Endangered and Threatened Wildlife and Plants; Removal of the Okaloosa Darter From the Federal List of Endangered and Threatened Wildlife, 41835-41854 [2023-12982]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 88, Number 123 (Wednesday, June 28, 2023)]
[Rules and Regulations]
[Pages 41835-41854]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-12982]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2021-0036; FF09E22000 FXES11130900000 234]
RIN 1018-BE57


Endangered and Threatened Wildlife and Plants; Removal of the 
Okaloosa Darter From the Federal List of Endangered and Threatened 
Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are removing 
the Okaloosa darter (Etheostoma okaloosae) from the Federal List of 
Endangered and Threatened Wildlife (List) due to recovery. This final 
rule is based on a thorough review of the best available scientific and 
commercial information which indicates that the threats to the species 
have been eliminated or reduced to the point that the species is no 
longer in danger of extinction or likely to become in danger of 
extinction within the foreseeable future. Therefore, the species no 
longer meets the definition of a threatened species, and does not meet 
the definition of an endangered species, under the Endangered Species 
Act of 1973, as amended (Act). Accordingly, the prohibitions and 
conservation measures provided by the Act will no longer apply to this 
species.

DATES: This rule is effective July 28, 2023.

ADDRESSES: This final rule, supporting documents in preparing this 
rule, the post-delisting monitoring plan, and the comments received on 
the proposed rule are available for public inspection at https://www.regulations.gov under Docket No. FWS-R4-ES-2021-0036.

FOR FURTHER INFORMATION CONTACT: Lourdes Mena, Division Manager, 
Florida Classification and Recovery, U.S. Fish and Wildlife Service, 
Florida Ecological Services Field Office, 7915 Baymeadows Way, 
Jacksonville, FL 32256-7517; telephone 904-731-3134. 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.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Act, a species may be 
removed from the Federal Lists of Endangered and Threatened Wildlife 
and Plants (i.e., ``delisted'') if it is determined that the species 
has recovered and no longer meets the definition of an endangered 
species or a threatened species. Delisting a species can only be 
completed by issuing a rule through the Administrative Procedure Act 
rulemaking process (5 U.S.C. 551 et seq.).
    What this document does. This rule removes the Okaloosa darter 
(Etheostoma okaloosae) from the List of Endangered and Threatened 
Wildlife based on its recovery.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered species or a threatened species based on any 
of five factors: (A) The present or threatened destruction, 
modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or

[[Page 41836]]

predation; (D) the inadequacy of existing regulatory mechanisms; or (E) 
other natural or manmade factors affecting its continued existence.
    The determination to delist a species must be based on an analysis 
of the same factors. Under the Act and our implementing regulations at 
50 CFR 424.11, we may delist a species if the best available scientific 
and commercial data indicate that: (1) The species is extinct; (2) the 
species does not meet the definition of an endangered species or a 
threatened species when considering the five factors listed above; or 
(3) the listed entity does not meet the statutory definition of a 
species. We have determined that the Okaloosa darter should be delisted 
because, based on an analysis of the five listing factors, it has 
recovered and no longer meets the definition of an endangered species 
or a threatened species.
    Specifically, our recent review indicated that actions by the U.S. 
Air Force and implementation of multiple conservation agreements with 
local landowners have reduced erosion into streams to background 
levels, restored and reconnected stream habitat, restored and improved 
management of longleaf and watersheds, maintained historical water 
flows, and improved and maintained water quality and riparian habitat 
to the point that the Okaloosa darter no longer requires protections 
under the Act. Accordingly, the species no longer meets the definition 
of an endangered or a threatened species under the Act.
    A species status assessment (SSA) report for the Okaloosa darter 
was prepared by an SSA team (USFWS 2019, entire). The SSA report 
represents a compilation of the best scientific and commercial data 
available concerning the status of the species, including the impacts 
of past, present, and future factors (both negative and beneficial) 
affecting the species.
    Peer review and public comment. We evaluated the species' needs, 
current conditions, and future conditions to inform our November 17, 
2021, proposed rule (86 FR 64158). We sought the expert opinions of six 
appropriate specialists regarding the species status assessment (SSA) 
report, which informed the proposed rule. Out of the six reviews 
requested, we received two responses. All comments were clarification-
based with some biological information submitted. All were readily 
incorporated into the final version of the SSA report. The purpose of 
peer review is to ensure our determination is based on scientifically 
sound data, assumptions, and analyses. We invited these peer reviewers 
to comment on the proposed rule and draft post-delisting monitoring 
plan. We considered all comments and information we received during the 
public comment period on the proposed delisting rule and the draft 
post-delisting monitoring plan when developing this final rule.

