[Federal Register Volume 89, Number 175 (Tuesday, September 10, 2024)]
[Proposed Rules]
[Pages 73330-73349]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-20158]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2024-0130; FXES111109FEDR-245-FF09E21000]
RIN 1018-BH45


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for the Alabama Hickorynut and Threatened Status With Section 
4(d) Rule for Obovaria cf. unicolor

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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[[Page 73331]]

SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
list the Alabama hickorynut (Obovaria unicolor) as an endangered 
species and the undescribed Obovaria cf. unicolor as a threatened 
species under the Endangered Species Act of 1973 (Act), as amended. 
Both species are freshwater mussels. This document also serves as our 
12-month finding on a petition to list the Alabama hickorynut. For 
Obovaria cf. unicolor, we also propose a rule issued under section 4(d) 
of the Act to provide for the conservation of the species. If we adopt 
this rule as proposed, it would apply the protections of the Act to 
these species. We find that designation of critical habitat for both 
the Alabama hickorynut and Obovaria cf. unicolor is prudent but not 
determinable at this time.

DATES: We will accept comments received or postmarked on or before 
November 12, 2024. 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 25, 2024.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter FWS-R4-ES-2024-0130, 
which is the docket number for this rulemaking. 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 submit a comment by clicking on 
``Comment.''
    (2) By hard copy: Submit by U.S. mail to: Public Comments 
Processing, Attn: FWS-R4-ES-2024-0130, 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 https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Information Requested, below, for more information).
    Availability of supporting materials: Supporting materials, such as 
the species status assessment report, are available at https://www.regulations.gov under Docket No. FWS-R4-ES-2024-0130.

FOR FURTHER INFORMATION CONTACT: Bill Pearson, Field Supervisor, U.S. 
Fish and Wildlife Service, Alabama Ecological Services Field Office, 
1208 Main Street, Daphne, AL 36526; telephone 251-441-5870. Individuals 
in the United States who are deaf, deafblind, hard of hearing, or have 
a speech disability may dial 711 (TTY, TDD, or TeleBraille) to access 
telecommunications relay services. Individuals outside the United 
States should use the relay services offered within their country to 
make international calls to the point-of-contact in the United States. 
Please see Docket No. FWS-R4-ES-2024-0130 on https://www.regulations.gov for a document that summarizes this rulemaking.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act (16 U.S.C. 1531 et 
seq.), a species warrants listing if it meets the definition of an 
endangered (in danger of extinction throughout all or a significant 
portion of its range) or a threatened species (likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range). If we determine that a species 
warrants listing, we must list the species promptly and designate the 
species' critical habitat to the maximum extent prudent and 
determinable. We have determined that the Alabama hickorynut meets the 
Act's definition of an endangered species and that Obovaria cf. 
unicolor meets the Act's definition of a threatened species; therefore, 
we are proposing to list them accordingly. Listing a species as an 
endangered species or a threatened species can be completed only by 
issuing a rule through the Administrative Procedure Act rulemaking 
process (5 U.S.C. 551 et seq.).
    What this document does. We propose to list the Alabama hickorynut 
as an endangered species, and we propose to list Obovaria cf. unicolor 
as a threatened species with a rule issued under section 4(d) of the 
Act (a ``4(d) rule'').
    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 the Alabama hickorynut is 
endangered due to the following threats: sedimentation, altered flow 
regimes, point and nonpoint source pollution, climate change, direct 
and indirect impacts of development and anthropogenic disturbances, and 
sea level rise associated with climate change. We have further 
determined that Obovaria cf. unicolor is threatened due to the 
following threats: sedimentation, altered flow regimes, point and 
nonpoint source pollution, climate change, direct and indirect impacts 
of development and anthropogenic disturbances, and sea level rise 
associated with climate change.

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 
and the locations of any additional populations of these species;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for these species, their 
habitats, or both.
    (2) Threats and conservation actions affecting these species, 
including:
    (a) Factors that may be affecting the continued existence of these 
species, which may include habitat modification or destruction, 
overutilization, disease, predation, the inadequacy of existing 
regulatory mechanisms, or other natural or manmade factors;
    (b) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to these species; and
    (c) Existing regulations or conservation actions that may be 
addressing threats to these species.
    (3) Additional information concerning the historical and current 
status of these species.

[[Page 73332]]

    (4) Information to assist with applying or issuing protective 
regulations under section 4(d) of the Act that may be necessary and 
advisable to provide for the conservation of the Obovaria cf. unicolor. 
In particular, we seek information concerning:
    (a) The extent to which we should include any of the Act's section 
9 prohibitions in the 4(d) rule; and
    (b) Whether we should consider any additional or different 
exceptions from the prohibitions in the 4(d) rule.
    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, do not provide substantial 
information necessary to support a determination. 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 https://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 https://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 https://www.regulations.gov.
    Our final determinations may differ from this proposal because we 
will consider all comments we receive during the comment period as well 
as any information that may become available after this proposal. Based 
on the new information we receive (and, if relevant, any comments on 
that new information), we may conclude that one or both species are a 
different status, or we may conclude that one or both species do not 
warrant listing as either an endangered species or a threatened 
species. In addition, for Obovaria cf. unicolor, we may change the 
parameters of the prohibitions or the exceptions to those prohibitions 
in the protective regulations under section 4(d) of the Act if we 
conclude it is appropriate in light of comments and new information 
received. For example, we may expand the prohibitions if we conclude 
that the protective regulation as a whole, including those additional 
prohibitions, is necessary and advisable to provide for the 
conservation of the species. Conversely, we may establish additional or 
different 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. In our final rule, we 
will clearly explain our rationale and the basis for our final 
decisions, including why we made changes, if any, that differ from this 
proposal.

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. We may hold the public hearing in person or virtually via 
webinar. We will announce any public hearing on our website, in 
addition to in the Federal Register. The use of virtual public hearings 
is consistent with our regulations at 50 CFR 424.16(c)(3).

Previous Federal Actions

    In April 2010, the Alabama hickorynut was included in a petition 
from the Center for Biological Diversity and others (CBD 2010, entire) 
requesting that the Service list 404 aquatic, riparian, and wetland 
species as endangered or threatened species under the Act. In response 
to the petition, on September 27, 2011, the Service published in the 
Federal Register (76 FR 59836) a partial 90-day finding in which we 
announced our finding that the petition contained substantial 
information indicating that listing may be warranted for numerous 
species, including the Alabama hickorynut.
    On February 27, 2020, the Center for Biological Diversity filed a 
lawsuit against the Service, alleging, among other claims, that the 
Service violated the Act (16 U.S.C. 1533(b)(3)(B)) by delaying the 12-
month finding for the listing of the Alabama hickorynut. The parties 
entered a settlement agreement on July 24, 2023, in which the Service 
committed to submit the 12-month finding to the Federal Register by 
September 2, 2024. This document complies with the settlement 
agreement.
    We note that the April 2010 petition specified an accepted range 
for the Alabama hickorynut of the eastern Gulf Coast drainages of the 
Mobile River Basin, the Pascagoula River drainage, the Pearl River 
drainage, and the Lake Pontchartrain drainages. However, as discussed 
below under I. Proposed Listing Determination, Background, preliminary 
data support that Alabama hickorynut (Obovaria unicolor) is found only 
in the Mobile River Basin, and the individuals from the other three 
drainages are a distinct species still undescribed, Obovaria cf. 
unicolor. Because the Alabama hickorynut was petitioned with the 
accepted range including all four drainages and because the genetic 
analysis distinguishing two distinct species is still unpublished, we 
evaluated the Alabama hickorynut and the undescribed species throughout 
the entire accepted petitioned range.

Peer Review

    A species status assessment (SSA) team prepared an SSA report for 
Alabama hickorynut, including the undescribed Obovaria cf. unicolor. 
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 in 
listing and recovery actions under the Act, we solicited independent 
scientific review of the information contained in the SSA report for 
the Alabama hickorynut and Obovaria cf. unicolor. We sent the SSA 
report to five independent peer reviewers and received no responses.

I. Proposed Listing Determination

Background

    The SSA report (Service 2023, pp. 9-16) presents a thorough review 
of the taxonomy, life history, and ecology of the Alabama hickorynut 
(Obovaria unicolor) and Obovaria cf. unicolor.
    Species taxonomic status remains unclear for the Alabama 
hickorynut.

[[Page 73333]]

Genetics data support Alabama hickorynut (Obovaria unicolor) as a 
Mobile River Basin endemic and the individuals of the western drainages 
(Pascagoula, Pearl, and Pontchartrain) comprising a distinct species 
yet to be formally described, Obovaria cf. unicolor (Inoue et al. 2013, 
pp. 2670-2683). Genetics work by the U.S. Geological Survey (USGS) is 
upcoming to resolve the taxonomic uncertainty. In the SSA report, we 
evaluated both the Alabama hickorynut and Obovaria cf. unicolor because 
the petitioned entity included the entire range of both species and 
because Obovaria cf. unicolor has not yet been formally described. Both 
species have a lifespan of 20 to 44 years. The two entities are 
allopatric, meaning they occur in separate, non-overlapping 
geographical areas. In the SSA report, we have assumed similarities 
between the two species in biology and ecology, but we have assessed 
their differences in geographic occupancy and threats faced.
    The Alabama hickorynut (Obovaria unicolor) has a generally round to 
oval shape with a moderately thick shell. The species is moderately 
inflated and grows up to a length of 50 to 70 millimeters (mm). Males 
grow to be slightly larger than females (Haag and Rypel 2011, pp. 225-
247). Posterior and anterior margins are rounded. The umbo is inflated 
and elevated above the hinge line (Williams et al. 2008, pp. 476-477; 
Haag, from Mirarchi et al. 2004, p. 99). The lateral teeth are short 
and straight. The pseudocardinal teeth are triangular and erect with 
two divergent teeth in the left valve and one in the right valve. The 
nacre inside the shell is usually white but occasionally pink (Williams 
et al. 2008, pp. 476-477). Obovaria cf. unicolor has yet to be formally 
described, but has a similar morphology to Alabama hickorynut.
    The Alabama hickorynut and Obovaria cf. unicolor occupy large 
creeks and streams to large rivers with sand, gravel, and silt 
substrates in slow to moderate current (Williams et al. 2008, p. 477; 
Mirarchi et al. 2004, p. 99). Historically, the Alabama hickorynut 
occupied the mainstem of the Tombigbee and Alabama Rivers along with 
their associated large tributaries. Obovaria cf. unicolor historically 
occupied the mainstem and associated large tributaries of the 
Pascagoula, Pearl, Tangipahoa, Tickfaw, and Amite Rivers. Occurrence 
data collected over time indicate that both species were historically 
found in low densities and were relatively rare in mussel assemblages.
    The Alabama hickorynut and Obovaria cf. unicolor have complex life 
cycles that rely on fish hosts for successful reproduction, similar to 
other mussels. Both species are long-term brooders, gravid from August 
to the following June, with glochidia being fully developed by November 
(Haag and Warren 2003, p. 83). Several host fish species have been 
documented for the Alabama hickorynut and Obovaria cf. unicolor, and 
all host fishes appear to be relatively common species of darters 
(Percidae) of the genera Ammocrypta, Etheostoma, and Percina.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for endangered and 
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 species' expected response 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.
    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, which is 
further described in the 2009 Memorandum Opinion on the foreseeable 
future from the Department of the Interior, Office of the Solicitor (M-
37021, January 16, 2009; ``M-Opinion,'' available online at https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf). 
The foreseeable future extends as far into the future as the U.S. Fish 
and Wildlife Service and National Marine Fisheries Service (hereafter, 
the Services) can make reasonably reliable predictions about the 
threats to the species and the species' responses to those threats. We 
need not identify the foreseeable future in terms of a specific period 
of time. We will describe the foreseeable future on a case-by-case 
basis, using the best available data and taking into account 
considerations such as the species' life-history characteristics, 
threat projection timeframes, and environmental variability. In other 
words, the foreseeable future is the period of time over which we can 
make reasonably

[[Page 73334]]

reliable predictions. ``Reliable'' does not mean ``certain''; it means 
sufficient to provide a reasonable degree of confidence in the 
prediction, in light of the conservation purposes of the Act.

