitting).
    (2) U.S. Department of Agriculture, including the Natural Resources 
Conservation Service and Farm Service Agency (technical and financial 
assistance for projects) and the Forest Service (aquatic habitat 
restoration, fire management plans, fire suppression, fuel reduction 
treatments, forest plans, mining permits).
    (3) U.S. Department of Energy (renewable and alternative energy 
projects).
    (4) Federal Energy Regulatory Commission (interstate pipeline 
construction and maintenance, dam relicensing, and hydrokinetics).
    (5) U.S. Department of Transportation (highway and bridge 
construction and maintenance).
    (6) U.S. Fish and Wildlife Service (issuance of section 10 permits 
for enhancement of survival, habitat conservation plans, and safe 
harbor agreements; National Wildlife Refuge planning and refuge 
activities; Partners for Fish and Wildlife program projects benefiting 
these species or other listed species; Wildlife and Sportfish 
Restoration program sportfish stocking).
    (7) Environmental Protection Agency (water quality criteria, 
permitting).
    (8) Tennessee Valley Authority (flood control, navigation, 
hydropower, and land management for the Tennessee River system).
    (9) Office of Surface Mining Reclamation and Enforcement (land 
resource management plans, mining permits, oil and natural gas permits, 
abandoned mine land projects, and renewable energy development).
    (10) National Park Service (aquatic habitat restoration, fire 
management plans, fire suppression, fuel reduction treatments, land 
management plans, mining permits).
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a proposed 
listing on proposed and ongoing activities within the range of the 
species proposed for listing. The discussion below regarding protective 
regulations under section 4(d) of the Act complies with our policy.

II. Proposed Rule Issued Under Section 4(d) of the Act

Background

    Section 4(d) of the Act contains two sentences. The first sentence 
states that the Secretary shall issue such regulations as he deems 
necessary and advisable to provide for the conservation of species 
listed as threatened. The U.S. Supreme Court has noted that statutory 
language like ``necessary and advisable'' demonstrates a large degree 
of deference to the agency (see Webster v. Doe, 486 U.S. 592 (1988)). 
Conservation is defined in the Act to mean 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 the Act are no longer necessary. Additionally, the second sentence 
of section 4(d) of the Act states that the Secretary may by regulation 
prohibit with respect to any threatened species any act prohibited 
under section 9(a)(1), in the case of fish or wildlife, or section 
9(a)(2), in the case of plants. Thus, the combination of the two 
sentences of section 4(d) provides the Secretary with wide latitude of 
discretion to select and promulgate appropriate regulations tailored to 
the specific conservation needs of the threatened species. The second 
sentence grants particularly broad discretion to the Service when 
adopting the prohibitions under section 9.
    The courts have recognized the extent of the Secretary's discretion 
under this standard to develop rules that are appropriate for the 
conservation of a species. For example, courts have upheld rules 
developed under section 4(d) as a valid exercise of agency authority 
where they prohibited take of threatened wildlife, or include a limited 
taking prohibition (see Alsea Valley Alliance v. Lautenbacher, 2007 
U.S. Dist. Lexis 60203 (D. Or. 2007); Washington Environmental Council 
v. National Marine Fisheries Service, 2002 U.S. Dist. Lexis 5432 (W.D. 
Wash. 2002)). Courts have also upheld 4(d) rules that do not address 
all of the threats a species faces (see State of Louisiana v. Verity, 
853 F.2d 322 (5th Cir. 1988)). As noted in the legislative history when 
the Act was initially enacted, ``once an animal is on the threatened 
list, the Secretary has an almost infinite number of options available 
to him with regard to the permitted activities for those species. He 
may, for example, permit taking, but not importation of such species, 
or he may choose to forbid both taking and importation but allow the 
transportation of such species'' (H.R. Rep. No. 412, 93rd Cong., 1st 
Sess. 1973).
    Exercising this authority under section 4(d), we have developed a 
proposed rule that is designed to address the pyramid pigtoe's 
conservation needs. Although the statute does not require us to make a 
``necessary and advisable'' finding with respect to the adoption of 
specific prohibitions under section 9, we find that this rule as a 
whole satisfies the requirement in section 4(d) of the Act to issue 
regulations deemed necessary and advisable to provide for the 
conservation of the pyramid pigtoe.
    As discussed above under Summary of Biological Status and Threats, 
we have concluded that the pyramid pigtoe is likely to become in danger 
of extinction within the foreseeable future primarily due to declines 
in water quality, alteration and deterioration of instream habitats, 
fragmentation and isolation of populations, and nonnative species. 
These threats, which are expected to be exacerbated by continued 
urbanization and land development, were central to our assessment of 
the future viability of the pyramid pigtoe. The provisions of this 
proposed 4(d) rule would promote conservation of the pyramid pigtoe by 
encouraging management of the landscape in ways that meet the 
conservation needs of the pyramid pigtoe and are consistent with land 
management considerations. The provisions of this proposed rule are one 
of many tools that we would use to promote the conservation of the 
pyramid pigtoe. This proposed 4(d) rule would apply only if and when we 
make final the listing of the pyramid pigtoe as a threatened species.
    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they fund,

