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[Federal Register Volume 90, Number 9 (Wednesday, January 15, 2025)]
[Proposed Rules]
[Pages 3765-3783]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-29641]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2024-0131; FXES1111090FEDR-256-FF09E21000]
RIN 1018-BH71

Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the San Francisco Bay-Delta Distinct Population 
Segment of the Longfin Smelt

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
designate critical habitat for the San Francisco Bay-Delta distinct 
population segment (DPS) of the longfin smelt (Spirinchus 
thaleichthys), a fish species from the San Francisco Bay estuary in 
California, under the Endangered Species Act of 1973, as amended (Act). 
In total, approximately 91,630 acres (37,082 hectares) in California 
fall within the boundaries of the proposed critical habitat 
designation. We also announce the availability of an economic analysis 
of the proposed designation of critical habitat for the species.

DATES: We will accept comments received or postmarked on or before 
March 17, 2025. Comments submitted

[[Page 3766]]

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 March 3, 2025.

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-R8-ES-2024-0131, 
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-R8-ES-2024-0131, 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 and 100-word summary of this 
proposed rule, are available at https://www.regulations.gov at Docket 
No. FWS-R8-ES-2024-0131. For the proposed critical habitat designation, 
the coordinates or plot points or both from which the maps are 
generated are included in the decision file for this critical habitat 
designation and are available at https://www.regulations.gov at Docket 
No. FWS-R8-ES-2024-0131.

FOR FURTHER INFORMATION CONTACT: Donald Ratcliff, Field Supervisor, 
U.S. Fish and Wildlife Service, San Francisco Bay-Delta Fish and 
Wildlife Office, 650 Capitol Mall Suite 8-300, Sacramento, CA 95814; 
telephone 916-930-5603. 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-R8-ES-2024-
0131 on https://www.regulations.gov for a document that summarizes this 
proposed rule.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act, a determination that 
a species is endangered or threatened requires that we must designate 
the species' critical habitat to the maximum extent prudent and 
determinable. We published a final rule in the Federal Register listing 
the San Francisco Bay-Delta distinct population segment (DPS) of the 
longfin smelt (Spirinchus thaleichthys) (Bay-Delta longfin smelt) as an 
endangered species on July 30, 2024 (89 FR 61029). We are now proposing 
to designate its critical habitat. Making a critical habitat 
designation 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 designate critical habitat 
for the San Francisco Bay-Delta DPS of the longfin smelt (Spirinchus 
thaleichthys).
    The basis for our action. Section 4(a)(3) of the Act requires that 
the Secretary of the Interior (Secretary), to the maximum extent 
prudent and determinable, designate critical habitat for listed 
species. Section 3(5)(A) of the Act defines critical habitat as (i) the 
specific areas within the geographical area occupied by the species, at 
the time it is listed, on which are found those physical or biological 
features (I) essential to the conservation of the species and (II) 
which may require special management considerations or protections; and 
(ii) specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination by the Secretary 
that such areas are essential for the conservation of the species. 
Section 4(b)(2) of the Act states that the Secretary must make the 
designation on the basis of the best scientific data available and 
after taking into consideration the economic impact, the impact on 
national security, and any other relevant impacts of specifying any 
particular area as critical habitat.

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) Specific information on:
    (a) Biological or ecological requirements of the Bay-Delta longfin 
smelt, including habitat requirements for feeding, breeding, rearing, 
and sheltering;
    (b) The amount and distribution of the Bay-Delta longfin smelt's 
habitat;
    (c) Any additional areas occurring within the range of the species 
in the San Francisco Bay estuary (e.g., Petaluma River, South San 
Francisco Bay) and ocean areas outside the Golden Gate, that should be 
included in the designation because the areas (i) were occupied at the 
time of listing and contain the physical or biological features that 
are essential to the conservation of the species and that may require 
special management considerations or protection, or (ii) were 
unoccupied at the time of listing and are essential for the 
conservation of the species;
    (d) Special management considerations or protection that may be 
needed in critical habitat areas we are proposing, including managing 
for the potential effects of climate change.
    (2) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (3) Any probable economic, national security, or other relevant 
impacts of designating any area that may be included in the final 
designation, and the related benefits of including or excluding 
specific areas.
    (4) Information on the extent to which the description of probable 
economic impacts in the draft economic analysis is a reasonable 
estimate of the likely economic impacts and any additional information 
regarding probable economic impacts that we should consider.
    (5) Whether any specific areas we are proposing for critical 
habitat designation should be considered for exclusion under section 
4(b)(2) of the Act, and whether the benefits of potentially excluding 
any specific area outweigh the benefits of including that area under 
section 4(b)(2) of the Act. If you think we should exclude any areas, 
please provide information supporting a benefit of exclusion.
    (6) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comments.
    Please include sufficient information with your submission (such as 
scientific

[[Page 3767]]

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)(2) of 
the Act directs that the Secretary shall designate critical habitat on 
the basis of the best scientific 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 designation 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), our final critical habitat designation may not 
include all areas proposed, may include some additional areas that meet 
the definition of critical habitat, or may exclude some areas if we 
find the benefits of exclusion outweigh the benefits of inclusion and 
exclusion will not result in the extinction of the species. In our 
final rule, we will clearly explain our rationale and the basis for our 
final decision, 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 the Federal Register. The use of virtual public hearings is 
consistent with our regulations at 50 CFR 424.16(c)(3).

Previous Federal Actions

    On October 7, 2022, we published in the Federal Register a proposed 
rule to list the Bay-Delta longfin smelt as endangered (87 FR 60957). 
On February 27, 2023, we reopened the comment period on the proposed 
rule for 30 days and announced an online public hearing, which took 
place March 14, 2023 (88 FR 12304). Our final rule determining 
endangered species status for the Bay-Delta longfin smelt was published 
in the Federal Register on July 30, 2024 (89 FR 61029). In our 2022 
proposed listing rule, we stated that the designation of critical 
habitat was not determinable due to the lack of incremental economic 
impact information. We have since obtained the necessary economic 
information and are now proposing critical habitat. Please see the 2022 
proposed listing rule and 2024 final listing rule (citations above in 
this paragraph) for additional information on previous Federal actions.

Peer Review

    A species status assessment (SSA) team prepared an SSA report for 
the Bay-Delta longfin smelt (Service 2024, entire). The SSA team was 
composed of Service biologists, in consultation with other species 
experts including those from the California Department of Fish and 
Wildlife (CDFW). The SSA report represents a compilation of the best 
scientific and commercial data available concerning the status of the 
Bay-Delta longfin smelt, 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 draft SSA report 
(Service 2021, entire). We sent the draft SSA report to five 
independent peer reviewers and received three responses. Results of 
this structured peer review process can be found at https://www.regulations.gov. A summary of the peer review comments and our 
response to those comments can be found in the final listing rule (see 
89 FR 61029; July 30, 2024, Peer Review section). Prior to preparing 
the proposed and final listing rules, we incorporated the results of 
these reviews as well as comments and information received from public 
comment, as appropriate, into the current (2024) SSA report. The 
information within the 2024 SSA report forms the foundation for this 
proposed critical habitat rule.

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 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

[[Page 3768]]

requirement that each Federal action agency 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 
designated 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 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 compiled in the SSA report and information developed during 
the listing process for the species. Additional information sources may 
include any generalized conservation strategy, 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. 
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 scientific data 
available 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.

Physical or Biological Features Essential to the Conservation of the 
Species

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12(b), in determining which areas we will designate as 
critical habitat from within the geographical area occupied by the 
species at the time of listing, we consider the physical or biological 
features that are essential to the conservation of the species and 
which may require special management considerations or protection. The 
regulations at 50 CFR 424.02 define ``physical or biological features 
essential to the conservation of the species'' as the features that 
occur in specific areas and that are essential to support the life-
history needs of the species, including, but not limited to, water 
characteristics, soil type, geological features, sites, prey, 
vegetation, symbiotic species, or other features. A feature may be a 
single habitat characteristic or a more complex combination of habitat 
characteristics. Features may include habitat characteristics that 
support ephemeral or dynamic habitat conditions. Features may also be 
expressed in terms relating to principles of conservation biology, such 
as patch size, distribution distances, and connectivity. For example, 
physical features essential to the conservation of the species might 
include gravel of a particular size required for spawning, alkaline 
soil for seed germination, protective cover for migration, or 
susceptibility to flooding or fire that maintains necessary early-
successional habitat characteristics. Biological features might include 
prey species, forage grasses, specific kinds or ages of trees for 
roosting or nesting, symbiotic fungi, or absence of a particular level 
of nonnative species consistent with conservation needs of the listed 
species. The features may also be combinations of habitat 
characteristics and may encompass the relationship between 
characteristics or the necessary amount of a characteristic essential 
to support the life history of the species.

[[Page 3769]]

    In considering whether features are essential to the conservation 
of the species, we may consider an appropriate quality, quantity, and 
spatial and temporal arrangement of habitat characteristics in the 
context of the life-history needs, condition, and status of the 
species. These characteristics include, but are not limited to, space 
for individual and population growth and for normal behavior; food, 
water, air, light, minerals, or other nutritional or physiological 
requirements; cover or shelter; sites for breeding, reproduction, or 
rearing (or development) of offspring; and habitats that are protected 
from disturbance.

Bay-Delta Longfin Smelt Description, Distribution, and Habitat 
Requirements

    Below is a summary of the description, distribution, and habitat 
requirements of the Bay-Delta longfin smelt. For a more thorough 
discussion of this information as well as information on the species' 
ecology, life history, and habitat needs, please see the SSA report 
(Service 2024, chapter 2, pp. 9-27).
BILLING CODE 4333-15-P
[GRAPHIC] [TIFF OMITTED] TP15JA25.000

BILLING CODE 4333-15-C
    The longfin smelt is a small fish 9 to 11 centimeters (cm) (3.5 to 
4.3 inches (in)) in length with a relatively short lifespan of 
approximately 2 to 3 years. The longfin smelt, as a species, occurs in 
bays and estuaries from northern California north along the coast 
through Alaska. The Bay-Delta DPS of the longfin smelt occupies the 
entire San Francisco Bay estuary and areas of the Pacific Ocean outside 
the Golden Gate (see figure 1 above) depending on time of year and 
lifestage. The Bay-Delta longfin smelt does not occur outside of the 
San Francisco Bay estuary or the near ocean areas in large numbers, and 
there does not appear to be substitutable habitat outside of currently 
occupied areas (e.g., salinity, water temperature); therefore, we have 
determined that proposing critical habitat in unoccupied areas is 
unnecessary, as these areas likely would not represent suitable habitat 
nor contribute to conservation of the Bay-Delta longfin smelt.
    The tidally influenced San Francisco Bay estuary includes the 
central and south San Francisco Bay, San Pablo Bay, and Suisun Bay (and 
their tributaries), the Sacramento and San Joaquin River Delta (Delta), 
and near-shore ocean waters outside the Golden Gate from the Marin 
headlands to the mouth of Tomales Bay into the Gulf of the Farallones 
(CDFW 2009, pp. 6-9). The San Francisco Bay estuary is a complex and 
dynamic system exhibiting a wide range of salinities, temperatures, and 
habitats. Tidal movement and freshwater inputs from the Sacramento 
River and San Joaquin River as well as local tributaries are two major 
drivers of estuary conditions. Incoming high-salinity tides and 
freshwater flows combine in creating a longitudinal and vertical 
salinity gradient. Water temperature is also influenced by tidal and 
freshwater inflow as well as wind, precipitation, and air temperatures. 
This salinity gradient and water temperature variability exert a strong 
physical and biological influence in the estuary and