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 our decision 
on whether the species should be proposed for listing as 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.
    To assess the viability of Alabama hickorynut and Obovaria cf. 
unicolor, we used the three conservation biology principles of 
resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 
306-310). Briefly, resiliency is the ability of the species to 
withstand environmental and demographic stochasticity (for example, wet 
or dry, warm or cold years), redundancy is the ability of the species 
to withstand catastrophic events (for example, droughts, large 
pollution events), and representation is the ability of the species to 
adapt to both near-term and long-term changes in its physical and 
biological environment (for example, climate conditions, pathogens). In 
general, species viability will increase with increases in resiliency, 
redundancy, and representation (Smith et al. 2018, p. 306). 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 each 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, which we then used to inform our regulatory decision.
    The following is a summary of the key results and conclusions from 
the SSA report; the full SSA report can be found at Docket No. FWS-R4-
ES-2024-0130 on https://www.regulations.gov.

Summary of Biological Status and Threats

    In this discussion, we review the biological conditions of the 
species and their resources, and the threats that influence the 
species' current and future conditions, in order to assess each 
species' overall viability and the risks to that viability.

Population and Species Needs

    The individual, population-level, and species-level needs of the 
species are summarized below in table 1. For additional information, 
please see the SSA report (Service 2023, pp. 19-20). Briefly, for 
populations to be sufficiently resilient, they must have adequate water 
quality, natural flow regimes, stable habitat, and substrates on a 
larger scale. Connectivity is also an important factor for populations 
because it facilitates gene flow within and among populations, thereby 
promoting adaptive potential, and it enables movement and dispersal of 
individuals to suitable habitat. Natural flow regimes are an important 
resource need for Alabama hickorynut and Obovaria cf. unicolor 
populations as flows are a habitat requirement for all life stages. 
More specifically, the species require flowing water for sheltering 
(habitat requirement), feeding, reproduction, and dispersal. Altered 
flow regimes may thus cause decreased spawning, recruitment, and 
survival. Adequate water quality is a need at the individual level for 
sheltering, reproduction, and feeding (to ensure food source is 
present). Stable habitat, and in particular the presence of stable 
sand, gravel, and silt substrates, is an important resource need for 
sheltering and feeding, especially for juveniles and adults due to 
their limited movement and dispersal abilities during these life 
stages. At the species level, both species need a sufficient number and 
distribution of healthy populations to withstand environmental and 
demographic stochasticity (resiliency), withstand catastrophes 
(redundancy), and adapt to biological and physical changes in their 
environment (representation). Genetic diversity should be high enough 
that the species will be able to adapt to changing environmental 
factors through the process of natural selection.

  Table 1--Summary of the Individual Resource Needs by Life Stage of the Alabama Hickorynut (Obovaria unicolor)
                                            and Obovaria cf. unicolor
----------------------------------------------------------------------------------------------------------------
                Life stage                                            Resources needed
----------------------------------------------------------------------------------------------------------------
Fertilized Eggs...........................  <bullet> Mature males upstream from mature females.
                                            <bullet> Suitable flow.
                                            <bullet> Suitable water quality and quantity.
Glochidia.................................  <bullet> Interactions with appropriate host fish.
                                            <bullet> Connectivity to suitable habitat for dispersal by fish.
                                            <bullet> Suitable flow.
                                            <bullet> Suitable water quality and quantity for glochidia and host
                                             fish.
Juveniles.................................  <bullet> Suitable, stable substrate.
                                            <bullet> Sufficient food availability within sediment.
                                            <bullet> Sufficient water flow.
                                            <bullet> Suitable water quality and quantity.
Adults....................................  <bullet> Suitable, stable substrate.
                                            <bullet> Sufficient food availability in water column.
                                            <bullet> Suitable flow.
                                            <bullet> Suitable water quality and quantity.
----------------------------------------------------------------------------------------------------------------


[[Page 73335]]

Summary of Threats

    To assess the status of the Alabama hickorynut and Obovaria cf. 
unicolor, we first examined the following influences on viability in 
our SSA analysis: sedimentation; altered flow regimes; point and 
nonpoint source pollution, which come from a variety of sources, 
including urbanization, agriculture, forestry, and mining; and a 
constricted range and reduced connectivity from impoundments (Service 
2023, p. 21). We then determined which influences were most significant 
for viability of both the species, then modeled those influences and 
carried them forward in our analysis. Those influences include: habitat 
loss, degradation, and fragmentation (Factor A); water quality 
degradation (Factor A); altered flow regimes (Factor A); sedimentation 
from land use (Factor A); the influences of climate change on stream 
flow, water temperature, and sea level rise (Factor E); and their 
cumulative effects. We summarize these threats, as well as their 
sources and the responses of the Alabama hickorynut and Obovaria cf. 
unicolor to those threats, below. For a detailed description of threats 
that may influence the viability of both species, please refer to 
chapter 4 of the SSA report (Service 2023, pp. 21-36).
Sedimentation
    Sedimentation due to a variety of sources, including agriculture, 
forestry practices, urbanization, bank erosion, and gravel mining, is 
considered a stressor to Alabama hickorynut and Obovaria cf. unicolor 
throughout their ranges. Sediment is composed of both organic 
(biological material) and inorganic (sand, silt, clay) particulate 
matter formed through various processes including weathering, wind/
wave/ice action, and tectonic uplift (Perkins et al. 2022, p. 2). 
Sediment is listed as the most common pollutant in rivers, streams, 
lakes, and reservoirs and is estimated to cause approximately $16 
billion in damage every year (EPA 2005, pp. 9-25; Du Plessis 2019, pp. 
86-87). While all streams carry some sediment, aquatic ecosystems are 
negatively affected if sediment loads are excessive enough to alter 
channel formation, stream productivity, or both.
    River channel erosion, precipitation runoff, and wind transport 
account for 30 percent of the total sediment load in aquatic systems, 
while land-use activities such as agriculture (Peacock et al. 2005, p. 
548), logging (Beschta 1978, entire), mining (Seakem Group et al. 1992, 
p. 17), urbanization (Guy and Ferguson 1963, entire), and hydrological 
alteration (Hastie et al. 2001, entire) account for the remaining 70 
percent (Du Plessis 2019, pp. 86-87). Agricultural activities have been 
found to produce the most significant amount of sedimentation (e.g., 
livestock grazing/trampling near water's edge; Nolte et al. 2013, p. 
296).
    Increased sedimentation may result in decreases in feeding and 
respiration, which could result in negative alterations to mussel's 
energetic metabolism and growth (Dimock and Wright 1993, p. 183; La 
Peyre et al. 2019, p. 5). Specifically, as sedimentation increases, 
clearance rates (i.e., volume of water completely cleared of particles 
per unit time) decrease and pseudofeces (i.e., waste) increase to 
prevent gill filaments from clogging (Bayne and Newell 1983, entire; 
Madon et al. 1998, p. 401). If the stressor becomes long-term, mussels 
may find feeding to be outweighed by the energetic cost of sorting food 
vs. non-food material, decreasing the individual's body condition 
(Bayne and Widdows 1978, p. 137; Madon et al. 1998, p. 401).
    Increased sedimentation is expected to interfere with mussel-host 
fish interaction, further impacting the reproductive success of mussels 
due to physical abrasion of the host fish's gills or decreased 
visibility within the water column. Successful glochidial attachment 
and metamorphosis has been found to be reduced at concentrations 
ranging from 1,250 to 5,000 milligrams per liter (mg/L) of 
montmorillonite clay in the water column (Beussink et al. 2007, pp. 15-
17). This reduction is attributed to physical abrasion of fish gill 
tissues from increased suspended sediment; increased fish mucus 
production in attempt to protect the gill from physical abrasion; 
coughing, which may dislodge glochidia from the gills; or declines in 
keratocytes (i.e., wound-healing cells), which would harm glochidia's 
ability to encapsulate (Beussink et al. 2007, pp. 15-17).
Dams and Impoundments
    The detrimental effects of impoundments and dams on aquatic 
habitats and freshwater mussels are relatively well-documented (Watters 
1999, p. 261). Increased demand for transportation, power, and water 
needs in the 1920s and 1930s led to rapid industrialization (Haag 2012, 
p. 329). Currently, there are an estimated 3,404 dams within the Mobile 
River basin. More than 1,000 miles of small and large river habitat in 
the Mobile River drainage have been impounded for navigation, flood 
control, water supply, and/or hydroelectric production purposes (58 FR 
14330 at 14335, March 17, 1993). These impoundments kill riverine 
mussels during construction and dredging, suffocate them by 
accumulating sediments, lower food and oxygen availability for the 
mussels by the reducing water flow, and cause local extirpation of host 
fish. Within the eastern United States, extinction and/or extirpation 
of native freshwater mussels has been attributed to impoundment and 
inundation of riffle habitats in all major river basins (Haag 2008 p. 
107; Neves et al. 1997, p. 63).
    After a dam is installed and reservoir created, the aquatic habitat 
typically accumulates more silt, loses shallow water habitat, decreases 
in water flow, accumulates more pollutants (adhered to sediment 
particles), and overall accumulates more nutrient-poor water (due to 
decaying algae within the reservoir, which depletes dissolved oxygen) 
(Watters 1999, p. 261). Typically, mussels are abundant in shallower 
waters and cannot tolerate impoundment depths and temperatures or 
fluctuating conditions found in tailwaters of dams (Fagin 2020, p. 2). 
Further, impoundments become sediment traps, which may increase the 
chance of smothering and decrease species' interactions with host fish. 
Mussels living in the tailwaters may experience fluctuations in 
temperatures and water levels (Watters 1999, p. 262). These 
fluctuations may expose individuals to dewatering events and/or 
excessively warm- or cold-water temperatures (Watters 1999, p. 262). 
Ultimately, the survival and overall reproductive success of mussels is 
influenced both upstream and downstream of dams.
    Within the range of Obovaria cf. unicolor, plans for a new 
reservoir on the Pearl River downstream of Ross Barnett Reservoir near 
Jackson, Mississippi, are under consideration (Lindeman 2013, pp. 202-
203). Of particular note is the proposed One Lake project, which 
includes a new dam and commercial development area 9 miles (14.5 
kilometers) south of the current Ross Barnett Reservoir Dam near 
Interstate 20. The intent of the One Lake project is to dredge the 
Pearl River in order to widen, deepen, and straighten an additional 10 
miles (16.1 kilometers) of waterway for flood control protection and 
commercial development opportunities. The One Lake project is still 
being debated, and the project's future is uncertain. If the One Lake 
project is implemented, it will likely alter the hydrologic regime and 
geomorphology of the Pearl River (similar to how the construction of 
Ross

[[Page 73336]]