[[Page 50008]]

authorize, or carry out is not likely to jeopardize the continued 
existence of any endangered species or threatened species or result in 
the destruction or adverse modification of designated critical habitat 
of such species. In addition, section 7(a)(4) of the Act requires 
Federal agencies to confer with the Service on any agency action which 
is likely to jeopardize the continued existence of any species proposed 
to be listed under the Act or result in the destruction or adverse 
modification of proposed critical habitat.
    If a Federal action may affect a listed species or its critical 
habitat, the responsible Federal agency (action agency) must enter into 
consultation with us. Examples of actions that are subject to the 
section 7 consultation process are actions on State, Tribal, local, or 
private lands that require a Federal permit or that involve some other 
Federal action such as funding, like those listed above under Available 
Conservation Measures. Federal actions not affecting listed species or 
critical habitat--and actions on State, Tribal, local, or private lands 
that are not federally funded, authorized, or carried out by a Federal 
agency--do not require section 7 consultation.
    This obligation does not change in any way for a threatened species 
with a species-specific 4(d) rule. Actions that a Federal agency 
determines ``may affect'' listed species or critical habitat continue 
to require consultation and actions that are ``likely to adversely 
affect'' a species require formal consultation and the formulation of a 
biological opinion.

Provisions of the Proposed 4(d) Rule

    This proposed 4(d) rule would provide for the conservation of the 
pyramid pigtoe by prohibiting the following activities, except as 
otherwise authorized or permitted: Importing or exporting; take; 
possession and other acts with unlawfully taken specimens; delivering, 
receiving, transporting, or shipping in interstate or foreign commerce 
in the course of commercial activity; or selling or offering for sale 
in interstate or foreign commerce.
    As discussed above under Summary of Biological Status and Threats, 
multiple factors are affecting the status of the pyramid pigtoe. A 
range of activities have the potential to affect the pyramid pigtoe, 
including declines in water quality, alteration and deterioration of 
instream habitats, fragmentation and isolation of populations, and 
nonnative species. These threats, which are expected to continue due to 
land development for urbanization, agriculture, and resource 
extraction, channel navigation, and dam operations were central to our 
assessment of the future viability of the pyramid pigtoe. Therefore, we 
prohibit actions resulting in the incidental take of the pyramid pigtoe 
by altering or degrading its habitat.
    Under the Act, ``take'' means to harass, harm, pursue, hunt, shoot, 
wound, kill, trap, capture, or collect, or to attempt to engage in any 
such conduct. Some of these provisions have been further defined in 
regulations at 50 CFR 17.3. Take can result knowingly or otherwise, by 
direct and indirect impacts, intentionally or incidentally. Regulating 
incidental and/or intentional take would help preserve the species' 
remaining populations, slow their rate of decline, and decrease 
synergistic, negative effects from other stressors.
    We may issue permits to carry out otherwise prohibited activities, 
including those described above, involving threatened wildlife under 
certain circumstances. Regulations governing permits are codified at 50 
CFR 17.32. With regard to threatened wildlife, a permit may be issued 
for the following purposes: For scientific purposes, to enhance 
propagation or survival, for economic hardship, for zoological 
exhibition, for educational purposes, for incidental taking, or for 
special purposes consistent with the purposes of the Act. The statute 
also contains certain exemptions from the prohibitions, which are found 
in sections 9 and 10 of the Act.
    The proposed 4(d) rule would also provide for the conservation of 
the species by allowing exceptions for take associated with actions and 
activities that, while they may have some minimal level of disturbance 
to pyramid pigtoe, are not expected to negatively impact conservation 
and recovery efforts for the species. The proposed exceptions to these 
prohibitions include incidental take associated with (1) conservation 
efforts by the Service or State wildlife agencies, (2) channel 
restoration projects, (3) bank restoration projects, and (4) take 
necessary to aid a sick or injured specimen, or to salvage a dead 
specimen.
    The first exception is for conservation and restoration efforts for 
pyramid pigtoe by the Service or State wildlife agencies, and 
including, but not limited to, collection of broodstock, tissue 
collection for genetic analysis, captive propagation, and subsequent 
stocking into unoccupied areas within the historical range of the 
species. We recognize the special and unique relationship with our 
State natural resource agency partners in contributing to conservation 
of listed species. State agencies often possess scientific data and 
valuable expertise on the status and distribution of endangered, 
threatened, and candidate species of wildlife and plants. State 
agencies, because of their authorities and their close working 
relationships with local governments and landowners, are in a unique 
position to assist the Service in implementing all aspects of the Act. 
In this regard, section 6 of the Act provides that the Service shall 
cooperate to the maximum extent practicable with the States in carrying 
out programs authorized by the Act. Therefore, any qualified employee 
or agent of a State conservation agency that is a party to a 
cooperative agreement with the Service in accordance with section 6(c) 
of the Act, who is designated by his or her agency for such purposes, 
would be able to conduct activities designed to conserve the pyramid 
pigtoe that may result in otherwise prohibited take without additional 
authorization.
    The second and third exceptions are for channel and bank 
restoration projects for creation of natural, physically stable, 
ecologically functioning streams, taking into consideration 
connectivity with floodplain and groundwater aquifers. These exceptions 
include a requirement that bank restoration projects require planting 
appropriate native vegetation, including woody species appropriate for 
the region and habitat. We also propose language that would require 
surveys and relocation prior to commencement of restoration actions for 
pyramid pigtoe that would otherwise be negatively affected by the 
actions. We reiterate that these actions and activities may have some 
minimal level of take of pyramid pigtoe, but any such take is expected 
to be rare and insignificant and is not expected to negatively impact 
conservation and recovery efforts. Rather, we expect they would have a 
net beneficial effect on the species. Across the species' range, 
instream habitats have been degraded physically by sedimentation and by 
direct and indirect channel disturbance. The habitat restoration 
activities in the proposed 4(d) rule are intended to improve habitat 
conditions for the species in the long term.
    Finally, the proposed 4(d) rule would allow take of pyramid pigtoe 
without a permit by any employee or agent of the Service or a State 
conservation agency designated by the agency for such purposes and when 
acting in the course of their official duties if such action is 
necessary to aid a sick or injured specimen, or to salvage a dead 
specimen which may be useful for scientific study. In addition, Federal 
and State wildlife law enforcement officers,