[[Page 3770]]

dictates habitat use by different life stages of Bay-Delta longfin 
smelt.
    The Bay-Delta longfin smelt is a facultatively anadromous species, 
meaning some older juveniles and adults may migrate to the ocean to 
seek cooler water temperatures, but adults return to less saline water 
for spawning activities to meet egg laying, hatching, larval 
development, and juvenile growth requirements.
    Water Temperature Conditions: Bay-Delta longfin smelt most 
frequently occur in cold- and cool-water habitats within the San 
Francisco Bay estuary (Jeffries et al. 2016, p. 1712; Yanagitsuru et 
al. 2021, fig. 1, p. 5). Adults are thought to be limited by water 
temperature of approximately >22 degrees Celsius ([deg]C) (>72 degrees 
Fahrenheit ([deg]F)) during the summer and are likely to spend the 
majority of this time in cooler water habitats of the San Francisco Bay 
and near-shore ocean areas. In general, fish over a year in age inhabit 
lower temperature water than fish below a year in age, although both 
age classes inhabit water temperature between 16-18 [deg]C (61-64 
[deg]F) in the summer and fall (Baxter 1999, fig. 8, p. 191). In the 
fall and early winter as water temperatures in the estuary decline, 
Bay-Delta longfin smelt return upstream to the estuary to seek 
appropriate spawning areas where water conditions are favorable for egg 
survival. These conditions vary by location depending on delta outflow, 
freshwater flow from tributaries, water salinity conditions, and other 
environmental conditions. See Spawning Conditions below for information 
on egg and larvae water temperature conditions.
    Water Turbidity Conditions: Turbidity, or the amount of suspended 
particles in the water, is an important habitat characteristic for the 
Bay-Delta longfin smelt. Turbidity in aquatic environments is similar 
to fog in terrestrial environments in that the greater the distance an 
object is from an individual the more obscure it becomes (Utne-Palm 
2002, p. 115; Pangle et al. 2012, pp. 10-11). Turbid waters assist fish 
such as the Bay-Delta longfin smelt by making it less visible to 
predators and making its prey (which are relatively translucent) more 
visible against the backdrop of the particles in the water (Utne-Palm 
2002, pp. 122-123). In laboratory studies, Bay-Delta longfin smelt 
larvae had higher survival rates in more turbid water measured at 40 
NTU (nephelometric turbidity units) and grew larger at 20 NTU and 40 
NTU as opposed to 10 NTU (Yanagitsuru 2020, entire).
    Water Salinity Conditions: Although spawning behavior of longfin 
smelt has not been observed in the San Francisco Bay estuary, it is 
believed that spawning behavior is similar to that of the Lake 
Washington population in Washington State, where adults make overnight 
runs into tributaries of the lake then return to the lake before dawn 
(Dryfoos 1965, p. 61; Moulton 1974, pp. 49-50). For the Bay-Delta 
longfin smelt this would entail adult longfin smelt making short runs 
upstream into fresh-water areas of the Delta, tributaries, or into 
areas of the San Francisco Bay (Suisun Bay, San Pablo Bay, or South 
Bay) that have low-salinity water and appropriate water temperature 
conditions (CDFW 2009, pp. 11-12; Rosenfield 2010, p. 8). One 
laboratory study has identified a salinity tolerance below 32 parts per 
thousand (ppt) with larvae surviving the longest and having the largest 
growth at lower salinity levels between 5 and 10 ppt (Yanagitsuru et 
al. 2022, p. 6). Another study identified that Bay-Delta longfin smelt 
can successfully spawn and rear in a range of low salinity (0.4-5 ppt), 
with fertilization being greatest at lower salinity levels (Rahman et 
al. 2023, pp. 7-8). Field studies have identified salinity levels 
between 2-4 ppt as having the greatest density of larvae (4-9 
millimeter (mm) (0.16-0.35 in) in length) (Grimaldo et al. 2017, p. 8).
    Spawning Conditions: Bay-Delta longfin smelt spawn only once in 
their lifetime but may have multiple spawning events during that single 
period depending on habitat conditions. Spawning, reproduction, and 
rearing occurs in low-salinity to freshwater habitats beginning in late 
fall/early winter and extends into the spring as water temperature and 
low-salinity conditions allow. The freshwater flow into the estuary as 
well as other environmental conditions and geomorphology greatly 
influence the habitat conditions, spawning success, and food 
availability for the Bay-Delta longfin smelt.
    Observations of yolk-sac staged larvae suggest spawning habitat 
extends from the tidal reaches of the Sacramento and San Joaquin Rivers 
to Suisun Bay and Suisun Marsh as well as tributaries to San Pablo Bay, 
and in the sloughs of Coyote Creek in the South Bay, although 
recruitment success in San Pablo Bay tributaries and the South Bay was 
confirmed only during wet years (Wang 1986, pp. 113-121; Meng and 
Matern 2001, p. 755; Grimaldo et al. 2017, p. 6; Lewis et al. 2019, p. 
31; Lewis et al. 2020, p. 1). Spawning substrate is composed of sandy 
or gravel substrates, rocks, or aquatic plants (Wang 1986, p. 113; 
Moyle 2002, p. 236; CDFW 2009, pp. 12, 16). Laboratory studies have 
identified that Bay-Delta longfin smelt release more eggs onto sand 
(approximately 94 percent) as opposed to gravel (approximately 6 
percent) (CDFW 2009, p. 11). In one study, high river flows during egg 
incubation were associated with poor recruitment, whereas increased 
river flows later in the season--during the hatching period--were 
associated with greater recruitment (Chigbu 2000, pp. 549-554).
    Spawning activity for Bay-Delta longfin smelt can begin as early as 
November and extends until late June, although spawning more typically 
occurs from December through April based on ripe females and when the 
presence of yolk-sac larvae have been observed in the environment 
(Radtke 1966, p. 116; Hieb and Baxter 1993, p. 110; Moyle 2002, p. 236; 
CDFW 2009, p. 10). Water temperature plays an important role in 
triggering spawning activity. Although spawning can start once water 
temperatures drop below 16 [deg]C (60.8 [deg]F) (CDFW 2009, p. 11), 
other information suggests lower water temperatures may be more ideal 
(Baxter 2016, entire; Tempel and Burns 2021, slide 12). Lab studies 
have identified a minimum spawning temperature of 5.6 [deg]C (41 
[deg]F) (Wang 1986, pp. 6-9) and reduced size of larvae and decrease in 
reproduction success near or above 15 [deg]C (59 [deg]F) (Yanagitsuru 
et al. 2021, Figure 1 and 3a, pp. 5 and 7). Within the San Francisco 
Bay estuary, spawning occurs when water temperature drops below ~14 
[deg]C (57.2 [deg]F) and becomes consistent when water temperatures 
remain 13 [deg]C or lower (55.4 [deg]F) (CDFW 2009, p. 11; Baxter 2016, 
entire; Grimaldo et al. 2017, p. 8).
    Larval Habitat Use: The majority of larvae are affiliated with the 
estuary's major low salinity zone (LSZ) generated by the mixing of 
freshwater outflow from the Delta with the brackish waters of the 
estuary (Service 2024, section 2.3, p. 11, and p. 20). However, larvae 
can also be found in tributaries when flows from those tributaries are 
high enough and temperatures low enough to support egg survival and 
hatching (Lewis et al. 2019, p. 3). The spatial distribution of these 
larvae reflects the year-to-year variation in the geographic location 
of the LSZ (Dege and Brown 2004, fig. 3, p. 57; Grimaldo et al. 2020, 
fig. 6, p. 10).
    Juvenile and Adult Habitat Use: Aggregated survey data have shown 
that juveniles (>20 mm in length) have been detected at one time or 
another throughout the estuary and into some tributaries to the Delta 
above tidal influence and have been collected most frequently from 
deeper water habitats as opposed to shoals or shoreline areas 
(Rosenfield and Baxter 2007, p. 1586; Merz et al. 2013, fig. 2, p. 
132).

[[Page 3771]]

Regardless of where spawning takes place and embryos develop, the 
spatial distribution of juveniles and adults shows a distinct seaward 
migration as water temperatures warm in the late spring and early 
summer in the Delta and upstream portions of the San Francisco Bay 
estuary (Rosenfield and Baxter 2007, p. 1590). However, in any given 
month, survey data indicate that some fraction of the Bay-Delta longfin 
smelt population remains in the San Francisco Bay with an unknown 
fraction moving out to the ocean off the coast of San Francisco 
(Rosenfield and Baxter 2007, p. 1590; Merz et al. 2013, p. 142; Garwood 
2017, pp. 98-104).
    Food Resources: Larval Bay-Delta longfin smelt select strongly for 
the calanoid copepod Eurytemora affinis as prey; all other prey types 
combined account for only about 10 percent of their diet (Barros et al. 
2022, fig. 6a and 6c, p. 10). When longfin smelt reach about 25 mm (1 
in) in length, their diet switches and is nearly all mysids (small 
shrimp-like crustaceans) (Barros et al. 2022, fig. 6b, p. 10). This 
finding of a highly specified diet applies to fresh- and brackish-water 
habitats throughout the estuary (Barros et al. 2022, fig. 2. p. 2). 
Bay-Delta longfin smelt larvae and small juveniles appear to focus on 
only two prey taxa. Larvae less than about 25 mm (1 in) in length 
appear to primarily feed on the copepod Eurytemora affinis. The same is 
true for larvae and small juveniles larger than 25 mm in length, which 
appear to prey most often on mysids. Bay-Delta longfin smelt adults 
that return to Suisun Marsh also show a strong dietary preference for 
mysids while relying on other copepods and amphipods when mysids are 
less abundant (CDFW unpub. Diet Study Data; Feyrer et al. 2003, p. 281; 
Burdi 2022, entire).