Barnett Reservoir altered the system in the 1960s). This potential 
altered regime could increase channel instability and erosion through 
drastic changes in water outflows at dams, which can lead to bank 
collapse.
    Also within the range of Obovaria cf. unicolor, plans for new 
reservoirs on Big Cedar Creek in the Pascagoula River drainage have 
been proposed in the past as the Lake George Project; however, the 
current status of the project is unknown. If the Lake George project is 
implemented, it will likely alter the hydrologic regime and 
geomorphology of the Big Cedar Creek and subsequently the Pascagoula 
River. This potential altered regime could lead to increased channel 
instability.
Channelization
    Channelization activities profoundly alter riverine habitats by 
reducing habitat heterogeneity and aquatic diversity (Ebert 1993, p. 
157; Watters 1999, p. 268). These activities affect many physical 
characteristics of streams through accelerated erosion (i.e., 
headcutting), increased bedload (sediment that moves along the 
streambed), reduced depth, decreased habitat diversity, geomorphic 
instability (channel modification and subsequent instability), and 
riparian canopy loss (Hartfield 1993, p. 139). Further, changes in 
water velocity and depth associated with channelization increase 
turbulence and suspended sediments. These impacts contribute to loss of 
habitat for the Alabama hickorynut and Obovaria cf. unicolor, as well 
as interfere with gravid female host-fish interactions.
    One of the largest water development projects within the United 
States, the Tennessee-Tombigbee Waterway (TTW) in Alabama and 
Mississippi is within the Alabama hickorynut's range. While the project 
was authorized in 1946, the TTW did not begin construction until 1972. 
The TTW constructed to provide more direct access from the Tennessee 
River to the Gulf of Mexico, was completed in 1984 and includes 10 lock 
and dams as well as 377 km of channelization (Haag 2012, p. 330). This 
project significantly altered the Tombigbee River, which had been the 
last free-flowing, unpolluted, diverse stream systems within the Mobile 
Basin, into a series of artificial canals and reservoirs. The 
construction of the TTW has significantly negatively impacted the 
Alabama hickorynut's range and abundance by rendering the majority of 
the mainstem of the Tombigbee River inhospitable to the Alabama 
hickorynut. The impacts of this channelization are ongoing.
    No other new channelization projects are on the horizon; however, 
the U.S. Army Corps of Engineers (USACE) is undergoing planning efforts 
to improve navigation in the TTW, which will include deepening the 
channel. Because the underlying geology is particularly sensitive to 
disturbance, further bed instability is likely throughout the channel 
and downstream without effective planning and designs to prevent head-
cuts.
    Dredging and channelization of fluvial (flowing water) systems 
include the widening and deepening of stream channels, which increases 
channel capacity, shortens stream length, and increases stream gradient 
(Pierce and King 2013, p. 223). These activities allow greater volumes 
of water to move through the system at a faster rate; however, they 
also hydrologically disconnect river channels from the adjacent 
floodplain. Within the southeastern United States, channelization has 
been used for navigation and to reduce flooding, and it is likely even 
more extensive than damming (Haag 2012, p. 330).
    Channels dredged for navigation or flood control will eventually 
begin to refill with material. To ensure minimum depth, the channel is 
often periodically re-dredged. Subsequent dredge spoil (i.e., 
unconsolidated mixed sediment composed of rock, soil, and/or shell 
material) and contaminants associated with the waste are often 
deposited in upland areas (Watters 1999, p. 268). Over time, this waste 
may re-enter the water via surface runoff, biological uptake and 
cycling, and/or leaching into groundwater (Watters 1999, p. 268), and 
may subsequently affect the Alabama hickorynut and Obovaria cf. 
unicolor directly or may affect their habitats.
Gravel Mining
    The Alabama hickorynut and Obovaria cf. unicolor are not found in 
impounded waters and are intolerant of lentic (standing water) habitats 
that may be formed by gravel mining or other landscape-altering 
practices. Incompatible sand and gravel mining, with its disruption of 
topography, vegetation, and flow pattern of streams, is considered a 
major stressor to the Bogue Chitto River in the Pearl River drainage 
where Obovaria cf. unicolor occurs (TNC 2004, p. 16). Although 
Louisiana has reduced the number of gravel mining permits issued, 
mining in the floodplain continues to be a significant threat to 
Obovaria cf. unicolor in that state.
    In Obovaria cf. unicolor's range in the Pascagoula River drainage, 
the results of historical sand and gravel dredging impacts have been a 
concern for the Bouie and Leaf Rivers (Mississippi Department of 
Environmental Quality (MDEQ) 2000, pp. 1-98) Historically, the American 
Sand and Gravel Company (1995, p. B4) has mined sand and gravel using a 
hydraulic suction dredge, operating within the banks or adjacent to the 
Bouie and Leaf Rivers. Large gravel bars of the river and its 
floodplain were removed over a period of 50 years, creating open-water 
areas that function as deep lake systems (American Sand and Gravel 
Company 1995, pp. B4-B8). The creation of these large, open-water areas 
has accelerated geomorphic processes, specifically headcutting 
(erosional feature causing an abrupt drop in the streambed) that has 
adversely affected the flora and fauna of many coastal plain streams 
(Patrick et al. 1993, p. 90). The infilling of these gravel pits and 
their downstream effects back to a natural riverine state is predicted 
to take hundreds of years (Grimball and Heitmuller 2012, p. 158). 
Mining in active river channels typically results in incision upstream 
of the mine by knickpoints (breaks in the slope of a river or stream 
profile caused by renewed erosion attributed to a bottom disturbance 
that may retreat upstream), sediment deposition downstream, and an 
alteration in channel morphology that can have impacts for years (Mossa 
and Coley 2004, pp. 1-20). The upstream migration of knickpoints, or 
headcutting, may cause undermining of structures, lowering of alluvial 
water tables (aquifer comprising unconsolidated materials deposited by 
water and typically adjacent to rivers), channel destabilization and 
widening, and loss of aquatic and riparian habitat. This geomorphic 
change may cause the extirpation of riparian and lotic (flowing water) 
species (Patrick et al. 1993, p. 96).
Contaminants
    Metals--Freshwater mussels are one of the most sensitive species to 
metals, ammonia, and ion constituents including copper, alachlor (i.e., 
an herbicide), nickel, chloride, sulfate, zinc, and potassium (Wang et 
al. 2017, p. 1). Despite limited research, data indicate mussels 
representing different families or tribes have similar sensitivities to 
most chemicals, regardless of mode of toxic exposure (Wang et al. 2017, 
p. 1). This information indicates thresholds identified for other 
freshwater mussels can be used to infer the response of the Alabama 
hickorynut and Obovaria cf. unicolor.

[[Page 73337]]

    Metals naturally occur in aquatic ecosystems and are primarily 
introduced to waterways due to weathering of rocks, soil erosion, and/
or dissolution of water-soluble salts (Garbarino et al. 1995, p. 1). 
While naturally occurring metals often move through aquatic ecosystems 
without detrimental effects to aquatic biota, this is not necessarily 
the case with anthropogenic sources of metals. Industrial and forestry 
activities within the region that do not employ best management 
practices (BMPs) and directly discharge into river systems 
significantly increase heavy metal loads (Suryawanshi 2017, p. 625; 
Uttermann et al. 2019, p. 200). As a result, river systems that are 
habitat for the Alabama hickorynut and Obovaria cf. unicolor may have 
metal contamination, which may negatively impact the species; however, 
we do not have specific data about the streams the two species 
inhabits.
    Nutrients and ions--The southeastern United States is affected by 
intense pressures of fossil fuel mining, urban development/sprawl, 
agricultural and forestry practices, and increasing demands for fresh 
water (Archambault et al. 2017, p. 395). Runoff associated with these 
practices when BMPs are not employed (i.e., fertilizers, pesticides, 
industrial and wastewater effluents, mining discharge, and sediment) 
increases nutrient and ion concentrations in waterways that (depending 
on magnitude and duration) may exceed freshwater mussel thresholds 
(Salerno et al. 2020, pp. 1-2).
Climate Change
    Climate change has the potential to increase vulnerability of the 
Alabama hickorynut and Obovaria cf. unicolor to catastrophic events or 
to alter habitat suitability (e.g., water temperature, dissolved 
oxygen, sea level rise) within the species' range. Over the years, 
climate change impacts (impaired waters and reduced water supply 
security) have been reportedly more frequent and intense 
(Intergovernmental Panel on Climate Change (IPCC) 2022, p. 1931). 
Extreme heat and precipitation trends have altered ecosystem processes 
(e.g., freshwater cycling). Further, projected droughts will become 
more intense because of higher temperatures, and the progressive loss 
of seasonal water storage will lead to lower summer stream flows (IPCC 
2022, p. 1932). Population growth and agricultural activities are 
expected to continue to place high demands on the water supply within 
the range of the species, impacting stream flow. These lower stream 
flows may negatively impact the Alabama hickorynut and Obovaria cf. 
unicolor.

Conservation Efforts and Regulatory Mechanisms

    Most of the land within the ranges of the Alabama hickorynut and 
Obovaria cf. unicolor is privately owned, with some exceptions. The 
Alabama hickorynut currently occupies 58 protected river miles of 
habitat in the Buttahatchee River, 28 protected river miles in the 
Sipsey River, and 30 protected river miles of the Noxubee River, all of 
which are tributaries to the Tombigbee River. The protected land of the 
Buttahatchee is Wildlife Mississippi property and the Sam R. Murphy 
Wildlife Management Area. In the Sipsey River, the protected land is 
State-owned Forever Wild land, and in the Noxubee River, the protected 
land is federally owned as the Sam D. Hamilton Noxubee National 
Wildlife Refuge.
    For Obovaria cf. unicolor, there are currently occupied protected 
lands in the Pascagoula River system and in the Pearl River system. In 
the Pascagoula River system, there are a total of 113 protected river 
miles, most of which are within the Pascagoula Wildlife Management Area 
(WMA) in the Pascagoula River, Black Creek, and Red Creek. The Nature 
Conservancy protects 7 river miles of currently occupied habitat in the 
Chickasawhay River, and there are 16 river miles protected on the Leaf 
River by the Camp Shelby and Mississippi Land Trust and the Mississippi 
River Trust. In the Pearl River system, there are a total of 69 
protected river miles that are currently occupied. Three river miles 
are protected in the upper Pearl River as Wildlife Mississippi 
property, and 66 river miles are protected on the lower Pearl River as 
the Bogue Chitto National Wildlife Refuge.
    Neither Alabama hickorynut or Obovaria cf. unicolor are protected 
under state laws. However, some streams that are occupied by the 
species have water quality protections in place. The Clean Water Act of 
1972 (33 U.S.C. 1251 et seq.) regulates dredge and fill activities that 
would adversely affect streams and wetlands. Such activities are 
commonly associated with dry land projects for development, flood 
control, and land clearing, as well as for water-dependent projects 
such as docks/marinas and maintenance of navigational channels. The 
USACE and the Environmental Protection Agency (EPA) share the 
responsibility for implementing the permitting program under section 
404 of the Clean Water Act. Permit review and issuance follows a 
process that encourages avoidance, minimizing and requiring mitigation 
for unavoidable impacts to the aquatic environment and habitats. This 
includes protecting the riverine habitat occupied by Alabama hickorynut 
and Obovaria cf. unicolor. This law has resulted in some enhancement of 
water quality and habitat for aquatic life, particularly by reducing 
point-source pollutants. For Alabama hickorynut, two occupied waterways 
have Total Maximum Daily Loads (TMDLs) established by Alabama 
Department of Environmental Management (ADEM) for E. coli: the 
Luxapallila River and the Noxubee River. For Obovaria cf. unicolor, 
Tallahala Creek in the Pascagoula drainage has a TMDL established by 
Mississippi Department of Environmental Quality (MDEQ) for biological 
impairment, total nitrogen, pH, and total phosphorous.

Cumulative Effects

    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have 
analyzed the cumulative effects of identified threats and conservation 
actions on the species. To assess the current and future condition of 
the species, we evaluate the effects of all the relevant 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.