Previous Federal Actions

    On November 17, 2021, we published in the Federal Register (86 FR 
64158) a proposed rule to delist the Okaloosa darter. Please refer to 
that proposed rule for a detailed description of previous Federal 
actions concerning this species. The proposed rule and supplemental 
documents are provided at https://www.regulations.gov under Docket No. 
FWS-R4-ES-2021-0036.

Summary of Comments and Changes From the Proposed Rule

    In the proposed rule published on November 17, 2021 (86 FR 64158), 
we requested that all interested parties submit written comments on the 
proposal by January 18, 2022. We also contacted the Florida Fish and 
Wildlife Commission (FWC), scientific experts and organizations, and 
other interested parties and invited them to comment on the proposal. A 
newspaper notice inviting the public to provide comments on the 
proposed rule was published in the Northwest Florida Daily News and the 
Tallahassee Democrat on November 19, 2021.
    In preparing this final rule, we reviewed and fully considered the 
two comments we received during the public period on the proposed rule 
to delist the Okaloosa darter. We received one substantive comment from 
the FWC that suggested increasing the frequency of surveys in the post-
delisting monitoring (PDM) plan from biannually to annually in years 1 
through 4. After further discussion between the Service and FWC staff, 
we collectively determined that biannual surveys would be adequate to 
capture any future changes in Okaloosa darter population size, and thus 
we made no changes to this final rule or the PDM plan based on this 
comment. The other comment we received was not substantive. In summary, 
we made no substantive changes to this final rule based on public 
comments received. Minor, nonsubstantive changes and corrections have 
been made throughout this final rule. In preparing this final rule, we 
also refined the Status Throughout a Significant Portion of Its Range 
analysis in order to better align with current policy and guidance.

Final Delisting Determination

Species Information

    Below, we present a review of the taxonomy, life history, ecology, 
and overall status of the Okaloosa darter, referencing data where 
appropriate from the SSA report that was finalized for the species in 
April 2019 (USFWS 2019, entire).
Background
    The Okaloosa darter is a small (maximum size 49 millimeters (mm), 
1.93 inches (in)) percid fish (perch family). General body coloration 
varies from red-brown to green-yellow dorsally, and lighter ventrally, 
although breeding males have a bright orange submarginal stripe on the 
first dorsal fin (Burkhead et al. 1992, p. 23). The Okaloosa darter is 
a member of Order Perciformes, Family Percidae and is a distinct 
species within the genus Etheostoma (Burkhead et al. 1992, p. 23), 
although it remains uncertain as to which subgenus this species belongs 
(e.g., Song et al. 1998, pp. 348-351; Smith et al. 2014, pp. 259-260).
    The Okaloosa darter is a narrow endemic, known to occur in only the 
tributaries and main channels of six clear stream systems that drain 
into three Choctawhatchee Bay bayous (Toms, Boggy, and Rocky) in Walton 
and Okaloosa Counties in northwest Florida: Toms, Turkey, Mill, Swift, 
Deer Moss (formerly known as East Turkey or Turkey Bolton), and Rocky 
Creeks. Approximately 90 percent of the 457-square-kilometer (176-
square-mile) watershed drainage area that historically supported the 
Okaloosa darter is Federal property under the management of Eglin Air 
Force Base (Eglin AFB), including about 98.7 percent of the stream 
length in the current range of the Okaloosa darter. Eglin AFB 
encompasses the headwaters of all six of these drainages, and the 
remainder of these streams flow out of Eglin AFB into the urban complex 
of the cities of Niceville and Valparaiso (USAF 2022c, p. 3-1; 76 FR 
18087, April 1, 2011).
    The Okaloosa darter's breeding season extends from late March 
through October, although it usually peaks in April. Spawning pairs 
attach small numbers of eggs to vegetation, woody debris, and root mats 
(Collete and Yerger 1962, p. 226; Burkhead et al. 1994, p. 81); 
however, little is known about larval development (Burkhead et al. 
1992, p. 26). As with most darters, fecundity is low (Burkhead et al. 
1992, p. 26). A mean of 76 total ova (eggs) and 29 mature ova were 
found in 201 female Okaloosa darters, although these numbers may 
underrepresent annual