Summary of Essential Physical or Biological Features

    The ecological conditions within the water areas of the San 
Francisco Bay estuary are complex and dynamic and exhibit a wide range 
of salinities, temperatures, and habitats as the result of tidal 
movement of ocean water, freshwater inputs from the Sacramento and San 
Joaquin Rivers and local tributaries, wind conditions, and air 
temperature. We derive the specific physical or biological features 
essential to the conservation of the Bay-Delta longfin smelt from 
studies of the species' habitat, ecology, and life history as described 
above. We focused our designation on areas that contained the 
appropriate physical or biological features needed by the species for 
successful spawning and rearing and that provide larvae sufficient food 
resources to grow and mature as described in our conservation strategy 
for determining critical habitat for the Bay-Delta longfin smelt (see 
Criteria Used to Identify Critical Habitat below). Although areas 
outside the designation, such as the Pacific Ocean or areas within the 
Sacramento-San Joaquin Delta, are used by the species and are important 
in providing appropriate life history conditions for adults and may 
provide for limited reproduction in years with extreme freshwater 
inflow, the majority of appropriate spawning conditions, spawning, and 
larval development occurs within the area we have identified as 
critical habitat. Additional information can be found in the SSA report 
(Service 2024, entire; available on https://www.regulations.gov under 
Docket No. FWS-R8-ES-2022-0082). The physical or biological features 
(PBFs) essential to the conservation of the Bay-Delta longfin smelt are 
comprised of water temperature, salinity, turbidity, food resources, 
substrate, and hydrologic conditions capable of supporting Bay-Delta 
longfin smelt spawning and rearing as well as larval and juvenile 
development. Within the San Francisco Bay estuary, different areas of 
the critical habitat unit provide all of the physical or biological 
features essential to the conservation of Bay-Delta longfin smelt, but 
not all of the features occur in all portions of the unit at all times. 
During various times of the year, different areas of the estuary 
provide the following essential physical or biological features:
    PBF 1, Water temperature requirements: Water temperature ranges to 
support reproduction, growth, and survival of the Bay-Delta longfin 
smelt at different life stages to include:
    (A) Estuary water temperatures below 13 [deg]Celsius ([deg]C) (55.4 
[deg]F ([deg]F)) from December through May to initiate and support 
successful spawning;
    (B) Estuary water temperatures less than 15 [deg]C (59.0 [deg]F) 
from December through May for egg development, hatching success, and 
early larval development;
    (C) Estuary water temperatures less than 20 [deg]C (60.0 [deg]F) 
from February through June for larvae 40 days post hatch and older to 
support growth and avoid physiological stress; and
    (D) Estuary and nearshore ocean water temperatures less than 22 
[deg]C (71.6 [deg]F) year-round for juveniles and adults to support 
growth and avoid physiological stress.
    PBF 2, Water salinity requirements: Suitable salinity 
concentrations to support successful reproduction, growth, and 
recruitment; such ranges include:
    (A) Salinity conditions between 2-4 parts per thousand (ppt) from 
December through May to support average larval salinity requirements; 
and
    (B) Salinity conditions between 0.4-10 ppt from December through 
May to support diversity of egg and early larval rearing conditions.
    PBF 3, Water turbidity requirements: Turbidity greater than 20 
nephelometric turbidity units to optimize feeding and predator 
avoidance.
    PBF 4, Food resource requirements: Food resources in abundances 
that support growth and recruitment of all life stages; these food 
resources include, but are not limited to:
    (A) The copepod Eurytemora affinis, the primary prey item 
supporting larvae less than 25 mm (approximately 1 inch length);
    (B) Mysids including Neomysis mercedis and Hyperacanthomysis 
longirostris, and other amphipods, the primary prey items supporting 
juveniles and larvae greater than 25 mm in length (approximately 1 inch 
length); and
    (C) Prey of various zooplankton species such as those identified in 
paragraphs (A) and (B) of this entry for juveniles and adults.
    PBF 5, Substrate requirements: Substrate composed mostly of sandy 
habitat, although portions may include gravel substrates, rocks, or 
aquatic plants that provide suitable habitat for spawning, protection, 
cover, and development of eggs and larvae.
    PBF 6, Hydrologic requirements: Contemporaneous with the 
appropriate seasonal needs by life stage of the species, inflow into 
the estuary of appropriate freshwater to provide the appropriate water 
salinity, temperature, and turbidity conditions as well as food 
resources set forth in PBFs 1-4 above.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the specific 
areas within the geographical area occupied by the species at the time 
of listing contain features which are essential to the conservation of 
the species and which may require special management considerations or 
protection. The features essential to the conservation of the Bay-Delta 
longfin smelt may require special management considerations or 
protections to address: (1) habitat alteration within and adjacent to 
water areas; (2) changes to hydrology associated with reduced and 
altered freshwater flows and resulting increases in saline habitat 
conditions; (3) increased water temperatures associated

[[Page 3772]]

with altered flow regimes or climate change conditions; (4) reduced 
food resource availability due to inappropriate water conditions or 
introduction of nonnative species; and (5) introduction of pollutants 
and other sources of contaminants that may degrade water quality 
conditions or impact food resources.
    Special management considerations or protection that could address 
these threats include, but are not limited to: (1) implement best 
management practices to reduce impacts associated with habitat 
alteration such as bank hardening, levee maintenance, and channel 
dredging or reduction of sand sources; (2) consider water management to 
mimic functional flow regimes (timing, intensity, and duration of 
flows), especially during periods of low flow or drought conditions; 
(3) consider water management to maintain appropriate water temperature 
conditions for all life stages of the Bay-Delta longfin smelt; (4) 
implement monitoring and other actions to prevent or limit introduction 
of nonnative species into the estuary that may reduce or alter food 
resources for the Bay-Delta longfin smelt; and (5) monitor and manage 
water quality to assist in reducing the amount of pollutants entering 
the estuary.

Criteria Used To Identify Critical Habitat

    As required by section 4(b)(2) of the Act, we use the best 
scientific data available to designate critical habitat. In accordance 
with the Act and our implementing regulations at 50 CFR 424.12(b), we 
review available information pertaining to the habitat requirements of 
the species and identify specific areas within the geographical area 
occupied by the species at the time of listing and any specific areas 
outside the geographical area occupied by the species to be considered 
for designation as critical habitat. We are not currently proposing to 
designate any areas outside the geographical area occupied by the Bay-
Delta longfin smelt because we have not identified any unoccupied areas 
that meet the definition of critical habitat. The range of the Bay-
Delta longfin smelt is only a portion of the range occupied by the 
species. The Bay-Delta longfin smelt as a DPS currently occupies the 
full extent of its identified range within the San Francisco Bay 
estuary and ocean areas outside the Golden Gate to the Farallon Islands 
depending on the time of year, life stage, and environmental conditions 
(see figure 1 in Bay-Delta Longfin Smelt Description, Distribution, and 
Habitat Requirements above).
    The sources of data used to determine and delineate the critical 
habitat for the Bay-Delta longfin smelt included: (1) the SSA report 
and references therein pertaining to the habitat needs of the DPS 
(Service 2024, entire); (2) Bay-Delta longfin smelt spawning and 
rearing habitat utilized during the winter/spring, fresher water phase 
of the life cycle as determined by study of the LSZ based on published 
data; (3) U.S. Geological Survey (USGS) National Hydrography Dataset 
(NHD) for California for the San Francisco Bay estuary and associated 
river systems and shorelines; (4) USGS digital ortho-photo quarter-
quadrangles base layer map using Universal Transverse Mercator (UTM) 
Zone 10N coordinates, which was used to delineate the critical habitat 
unit; and (5) Environmental Systems Research Institute's (ESRI's) 
Aeronautical Reconnaissance Coverage Geographical Information System 
(ArcGIS) online basemap aerial imagery, which was used to cross-check 
the base layer map. Land ownership or management information was 
obtained from digitized surface land management data managed by the 
Bureau of Land Management.
    In order to determine the specific areas within the geographical 
area occupied by the species at the time of listing on which are found 
those PBFs essential to the conservation of the species and delineating 
the critical habitat unit boundaries, we developed a conservation 
strategy. Below we summarize our strategy and criteria for this 
designation. Please see the full description of our strategy for 
additional information (Service 2023a, entire).
    The goal of our conservation strategy for this critical habitat 
designation is to identify the specific areas within the Bay-Delta 
longfin smelt's range that provide essential physical or biological 
features; without these areas, range-wide resiliency, redundancy, and 
representation could not be achieved. The strategy focuses on the 
fundamental parameters of the species' biology and ecology based on 
well-accepted conservation-biology and ecological principles for 
conserving species and their habitats, such as those described by 
Carroll et al. (1996, pp. 1-12); Meffe and Carroll (1997, pp. 347-383); 
Shaffer and Stein (2000, pp. 301-321); Natural Resources Conservation 
Service (NRCS) 2004 (entire); Tear et al. (2005, pp. 835-849); Groom et 
al. (2006, entire); and Wolf et al. (2015, pp. 200-207).
    In developing our conservation strategy, we focused on increasing 
the resiliency of Bay-Delta longfin smelt by improving the DPS's 
abundance. To this end, our conservation strategy and rule set for 
determining critical habitat for the Bay-Delta longfin smelt looked at 
conserving and maintaining those areas within the San Francisco Bay 
estuary that provide sufficient amount of high-quality spawning and 
rearing habitat with appropriate physical and hydrological 
characteristics to provide for recruitment over the long term. We 
considered the habitat and conditions necessary for successful 
recruitment of individuals to the different life stages of the species. 
The Bay-Delta longfin smelt relies on the San Francisco Bay estuary and 
the unique suite of environmental conditions it provides for spawning, 
larval rearing, juvenile growth, and maturation.
    Salinity and water temperature are two primary factors that 
determine the distribution of the Bay-Delta longfin smelt in the 
estuary and are especially important for spawning and rearing life 
stages. Both salinity and water temperature conditions are influenced 
by freshwater input, primarily from the San Joaquin and Sacramento 
Rivers. The species uses most of the estuary during its life cycle, 
focusing spawning and larval rearing in the more landward LSZ, and 
juvenile growth and maturation at greater salinities typical of the 
more seaward areas of the estuary. The location and extent of the LSZ 
and suitable spawning and rearing habitat varies annually depending on 
the magnitude, timing, and duration of freshwater inputs into the 
estuary. Numerous studies have shown a positive and persistent 
correlation between longfin smelt juvenile abundance indices and 
freshwater flow (Stevens and Miller 1983, pp. 431-432; Jassby et al. 
1995, p. 285; Sommer et al. 2007, p. 274; Thomson et al. 2010, pp. 
1439-1440; Kimmerer 2002, p. 47; Rosenfield and Baxter 2007, p. 1585; 
Kimmerer et al. 2009, p. 381; Mac Nally et al. 2010, p. 1422; Maunder 
et al. 2015, p. 108; Nobriga and Rosenfield 2016, p. 53; Kimmerer and 
Gross 2022, p. 2734).
    While the overall pattern relating freshwater flows to abundance 
indices for the Bay-Delta longfin smelt is widely accepted, the 
mechanisms driving this correlation are not fully quantified or 
resolved. Potential mechanisms have been identified and include how 
freshwater may affect spawning locations, the duration of the spawning 
season, the transport of eggs and larvae downstream to favorable 
rearing habitats, the location of the LSZ and larval and young juvenile 
retention, entrainment of larvae and juveniles, prey availability for 
larvae and juveniles, prey delivery, and turbidity of the LSZ (for 
further information see SSA section 3.1.1.). These mechanisms likely