Current Conditions

Delineating Populations
    To assess resiliency of Alabama hickorynut and Obovaria cf. 
unicolor populations, we first delineated populations in the most 
biologically meaningful way. We based our delineations on occurrence 
records through time, on our knowledge of the species' habitat and 
resource needs, and on expert input. We determined there to be three 
total Alabama hickorynut populations and six total Obovaria cf. 
unicolor populations. We also delineated subpopulations for each 
species to refine occupancy, influence of threats, and average 
abundance. The Alabama hickorynut has 13 subpopulations within its 
three populations, and Obovaria cf. unicolor has 16 subpopulations 
within its six populations.

[[Page 73338]]

Delineating Representative Units
    Representation is the ability of a species to adapt to both near-
term and long-term changes in its physical and biological environment. 
Differences in life-history traits, habitat features, and/or genetics 
often aid in the delineation of representative units, which are used to 
assess species representation. For representative unit delineation, we 
consulted with experts in each State and considered differences in 
ecological setting and connectivity at a larger scale. Based on the 
natural lack of large-scale connectivity, the Alabama hickorynut in the 
Mobile River Basin was split into two representative units: Eastern 
Mobile River Basin (Alabama and Cahaba Rivers) and Western Mobile River 
Basin (Tombigbee River). Obovaria cf. unicolor was divided into five 
representative units: the Pascagoula, the Pearl, the Tangipahoa, the 
Tickfaw, and the Amite Rivers. The Tangipahoa, Tickfaw, and Amite 
Rivers all drain into Lake Pontchartrain, and occurrences extend very 
close to the mouth of each river; however, the influence of salt water 
in Lake Pontchartrain likely limits any connectivity between these 
representative units.
Current Resiliency
    Sufficiently resilient populations of the Alabama hickorynut and 
Obovaria cf. unicolor should be robust following normal demographic and 
environmental stochastic events or disturbances. We assessed the 
resilience of each Alabama hickorynut and Obovaria cf. unicolor 
population by synthesizing the best available information about habitat 
condition and population demographics. Based on the individual and 
population needs of the Alabama hickorynut and Obovaria cf. unicolor 
(such as adequate water quality/quantity; the presence of stable, 
unaltered habitat; and appropriate population size and connectivity to 
support reproduction and recruitment within a population), we developed 
an approach using key habitat and demographic factors to assess 
population resiliency. We assessed two demographic condition parameters 
(persistence through time (amount of historical range that is still 
currently occupied) and estimated average abundance) and one habitat 
condition parameter (amount of altered habitat (impoundment, 
channelization, head cutting, etc.)). Based on the Alabama hickorynut's 
lifespan, we determined the time period from 2000 to 2023 to represent 
the current condition of these species. We ranked subpopulations based 
on estimated average abundance by reviewing count data from occurrence 
records and using expert elicitation based on the experts' knowledge of 
historical numbers. We considered a subpopulation to have a low 
abundance if the estimated average count per sample is 0 to 5 
individuals. A subpopulation with moderate abundance has an estimated 
average count per sample of 6 to 10 individuals, and a subpopulation 
with high abundance has an estimated average count of more than 10 
individuals.
    In order to better facilitate comparisons of current and future 
conditions, we categorized resiliency into three levels, as follows:
    <bullet> High--population substantially contributes to overall 
species viability by having more than 75 percent of its historical 
range that is currently occupied, relatively low amounts of altered 
habitat, and high abundance.
    <bullet> Moderate--population contributes to overall species 
viability by having 50-75 percent of its historical range that is 
currently occupied, relatively moderate amounts of altered habitat, and 
ample abundance.
    <bullet> Low--population is likely persisting but also likely does 
not contribute to overall species viability because less than 50 
percent of its historical range is currently occupied, there is 
relatively high amounts of altered habitat, and low abundance.
i. Alabama Hickorynut (Obovaria Unicolor)
    Alabama River--There are two subpopulations within the Alabama 
River population: mainstem Alabama River and Pine Barren Creek. The 
Alabama hickorynut historically occupied at least 233 river miles in 
the Alabama River and 11 river miles in Pine Barren Creek. Degradation 
and loss of habitat due to impoundment resulted in the extirpation of 
this population. Live individuals were last detected in the Alabama 
River mainstem in 1999 (Mcgregor et al. 2000, pp. 215-237) and last 
detected in Pine Barren Creek in 1917. Our analysis indicated that 100 
percent of the Alabama River population's habitat has been altered.
    Cahaba River--Historically, Alabama hickorynut occupied 117 river 
miles in the Cahaba River, a major tributary to the Alabama River. The 
species is now considered extirpated from this system. Surveys from 
2000 to present have only detected relic, weathered shells. Seventy-
four river miles of the historical range within the Cahaba River are 
altered.
    Tombigbee River--The Alabama hickorynut occurred throughout 
approximately 1,077 river miles of the mainstem Tombigbee River and 
several large tributaries: the Buttahatchee River, the East Fork of the 
Tombigbee, the Sucarnoochee River, the Sipsey River, the Black Warrior 
River, Luxapallila Creek, the Noxubee River, Lubbub Creek, Trussels 
Creek, Tibbee Creek, Bogue Chitto Creek, and Santa Bogue Creek. The 
construction of the TTW, which artificially connects the Tennessee 
River to the Tombigbee River, has led to the extirpation of many 
species from the river's main channel (Bennett et al. 2008, p. 467). 
Today, the Alabama hickorynut is considered extirpated from the 
mainstem Tombigbee River (approximately 300 river miles) and the Black 
Warrior River (approximately 170 river miles) due to impoundment, 
dredging, and the creation of the TTW. Most of the tributaries also 
experienced a reduction in extant range due to these effects. As 
discussed previously, the Alabama hickorynut is naturally a larger 
river species, occupying mostly mainstem rivers and then branching out 
into larger tributaries of those rivers. In the Tombigbee River system, 
the species has lost suitable habitat in the mainstem Tombigbee and is 
now isolated to several tributaries. We do not find there is much, if 
any, subpopulation connectivity between these tributaries due to the 
loss of the connecting mainstem Tombigbee habitat. However, 
historically, these units would all have been connected, so we consider 
the entire Tombigbee River system one population with 13 
subpopulations. Of the 1,077 river miles historically occupied in this 
population, only 362 river miles are considered to be currently 
occupied, meaning the Alabama hickorynut currently occupies 33.62 
percent of its historical range in the Tombigbee population. As a 
result, we consider the Tombigbee population to have low resiliency.
    Currently, the Alabama hickorynut is extant in seven subpopulations 
of the Tombigbee population, and the species is considered extirpated 
in six subpopulations. Extant subpopulations are the East Fork of the 
Tombigbee, the Buttahatchee River, the Sipsey River, Luxapallila Creek, 
Lubbub Creek, the Noxubee River, and the Sucarnoochee River. Although 
the species is still extant in those subpopulations, it experienced 
range contraction in five of the seven extant subpopulations. All the 
extant subpopulations were classified as having low abundance except 
for the Sipsey River, which is considered to have high abundance. The 
Alabama hickorynut is considered extirpated from the following 
subpopulations: the

[[Page 73339]]

mainstem Tombigbee River, Tibbee Creek, Santa Bogue Creek, the Black 
Warrior River, Trussels Creek, and Bogue Chitto Creek.
    The stronghold for the entire species is in the Sipsey River. 
Samples collected from the Sipsey River frequently contain counts of 
Alabama hickorynut that are orders of magnitude higher than counts 
currently found anywhere else within the species' range. The Sipsey 
River supports other rare mussel species that have also experienced 
precipitous declines elsewhere within their range in the Mobile River 
Basin, including Alabama spike (Elliptio arca), Alabama moccasinshell 
(Medionidus acutissimus), and Southern clubshell (Pleurobema decisum), 
indicating that the Sipsey River has maintained its ecological 
integrity through time (Mirarchi et al. 2004, entire; Williams et al. 
2008, entire; Haag and Warren 2010, pp. 655-667). As noted above, the 
Sipsey River is the only subpopulation that we consider to have a 
``high'' abundance rating.
Alabama Hickorynut: Summary Resiliency Results
    Of the three populations of Alabama hickorynut in the Mobile River 
Basin, two are considered extirpated (Alabama and Cahaba), and one has 
low resiliency (Tombigbee). The species historically has been known to 
occur in 1,438 river miles in Alabama and Mississippi in the Mobile 
River Basin. The species currently occupies 362 river miles across its 
range, meaning it currently occupies 25.17 percent of its historical 
range. Overall, resiliency is considered low, meaning the species is 
not likely to withstand environmental stochasticity (fire, flood, 
storms) or disease and mortality events.
ii. Obovaria cf. Unicolor
    Pascagoula River--Obovaria cf. unicolor historically occupied 549 
river miles and is presumed to still occupy the full extent of the 
river system. The Pascagoula population is divided into five 
subpopulations: Pascagoula River, Leaf River, Chickasawhay River, Black 
Creek, and Red Creek. The Service surveyed the Pascagoula River for the 
species in 2023, and we confirmed current presence with a moderate 
abundance level. The other four subpopulations do not have current 
records of the species; however, these rivers and creeks have also not 
been surveyed recently. A system-wide mussel survey is planned for 2024 
by the Mississippi Department of Fish, Wildlife, and Parks (MDWFP). We 
still assume presence throughout the entire Pascagoula River system 
despite not having current records because the Pascagoula River is 
undammed and not impounded, with 0 miles of the species' range altered. 
Additionally, 113 river miles of the system are considered protected. 
Because we predict the Pascagoula River population occupies all of its 
historical range within the river system, the population is considered 
to have high resiliency.
    Upper Pearl River, above Ross Barnett Reservoir--Above the Ross 
Barnett Reservoir in the Pearl River system, Obovaria cf. unicolor 
historically occupied 92 river miles within two subpopulations: 27 
river miles in the Yockanookany River and 65 river miles in the 
mainstem Pearl River. Currently, the species occupies 32 river miles 
within this population: 27 river miles in the Yockanookany River and 5 
river miles in the mainstem Pearl River.
    The Yockanookany River is considered unaltered and 18 river miles 
are protected in the Natchez Trace Parkway. Twenty-seven river miles of 
the 65 historically occupied river miles of the mainstem Pearl River in 
this population are considered altered. Three river miles are in the 
mainstem Pearl River are protected by Wildlife Mississippi property. 
The species occupies 34.78 percent of its historical range in the upper 
Pearl River population. Where found in the upper Pearl population, 
Obovaria cf. unicolor is considered to have low abundance.
    Therefore, the upper Pearl River population above Ross Barnett 
Reservoir is considered to have low resiliency.
    Lower Pearl River, below Ross Barnett Reservoir--Of the total 589 
river miles historically occupied in the lower Pearl population, 
Obovaria cf. unicolor still currently occupies 112 river miles, which 
is 19.02 percent of its historical range. Historically, there were 
three subpopulations in the Pearl River system below the Ross Barnett 
Reservoir; however, the Strong River subpopulation, which historically 
occupied 46 river miles, is now considered extirpated. Obovaria cf. 
unicolor is extant in the Bogue Chitto River and in the mainstem Pearl 
River. All of the historical range in the lower Pearl population has 
been altered, and where the species is still found, its abundance is 
considered low. The lower Pearl River population below Ross Barnett 
Reservoir is considered to have low resiliency.
    Tangipahoa River--Obovaria cf. unicolor historically occurred in 78 
river miles of the Tangipahoa River and currently occupies 60 river 
miles of this system, meaning it occupies 76.92 percent of its 
historical range within the Tangipahoa River. Twenty river miles of the 
historical range are considered altered. The Tangipahoa River 
population is considered to have high resiliency.
    Tickfaw River--Obovaria cf. unicolor historically occurred in 44 
river miles of the Tickfaw and currently occupies 35 river miles of 
this system, meaning it occupies 79.55 percent of its historical range 
within the Tickfaw River. The entire historical range within this 
population is considered unaltered. The Tickfaw River population is 
considered to have high resiliency.
    Amite River--Obovaria cf. unicolor historically occurred in 102 
river miles of the Amite River but has not been detected in the system 
since 1988, so the Amite population is considered extirpated. There are 
49 river miles within the historical range that are considered altered.
Obovaria cf. Unicolor: Summary Resiliency Results
    Of the six populations of Obovaria cf. unicolor, one population is 
considered extirpated (Amite), two populations are considered to have 
low resiliency (Upper Pearl and Lower Pearl), and three populations are 
considered to have high resiliency (Pascagoula, Tangipahoa, and 
Tickfaw). The species historically has been known to occur in 1,454 
river miles in Mississippi and Louisiana. The species currently 
occupies 788 river miles across its range, meaning it currently 
occupies 54.2 percent of its historical range. Overall, Obovaria cf. 
unicolor has moderate resiliency.