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fecundity as their prolonged spawning season is an indication of 
fractional spawning (eggs develop and mature throughout the spawning 
season) (Ogilvie 1980, p. 4; 76 FR 18087, April 1, 2011).
    Longleaf pine-wiregrass-red oak sandhill communities dominate the 
vegetation landscape in Okaloosa darter watersheds. These areas are 
characterized by high sand ridges where soil nutrients are low and 
woodland fire is a regular occurrence. Where water seeps from these 
hills, acid bog communities develop, consisting of sphagnum moss 
(Sphagnum sp.), pitcher plants (Sarracenia sp.), and other plants 
adapted to low-nutrient soils. In other areas, the water emerges from 
seepage springs directly into clear flowing streams where variation of 
both temperature and flow is moderated by the deep layers of sand. The 
streams support a mixture of bog moss (Mayaca fluviatilis), bulrush 
(Schoenoplectus etuberculatus), golden club (Orontium aquaticum), bur-
reed (Sparganium americanum), pondweed (Potamogeton diversifolius), 
spikerush (Eleocharis sp.), and other aquatic and emergent plants. 
Okaloosa darters typically inhabit the margins of moderate- to fast-
flowing streams where detritus (organic matter, including leaves, 
twigs, and sticks), root mats, and vegetation are present (Burkhead et 
al. 1992, p. 25; 76 FR 18087, April 1, 2011). They are rarely found in 
areas with no current or in open sandy areas in the middle of the 
stream channel. Creeks with Okaloosa darters have temperatures ranging 
from 7 to 22 degrees Celsius ([deg]C) (44 to 72 degrees Fahrenheit 
([deg]F)) in the winter to 22 to 29 [deg]C (72 to 84 [deg]F) in the 
summer (Mettee and Crittenden 1977, p. 5; Tate 2018, pers. comm.; Jelks 
2018, pers. comm). Overhead canopies range from open to fully closed 
depending on stream width and fire history (Jordan 2018, pers. comm.). 
Okaloosa darters thrive in reaches with relatively open canopies, 
likely due to either increased abundance of submerged vegetation that 
is used preferentially for spawning or increased secondary production 
of insect prey (Ingram 2018, p. 11).
    Okaloosa darter abundance has been quantified by visual census at 
multiple sites annually since 1995. Densities in 1995 averaged 1.2 
( 0.8;  1 standard deviation) Okaloosa darter 
per meter (3.28 feet) of stream length. In 2005, a rangewide survey 
estimated the species' population size at 822,500 (95 percent 
confidence interval: 662,916 to 1,058,009). Repeated rangewide surveys 
in 2014 and 2020 indicated that overall abundance declined by about 24 
percent from 2005 to 2014 and then a further 20 percent in 2020 (Jordan 
and Jelks 2021, pp. 12). However, 2005 was an unusually good year for 
the Okaloosa darter, and the 2014 and 2020 estimates likely reflect 
some declines associated with dense canopy cover.
    A thorough review of the taxonomy, life history, ecology, and 
overall viability of the Okaloosa darter is presented in the SSA report 
(USFWS 2019, entire; available at https://ecos.fws.gov/ecp/species/E00H/ and at https://www.regulations.gov under Docket No. FWS-R4-ES-
2021-0036).

Recovery

    Section 4(f) of the Act (16 U.S.C. 1531 et seq.) directs us to 
develop and implement recovery plans for the conservation and survival 
of endangered and threatened species unless we determine that such a 
plan will not promote the conservation of the species. Under section 
4(f)(1)(B)(ii), recovery plans must, to the maximum extent practicable, 
include objective, measurable criteria which, when met, would result in 
a determination, in accordance with the provisions of section 4 of the 
Act, that the species be removed from the List.
    Recovery plans provide a roadmap for us and our partners on methods 
of enhancing conservation and minimizing threats to listed species, as 
well as measurable criteria against which to evaluate progress towards 
recovery and assess the species' likely future condition. However, they 
are not regulatory documents and do not substitute for the 
determinations and promulgation of regulations required under section 
4(a)(1) of the Act. A decision to delist a species is ultimately based 
on an analysis of the best scientific and commercial data available and 
consideration of the standards listed in 50 CFR 424.11(e) to determine 
whether a species is no longer an endangered species or a threatened 
species, regardless of whether that information differs from the 
recovery plan.
    There are many paths to accomplishing recovery of a species, and 
recovery may be achieved without all of the criteria in a recovery plan 
being fully met. For example, one or more criteria may be exceeded 
while other criteria may not yet be accomplished. In that instance, we 
may determine that the threats are minimized sufficiently, and that the 
species is robust enough that it no longer meets the Act's definition 
of an endangered species or a threatened species. In other cases, we 
may discover new recovery opportunities after having finalized the 
recovery plan. Parties seeking to conserve the species may use these 
opportunities instead of methods identified in the recovery plan. 
Likewise, we may learn new information about the species after we 
finalize the recovery plan. The new information may change the extent 
to which existing criteria are appropriate for identifying recovery of 
the species. The recovery of a species is a dynamic process requiring 
adaptive management that may, or may not, follow all guidance provided 
in a recovery plan.
    The objective of the Okaloosa darter recovery plan is to restore 
and protect habitat and stream ecosystems so that Okaloosa darter may 
be initially downlisted (which occurred in 2011; see 76 FR 18087, April 
1, 2011) and eventually delisted. Because the Okaloosa darter is a 
narrow endemic that occupies the unique habitats of only six stream 
systems, recovery objectives are focused on habitats within their 
historical range. The recovery plan states that the Okaloosa darter 
will be considered for delisting when:
    1. (a) All downlisting criteria have been met; (b) historical 
habitat of all six streams has been restored to support viable 
populations of Okaloosa darter (including degraded sections of Mill, 
Swift, and Tom Creeks); (c) erosion at clay pits, road crossings, and 
steep slopes has been minimized to the extent that resembles historical 
predisturbance condition; (d) longleaf restoration and watershed 
management practices on Eglin AFB are in effect; (e) natural, 
historical flow regimes are maintained; and (f) water quality and 
riparian habitat have been significantly improved and maintained.
    2. (a) Cooperative and enforceable agreements are in place to 
protect habitat and water quality and quantity for the historical range 
outside of Eglin AFB; and (b) management plans that protect and restore 
habitat and water quality and quantity have been effective and are 
still in place for the 90 percent of the historical range currently 
managed by Eglin AFB.
    3. Okaloosa darter populations at monitoring sites consist of two 
or more age-classes and remain stable or increasing in all six streams 
over a period of 20 consecutive years.
    4. No foreseeable threats exist that would impact the survival of 
this species (assumes military mission is compatible).