[[Page 3773]]

act in concert and influence recruitment in a manner determined by 
prevailing freshwater conditions. Our critical habitat designation was 
informed by the relationship between these mechanisms and freshwater 
inputs into the estuary.
    With this information, we have determined that the specific areas 
occupied by the species that provide spawning and rearing habitat that 
is utilized by the Bay-Delta longfin smelt during the fresher-water 
phase of the life cycle in the winter/spring period are the focus of 
our critical habitat designation. Without appropriate areas for 
spawning and rearing of offspring, the Bay-Delta longfin smelt would 
not be able to sustain populations in the wild. Therefore, we initially 
follow the PBFs to predict distribution, using salinity at these key 
life stages, as the primary predictive factor. These areas were 
determined by using the best available scientific information on the 
approximation of the LSZ of the San Francisco Bay-Delta, using the 95 
percent occurrence interval (actual observed values) of X2 values 
between January through May for water years stretching the last nine 
decades (Hutton et al. 2017a, entire; Hutton et al. 2017b, entire). X2 
is defined as the location (in kilometers) along a linear axis 
stretching from the Golden Gate Bridge eastwards into the Sacramento/
San Joaquin River Delta where salinity measures two practical salinity 
units. This representation is a static estimate of a very dynamic 
phenomenon, as outflow and tidal dynamics influence this metric such 
that the actual position of X2 fluctuates in space and time. We also 
included areas within the Napa River that contain those low salinity 
habitat areas that were contiguous with the data on LSZ for the San 
Francisco Bay-Delta. Additional information on our conservation 
strategy can be found in our PBF and conservation strategy document 
(Service 2023a, entire)
    The area identified as critical habitat is occupied during the 
spawning and rearing life stage (~January through May) and contains 
those physical or biological features essential to the conservation of 
the Bay-Delta longfin smelt reflecting the habitat characteristics 
required by pre-spawning adults, eggs, larvae, and early juveniles of 
the Bay-Delta longfin smelt for survival and successful reproduction. 
The Bay-Delta longfin smelt does not occur outside of the San Francisco 
Bay estuary or the near ocean, and there does not appear to be 
substitutable habitat outside of currently occupied areas (e.g., 
salinity, water temperature); therefore, we have determined that 
proposing critical habitat in unoccupied areas is unnecessary, as these 
areas likely would not represent suitable habitat nor contribute to 
conservation of the Bay-Delta longfin smelt.
    When determining proposed critical habitat boundaries, we made 
every effort to avoid including developed areas such as lands covered 
by buildings, pavement, and other structures because such lands lack 
physical or biological features necessary for the Bay-Delta longfin 
smelt. Because the designation focuses on water areas, very little if 
any developed areas such as buildings or other structures are included 
in the designation. However, any such lands inadvertently left inside 
critical habitat boundaries shown on the maps of this proposed rule are 
excluded by text in the proposed rule and are not proposed for 
designation as critical habitat. Therefore, if the critical habitat is 
finalized as proposed, a Federal action involving these lands would not 
trigger section 7 consultation with respect to critical habitat and the 
requirement of no adverse modification unless the specific action would 
affect the physical or biological features in the adjacent critical 
habitat.
    We propose to designate as critical habitat areas that we have 
determined are occupied at the time of listing (i.e., currently 
occupied) and contain one or more of the physical or biological 
features that are essential to support life-history processes of the 
Bay-Delta longfin smelt.
    The proposal includes one unit for designation based on one or more 
of the physical or biological features being present to support the 
Bay-Delta longfin smelt's life-history processes. This unit contains 
all of the identified physical or biological features and supports the 
Bay-Delta longfin smelt's particular use of that habitat.
    The proposed critical habitat designation is defined by the map, as 
modified by any accompanying regulatory text, presented at the end of 
this document under Proposed Regulation Promulgation. We include more 
detailed information on the boundaries of the critical habitat 
designation in the preamble of this document. We will make the 
coordinates or plot points or both on which the map is based available 
to the public on https://www.regulations.gov at Docket No. FWS-R8-ES-
2024-0131 and on our internet site at https://www.fws.gov/office/san-francisco-bay-delta-fish-and-wildlife/, and at the field office 
responsible for the designation (see FOR FURTHER INFORMATION CONTACT).

Proposed Critical Habitat Designation

    We are proposing to designate one unit of approximately 91,630 ac 
(37,082 ha) as critical habitat for the Bay-Delta longfin smelt, 
identified as the San Francisco Bay-Delta Unit (see table below). The 
critical habitat area we describe below constitutes our current best 
assessment of areas that meet the definition of critical habitat for 
the Bay-Delta longfin smelt.

                     Table 1--Proposed Critical Habitat Unit for the Bay-Delta Longfin Smelt
              [Area estimates reflect all water and land within the critical habitat unit boundary]
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Critical habitat unit               Land ownership by      Size of unit in acres/hectares  Occupied?
                                     type.
----------------------------------------------------------------------------------------------------------------
San Francisco Bay-Delta...........  Federal..............              20               8  Yes.
                                    State................             257             104
                                    Local government.....               7               3
                                    Non-profit/                        49              20
                                     nongovernmental
                                     organization.
                                    Undetermined                      913             370
                                     Shoreline.
                                    Undetermined waters..          90,384          36,578
                                                          --------------------------------
                                       Total.............          91,630          37,082
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

[[Page 3774]]

    We present a brief description of the unit, and reasons why it 
meets the definition of critical habitat for the Bay-Delta longfin 
smelt, below.

San Francisco Bay-Delta Unit

    The San Francisco Bay-Delta Unit consists of 91,630 ac (37,082 ha) 
in total and is made up of 1,246 ac (504 ha) of shoreline area and 
90,384 ac (36,578 ha) of stream and estuary water area within the San 
Francisco Bay estuary within Contra Costa, Napa, Sacramento, Solano, 
and Sonoma Counties, California. The unit extends from the numerous 
tributaries flowing into the Suisun Bay near the confluence of the 
Sacramento and San Joaquin Rivers at Sherman Island downstream 
approximately 7 to 10 miles (mi) (10 to 16 kilometers (km)) into San 
Pablo Bay near Point Pinole (Contra Costa County) and Midshipman Point 
at Tubbs Island (Sonoma County).
    Ownership of shoreline areas within the proposed designation 
includes the U.S. Fish and Wildlife Service (20 ac (8 ha)), California 
Department of Fish and Wildlife (181 ac (73 ha)), California State 
Parks (3 ac (1.1 ha)), California Department of Water Resources (45 ac 
(18 ha)), California State Lands Commission (29 ac (12 ha)), local 
government (7 ac (3 ha)), and nonprofit and nongovernmental 
organizations (49 ac (20 ha)). Additionally, the proposed designation 
includes water areas of the San Francisco Bay estuary totaling 
approximately 90,384 ac (36,578 ha) of undetermined ownership. We have 
exempted Department of Defense (DoD) areas owned, managed, and 
controlled by the U.S. Army Military Ocean Terminal Concord (MOTCO) 
totaling approximately 753 ac (304 ha) under section 4(a)(3)(B)(i) of 
the Act (see Exemptions Application of Section 4(a)(3) of the Act, 
below).
    The unit was occupied by the species at the time of listing and is 
still occupied. Seasonally, this unit contains all the identified PBFs 
essential to the conservation of the Bay-Delta longfin smelt. 
Particularly, those PBFs reflecting the habitat characteristics 
required by pre-spawning adults, eggs, larvae, and early juveniles for 
survival and successful reproduction are geographically associated with 
this area. The identified specific critical habitat areas may require 
special management considerations or protection to address activities 
that impact the PBFs identified for the Bay-Delta longfin smelt and may 
include those activities associated with habitat alteration (such as 
dredging, shoreline protection activities, or levee maintenance); 
changes to hydrology associated with reduced and altered freshwater 
flows and its resulting potential increases in saline habitat 
conditions; increased water temperatures; reduced food resource 
availability; and activities that introduce or increase pollutants and 
other contaminants into the estuary.

Effects of Critical Habitat Designation

Section 7 Consultation

    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they 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, section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any agency action which is likely to 
jeopardize the continued existence of any species proposed to be listed 
under the Act or result in the destruction or adverse modification of 
proposed critical habitat.
    Destruction or adverse modification means a direct or indirect 
alteration that appreciably diminishes the value of critical habitat as 
a whole for the conservation of a listed species (50 CFR 402.02).
    Compliance with the requirements of section 7(a)(2) is documented 
through our issuance of:
    (1) A concurrence letter for Federal actions that may affect, but 
are not likely to adversely affect, listed species or critical habitat; 
or
    (2) A biological opinion for Federal actions that may affect, and 
are likely to adversely affect, listed species or critical habitat.
    When we issue a biological opinion concluding that a project is 
likely to jeopardize the continued existence of a listed species and/or 
destroy or adversely modify critical habitat, we provide reasonable and 
prudent alternatives to the project, if any are identifiable, that 
would avoid the likelihood of jeopardy and/or destruction or adverse 
modification of critical habitat. We define ``reasonable and prudent 
alternatives'' (at 50 CFR 402.02) as alternative actions identified 
during formal consultation that:
    (1) Can be implemented in a manner consistent with the intended 
purpose of the action,
    (2) Can be implemented consistent with the scope of the Federal 
agency's legal authority and jurisdiction,
    (3) Are economically and technologically feasible, and
    (4) Would, in the Service Director's opinion, avoid the likelihood 
of jeopardizing the continued existence of the listed species or avoid 
the likelihood of destroying or adversely modifying critical habitat.
    Reasonable and prudent alternatives can vary from slight project 
modifications to extensive redesign or relocation of the project. Costs 
associated with implementing a reasonable and prudent alternative are 
similarly variable.
    Regulations at 50 CFR 402.16 set forth requirements for Federal 
agencies to reinitiate consultation. Reinitiation of consultation is 
required and shall be requested by the Federal agency, where 
discretionary Federal involvement or control over the action has been 
retained or is authorized by law and: (1) if the amount or extent of 
taking specified in the incidental take statement is exceeded; (2) if 
new information reveals effects of the action that may affect listed 
species or critical habitat in a manner or to an extent not previously 
considered; (3) if the identified action is subsequently modified in a 
manner that causes an effect to the listed species or critical habitat 
that was not considered in the biological opinion or written 
concurrence; or (4) if a new species is listed or critical habitat 
designated that may be affected by the identified action. As provided 
in 50 CFR 402.16, the requirement to reinitiate consultations for new 
species listings or critical habitat designation does not apply to 
certain agency actions (e.g., land management plans issued by the 
Bureau of Land Management in certain circumstances).

Destruction or Adverse Modification of Critical Habitat

    The key factor related to the destruction or adverse modification 
determination is whether implementation of the proposed Federal action 
directly or indirectly alters the designated critical habitat in a way 
that appreciably diminishes the value of the critical habitat for the 
conservation of the listed species. As discussed above, the role of 
critical habitat is to support physical or biological features 
essential to the conservation of a listed species and provide for the 
conservation of the species.
    Section 4(b)(8) of the Act requires that our Federal Register 
documents ``shall, to the maximum extent practicable, also include a 
brief description and evaluation of those activities (whether public or 
private) which, in the opinion of the Secretary, if undertaken may 
adversely modify such [critical] habitat, or may be affected by such 
designation.'' Activities that may be affected by

[[Page 3775]]

designation of critical habitat for the Bay-Delta longfin smelt include 
those that may affect the physical or biological features of the Bay-
Delta longfin smelt's critical habitat. See the sections above on 
Physical or Biological Features Essential to the Conservation of the 
Species and Special Management Considerations or Protection for 
additional information.