Current Representation

    Representation is the ability of a species to adapt to both near-
term and long-term changes in its physical and biological environment. 
The greater the genetic diversity a species has, the more successfully 
a species can respond to changing environmental conditions. In the 
absence of population-level genetic data for the Alabama hickorynut and 
Obovaria cf. unicolor, we considered environmental diversity across 
each species' range. The best available data indicate two 
representative units (i.e., two major river systems) where the Alabama 
hickorynut was historically found, the Alabama River system and the 
Tombigbee River system, and four representative units where Obovaria 
cf. unicolor is currently found, the Pascagoula River system, the Pearl 
River system, the Tangipahoa River, and the Tickfaw River.
Alabama Hickorynut
    Of the two representative units for Alabama hickorynut, only one 
remains

[[Page 73340]]

extant. The species has been extirpated from the Eastern Mobile River 
Basin and now only occupies about 25 percent of its historical range. 
Although still extant, the Western Mobile River Basin representative 
unit has been left highly fragmented with no connectivity between 
subpopulations. The Alabama hickorynut was extirpated from the mainstem 
of the Tombigbee because of the TTW. This also eliminated gene flow 
between the tributaries of the Tombigbee River. The variety of trend 
information available across its range (i.e., loss of populations in 
tributaries or major river systems, declines in population extent and 
size in portions of the species' range) indicate that the Alabama 
hickorynut's overall ability to adapt to changing environmental 
conditions is minimal. This is largely due to pervasive human 
alteration of habitats, such as the construction and operation of 
impoundments. Thus, overall representation for the Alabama hickorynut 
is considered low.
Obovaria cf. Unicolor
    Of the five representative units for Obovaria cf. unicolor, four 
remain extant. The Pearl River unit, though still extant, lost nearly 
80 percent of its historical range due to human habitat alteration and 
degradation, which exemplifies that like Alabama hickorynut, Obovaria 
cf. unicolor also has minimal ability to adapt to changing 
environmental conditions. The loss of connectivity is a significant 
issue in the Pearl River representative unit. However, Obovaria cf. 
unicolor has representative units still spread across its historical 
range. One representative unit is considered extirpated, and because 
the species has shown that it is intolerant of major environmental 
changes (sedimentation, significant changes in water chemistry, habitat 
destabilization), we do not expect that the species will return to the 
unit without significant efforts to address the identified threats in 
this unit. For these reasons, we consider Obovaria cf. unicolor to have 
moderate representation.

Current Redundancy

    Redundancy refers to the ability of a species to withstand a 
catastrophic event. To determine species redundancy, we assess the 
species' distribution across its range. The greater the size, 
resiliency, and/or number of populations, and the more widely they are 
distributed, the greater the likelihood that the species will be able 
to withstand and bounce back from a significant loss (e.g., extirpation 
of a population) from a catastrophic event.
Alabama Hickorynut
    Of the three populations known for Alabama hickorynut, only one, 
the Tombigbee River population, remains extant, and this population has 
low resiliency. Within the Tombigbee River population, 7 of the 13 
subpopulations are still extant. However, all but one of the extant 
subpopulations are considered to have low abundance, and two of the 
subpopulations span less than 10 river miles within their tributaries, 
making them more vulnerable to potential extirpation; the other 
subpopulations each span at least 20 river miles. All of the extant 
subpopulations face ongoing headcutting, sedimentation, and erosional 
issues from surrounding land use practices and dredging operations in 
the main channel. Due to the lack of connectivity between 
subpopulations, the species' ability to rebound or recolonize areas 
after catastrophic events is severely limited. We consider the Alabama 
hickorynut to have a low level of redundancy overall because only one 
extant population remains with a low level of resiliency.
Obovaria cf. Unicolor
    Of the six populations of Obovaria cf. unicolor, one is considered 
extirpated and five are extant. Three of the extant populations, the 
Pascagoula, the Tangipahoa, and the Tickfaw, are considered to have a 
high level of resiliency. The other two extant populations, the upper 
Pearl (above Ross Barnett Reservoir) and the lower Pearl (below Ross 
Barnett Reservoir), have low resiliency. Although the Tangipahoa and 
Tickfaw populations show a high level of resiliency in the current 
condition, these two populations represent a small proportion of the 
total range of the species. The Tangipahoa population made up 5.4 
percent of the species' historical range, and currently makes up 7.6 
percent of the species' range. The Tickfaw population made up 3 percent 
of the species' historical range, and now makes up 4.4 percent of the 
species' range. In contrast, the Pascagoula currently makes up 70 
percent of the occupied range and has high resiliency, the lower Pearl 
currently makes up 14 percent of the occupied range and has low 
resiliency, and the upper Pearl makes up 4 percent of the currently 
occupied range and has low resiliency. Overall, we consider Obovaria 
cf. unicolor to have moderate redundancy.

Future Conditions

    As a part of the SSA, we considered multiple future influences and 
projected responses by Alabama hickorynut and Obovaria cf. unicolor. 
Because we determined that the current condition of Alabama hickorynut 
is consistent with an endangered status (see Determination of Alabama 
hickorynut Status, below), we are not presenting the results of the 
future scenarios for Alabama hickorynut in this proposed rule. Below. 
we present the results for Obovaria cf. unicolor. Please refer to the 
SSA report (Service 2023, pp. 51-55) for the full analysis of future 
scenarios for both species. Obovaria cf. unicolor is most susceptible 
to climate change, sea level rise, and destruction and/or modification 
of habitat. We developed multiple future scenarios to capture the range 
of uncertainties regarding sea level rise and the projected responses 
by Obovaria cf. unicolor.
Climate Change
    Climate change predictions under all scenarios are likely to 
exacerbate the currently declining trend of Obovaria cf. unicolor. Most 
climate change models predict an increase in extreme weather events, 
such as droughts and heavy precipitation (IPCC 2022 p. 15), and they 
project that average annual temperatures will increase, cold days will 
become less frequent, the freeze-free season will lengthen by up to a 
month, temperatures exceeding 95 degrees Fahrenheit ([deg]F) will 
increase, and heat waves will become longer (Ingram et al. 2013, p. 32; 
IPCC 2021, entire). Since the 1970s, moderate to severe droughts in the 
Southeast have increased by 12 percent during spring months and by 14 
percent during summer months (Jones et al. 2015, p. 126). Declines of 
65-83 percent in mussel density were observed after severe droughts in 
the upper reaches of the Sipsey River, and decreases in dissolved 
oxygen and increases in temperature were cited as causes for the 
decline (Haag and Warren 2008, pp. 1165-1178). As mentioned, Obovaria 
cf. unicolor is sensitive to drops and fluctuations in dissolved oxygen 
and to elevated temperatures (van Ee et al. 2022, pp.1-14) since it is 
naturally adapted to larger riverine systems. The effects of higher 
temperatures and reduced flows are expected to affect subpopulations of 
the species in upstream reaches first, reducing overall population 
resiliency (Haag and Warren 2008, pp.1165-1178).
Sea Level Rise
    Sea level rise (SLR) impacts future resilience of Obovaria cf. 
unicolor by influencing the area occupied and habitat available through 
increased salinity. To estimate loss/degradation of

[[Page 73341]]

habitat due to inundation from SLR, we used the National Oceanic and 
Atmospheric Administration's (NOAA's) shapefiles available at their 
online sea level rise viewer (NOAA 2020, unpaginated). Projected SLR 
scenarios from NOAA provide a range of inundation levels from low to 
extreme. We chose NOAA's intermediate-high and extreme scenarios, which 
correspond to the representative concentration pathway (RCP)4.5 and 
RCP8.5 emission scenarios, to encompass the breadth of possible 
scenarios (IPCC 2013, p. 20). Local scenarios are available at a 
location near Mobile Bay in Alabama, and they provide estimates of SLR 
affecting the range of Obovaria cf. unicolor at decadal time steps out 
to the year 2100. We found the average+ SLR estimate for the 
intermediate and extreme NOAA scenarios from this station and used the 
estimate (rounded to the nearest foot, because shapefiles are only 
available at 1-foot increments) to project estimated habitat loss at 
years 2040 and 2070. Where SLR estimates overlap with known occupied 
portions of the river system, we assume that area is no longer 
occupiable by Obovaria cf. unicolor.
    As expected, projections of SLR only impacted Obovaria cf. unicolor 
in occupied habitat of coastal drainages. Obovaria cf. unicolor has 
projected SLR impacts in the three Pontchartrain drainages: the Amite, 
the Tickfaw, and the Tangipahoa. The Amite population is already 
considered extirpated, but we expect SLR to result in contraction of 
the Tickfaw and Tangipahoa populations in the future, which would 
reduce each of these population's resiliency from high resiliency to 
moderate resiliency, and thus reduce their contribution to species 
representation and redundancy in the future. In the Tickfaw, we project 
a loss of 8.4 to 17.9 river miles, which corresponds to a 24 to 51 
percent range reduction, and in the Tangipahoa, we project a loss of 
4.5 to 7.3 river miles, which corresponds to a 7.5 to 12.1 percent 
range reduction.
Future Viability Summary
    In summary, we expect decreased resiliency, redundancy, and 
representation in the future for Obovaria cf. unicolor. The magnitude 
of reduction in resiliency, redundancy, and representation for this 
species will depend on the climate change scenario realized and the 
outcomes of future water engineering projects, which are the two main 
influences that are expected to exacerbate the negative impacts that 
populations are experiencing due to habitat fragmentation and range 
constriction.
    Obovaria cf. unicolor will be vulnerable to future impacts 
throughout its remaining range. The effects of climate change from sea 
level rise will reduce the already limited ranges of the Tangipahoa and 
Tickfaw populations. Obovaria cf. unicolor will also experience 
negative impacts from the increased temperatures, increased occurrences 
of drought, and reduced dissolved oxygen across the species' range. 
Meanwhile, the effects of future channel modification projects have the 
potential to reduce resiliency in the Upper Pearl, Lower Pearl, and 
Pascagoula populations. Only one population will have high resiliency 
(Pascagoula), two will have moderate resiliency (Tangipahoa and 
Tickfaw), and one will have low resiliency (Pearl); the Amite 
population would remain extirpated. Additionally, due to this expected 
decrease in future population resiliency and to the expected continued 
reduction in population ranges, species redundancy and representation 
are also expected to decrease in the future. Representation will move 
from currently moderate to low. This will result in decreased adaptive 
capacity. Redundancy will move from currently moderate to low.