[[Page 50009]]

working in coordination with Service field office personnel, may 
possess, deliver, carry, transport, or ship pyramid pigtoe taken in 
violation of the Act as necessary.
    Nothing in this proposed 4(d) rule would change in any way the 
recovery planning provisions of section 4(f) of the Act, the 
consultation requirements under section 7 of the Act, or the ability of 
the Service to enter into partnerships for the management and 
protection of the pyramid pigtoe. However, interagency cooperation may 
be further streamlined through planned programmatic consultations for 
the species between Federal agencies and the Service, where 
appropriate. We ask the public, particularly State agencies and other 
interested stakeholders that may be affected by the proposed 4(d) rule, 
to provide comments and suggestions regarding additional guidance and 
methods that the Service could provide or use, respectively, to 
streamline the implementation of this proposed 4(d) rule (see 
Information Requested, above).

III. Critical Habitat

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, the Secretary shall designate critical habitat at the 
time the species is determined to be an endangered or threatened 
species. Our regulations (50 CFR 424.12(a)(1)) state that the Secretary 
may, but is not required to, determine that a designation would not be 
prudent in the following circumstances:
    (i) The species is threatened by taking or other human activity and 
identification of critical habitat can be expected to increase the 
degree of such threat to the species;
    (ii) The present or threatened destruction, modification, or 
curtailment of a species' habitat or range is not a threat to the 
species, or threats to the species' habitat stem solely from causes 
that cannot be addressed through management actions resulting from 
consultations under section 7(a)(2) of the Act;
    (iii) Areas within the jurisdiction of the United States provide no 
more than negligible conservation value, if any, for a species 
occurring primarily outside the jurisdiction of the United States;
    (iv) No areas meet the definition of critical habitat; or
    (v) The Secretary otherwise determines that designation of critical 
habitat would not be prudent based on the best scientific data 
available.
    As discussed earlier in this document, there is currently no 
imminent threat of collection or vandalism identified under Factor B 
for this species, and identification and mapping of critical habitat is 
not expected to initiate any such threat. In our SSA and proposed 
listing determination for the pyramid pigtoe, we determined that the 
present or threatened destruction, modification, or curtailment of 
habitat or range is a threat to the pyramid pigtoe and that those 
threats in some way can be addressed by section 7(a)(2) consultation 
measures. The species occurs wholly in the jurisdiction of the United 
States, and we are able to identify areas that meet the definition of 
critical habitat. Therefore, because none of the circumstances 
enumerated in our regulations at 50 CFR 424.12(a)(1) have been met and 
because there are no other circumstances the Secretary has identified 
for which this designation of critical habitat would be not prudent, we 
have determined that the designation of critical habitat is prudent for 
the pyramid pigtoe.
Critical Habitat Determinability
    Having determined that designation is prudent, under section 
4(a)(3) of the Act we consider whether critical habitat for the pyramid 
pigtoe is determinable. Our regulations at 50 CFR 424.12(a)(2) state 
that critical habitat is not determinable when one or both of the 
following situations exist:
    (i) Data sufficient to perform required analyses are lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to identify any area that meets the definition of ``critical 
habitat.''
    For the pyramid pigtoe, the species' needs are sufficiently well 
known. However, there is some uncertainty regarding the taxonomic 
identity of populations outside the Ohio, Cumberland, and Tennessee 
River basins (see Background), which is currently under investigation 
using different genetic markers than assessed thus far. Results of this 
taxonomic investigation, which may more accurately delineate the 