Exemptions

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

    The Sikes Act Improvement Act of 1997 (Sikes Act) (16 U.S.C. 670a) 
required each military installation that includes land and water 
suitable for the conservation and management of natural resources to 
complete an integrated natural resources management plan (INRMP) by 
November 17, 2001. An INRMP integrates implementation of the military 
mission of the installation with stewardship of the natural resources 
found on the base. Each INRMP includes:
    (1) An assessment of the ecological needs on the installation, 
including the need to provide for the conservation of listed species;
    (2) A statement of goals and priorities;
    (3) A detailed description of management actions to be implemented 
to provide for these ecological needs; and
    (4) A monitoring and adaptive management plan.
    Among other things, each INRMP must, to the extent appropriate and 
applicable, provide for fish and wildlife management; fish and wildlife 
habitat enhancement or modification; wetland protection, enhancement, 
and restoration where necessary to support fish and wildlife; and 
enforcement of applicable natural resource laws.
    The National Defense Authorization Act for Fiscal Year 2004 (Pub. 
L. 108-136) amended the Act to limit areas eligible for designation as 
critical habitat. Specifically, section 4(a)(3)(B)(i) of the Act (16 
U.S.C. 1533(a)(3)(B)(i)) provides that the Secretary shall not 
designate as critical habitat any lands or other geographical areas 
owned or controlled by the Department of Defense, or designated for its 
use, that are subject to an integrated natural resources management 
plan prepared under section 101 of the Sikes Act (16 U.S.C. 670a), if 
the Secretary determines in writing that such plan provides a benefit 
to the species for which critical habitat is proposed for designation.
    We consult with the military on the development and implementation 
of INRMPs for installations with listed species. We analyzed INRMPs 
developed by military installations located within the range of the 
proposed critical habitat designation for the Bay-Delta longfin smelt 
to determine if they meet the criteria for exemption from critical 
habitat under section 4(a)(3) of the Act. The following areas are 
Department of Defense (DoD) lands with completed, Service-approved 
INRMPs within the areas preliminarily identified as meeting the 
definition of critical habitat.

Approved INRMPs

    U.S. Army Military Ocean Terminal Concord (MOTCO), Contra Costa and 
Solano Counties, California, 753 ac (304 ha).
    Within the areas preliminarily identified as meeting the definition 
of critical habitat for the Bay-Delta longfin smelt, we identified a 
portion of shoreline (50 ac (20 ha)) and water area (703 ac (284 ha)) 
(753 ac (304 ha) total) of the San Francisco Bay estuary owned, 
controlled, and managed by the U.S. Army Military Surface Deployment 
and Distribution Command's 834th Transportation Battalion, which 
manages and operates the U.S. Army Military Ocean Terminal Concord 
(MOTCO). MOTCO is the primary munitions trans-shipment facility for the 
DoD on the West Coast of the United States.
    The U.S. Army received full management authority for MOTCO on 
October 1, 2008, as a result of the 2005 Base Realignment and Closure 
process. Prior to this, MOTCO was a tenant command to Naval Weapon 
Station Seal Beach Detachment (NWSSBD) Concord, operating under the 
U.S. Navy. Military lands on MOTCO include a total of 6,641 ac (2,688 
ha) of uplands, shoreline, and island areas adjacent to or within 
Suisun Bay in Contra Costa and Solano Counties, California. Other 
military lands formerly belonging to the NWSSBD have been declared 
surplus and have been operationally closed and transferred to the City 
of Concord.
    In August 2023, staff at MOTCO in coordination with the Service and 
U.S. Department of Commerce National Oceanic and Atmospheric 
Administration-Fisheries, West Coast Region (NOAA) finalized and signed 
the Final MOTCO Integrated Natural Resources Management Plan (INRMP) 
(U.S. Army Corps of Engineers 2023, entire).
    The INRMP provides the staff of MOTCO with an adaptive plan for 
managing natural resources to support and be consistent with the 
military mission while protecting and enhancing those natural resources 
for multiple use and ecological integrity. The INRMP is designed to 
meet statutory requirements of the Sikes Act as amended as well as 
manage and implement measures concerning conservation, protection, and 
management of fish and wildlife resources. The total area owned by the 
DoD at MOTCO includes inland areas (115 ac (47 ha)) and tidal areas 
(6,242 ac (2,526 ha)). The tidal area comprises a mainland operational 
portion and island areas that include approximately 5 miles (8 
kilometers) of mainland shoreline; three ocean terminal piers and 
facilities for reception, staging, and loading of ammunition; railroad 
infrastructure; and the Los Medanos Hills. Approximately 703 ac (284 
ha) of water area of the San Francisco Bay estuary are restricted use 
areas controlled by MOTCO that are used for docking and loading of 
vessels for military purposes. The offshore islands consist of 
approximately 2,045 ac (828 ha). The offshore islands and most of the 
marshlands within the tidal area at MOTCO are part of a wetland 
preserve area, established through a memorandum of understanding 
between the U.S. Navy and the Service (U.S. Navy and U.S. Fish and 
Wildlife Service 1984, entire). The islands are undeveloped, except for 
natural gas wells operated on the southern shore of Ryer Island 
operated by Chevron U.S.A. Inc. (California Department of Conservation 
1982, pp. 1-11, 250). The mainland operational area is composed of old 
and new buildings, roads, and other developed infrastructure and 
landscaping.
    The overall goal of the MOTCO INRMP is to integrate natural 
resources stewardship and compliance responsibilities with operational 
requirements to sustain the military mission at MOTCO as well as 
develop, initiate, and maintain programs for the conservation, 
utilization, and rehabilitation of natural resources at MOTCO. The 
following measures, objectives, and management strategies that have 
been identified and implemented to further the goal include:
     Ensure compliance with applicable Federal laws and 
regulations as they pertain to natural resources.
     Maintain and enhance biodiversity within the constraints 
of the military mission.
     Implement adaptive management strategies using flexible 
and responsive management techniques based upon scientific data 
gathered from monitoring programs, literature, and resource experts.
     Conserve the quality of habitat for Federal and State-
listed endangered and threatened species.

[[Page 3776]]

     Maintain sufficient natural resources support personnel to 
implement, oversee, and monitor the management strategies of the INRMP.
     Provide for an institutional memory and Geographic 
Information System (GIS) based data inventory that may be used as a 
framework for future resources personnel to make installation 
management decisions.
     Maintain the distributions of sensitive plant and animal 
species and native plant communities, as well as their relationships to 
tidal hydrology and landscape features, until they become progressively 
better understood.
     Maintain or enhance levels of biodiversity and habitat 
quality on the installation.
     Maintain or enhance tidally influenced marsh habitats 
capable of supporting viable populations of the federally listed salt 
marsh harvest mouse (Reithrodontomys raviventris), California Ridgway's 
rail (Rallus obsoletus obsoletus), and State listed California black 
rail (Laterallus jamaicensis coturniculus).
     Maintain landscape-scale native habitat diversity and 
species richness.
     Monitor, control, and eventually eliminate the spread of 
nonnative invasive aquatic and marsh species, such as Brazilian 
waterweed (Egeria densa) and perennial pepperweed (Lepidium 
latifolium), to enhance native aquatic and wetland communities.
     Adaptively manage approximately 3,227 ac (1,306 ha) of 
tidal wetlands at MOTCO using an improved understanding of the 
installation's tidal hydrology and its effects on native species 
diversity and habitat quality, as well as maintain and improve wetland 
functions and values.
     Continue management of the Wetland Preserve Area in 
collaboration with the Service and coordinate with other stakeholders 
on tidal wetland management issues.
     Ensure hydrologic regimes and erosion rates reflect 
natural conditions on-site.
    MOTCO has shown a track record of implementing conservation actions 
related to their activities that protect and maintain habitat for 
sensitive species including reducing erosion and run-off into the 
estuary, protecting water quality, and managing, conserving, and 
protecting wetland and estuary habitat adjacent to the San Francisco 
Bay-Delta and areas occupied by the Bay-Delta longfin smelt. The 
conservation efforts identified in the INRMP and being implemented by 
MOTCO will provide a benefit to the Bay-Delta longfin smelt by reducing 
or eliminating negative water quality impacts from erosion, maintaining 
tidally influenced wetland habitat adjacent to the bay, providing 
better water conditions for the DPS's food resources, and adaptively 
managing tidal wetlands to maintain and improve wetland functions and 
values.
    Based on the above considerations, and in accordance with section 
4(a)(3)(B)(i) of the Act, we have determined that the identified lands 
are subject to the MOTCO INRMP and that conservation efforts identified 
in the INRMP will provide a benefit to the Bay-Delta longfin smelt. 
Therefore, lands within this installation are exempt from critical 
habitat designation under section 4(a)(3) of the Act. We are not 
including approximately 753 ac (304 ha) of shoreline and water habitat 
used by the Bay-Delta longfin smelt in this proposed critical habitat 
designation because of this exemption.

Consideration of Impacts Under Section 4(b)(2) of the Act

    Section 4(b)(2) of the Act states that the Secretary shall 
designate and make revisions to critical habitat on the basis of the 
best available scientific data after taking into consideration the 
economic impact, national security impact, and any other relevant 
impact of specifying any particular area as critical habitat. The 
Secretary may exclude an area from designated critical habitat based on 
economic impacts, impacts on national security, or any other relevant 
impacts. Exclusion decisions are governed by the regulations at 50 CFR 
424.19 and the Policy Regarding Implementation of Section 4(b)(2) of 
the Endangered Species Act (hereafter, the ``2016 Policy''; 81 FR 7226, 
February 11, 2016), both of which were developed jointly with the 
National Marine Fisheries Service (NMFS). We also refer to a 2008 
Department of the Interior Solicitor's opinion entitled ``The 
Secretary's Authority to Exclude Areas from a Critical Habitat 
Designation under Section 4(b)(2) of the Endangered Species Act'' (M-
37016).
    In considering whether to exclude a particular area from the 
designation, we identify the benefits of including the area in the 
designation, identify the benefits of excluding the area from the 
designation, and evaluate whether the benefits of exclusion outweigh 
the benefits of inclusion. If the analysis indicates that the benefits 
of exclusion outweigh the benefits of inclusion, the Secretary may 
exercise discretion to exclude the area only if such exclusion would 
not result in the extinction of the species. In making the 
determination to exclude a particular area, the statute on its face, as 
well as the legislative history, are clear that the Secretary has broad 
discretion regarding which factor(s) to use and how much weight to give 
to any factor. In our final rules, we explain any decision to exclude 
areas, as well as decisions not to exclude, to make clear the rational 
basis for our decision. We describe below the process that we use for 
taking into consideration each category of impacts and any initial 
analyses of the relevant impacts.