Determination of 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 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.
i. Alabama Hickorynut
Alabama Hickorynut--Status Throughout All of Its Range
    After evaluating threats to the species and assessing the 
cumulative effect of the threats under the Act's section 4(a)(1) 
factors, we determined the primary threats affecting the biological 
status of Alabama hickorynut include the following: sedimentation, 
altered flow regimes, point and nonpoint source pollution, and direct 
and indirect impacts of development and anthropogenic disturbances 
(Factor A), and impacts of climate change, including sea level rise 
(Factor E). We delineated 16 Alabama hickorynut subpopulations in three 
populations across the species' historical range; 13 subpopulations in 
one population are extant. In our current condition analysis, we 
assessed habitat condition and population demographics to determine the 
species' current resiliency. Populations with occurrences since 2000 
were considered current. Two Alabama hickorynut populations in the 
Mobile River Basin have been extirpated (Alabama and Cahaba) and are 
not expected to naturally re-establish. The one extant Alabama 
hickorynut population exhibits low current resiliency (Tombigbee).
    Based on differences in ecological settings and connectivity at a 
larger scale, we delineated two representative units for the Alabama 
hickorynut in the Mobile River Basin: the extirpated Eastern Mobile 
River Basin (Alabama and Cahaba Rivers) and the Western Mobile River 
Basin (Tombigbee River). The extant Western Mobile River Basin 
representative unit is highly fragmented with no connectivity between 
subpopulations following the completion of the TTW in 1984. This 
project led to the extirpation of the species from the Tombigbee 
mainstem due to dredging, channelization, and installation of 
impoundments, which eliminated gene flow between the tributaries of the 
Tombigbee River. We determined that the Alabama hickorynut's overall 
ability to adapt to changing environmental conditions (representation 
or adaptive capacity) is low.
    With one population in low resiliency, the Alabama hickorynut has 
low redundancy. However, some redundancy is possible within the 
population, with 7 of the 13 subpopulations distributed such that it 
would be unlikely for one catastrophic event to extirpate all the 
subpopulations at once. However, six of seven subpopulations have low 
abundance, making them more vulnerable to

[[Page 73342]]

potential extirpation by catastrophic events.
    Our analysis of the species' current condition, as well as the 
conservation efforts discussed above, show that the Alabama hickorynut 
is currently in danger of extinction throughout all of its range due to 
the severity and immediacy of threats currently impacting its 
populations. The threats are occurring across the entire range of this 
species, and the species currently exhibits low resiliency, redundancy, 
and representation. Thus, after assessing the best scientific and 
commercial data available, we determined that the species meets the 
definition of an endangered species throughout all of its range.
Alabama Hickorynut--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 
within the foreseeable future throughout all or a significant portion 
of its range. We have determined that the Alabama hickorynut is in 
danger of extinction throughout all of its range and accordingly did 
not undertake an analysis of any significant portion of its range. 
Because the Alabama hickorynut warrants listing as endangered 
throughout all of its range, our determination does not conflict with 
the decision in Center for Biological Diversity v. Everson, 435 F. 
Supp. 3d. 69 (D.D.C. 2020) (Everson), because that decision related to 
significant portion of the range analyses for species that warrant 
listing as threatened, not endangered, throughout all of their range.
Alabama Hickorynut--Determination of Status
    Our review of the best available scientific and commercial 
information indicates that the Alabama hickorynut meets the Act's 
definition of an endangered species. Therefore, we propose to list the 
Alabama hickorynut as an endangered species in accordance with sections 
3(6) and 4(a)(1) of the Act.
ii. Obovaria cf. Unicolor
Obovaria cf. Unicolor--Status Throughout All of Its Range
    After evaluating threats to the species and assessing the 
cumulative effect of the threats under the Act's section 4(a)(1) 
factors, we determined that the primary threats affecting the 
biological status of Obovaria cf. unicolor include: sedimentation, 
altered flow regimes, point and nonpoint source pollution, and direct 
and indirect impacts of development and anthropogenic disturbances 
(Factor A), and impacts of climate change, including sea level rise 
(Factor E).
    Historically, Obovaria cf. unicolor was known from 1,454 river 
miles in Mississippi and Louisiana. The species currently occupies 788 
river miles, or 54 percent of its historical range. We delineated 13 
subpopulations in 6 populations across the species' historical range. 
The Amite population of Obovaria cf. unicolor is extirpated. Of five 
extant populations, two exhibit low current resiliency (Upper Pearl, 
Lower Pearl), and three exhibit high current resiliency (Pascagoula, 
Tangipahoa, Tickfaw).
    Although Obovaria cf. unicolor is extant in four of five 
representative units: Pascagoula, Pearl, Tangipahoa, and Tickfaw, 
connectivity within and between the representative units is very low 
due to unsuitable habitat conditions. The species declines in abundance 
and distribution indicate it may not be able to tolerate major 
environmental changes; therefore, we determined Obovaria cf. unicolor 
also has minimal ability to adapt to changing environmental conditions 
(adaptive capacity). However, three Obovaria cf. unicolor populations 
currently with high resiliency are distributed across the species 
range, so the species currently has moderate redundancy. Given that 
Obovaria cf. unicolor is still present in four representative units, 
three of the populations are high resiliency, and these populations are 
distributed across the range, Obovaria cf. unicolor is not currently in 
danger of extinction.
    In the future, continued modification to channels and resource 
extraction are expected to occur within the range of Obovaria cf. 
unicolor. Additionally, one to 5 feet of sea level rise (depending on 
the sea level rise scenario) would affect the Tickfaw and Tangipahoa 
populations, causing a range contraction for the species. Species 
resilience will decrease, with only one population with high resiliency 
(Pascagoula), two with moderate resiliency (Tangipahoa and Tickfaw), 
and one with low resiliency (Pearl); the Amite population will remain 
extirpated. Representation will move from currently moderate to low. 
This will result in decreased adaptive capacity. Redundancy will move 
from currently moderate to low.
    Thus, after assessing the best scientific and commercial data 
available, we determine that Obovaria cf. unicolor is not currently in 
danger of extinction but is likely to become in danger of extinction 
within the foreseeable future throughout all of its range.
Obovaria cf. Unicolor--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 
within the foreseeable future throughout all or a significant portion 
of its range. The court in Everson 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'' (hereafter ``Final Policy''; 79 FR 
37578, July 1, 2014) that provided if the Services determine that a 
species is threatened throughout all of its range, the Services will 
not analyze whether the species is endangered in a significant portion 
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 Everson, we now consider whether 
the species is in danger of extinction in a significant portion of its 
range. In undertaking this analysis for Obovaria cf. unicolor, we 
choose to address the status question first.
    We evaluated the range of the Obovaria cf. unicolor to determine if 
the species is in danger of extinction in any portion of its range. The 
range of the species can theoretically be divided into portions in an 
infinite number of ways. We focused our analysis on portions of the 
species' range that may meet the definition of an endangered species. 
For Obovaria cf. unicolor, we considered whether the threats or their 
effects on the species are greater in any biologically meaningful 
portion of the species' range than in other portions such that the 
species is in danger of extinction in that portion.
    We examined the following threats: sedimentation, altered flow 
regimes, point and nonpoint source pollution, impacts of climate 
change, including sea

[[Page 73343]]

level rise, and direct and indirect impacts of development and 
anthropogenic disturbances, including cumulative effects.
    The Pearl River unit (upper and lower populations) is the only unit 
that could conceivably be in danger of extinction now. The Amite 
population is extirpated, and lost historical range cannot be a 
significant portion of a species' range under the Final Policy. The 
Pascagoula, Tangipahoa, and Tickfaw populations all currently exhibit 
high resiliency. On the other hand, the Pearl River unit has highly 
fragmented habitat and low resiliency, representation, and redundancy. 
Additionally, within this unit, Obovaria cf. unicolor has lost a large 
portion of its range, and the Pearl River (above and below the 
reservoir) has experienced a high degree of channel modification and 
changes in flow regime, resulting in degraded and unsuitable habitat 
conditions for Obovaria cf. unicolor Therefore, the populations in this 
unit may have a different status than the rest of the range (i.e., this 
portion may be in danger of extinction).
    As a result, we move to the significance question. We considered 
whether the portion may (1) occur in a unique habitat or ecoregion for 
the species; (2) contain high-quality or high-value habitat relative to 
the remaining portions of the range; (3) contain habitat that is 
essential to a specific life-history function for the species and that 
is not found in the other portions (for example, the principal breeding 
ground for the species); or (4) contain a large geographic portion of 
the suitable habitat relative to the remaining portions of the range 
for the species. The Pearl River unit is not a significant portion of 
the range because it does not represent a large geographic portion of 
Obovaria cf. unicolor's range (i.e., it constitutes approximately 18 
percent of the occupied range), it is not high-quality habitat relative 
to the remaining portion of the range (the highest quality habitat is 
in the Pascagoula unit), and it does not provide unique or important 
resources to a particular life stage of Obovaria cf. unicolor.
    Therefore, no portion of the species' range provides a basis for 
determining that the species is in danger of extinction in a 
significant portion of its range, and we determine that the species is 
likely to become in danger of extinction within the foreseeable future 
throughout all of its range. This does not conflict with the courts' 
holdings in Desert Survivors v. Department of the Interior, 321 F. 
Supp. 3d 1011, 1070-74 (N.D. Cal. 2018), and Center for Biological 
Diversity v. Jewell, 248 F. Supp. 3d, 946, 959 (D. Ariz. 2017), 
because, in reaching this conclusion, we did not apply the aspects of 
the Final Policy, including the definition of ``significant'' that 
those court decisions held to be invalid.
Obovaria cf. Unicolor--Determination of Status
    Our review of the best available scientific and commercial 
information indicates that Obovaria cf. unicolor meets the Act's 
definition of a threatened species. Therefore, we propose to list 
Obovaria cf. unicolor 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 as a listed 
species, planning and implementation of 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, foreign 
governments, 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, including the Service, 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 goal of this process is to restore listed 
species to a point where they are secure, self-sustaining, and 
functioning components of their ecosystems.
    The recovery planning process begins with development of a recovery 
outline made available to the public soon after a final listing 
determination. The recovery outline guides the immediate implementation 
of urgent recovery actions while a recovery plan is being developed. 
Recovery teams (composed of species experts, Federal and State 
agencies, nongovernmental organizations, and stakeholders) may be 
established to develop and implement recovery plans. The recovery 
planning process involves the identification of actions that are 
necessary to halt and reverse the species' decline by addressing the 
threats to its survival and recovery. The recovery plan 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. Revisions of the plan may 
be done to address continuing or new threats to the species, as new 
substantive information becomes available. The recovery outline, draft 
recovery plan, final recovery plan, and any revisions will be available 
on our website as they are completed (https://www.fws.gov/program/endangered-species), or from our Alabama Ecological Services Field 
Office (see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (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 ranges 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 these species are listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost-share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the State of Alabama would be 
eligible for Federal funds to implement management actions that promote 
the protection or recovery of Alabama hickorynut or Obovaria cf. 
unicolor. Information on our grant programs that are available to aid 
species recovery can be found at: https://www.fws.gov/service/financial-assistance.
    Although the Alabama hickorynut and Obovaria cf. unicolor are only 
proposed for listing under the Act at this time, please let us know if 
you are interested in participating in recovery efforts for this 
species. Additionally, we invite you to submit any new