species' occupied range, are likely to be completed and submitted to a 
peer-reviewed journal within 1 year. In addition to this taxonomic 
investigation that may better determine critical habitat areas, a 
careful assessment of the economic impacts that may occur due to a 
critical habitat designation is ongoing, and we are in the process of 
acquiring the necessary information to perform that assessment. Because 
the information sufficient to perform a required analysis of the 
impacts of the designation is lacking, we find designation of critical 
habitat for the pyramid pigtoe to be not determinable at this time. The 
Act allows the Service an additional year to publish a critical habitat 
designation that is not determinable at the time of listing (16 U.S.C. 
1533(b)(6)(C)(ii)).

Required Determinations

Clarity of the Rule
    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the numbers of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
    It is our position that, outside the jurisdiction of the U.S. Court 
of Appeals for the Tenth Circuit, we do not need to prepare 
environmental analyses pursuant to the National Environmental Policy 
Act (NEPA; 42 U.S.C. 4321 et seq.) in connection with regulations 
adopted pursuant to section 4(a) of the Act. We published a notice 
outlining our reasons for this determination in the Federal Register on 
October 25, 1983 (48 FR 49244). This position was upheld by the U.S. 
Court of Appeals for the Ninth Circuit (Douglas County v. Babbitt, 48 
F.3d 1495 (9th Cir. 1995), cert. denied 516 U.S. 1042 (1996)).
Government-to-Government Relationship With Tribes
    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal

[[Page 50010]]

Governments), and the Department of the Interior's manual at 512 DM 2, 
we readily acknowledge our responsibility to communicate meaningfully 
with recognized Federal Tribes on a government-to-government basis. In 
accordance with Secretarial Order 3206 of June 5, 1997 (American Indian 
Tribal Rights, Federal-Tribal Trust Responsibilities, and the 
Endangered Species Act), we readily acknowledge our responsibilities to 
work directly with Tribes in developing programs for healthy 
ecosystems, to acknowledge that Tribal lands are not subject to the 
same controls as Federal public lands, to remain sensitive to Indian 
culture, and to make information available to Tribes. There are no 
Tribal lands within or adjacent to known pyramid pigtoe occupied 
habitat. We will coordinate with Tribes whose lands are close to 
pyramid pigtoe populations.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at http://www.regulations.gov and upon request from the 
Asheville Ecological Services Field Office (see FOR FURTHER INFORMATION 
CONTACT).

Authors

    The primary authors of this proposed rule are the staff members of 
the Fish and Wildlife Service's Species Assessment Team and the 
Asheville Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

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

    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--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.


0
2. Amend Sec.  17.11(h) by adding an entry for ``Pigtoe, pyramid'' to 
the List of Endangered and Threatened Wildlife in alphabetical order 
under Clams to read as set forth below:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
            Common name                 Scientific name          Where listed              Status             Listing citations and applicable rules
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      * * * * * * *
               Clams
 
                                                                      * * * * * * *
Pigtoe, pyramid....................  Pleurobema rubrum....  Wherever found.......  T....................  [Federal Register citation when published as a
                                                                                                           final rule]; 50 CFR 17.45(e); \4d\.
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------



0
3. As proposed to be added at 83 FR 51570 (Oct. 11, 2018), and amended 
at 85 FR 44821 (July 24, 2020), 85 FR 59487 (Sept. 22, 2020), 85 FR 
61384 (Sept. 29, 2020), and 86 FR 47916 (August 26, 2021), Sec.  17.45 
is further amended by adding paragraph (e) to read as follows:


Sec.  17.45  Special rules--snails and clams.