Consideration of Economic Impacts

    Section 4(b)(2) of the Act and its implementing regulations require 
that we consider the economic impact that may result from a designation 
of critical habitat. To assess the probable economic impacts of a 
designation, we must first evaluate specific land uses or activities 
and projects that may occur in the area of the critical habitat. We 
then must evaluate the impacts that a specific critical habitat 
designation may have on restricting or modifying specific land uses or 
activities for the benefit of the species and its habitat within the 
areas proposed. We then identify which conservation efforts may be the 
result of the species being listed under the Act versus those 
attributed solely to the designation of critical habitat for this 
particular species. The probable economic impact of a proposed critical 
habitat designation is analyzed by comparing scenarios both ``with 
critical habitat'' and ``without critical habitat.''
    The ``without critical habitat'' scenario represents the baseline 
for the analysis, which includes the existing regulatory and socio-
economic burden imposed on landowners, managers, or other resource 
users potentially affected by the designation of critical habitat 
(e.g., under the Federal listing as well as other Federal, State, and 
local regulations). Therefore, the baseline represents the costs of all 
efforts attributable to the listing of the species under the Act (i.e., 
conservation of the species and its habitat incurred regardless of 
whether critical habitat is designated). The ``with critical habitat'' 
scenario describes the incremental impacts associated specifically with 
the designation of critical habitat for the species. The incremental 
conservation efforts and associated impacts would not be expected 
without the designation of critical habitat for the species. In other 
words, the incremental costs are those attributable solely to the 
designation of critical habitat, above and beyond the baseline costs. 
These are the costs we use when evaluating the benefits of inclusion 
and exclusion of particular areas from the final designation of 
critical habitat should we

[[Page 3777]]

choose to conduct a discretionary 4(b)(2) exclusion analysis.
    Executive Orders (E.O.s) 12866 and 13563 direct Federal agencies to 
assess the costs and benefits of available regulatory alternatives in 
quantitative (to the extent feasible) and qualitative terms. Consistent 
with these E.O. regulatory analysis requirements, our effects analysis 
under the Act may take into consideration impacts to both directly and 
indirectly affected entities, where practicable and reasonable. If 
sufficient data are available, we assess to the extent practicable the 
probable impacts to both directly and indirectly affected entities. To 
determine whether the designation of critical habitat may have an 
economic effect of $200 million or more in any given year (which would 
trigger section 3(f)(1) of E.O. 12866, as amended by E.O. 14094), we 
used a screening analysis to assess whether a designation of critical 
habitat for the Bay-Delta longfin smelt is likely to exceed this 
threshold.
    For this particular designation, we developed an incremental 
effects memorandum (IEM) considering the probable incremental economic 
impacts that may result from this proposed designation of critical 
habitat (Service 2023b, entire). The information contained in our IEM 
was then used to develop a screening analysis of the probable effects 
of the designation of critical habitat for the Bay-Delta longfin smelt 
(Industrial Economic Inc. (IEc) 2024, entire). We began by conducting a 
screening analysis of the proposed designation of critical habitat in 
order to focus our analysis on the key factors that are likely to 
result in incremental economic impacts. The purpose of the screening 
analysis is to filter out particular geographical areas of critical 
habitat that are already subject to such protections and are, 
therefore, unlikely to incur incremental economic impacts. In 
particular, the screening analysis considers baseline costs (i.e., 
absent critical habitat designation) and includes any probable 
incremental economic impacts where land and water use may already be 
subject to conservation plans, land management plans, best management 
practices, or regulations that protect the habitat area as a result of 
the Federal listing status of the species. Ultimately, the screening 
analysis allows us to focus our analysis on evaluating the specific 
areas or sectors that may incur probable incremental economic impacts 
as a result of the designation.
    The presence of the listed species in occupied areas of critical 
habitat means that any destruction or adverse modification of those 
areas is also likely to jeopardize the continued existence of the 
species. Therefore, designating occupied areas as critical habitat 
typically causes little if any incremental impacts above and beyond the 
impacts of listing the species. As a result, we generally focus the 
screening analysis on areas of unoccupied critical habitat (unoccupied 
units or unoccupied areas within occupied units). Overall, the 
screening analysis assesses whether designation of critical habitat is 
likely to result in any additional management or conservation efforts 
that may incur incremental economic impacts. This screening analysis 
combined with the information contained in our IEM constitute what we 
consider to be our economic analysis of the proposed critical habitat 
designation for the Bay-Delta longfin smelt and is summarized in the 
narrative below.
    As part of our screening analysis, we considered the types of 
economic activities that are likely to occur within the areas likely 
affected by the critical habitat designation. In our evaluation of the 
probable incremental economic impacts that may result from the proposed 
designation of critical habitat for the Bay-Delta longfin smelt, first 
we identified, in the IEM dated December 29, 2023 (Service 2023b), 
probable incremental economic impacts associated with the following 
categories of activities: (1) dredging; (2) levee construction; (3) 
sand mining; (4) in-water construction; (5) aquatic weed control; (6) 
flood/sea level rise protection projects; (7) habitat restoration 
projects; and (8) scientific monitoring activities. Indirect upstream 
impacts associated with water management or water withdrawal activities 
associated with water infrastructure and agriculture or municipal water 
use may also occur but the impacts associated with these activities 
would be overshadowed by the effects of climate change and reduced 
precipitation and water flows into the estuary. We considered each 
industry or category individually. Additionally, we considered whether 
their activities have any Federal involvement. Critical habitat 
designation generally will not affect activities that do not have any 
Federal involvement; under the Act, designation of critical habitat 
affects only activities conducted, funded, permitted, or authorized by 
Federal agencies.
    In areas where the Bay-Delta longfin smelt is present, Federal 
agencies would be required to consult with the Service under section 7 
of the Act on activities they authorize, fund, or carry out that may 
affect the species. If we finalize this critical habitat designation as 
proposed, Federal agencies would be required to consider the effects of 
their actions on the designated habitat, and if the Federal action may 
affect critical habitat, our consultations would include an evaluation 
of measures to avoid the destruction or adverse modification of 
critical habitat.
    In our IEM, we attempted to clarify the distinction between the 
effects that would result from the species being listed and those 
attributable to the critical habitat designation (i.e., difference 
between the jeopardy and adverse modification standards) for the Bay-
Delta longfin smelt's critical habitat. Because the designation of 
critical habitat for Bay-Delta longfin smelt is being proposed nearly 
concurrently with the listing, it has been our experience that it is 
more difficult to discern which conservation efforts are attributable 
to the species being listed and those which will result solely from the 
designation of critical habitat. However, the following specific 
circumstances in this case help to inform our evaluation: (1) The 
essential physical or biological features identified for critical 
habitat are the same features essential for the life requisites of the 
species, and (2) any actions that would likely adversely affect the 
essential physical or biological features of occupied critical habitat 
are also likely to adversely affect the Bay-Delta longfin smelt. The 
IEM outlines our rationale concerning this limited distinction between 
baseline conservation efforts and incremental impacts of the 
designation of critical habitat for this species. This evaluation of 
the incremental effects has been used as the basis to evaluate the 
probable incremental economic impacts of this proposed designation of 
critical habitat.
    The proposed critical habitat designation for the Bay-Delta longfin 
smelt includes a single occupied unit, totaling approximately 91,630 ac 
(37,082 ha). The areas being considered are shoreline areas ((less than 
1 percent of the proposed designation) that are Federal (2 percent), 
State (21 percent), local government (1 percent), private or other non-
profit areas (4 percent), and other undetermined shoreline areas (73 
percent)) and a water area of undetermined ownership (over 99 percent 
of the proposed designation) within the San Francisco Bay-Delta. In 
these areas, any actions that may affect the Bay-Delta longfin smelt or 
its habitat would also affect the proposed critical habitat, and it is 
unlikely that any additional conservation efforts would be recommended 
to address the adverse modification standard over and above those 
recommended as necessary to

[[Page 3778]]

avoid jeopardizing the continued existence of Bay-Delta longfin smelt. 
The entities most likely to incur incremental costs are parties to 
section 7 consultations, including Federal action agencies (such as the 
Bureau of Reclamation, U.S. Army Corps of Engineers, Federal Highway 
Administration, U.S. Fish and Wildlife Service, and U.S. Department of 
Agriculture) and, in some cases, third parties, most frequently State 
agencies, local government entities, and private land-owners. While 
this additional analysis will require time and resources by both the 
Federal action agency and the Service, in most circumstances, these 
costs would be administrative in nature.
    The total number of formal consultations expected to occur is 
between 7 and 13 consultations annually and the number of informal 
consultations is 7 to 15 annually (IEc 2024, Table 2, p. 12). The total 
incremental costs for each technical assistance interaction and 
informal, formal, and programmatic section 7 consultation conducted is 
estimated to total $440, $2,700, $5,700, and $11,000, respectively, 
across all Federal and third party participants. These estimates assume 
that consultations would occur even in the absence of critical habitat 
due to the presence of the listed Bay-Delta longfin smelt, and the 
amount of administrative effort to address critical habitat during this 
process is relatively minor.
    Applying these incremental costs to the estimated future 
consultations forecast, we estimate the incremental annual 
administrative costs of consultations pursuant to the proposed critical 
habitat for the Bay-Delta longfin smelt is likely between $56,500 to 
$120,000 per year (2024 dollars), including approximately $38,000 to 
$76,000 for formal consultations, and $18,000 to $42,000 for informal 
consultations.
    We are soliciting data and comments from the public on the economic 
analysis discussed above. During the development of a final 
designation, we will consider the information presented in the economic 
analysis and any additional information on economic impacts we receive 
during the public comment period to determine whether any specific 
areas should be excluded from the final critical habitat designation 
under authority of section 4(b)(2), our implementing regulations at 50 
CFR 424.19, and the 2016 Policy. We may exclude an area from critical 
habitat if we determine that the benefits of excluding the area 
outweigh the benefits of including the area, provided the exclusion 
will not result in the extinction of this species. The benefits of 
designating areas as critical habitat include identifying and informing 
landowners and the public of which specific areas are important to a 
species' conservation and recovery. Critical habitat designation also 
raises awareness of the habitat needs of imperiled species and focuses 
efforts of our conservation partners.

Consideration of National Security Impacts

    Section 4(a)(3)(B)(i) of the Act may not cover all DoD lands or 
areas that pose potential national-security concerns (e.g., a DoD 
installation that is in the process of revising its INRMP for a newly 
listed species or a species previously not covered). If a particular 
area is not covered under section 4(a)(3)(B)(i), then national-security 
or homeland-security concerns are not a factor in the process of 
determining what areas meet the definition of ``critical habitat.'' 
However, we must still consider impacts on national security, including 
homeland security, on those lands or areas not covered by section 
4(a)(3)(B)(i) because section 4(b)(2) requires us to consider those 
impacts whenever it designates critical habitat. Accordingly, if DoD, 
Department of Homeland Security (DHS), or another Federal agency has 
requested exclusion based on an assertion of national-security or 
homeland-security concerns, or we have otherwise identified national-
security or homeland-security impacts from designating particular areas 
as critical habitat, we generally have reason to consider excluding 
those areas.
    However, we cannot automatically exclude requested areas. When DoD, 
DHS, or another Federal agency requests exclusion from critical habitat 
on the basis of national-security or homeland-security impacts, we must 
conduct an exclusion analysis if the Federal requester provides 
information, including a reasonably specific justification of an 
incremental impact on national security that would result from the 
designation of that specific area as critical habitat. That 
justification could include demonstration of probable impacts, such as 
impacts to ongoing border-security patrols and surveillance activities, 
or a delay in training or facility construction, as a result of 
compliance with section 7(a)(2) of the Act. If the agency requesting 
the exclusion does not provide us with a reasonably specific 
justification, we will contact the agency to recommend that it provide 
a specific justification or clarification of its concerns relative to 
the probable incremental impact that could result from the designation. 
If we conduct an exclusion analysis because the agency provides a 
reasonably specific justification or because we decide to exercise the 
discretion to conduct an exclusion analysis, we will defer to the 
expert judgment of DoD, DHS, or another Federal agency as to: (1) 
Whether activities on its lands or waters, or its activities on other 
lands or waters, have national-security or homeland-security 
implications; (2) the importance of those implications; and (3) the 
degree to which the cited implications would be adversely affected in 
the absence of an exclusion. In that circumstance, in conducting a 
discretionary section 4(b)(2) exclusion analysis, we will give great 
weight to national-security and homeland-security concerns in analyzing 
the benefits of exclusion.
    Under section 4(b)(2) of the Act, we also consider whether a 
national security or homeland security impact might exist on lands 
owned or managed by DoD or DHS. In preparing this proposal, we have 
determined that, other than the land exempted under section 
4(a)(3)(B)(i) of the Act based upon the existence of an approved INRMP 
(see Exemptions, above), the lands and water area within the proposed 
designation of critical habitat for the Bay-Delta longfin smelt are not 
owned or managed by DoD or DHS. Therefore, we anticipate no impact on 
national security or homeland security.