[[Page 73344]]

information on these species whenever it becomes available and any 
information you may have for recovery planning purposes (see FOR 
FURTHER INFORMATION CONTACT).
    Section 7 of the Act is titled, ``Interagency Cooperation,'' and it 
mandates all Federal action agencies to use their existing authorities 
to further the conservation purposes of the Act and to ensure that 
their actions are not likely to jeopardize the continued existence of 
listed species or adversely modify critical habitat. Regulations 
implementing section 7 are codified at 50 CFR part 402.
    Section 7(a)(2) states that each Federal action agency shall, in 
consultation with the Secretary, ensure that any action they authorize, 
fund, or carry out is not likely to jeopardize the continued existence 
of a listed species or result in the destruction or adverse 
modification of designated critical habitat. Each Federal agency shall 
review its action at the earliest possible time to determine whether it 
may affect listed species or critical habitat. If a determination is 
made that the action may affect listed species or critical habitat, 
formal consultation is required (50 CFR 402.14(a)), unless the Service 
concurs in writing that the action is not likely to adversely affect 
listed species or critical habitat. At the end of a formal 
consultation, the Service issues a biological opinion, containing its 
determination of whether the Federal action is likely to result in 
jeopardy or adverse modification.
    In contrast, section 7(a)(4) of the Act requires Federal agencies 
to confer with the Service on any 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 critical 
habitat proposed to be designated for such species. Although the 
conference procedures are required only when an action is likely to 
result in jeopardy or adverse modification, action agencies may 
voluntarily confer with the Service on actions that may affect species 
proposed for listing or critical habitat proposed to be designated. In 
the event that the subject species is listed or the relevant critical 
habitat is designated, a conference opinion may be adopted as a 
biological opinion and serve as compliance with section 7(a)(2) of the 
Act.
    Examples of discretionary actions for Alabama hickorynut and 
Obovaria cf. unicolor that may be subject to conference and 
consultation under section 7 are land management or other landscape-
altering activities on Federal lands administered by the USACE, U.S. 
Department of Agriculture (including the Natural Resources Conservation 
Service, Farm Services Agency, and U.S. Forest Service), U.S. 
Department of Energy, U.S. Department of Transportation, U.S. 
Environmental Protection Agency (EPA), and U.S. Fish and Wildlife 
Service, as well as actions on State, Tribal, local, or private lands 
that require a Federal permit (such as a permit from the USACE under 
section 404 of the Clean Water Act (33 U.S.C. 1251 et seq.) or a permit 
from the Service under section 10 of the Act) or that involve some 
other Federal action (such as funding from the Federal Highway 
Administration, Federal Aviation Administration, or the Federal 
Emergency Management Agency). Federal actions not affecting listed 
species or critical habitat--and actions on State, Tribal, local, or 
private lands that are not federally funded, authorized, or carried out 
by a Federal agency--do not require section 7 consultation. Federal 
agencies should coordinate with the local Service Field Office (see FOR 
FURTHER INFORMATION CONTACT, above) with any specific questions on 
section 7 consultation and conference requirements.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to endangered wildlife. 
The prohibitions of section 9(a)(1) of the Act, and the Service's 
implementing regulations codified at 50 CFR 17.21, make it illegal for 
any person subject to the jurisdiction of the United States to commit, 
to attempt to commit, to solicit another to commit, or to cause to be 
committed any of the following acts with regard to any endangered 
wildlife: (1) import into, or export from, the United States; (2) take 
(which includes harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect, or to attempt to engage in any such conduct) 
within the United States, within the territorial sea of the United 
States, or on the high seas; (3) possess, sell, deliver, carry, 
transport, or ship, by any means whatsoever, any such wildlife that has 
been taken illegally; (4) deliver, receive, carry, transport, or ship 
in interstate or foreign commerce, by any means whatsoever and in the 
course of commercial activity; or (5) sell or offer for sale in 
interstate or foreign commerce. Certain exceptions to these 
prohibitions apply to employees or agents of the Service, the National 
Marine Fisheries Service, other Federal land management agencies, and 
State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered wildlife under certain circumstances. Regulations 
governing permits for endangered wildlife are codified at 50 CFR 17.22, 
and general Service permitting regulations are codified at 50 CFR part 
13. With regard to endangered wildlife, a permit may be issued: for 
scientific purposes, for enhancing the propagation or survival of the 
species, or for take incidental to otherwise lawful activities. The 
statute also contains certain exemptions from the prohibitions, which 
are found in sections 9 and 10 of the Act.

II. Protective Regulations Under Section 4(d) of the Act for Obovaria 
cf. Unicolor

Background

    Section 4(d) of the Act contains two sentences. The first sentence 
states that the Secretary shall issue such regulations as she deems 
necessary and advisable to provide for the conservation of species 
listed as threatened species. 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. 
With these two sentences in section 4(d), Congress delegated broad 
authority to the Secretary to determine what protections would be 
necessary and advisable to provide for the conservation of threatened 
species, and even broader authority to put in place any of the section 
9 prohibitions for a given species.
    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, as a valid 
exercise of agency authority, rules developed under section 4(d) that 
included limited prohibitions against takings (see Alsea Valley 
Alliance v. Lautenbacher, 2007 WL 2344927 (D. Or. 2007); Washington 
Environmental Council v. National Marine Fisheries Service, 2002 WL 
511479 (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

[[Page 73345]]

almost infinite number of options available to [her] with regard to the 
permitted activities for those species. [She] may, for example, permit 
taking, but not importation of such species, or [she] 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).
    The provisions of this species' proposed protective regulations 
under section 4(d) of the Act are one of many tools that we would use 
to promote the conservation of Obovaria cf. unicolor. The proposed 
protective regulations would apply only if and when we make final the 
listing of Obovaria cf. unicolor as a threatened species. Nothing in 
4(d) rules 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 Obovaria cf. unicolor. As 
mentioned previously in Available Conservation Measures, section 
7(a)(2) of the Act requires Federal agencies, including the Service, to 
ensure that any action they authorize, fund, 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, even 
before the listing of any species or the designation of its critical 
habitat is finalized, 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 critical habitat proposed to be designated for such 
species. These requirements are the same for a threatened species 
regardless of what is included in its 4(d) rule.
    Section 7 consultation is required for Federal actions that ``may 
affect'' a listed species regardless of whether take caused by the 
activity is prohibited or excepted by a 4(d) rule (under general 
application of the ``blanket rule'' option (for more information, see 
89 FR 23919, April 5, 2024) or a species-specific 4(d) rule). A 4(d) 
rule does not change the process and criteria for informal or formal 
consultations and does not alter the analytical process used for 
biological opinions or concurrence letters. For example, as with an 
endangered species, if a Federal agency determines that an action is 
``not likely to adversely affect'' a threatened species, this will 
require the Service's written concurrence (50 CFR 402.13(c)). 
Similarly, if a Federal agency determinates that an action is ``likely 
to adversely affect'' a threatened species, the action will require 
formal consultation with the Service and the formulation of a 
biological opinion (50 CFR 402.14(a)). Because consultation obligations 
and processes are unaffected by 4(d) rules, we may consider developing 
tools to streamline future intra-Service and interagency consultations 
for actions that result in forms of take that are not prohibited by the 
4(d) rule (but that still require consultation). These tools may 
include consultation guidance, Information for Planning and 
Consultation effects determination keys, template language for 
biological opinions, or programmatic consultations.

Provisions of the Proposed 4(d) Rule

    Exercising the Secretary's authority under section 4(d) of the Act, 
we have developed a proposed rule that is designed to address Obovaria 
cf. unicolor's conservation needs. As discussed previously under 
Summary of Biological Status and Threats, we have concluded that 
Obovaria cf. unicolor is likely to become in danger of extinction 
within the foreseeable future primarily due to sedimentation, altered 
flow regimes, point and nonpoint source pollution, impacts of climate 
change, including sea level rise, and direct and indirect impacts of 
development and anthropogenic disturbances. There are other activities 
that could affect the species and its habitat if they occur in areas 
occupied by the species, such as impacts to water quality and quantity.
    Section 4(d) requires the Secretary to issue such regulations as 
she deems necessary and advisable to provide for the conservation of 
each threatened species and authorizes the Secretary to include among 
those protective regulations any of the prohibitions that section 
9(a)(1) of the Act prescribes for endangered species. We are not 
required to make a ``necessary and advisable'' determination when we 
apply or do not apply specific section 9 prohibitions to a threatened 
species (In re: Polar Bear Endangered Species Act Listing and 4(d) Rule 
Litigation, 818 F. Supp. 2d 214, 228 (D.D.C. 2011) (citing Sweet Home 
Chapter of Cmtys. for a Great Or. v. Babbitt, 1 F.3d 1, 8 (D.C. Cir. 
1993), rev'd on other grounds, 515 U.S. 687 (1995))). Nevertheless, 
even though we are not required to make such a determination, we have 
chosen to be as transparent as possible and explain below why we find 
that, if finalized, the protections, prohibitions, and exceptions in 
this proposed rule as a whole would satisfy the requirement in section 
4(d) of the Act to issue regulations deemed necessary and advisable to 
provide for the conservation of the Obovaria cf. unicolor.
    The protective regulations we are proposing for Obovaria cf. 
unicolor incorporate prohibitions from section 9(a)(1) of the Act to 
address the threats to the species. The prohibitions of section 9(a)(1) 
of the Act, and implementing regulations codified at 50 CFR 17.21, make 
it illegal for any person subject to the jurisdiction of the United 
States to commit, to attempt to commit, to solicit another to commit or 
to cause to be committed any of the following acts with regard to any 
endangered wildlife: (1) import into, or export from, the United 
States; (2) take (which includes harass, harm, pursue, hunt, shoot, 
wound, kill, trap, capture, or collect) within the United States, 
within the territorial sea of the United States, or on the high seas; 
(3) possess, sell, deliver, carry, transport, or ship, by any means 
whatsoever, any such wildlife that has been taken illegally; (4) 
deliver, receive, carry, transport, or ship in interstate or foreign 
commerce, by any means whatsoever and in the course of commercial 
activity; or (5) sell or offer for sale in interstate or foreign 
commerce.
    In particular, this proposed 4(d) rule would provide for the 
conservation of the Obovaria cf. unicolor by prohibiting the following 
activities, unless they fall within specific exceptions or are 
otherwise authorized or permitted: importing or exporting; take; 
possession and other acts with unlawfully taken specimens; delivering, 
receiving, carrying, 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.
    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 
take would help preserve the species' remaining populations and 
decrease synergistic, negative effects from other ongoing or future 
threats. Therefore, we propose to prohibit take of Obovaria cf. 
unicolor, except for take resulting from those actions and activities 
specifically excepted by the 4(d) rule.
    Exceptions to the prohibition on take would include all of the 
general exceptions to the prohibition on take of