* * * * *
    (e) Pyramid pigtoe (Pleurobema rubrum).
    (1) Prohibitions. The following prohibitions that apply to 
endangered wildlife also apply to the pyramid pigtoe. Except as 
provided under paragraph (e)(2) of this section and Sec. Sec.  17.4 and 
17.5, it is unlawful for any person subject to the jurisdiction of the 
United States to commit, to attempt to commit, to solicit another to 
commit, or cause to be committed, any of the following acts in regard 
to this species:
    (i) Import or export, as set forth at Sec.  17.21(b) for endangered 
wildlife.
    (ii) Take, as set forth at Sec.  17.21(c)(1) for endangered 
wildlife.
    (iii) Possession and other acts with unlawfully taken specimens, as 
set forth at Sec.  17.21(d)(1) for endangered wildlife.
    (iv) Interstate or foreign commerce in the course of commercial 
activity, as set forth at Sec.  17.21(e) for endangered wildlife.
    (v) Sale or offer for sale, as set forth at Sec.  17.21(f) for 
endangered wildlife.
    (2) Exceptions from prohibitions. In regard to this species, you 
may:
    (i) Conduct activities as authorized by a permit under Sec.  17.32.
    (ii) Take, as set forth at Sec.  17.21(c)(3) and (4) for endangered 
wildlife.
    (iii) Take as set forth at Sec.  17.31(b).
    (iv) Take incidental to an otherwise lawful activity caused by:
    (A) Channel restoration projects that create natural, physically 
stable, ecologically functioning streams (or stream and wetland 
systems). These projects can be accomplished using a variety of 
methods, but the desired outcome is a natural channel with low shear 
stress (force of water moving against the channel); bank heights that 
enable reconnection to the floodplain; connection of surface and 
groundwater systems, resulting in perennial flows in the channel; 
riffles and pools composed of existing soil, rock, and wood instead of 
large imported materials; low compaction of soils within adjacent 
riparian areas; and inclusion of riparian wetlands. Streams 
reconstructed in this way would offer suitable habitats for the pyramid 
pigtoe and contain stable channel features, such as pools, glides, 
runs, and riffles, which could be used by the species and its host fish 
for spawning, rearing, growth, feeding, migration, and other normal 
behaviors. Prior to commencement of restoration actions, surveys to 
determine presence of the pyramid pigtoe must be performed, and, if any 
pyramid pigtoe are located, in coordination with the local Service 
field office, they must be relocated prior to project implementation 
and monitored post-implementation. To qualify under this exemption, a 
channel restoration project must satisfy all Federal, State, and local 
permitting requirements.
    (B) Bank restoration projects that use bioengineering methods to 
replace preexisting, bare, eroding stream banks with vegetated, stable 
stream banks, thereby reducing bank erosion and instream sedimentation 
and improving habitat conditions for the species. Following these 
bioengineering methods, stream banks may be stabilized using native 
species live stakes (live, vegetative cuttings inserted

[[Page 50011]]

or tamped into the ground in a manner that allows the stake to take 
root and grow), native species live fascines (live branch cuttings, 
usually willows, bound together into long, cigar-shaped bundles), or 
native species brush layering (cuttings or branches of easily rooted 
tree species layered between successive lifts of soil fill). Bank 
restoration projects would require planting appropriate native 
vegetation, including woody species appropriate for the region and 
habitat. These methods will not include the sole use of quarried rock 
(rip-rap) or the use of rock baskets or gabion structures. Prior to 
commencement of bank stabilization actions, surveys to determine 
presence of pyramid pigtoe must be performed, and, if any pyramid 
pigtoe are located, in coordination with the local Service field 
office, they must be relocated prior to project implementation and 
monitored post-implementation. To qualify under this exemption, a bank 
restoration project must satisfy all Federal, State, and local 
permitting requirements.
    (v) Possess and engage in other acts with unlawfully taken 
wildlife, as set forth at Sec.  17.21(d)(2) for endangered wildlife.

Martha Williams,
Principal Deputy Director, Exercising the Delegated Authority of the 
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2021-19091 Filed 9-3-21; 8:45 am]
BILLING CODE 4333-15-P