Consideration of Other Relevant Impacts

    Under section 4(b)(2) of the Act, we consider any other relevant 
impacts, in addition to economic impacts and impacts on national 
security discussed above. To identify other relevant impacts that may 
affect the exclusion analysis, we consider a number of factors, 
including whether there are approved and permitted conservation 
agreements or plans covering the species in the area--such as safe 
harbor agreements (SHAs), candidate conservation agreements with 
assurances (CCAAs) or ``conservation benefit agreement'' or 
``conservation agreement'' (``CBAs'') (CBAs are a new type of agreement 
replacing SHAs and CCAAs in use after April 2024 (89 FR 26070; April 
12, 2024)) or HCPs--or whether there are non-permitted conservation 
agreements and partnerships that may be impaired by designation of, or 
exclusion from, critical habitat. In addition, we look at whether 
Tribal conservation plans or partnerships, Tribal resources, or 
government-to-government

[[Page 3779]]

relationships of the United States with Tribal entities may be affected 
by the designation. We also consider any State, local, social, or other 
impacts that might occur because of the designation.

Summary of Exclusions Considered Under 4(b)(2) of the Act

    In preparing this proposal, we have determined that no HCPs or 
other management plans for the Bay-Delta longfin smelt currently exist, 
and the proposed designation does not include any Tribal lands or trust 
resources or any lands for which designation would have any economic or 
national security impacts. Therefore, we anticipate no impact on Tribal 
lands, partnerships, or HCPs from this proposed critical habitat 
designation, and thus, as described above, we are not considering 
excluding any particular areas on the basis of the presence of 
conservation agreements or impacts to trust resources.
    However, if through the public comment period we receive 
information that we determine indicates that there are potential 
economic, national security, or other relevant impacts from designating 
particular areas as critical habitat, then as part of developing the 
final designation of critical habitat, we will evaluate that 
information and may conduct a discretionary exclusion analysis to 
determine whether to exclude those areas under authority of section 
4(b)(2) and our implementing regulations at 50 CFR 424.19. If we 
receive a request for exclusion of a particular area and after 
evaluation of supporting information we do not exclude, we will fully 
describe our decision in the final rule for this action.

Required Determinations

Clarity of the Rule

    We are required by E.O.s 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.

Regulatory Planning and Review (Executive Orders 12866, 13563 and 
14094)

    Executive Order 14094 amends and reaffirms the principles of E.O. 
12866 and E.O. 13563 and states that regulatory analysis should 
facilitate agency efforts to develop regulations that serve the public 
interest, advance statutory objectives, and are consistent with E.O. 
12866, and E.O. 13563, and the Presidential Memorandum of January 20, 
2021 (Modernizing Regulatory Review). Regulatory analysis, as 
practicable and appropriate, shall recognize distributive impacts and 
equity, to the extent permitted by law. E.O. 13563 emphasizes further 
that regulations must be based on the best available science and that 
the rulemaking process must allow for public participation and an open 
exchange of ideas. We have developed this proposed rule in a manner 
consistent with these requirements.
    Executive Order 12866, as reaffirmed by E.O. 13563 and amended and 
reaffirmed by E.O. 14094, provides that the Office of Information and 
Regulatory Affairs (OIRA) in the Office of Management and Budget will 
review all significant rules. OIRA has determined that this rule is 
significant.

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

    Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.), 
as amended by the Small Business Regulatory Enforcement Fairness Act of 
1996 (SBREFA; title II of Pub. L. 104-121, March 29, 1996), whenever an 
agency is required to publish a notice of rulemaking for any proposed 
or final rule, it must prepare and make available for public comment a 
regulatory flexibility analysis that describes the effects of the rule 
on small entities (i.e., small businesses, small organizations, and 
small government jurisdictions). However, no regulatory flexibility 
analysis is required if the head of the agency certifies the rule will 
not have a significant economic impact on a substantial number of small 
entities. The SBREFA amended the RFA to require Federal agencies to 
provide a certification statement of the factual basis for certifying 
that the rule will not have a significant economic impact on a 
substantial number of small entities.
    According to the Small Business Administration, small entities 
include small organizations such as independent nonprofit 
organizations; small governmental jurisdictions, including school 
boards and city and town governments that serve fewer than 50,000 
residents; and small businesses (13 CFR 121.201). Small businesses 
include manufacturing and mining concerns with fewer than 500 
employees, wholesale trade entities with fewer than 100 employees, 
retail and service businesses with less than $5 million in annual 
sales, general and heavy construction businesses with less than $27.5 
million in annual business, special trade contractors doing less than 
$11.5 million in annual business, and agricultural businesses with 
annual sales less than $750,000. To determine whether potential 
economic impacts to these small entities are significant, we considered 
the types of activities that might trigger regulatory impacts under 
this designation as well as types of project modifications that may 
result. In general, the term ``significant economic impact'' is meant 
to apply to a typical small business firm's business operations.
    Under the RFA, as amended, and as understood in light of court 
decisions (see, e.g., American Trucking Ass'ns v. U.S. Envtl. 
Protection Agency, 175 F.3d 1027, 1044 (D.C. Cir. 1999)), Federal 
agencies are required to evaluate the potential incremental impacts of 
rulemaking on those entities directly regulated by the rulemaking 
itself; in other words, the RFA does not require agencies to evaluate 
the potential impacts to indirectly regulated entities. The regulatory 
mechanism through which critical habitat protections are realized is 
section 7 of the Act, which requires Federal agencies, in consultation 
with the Service, to ensure that any action authorized, funded, or 
carried out by the agency is not likely to destroy or adversely modify 
critical habitat. Therefore, under section 7, only Federal action 
agencies are directly subject to the specific regulatory requirement 
(avoiding destruction and adverse modification) imposed by critical 
habitat designation. Consequently, only Federal action agencies would 
be directly regulated if we adopt the proposed critical habitat 
designation. The RFA does not require evaluation of the potential 
impacts to entities not directly regulated. Moreover, Federal agencies 
are not small entities. Therefore, because no small entities would be 
directly regulated by this rulemaking, the Service certifies that, if 
made final as proposed, the critical habitat designation will not have 
a significant economic impact on a substantial number of small 
entities.

[[Page 3780]]

    In summary, we have considered whether the proposed designation 
would result in a significant economic impact on a substantial number 
of small entities. For the above reasons and based on currently 
available information, we certify that, if made final, the critical 
habitat designation would not have a significant economic impact on a 
substantial number of small business entities. Therefore, an initial 
regulatory flexibility analysis is not required.

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

    Executive Order 13211 (Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use) requires 
agencies to prepare statements of energy effects ``to the extent 
permitted by law'' when undertaking actions identified as significant 
energy actions (66 FR 28355; May 22, 2001). E.O. 13211 defines a 
``significant energy action'' as an action that (i) is a significant 
regulatory action under E.O. 12866 or any successor order; and (ii) is 
likely to have a significant adverse effect on the supply, 
distribution, or use of energy. This proposed rule is a significant 
regulatory action under E.O. 12866, as amended by E.O. 14094 (88 FR 
21879; April 11, 2023). In our economic analysis, we did not find that 
this proposed critical habitat designation would significantly affect 
energy supplies, distribution, or use. This is because the proposed 
critical habitat is limited to a portion of the water and shoreline 
area of the San Francisco Bay estuary which is not used for energy 
supply, distribution or use. Therefore, this action is not a 
significant energy action, and no statement of energy effects is 
required.

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

    In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501 
et seq.), we make the following finding:
    (1) This proposed rule would not produce a Federal mandate. In 
general, a Federal mandate is a provision in legislation, statute, or 
regulation that would impose an enforceable duty upon State, local, or 
Tribal governments, or the private sector, and includes both ``Federal 
intergovernmental mandates'' and ``Federal private sector mandates.'' 
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal 
intergovernmental mandate'' includes a regulation that ``would impose 
an enforceable duty upon State, local, or Tribal governments'' with two 
exceptions. It excludes ``a condition of Federal assistance.'' It also 
excludes ``a duty arising from participation in a voluntary Federal 
program,'' unless the regulation ``relates to a then-existing Federal 
program under which $500,000,000 or more is provided annually to State, 
local, and Tribal governments under entitlement authority,'' if the 
provision would ``increase the stringency of conditions of assistance'' 
or ``place caps upon, or otherwise decrease, the Federal Government's 
responsibility to provide funding,'' and the State, local, or Tribal 
governments ``lack authority'' to adjust accordingly. At the time of 
enactment, these entitlement programs were: Medicaid; Aid to Families 
with Dependent Children work programs; Child Nutrition; Food Stamps; 
Social Services Block Grants; Vocational Rehabilitation State Grants; 
Foster Care, Adoption Assistance, and Independent Living; Family 
Support Welfare Services; and Child Support Enforcement. ``Federal 
private sector mandate'' includes a regulation that ``would impose an 
enforceable duty upon the private sector, except (i) a condition of 
Federal assistance or (ii) a duty arising from participation in a 
voluntary Federal program.''
    The designation of critical habitat does not impose a legally 
binding duty on non-Federal Government entities or private parties. 
Under the Act, the only regulatory effect is that Federal agencies must 
ensure that their actions are not likely to destroy or adversely modify 
critical habitat under section 7. While non-Federal entities that 
receive Federal funding, assistance, or permits, or that otherwise 
require approval or authorization from a Federal agency for an action, 
may be indirectly impacted by the designation of critical habitat, the 
legally binding duty to avoid destruction or adverse modification of 
critical habitat rests squarely on the Federal agency. Furthermore, to 
the extent that non-Federal entities are indirectly impacted because 
they receive Federal assistance or participate in a voluntary Federal 
aid program, the Unfunded Mandates Reform Act would not apply, nor 
would critical habitat shift the costs of the large entitlement 
programs listed above onto State governments.
    (2) We do not believe that this proposed rule would significantly 
or uniquely affect small governments because the majority of area 
associated with the proposal is water area of the San Francisco Bay 
estuary and not owned or managed by small governments. Small 
governments will be affected only to the extent that any programs 
having Federal funds, permits, or other authorized activities must 
ensure that their actions will not be likely to result in destruction 
or adverse modification of the species' critical habitat. Therefore, a 
small government agency plan is not required.