[[Page 73346]]

endangered wildlife, as set forth in 50 CFR 17.21, and additional 
exceptions, as described below.
    Despite the prohibitions regarding threatened species, we may under 
certain circumstances issue permits to carry out one or more otherwise-
prohibited activities, including those described above. The regulations 
that govern permits for threatened wildlife state that the Director may 
issue a permit authorizing any activity otherwise prohibited with 
regard to threatened species. These include permits 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 (see 50 CFR 17.32). The statute 
also contains certain exemptions from the prohibitions, which are found 
in sections 9 and 10 of the Act.
    In addition, to further the conservation of the species, any 
employee or agent of the Service, any other Federal land management 
agency, the National Marine Fisheries Service, a State conservation 
agency, or a federally recognized Tribe, who is designated by their 
agency or Tribe for such purposes, may, when acting in the course of 
their official duties, take threatened wildlife without a permit if 
such action is necessary to: (i) Aid a sick, injured, or orphaned 
specimen; or (ii) dispose of a dead specimen; or (iii) salvage a dead 
specimen that may be useful for scientific study; or (iv) remove 
specimens that constitute a demonstrable but nonimmediate threat to 
human safety, provided that the taking is done in a humane manner; the 
taking may involve killing or injuring only if it has not been 
reasonably possible to eliminate such threat by live capturing and 
releasing the specimen unharmed, in an appropriate area.
    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 us in implementing all aspects of the Act. In this 
regard, section 6 of the Act provides that we must 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 us 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 Obovaria cf. unicolor that may result 
in otherwise prohibited take without additional authorization.
    The proposed 4(d) rule would also provide for the conservation of 
the species by allowing exceptions that incentivize conservation 
actions or that, while they may have some minimal level of take of 
Obovaria cf. unicolor, are not expected to rise to the level that would 
have a negative impact (i.e., would have only de minimis impacts) on 
the species' conservation. The proposed exceptions to the prohibitions 
include (1) channel and bank restoration projects, (2) silviculture 
practices and forest management activities that implement State-
approved best management practices (BMPs), and (3) transportation 
projects that avoid instream disturbance in waters occupied by Obovaria 
cf. unicolor. These proposed exceptions to the prohibitions are 
described further below and are expected to have negligible impacts to 
Obovaria cf. unicolor and its habitat.
    The first exception is for incidental take resulting from channel 
and bank restoration projects for creation of natural, physically 
stable, ecologically functioning streams, taking into consideration 
connectivity with floodplain and groundwater aquifers. This exception 
includes a requirement that stream bank restoration projects require 
planting appropriate native vegetation, including woody species 
appropriate for the region and habitat. Actions related to these 
restoration projects that would negatively affect Obovaria cf. unicolor 
include individual mussels being removed, crushed, and/or killed by 
heavy equipment operations and rip-rap placement; removal, destruction, 
and/or replacement of habitat; increased turbidity from streambed 
disturbance; and alterations to flow and turbidity from permanent 
(weirs) or temporary (causeways) structures needed for construction. 
This provision of the proposed 4(d) rule for channel and bank 
restoration would promote conservation of Obovaria cf. unicolor by 
excepting incidental take resulting from activities that would improve 
channel conditions and restore degraded, physically unstable streams or 
stream segments. We anticipate these activities will advance ecological 
conditions within a watershed to a more natural state that would 
benefit Obovaria cf. unicolor, providing for its conservation.
    The second exception is for incidental take resulting from 
silviculture practices and forest management activities that use State-
approved BMPs to protect water and sediment quality and stream and 
riparian habitat. Silviculture and forest management activities that 
use State-approved BMPs to protect water and sediment quality and 
stream and riparian habitat would provide for the conservation of 
Obovaria cf. unicolor. Best management practices would have to be 
designed to reduce sedimentation, erosion, and bank destruction, 
thereby protecting instream habitat for the species. We recognize that 
silvicultural operations are widely implemented in accordance with 
State-approved BMPs (as reviewed by Cristan et al. 2018, entire), and 
the adherence to these BMPs broadly protects water quality, 
particularly related to sedimentation (as reviewed by Cristan et al. 
2016, entire; Warrington et al. 2017, entire; Schilling et al. 2021, 
entire). This provision of the 4(d) rule would promote conservation of 
Obovaria cf. unicolor by excepting from the prohibition on incidental 
take those silviculture and forest management activities that use 
State-approved BMPs because this exception would allow these activities 
to continue while protecting Obovaria cf. unicolor's habitat.
    The third exception is for incidental take resulting from 
transportation projects that avoid or do not include activities that 
disturb instream habitat. Bridge designs that include spanning the 
stream and avoiding stream bank disturbance reduce sedimentation and 
erosion, thereby protecting instream habitat for Obovaria cf. unicolor. 
This provision of the 4(d) rule would promote conservation of Obovaria 
cf. unicolor by encouraging project designs that preserve and 
potentially improve stream habitat.

III. Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (a) Essential to the conservation of the species, and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are

[[Page 73347]]

essential for the conservation of the species.
    Our regulations at 50 CFR 424.02 define the geographical area 
occupied by the species as an area that may generally be delineated 
around species' occurrences, as determined by the Secretary (i.e., 
range). Such areas may include those areas used throughout all or part 
of the species' life cycle, even if not used on a regular basis (e.g., 
migratory corridors, seasonal habitats, and habitats used periodically, 
but not solely by vagrant individuals).
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the requirement that Federal agencies ensure, in consultation 
with the Service, that any action they authorize, fund, or carry out is 
not likely to result in the destruction or adverse modification of 
critical habitat. The designation of critical habitat does not affect 
land ownership or establish a refuge, wilderness, reserve, preserve, or 
other conservation area. Such designation also does not allow the 
government or public to access private lands. Such designation does not 
require implementation of restoration, recovery, or enhancement 
measures by non-Federal landowners. Rather, designation requires that, 
where a landowner requests Federal agency funding or authorization for 
an action that may affect an area designated as critical habitat, the 
Federal agency consult with the Service under section 7(a)(2) of the 
Act. If the action may affect the listed species itself (such as for 
occupied critical habitat), the Federal agency would have already been 
required to consult with the Service even absent the designation 
because of the requirement to ensure that the action is not likely to 
jeopardize the continued existence of the species. Even if the Service 
were to conclude after consultation that the proposed activity is 
likely to result in destruction or adverse modification of the critical 
habitat, the Federal action agency and the landowner are not required 
to abandon the proposed activity, or to restore or recover the species; 
instead, they must implement ``reasonable and prudent alternatives'' to 
avoid destruction or adverse modification of critical habitat.
    Under the first prong of the Act's definition of critical habitat, 
areas within the geographical area occupied by the species at the time 
it was listed are included in a critical habitat designation if they 
contain physical or biological features (1) which are essential to the 
conservation of the species and (2) which may require special 
management considerations or protection. For these areas, critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, those physical or biological 
features that are essential to the conservation of the species (such as 
space, food, cover, and protected habitat).
    Under the second prong of the Act's definition of critical habitat, 
we can designate critical habitat in areas outside the geographical 
area occupied by the species at the time it is listed, upon a 
determination that such areas are essential for the conservation of the 
species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information from the SSA report and information developed during the 
listing process for the species. Additional information sources may 
include any generalized conservation, criteria, or outline that may 
have been developed for the species; the recovery plan for the species; 
articles in peer-reviewed journals; conservation plans developed by 
States and counties; scientific status surveys and studies; biological 
assessments; other unpublished materials; or experts' opinions or 
personal knowledge.
    Habitat is dynamic, and species may move from one area to another 
over time. We recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be needed 
for recovery of the species. Areas that are important to the 
conservation of the species, both inside and outside the critical 
habitat designation, will continue to be subject to: (1) Conservation 
actions implemented under section 7(a)(1) of the Act; (2) regulatory 
protections afforded by the requirement in section 7(a)(2) of the Act 
for Federal agencies to ensure their actions are not likely to 
jeopardize the continued existence of any endangered or threatened 
species; and (3) the prohibitions found in section 9 of the Act for 
Alabama hickorynut and in the 4(d) rule for Obovaria cf. unicolor. 
Federally funded or permitted projects affecting listed species outside 
their designated critical habitat areas may still result in jeopardy 
findings in some cases. These protections and conservation tools will 
continue to contribute to recovery of the species. Similarly, critical 
habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans 
(HCPs), or other species conservation planning efforts if new 
information available at the time of those planning efforts calls for a 
different outcome.

Critical Habitat Determinability

    We determine that designating critical habitat for the Alabama 
hickorynut and Obovaria cf. unicolor is prudent. Our regulations at 50 
CFR 424.12(a)(2) state that designation of 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.''
    We reviewed the available informationpertaining to the biological 
needs of the species and habitat characteristics where these species 
are

[[Page 73348]]

located. The species' needs of both the Alabama hickorynut and Obovaria 
cf. unicolor are sufficiently well known, but a careful assessment of 
the economic impacts that may occur due to a critical habitat 
designation is ongoing. Until these efforts are complete, information 
sufficient to perform a required analysis of the impacts of the 
designation is lacking; therefore, we find designation of critical 
habitat for both the Alabama hickorynut and Obovaria cf. unicolor is 
prudent but not determinable at this time. We plan to publish a 
proposed rule to designate critical habitat for both the Alabama 
hickorynut and Obovaria cf. unicolor concurrently with the availability 
of an economic analysis of the proposed designation.

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.)

    Regulations adopted pursuant to section 4(a) of the Act are exempt 
from the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et 
seq.) and do not require an environmental analysis under NEPA. We 
published a notice outlining our reasons for this determination in the 
Federal Register on October 25, 1983 (48 FR 49244). This includes 
listing, delisting, and reclassification rules, as well as critical 
habitat designations and species-specific protective regulations 
promulgated concurrently with a decision to list or reclassify a 
species as threatened. The courts have upheld this position (e.g., 
Douglas County v. Babbitt, 48 F.3d 1495 (9th Cir. 1995) (critical 
habitat); Center for Biological Diversity v. U.S. Fish and Wildlife 
Service, 2005 WL 2000928 (N.D. Cal. Aug. 19, 2005) (concurrent 4(d) 
rule)).

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, May 4, 1994), Executive Order 13175 
(Consultation and Coordination with Indian Tribal Governments), the 
President's memorandum of November 30, 2022 (Uniform Standards for 
Tribal Consultation; 87 FR 74479, December 5, 2022), and the Department 
of the Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with Federally recognized 
Tribes and Alaska Native Corporations (ANCs) on a government-to-
government basis. In accordance with Secretary's Order 3206 of June 5, 
1997 (American Indian Tribal Rights, Federal-Tribal Trust 
Responsibilities, and the Endangered Species Act), we readily 
acknowledge our responsibilities to work directly with Tribes in 
developing programs for healthy ecosystems, to acknowledge that Tribal 
lands are not subject to the same controls as Federal public lands, to 
remain sensitive to Indian culture, and to make information available 
to Tribes. We have determined that no Tribal lands fall within the 
range of the Alabama hickorynut or Obovaria cf. unicolor, and no Tribes 
will be affected if we list these species.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov and upon request from 
the Alabama 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 Alabama 
Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

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

Proposed Regulation Promulgation

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

PART 17--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. In Sec.  17.11, amend paragraph (h) by adding entries for 
``Hickorynut, [no common name]'' and ``Hickorynut, Alabama'' to the 
List of Endangered and Threatened Wildlife in alphabetical order under 
CLAMS to read as follows:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

----------------------------------------------------------------------------------------------------------------
                                                                                         Listing citations and
          Common name            Scientific name        Where listed         Status        applicable rules
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                      Clams
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Hickorynut, [no common name]..  Obovaria cf.       Wherever found........  T          [Federal Register citation
                                 unicolor.                                             when published as a final
                                                                                       rule]; 50 CFR
                                                                                       17.45(i).\4d\
Hickorynut, Alabama...........  Obovaria unicolor  Wherever found........  E          [Federal Register citation
                                                                                       when published as a final
                                                                                       rule].
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------


[[Page 73349]]

0
3. Further amend Sec.  17.45, as proposed to be amended on March 20, 
2023, at 88 FR 16776 and on July 26, 2023, at 88 FR 48294, by adding 
paragraph (i) to read as follows:


Sec.  17.45  Species-specific rules--snails and clams.

* * * * *
    (i) Hickorynut, [no common name] (Obovaria cf. unicolor)--(1) 
Prohibitions. The following prohibitions that apply to endangered 
wildlife also apply to Obovaria cf. unicolor. Except as provided under 
paragraph (i)(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 a 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) Possess and engage in other acts with unlawfully taken 
wildlife, as set forth at Sec.  17.21(d)(2) for endangered wildlife.
    (v) Take incidental to an otherwise lawful activity caused by:
    (A) Channel and bank restoration projects for creation of natural, 
physically stable, ecologically functioning streams, taking into 
consideration connectivity with floodplain and groundwater aquifers. 
Stream bank restoration projects require planting appropriate native 
vegetation, including woody species appropriate for the region and 
habitat.
    (B) Silviculture practices and forest management activities that 
implement State-approved best management practices to protect water and 
sediment quality and stream and riparian habitat.
    (C) Transportation projects that avoid or do not include activities 
that disturb instream habitat, including, but not limited to, bridge 
designs that span the stream and avoid stream bank disturbance.

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2024-20158 Filed 9-9-24; 8:45 am]
BILLING CODE 4333-15-P