Takings--Executive Order 12630

    In accordance with E.O. 12630 (Government Actions and Interference 
with Constitutionally Protected Private Property Rights), we have 
analyzed the potential takings implications of designating critical 
habitat for the Bay-Delta longfin smelt in a takings implications 
assessment. The Act does not authorize the Services to regulate private 
actions on private lands or confiscate private property as a result of 
critical habitat designation. Designation of critical habitat does not 
affect land ownership, or establish any closures, or restrictions on 
use of or access to the designated areas. Furthermore, the designation 
of critical habitat does not affect landowner actions that do not 
require Federal funding or permits, nor does it preclude development of 
habitat conservation programs or issuance of incidental take permits to 
permit actions that do require Federal funding or permits to go 
forward. However, Federal agencies are prohibited from carrying out, 
funding, or authorizing actions that would destroy or adversely modify 
critical habitat. A takings implications assessment has been completed 
for the proposed designation of critical habitat for the Bay-Delta 
longfin smelt, and it concludes that, if adopted, this designation of 
critical habitat does not pose significant takings implications for 
lands within or affected by the designation.

Federalism--Executive Order 13132

    In accordance with E.O. 13132 (Federalism), this proposed rule does 
not have significant Federalism effects. A federalism summary impact 
statement is not required. In keeping with Department of the Interior 
and Department of Commerce policy, we requested information from, and 
coordinated development of this proposed critical habitat designation 
with, appropriate State resource agencies. From a federalism 
perspective, the designation of critical habitat directly affects only 
the responsibilities of Federal agencies. The Act imposes no other 
duties with respect to critical habitat, either for States and local 
governments, or for anyone else. As a result, the proposed rule does 
not have substantial direct effects either on the States, or on the 
relationship between the Federal government and the States, or on the 
distribution of powers and responsibilities among the various levels of 
government. The proposed

[[Page 3781]]

designation may have some benefit to these governments because the 
areas that contain the features essential to the conservation of the 
species are more clearly defined, and the physical or biological 
features of the habitat necessary for the conservation of the species 
are specifically identified. This information does not alter where and 
what federally sponsored activities may occur. However, it may assist 
State and local governments in long-range planning because they no 
longer have to wait for case-by-case section 7 consultations to occur.
    Where State and local governments require approval or authorization 
from a Federal agency for actions that may affect critical habitat, 
consultation under section 7(a)(2) of the Act would be required. While 
non-Federal entities that receive Federal funding, assistance, or 
permits, or that otherwise require approval or authorization from a 
Federal agency for an action, may be indirectly impacted by the 
designation of critical habitat, the legally binding duty to avoid 
destruction or adverse modification of critical habitat rests squarely 
on the Federal agency.

Civil Justice Reform--Executive Order 12988

    In accordance with E.O. 12988 (Civil Justice Reform), the Office of 
the Solicitor has determined that the proposed rule would not unduly 
burden the judicial system and that it meets the requirements of 
sections 3(a) and 3(b)(2) of the Order. We have proposed designating 
critical habitat in accordance with the provisions of the Act. To 
assist the public in understanding the habitat needs of the species, 
this proposed rule identifies the physical or biological features 
essential to the conservation of the species. The proposed areas of 
critical habitat are presented on maps, and the proposed rule provides 
several options for the interested public to obtain more detailed 
location information, if desired.

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

    This rule does not contain information collection requirements, and 
a submission to the Office of Management and Budget (OMB) under the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.) is not 
required. We may not conduct or sponsor and you are not required to 
respond to a collection of information unless it displays a currently 
valid OMB control number.

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

    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. In a line of cases starting with Douglas County 
v. Babbitt, 48 F.3d 1495 (9th Cir. 1995), the courts have upheld this 
position.

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), E.O. 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 
boundaries of the proposed critical habitat for the Bay-Delta longfin 
smelt, so no Tribal lands would be affected by the proposed 
designation. Accordingly, we have concluded that this action does not 
have Tribal implications as specified in E.O. 13175 because it will not 
have substantial direct effects on Tribal governments, on the 
relationship between the Federal Government and the Indian Tribes, or 
on the distribution of power and responsibilities between the Federal 
Government and Indian Tribes.

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 San Francisco Bay-Delta Fish and Wildlife 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 Status Assessment Team, which 
includes staff from the Region 8 Regional Office and the San Francisco 
Bay-Delta Fish and Wildlife Office.

List of Subjects in 50 CFR Part 17

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

Signing Authority

    Martha Williams, Director of the U.S. Fish and Wildlife Service, 
approved this action on December 11, 2024, for publication. On December 
11, 2024, Martha Williams authorized the undersigned to sign the 
document electronically and submit it to the Office of the Federal 
Register for publication as an official document of the U.S. Fish and 
Wildlife Service.

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) in the List of Endangered and 
Threatened Wildlife under Fishes by revising the entry for ``Smelt, 
longfin [San Francisco Bay-Delta DPS]'' to read as follows:

Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

[[Page 3782]]

----------------------------------------------------------------------------------------------------------------
                                                                                               Listing citations
           Common name              Scientific name         Where listed           Status       and applicable
                                                                                                     rules
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                     Fishes
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Smelt, longfin [San Francisco     Spirinchus          U.S.A. (CA)............  E              89 FR 61029, 07/30/
 Bay-Delta DPS].                   thaleichthys.                                               2024; 50 CFR
                                                                                               17.95(e).\CH\
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------

0
3. Amend Sec.  17.95(e) by adding an entry for ``San Francisco Bay-
Delta Distinct Population Segment of the Longfin Smelt (Spirinchus 
thaleichthys)'' after the entry for ``Delta Smelt (Hypomesus 
transpacificus)'' to read as follows:

Sec.  17.95  Critical habitat--fish and wildlife.

* * * * *
    (e) Fishes.
* * * * *
    San Francisco Bay-Delta Distinct Population Segment of the Longfin 
Smelt (Spirinchus thaleichthys)
    (1) Critical habitat consists of one unit located in the San 
Francisco Bay estuary in Contra Costa, Napa, Sacramento, Solano, and 
Sonoma Counties, California, and is depicted on the map in this entry. 
The San Francisco Bay estuary is a complex and dynamic system 
exhibiting a wide range of salinities, temperatures, and habitats as 
the result of tidal movement of ocean water and freshwater inputs from 
the Sacramento and San Joaquin Rivers and local tributaries. This unit 
provides the unique suite of environmental conditions needed for 
spawning, larval rearing, juvenile growth, and maturation of the San 
Francisco Bay-Delta distinct population segment of the longfin smelt 
(Bay-Delta longfin smelt).
    (2) The essential physical or biological features for the Bay-Delta 
longfin smelt consist of water and shoreline areas with the appropriate 
water temperature, salinity, turbidity, food resources, substrate, and 
hydrologic conditions capable of supporting spawning, rearing, and 
larval and juvenile development. Within the San Francisco Bay estuary, 
different areas of the critical habitat unit provide all of the 
physical or biological features essential to the conservation of Bay-
Delta longfin smelt, but not all of the features occur in all portions 
of the unit at all times. During various times of the year, different 
areas of the estuary provide the following essential physical or 
biological features:
    (i) Water temperature requirements: Water temperature ranges to 
support reproduction, growth, and survival of the Bay-Delta longfin 
smelt at different life stages to include:
    (A) Estuary water temperatures below 13 [deg]Celsius ([deg]C) (55.4 
[deg]F ([deg]F)) from December through May to initiate and support 
successful spawning;
    (B) Estuary water temperatures less than 15 [deg]C (59.0 [deg]F) 
from December through May for egg development, hatching success, and 
early larval development;
    (C) Estuary water temperatures less than 20 [deg]C (60.0 [deg]F) 
from February through June for larvae 40 days post hatch and older to 
support growth and avoid physiological stress; and
    (D) Estuary and nearshore ocean water temperatures less than 22 
[deg]C (71.6 [deg]F) year-round for juveniles and adults to support 
growth and avoid physiological stress.
    (ii) Water salinity requirements: Suitable salinity concentrations 
to support successful reproduction, growth, and recruitment; such 
ranges include:
    (A) Salinity conditions between 2-4 parts per thousand (ppt) from 
December through May to support average larval salinity requirements; 
and
    (B) Salinity conditions between 0.4-10 ppt from December through 
May to support diversity of egg and early larval rearing conditions.
    (iii) Water turbidity requirements: Turbidity greater than 20 
nephelometric turbidity units to optimize feeding and predator 
avoidance.
    (iv) Food resource requirements: Food resources in abundances that 
support growth and recruitment of all life stages; these food resources 
include, but are not limited to:
    (A) The copepod Eurytemora affinis, the primary prey item 
supporting larvae less than 25 mm (approximately 1 inch length);
    (B) Mysids including Neomysis mercedis and Hyperacanthomysis 
longirostris, and other amphipods, the primary prey items supporting 
juveniles and larvae greater than 25 mm in length (approximately 1 inch 
length); and
    (C) Prey of various zooplankton species such as those identified in 
paragraphs (2)(iv)(A) and (B) of this entry for juveniles and adults.
    (v) Substrate requirements: Substrate composed mostly of sandy 
habitat, although portions may include gravel substrates, rocks, or 
aquatic plants that provide suitable habitat for spawning, protection, 
cover, and development of eggs and larvae.
    (vi) Hydrologic requirements: Contemporaneous with the appropriate 
seasonal needs by life stage of the species, inflow into the estuary of 
appropriate freshwater to provide the conditions set forth in 
paragraphs (2)(i) through (iv) of this entry.
    (3) Critical habitat does not include manmade structures (such as 
buildings, aqueducts, runways, roads, and other paved areas) and the 
land on which they are located existing within the legal boundaries on 
the [EFFECTIVE DATE OF THE FINAL RULE].
    (4) Data layers defining the map unit were created on a base of 
U.S. Geological Survey digital ortho-photo quarter-quadrangles, and the 
critical habitat unit was then mapped using Universal Transverse 
Mercator (UTM) North American Datum of 1983 (NAD 83) Zone 10N projected 
coordinate system. The map in this entry, as modified by any 
accompanying regulatory text, establish the boundaries of the critical 
habitat designation. The coordinates or plot points or both on which 
the map is based are available to the public at the Service's internet 
site at https://www.fws.gov/office/san-francisco-bay-delta-fish-and-wildlife, at https://www.regulations.gov at Docket No. FWS-R8-ES-2024-
0131, and at the field office responsible for this designation. You may 
obtain field office location information by contacting one of the 
Service regional offices, the addresses of which are listed at 50 CFR 
2.2.
    (5) San Francisco Bay-Delta Unit, Contra Costa, Napa, Sacramento,

[[Page 3783]]

Solano, and Sonoma Counties, California.
    (i) The San Francisco Bay-Delta Unit consists of a total of 91,603 
ac (37,082 ha) of water and shoreline areas in a portion of the San 
Francisco Bay estuary bordering Contra Costa, Napa, Sacramento, Solano, 
and Sonoma Counties, California, and is composed of Federal (20 ac (8 
ha)), State (257 ac (104 ha)), local government (7 ac (3 ha)), private, 
and nonprofit or nongovernmental organization lands (49 ac (20 ha)), 
and other water and shoreline area of undetermined ownership (91,297 ac 
(36,947 ha)).
    (ii) Map of the San Francisco Bay-Delta Unit follows:
BILLING CODE 4333-15-P
Figure 1 to San Francisco Bay-Delta longfin smelt (Spirinchus 
thaleichthys) paragraph (5)(ii)
[GRAPHIC] [TIFF OMITTED] TP15JA25.001

* * * * *

Sara Prigan,
Federal Register Liaison Officer, U.S. Fish and Wildlife Service.
[FR Doc. 2024-29641 Filed 1-14-25; 8:45 am]
BILLING CODE 4333-15-C
```