Recovery Plan Implementation

    The following discussion summarizes the recovery criteria and 
information on recovery actions that have been

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implemented under each delisting criterion.
Recovery Criteria
    Delisting Criterion 1: All reclassification criteria have been met. 
This criterion has been met.
    Delisting Criterion 2: Restore and protect habitat in the six 
Okaloosa darter stream watersheds.
    The Okaloosa darter is naturally restricted in distribution to six 
streams, of which about 90 percent of the basins are on Eglin AFB and 
the remaining 10 percent in the Niceville and Valparaiso, Florida, 
municipal area. Because of the specific habitat requirements and 
limited distribution of the darter, habitat that is essential for 
spawning, rearing, feeding, and cover needs to be restored and 
protected to prevent the species from declining irreversibly and to 
recover the species.
    Much progress has been made towards actions identified for the 
Okaloosa darter under this criterion since 2011, when the species was 
downlisted from endangered to threatened. Erosion into the streams has 
been reduced to background levels, nearly all fish passage barriers on 
Eglin AFB have been removed, more than 20 projects have been completed 
to restore and reconnect stream habitat, and conservation agreements 
with local landowners have been put in place on private lands to 
protect stream and floodplain habitat. The Eglin AFB erosion control 
program, habitat restoration programs, and habitat protections agreed 
to by private landowners have improved habitat for Okaloosa darter 
sufficient to partially meet this criterion.
    Delisting Criterion 3: Erosion at clay pits, road crossings, and 
steep slopes has been minimized to the extent that resemble historical 
pre-disturbance condition. Between 1995 and 2005, over 510 borrow pits 
and non-point erosion sites (680 acres) have been rehabilitated and 
maintained within Okaloosa darter watersheds (USAF 2022, p. 142) and 
erosion rates are calculated to be nearly at background levels (USAF 
2022, p. 143). This work was a major factor in the decision to 
reclassify the species from Endangered to Threatened (USFWS 2011, 
entire) and as such, this criterion should be considered fulfilled.
    Delisting Criterion 4: Longleaf restoration and watershed 
management practices on the Eglin AFB are in effect. This criterion is 
largely fulfilled. Both longleaf and watershed management practices are 
in effect on Eglin AFB. In fact, Eglin's longleaf pine/sandhill 
management has been so effective, Eglin reached its recovery goal for 
the Red-cockaded Woodpecker (RCW) in 2009 (USAF 2022, p. 134) with 
continued population growth. Because the ranges of RCW and Okaloosa 
darter overlap, continued management and protections associated with 
RCW in the uplands will benefit Okaloosa darters. Additionally, Eglin 
has committed to maintaining buffers around Okaloosa darter streams for 
infrastructure and mission planning (Felix 2020, pers comm.). In 
addition to protections and management associated with endangered 
species, Eglin continues to monitor aquatic habitat quality through 
macroinvertebrate and water quality monitoring (USAF 2022, p. 160).
    Delisting Criterion 5: Natural, historical flow regimes are 
maintained. Water withdrawals for human consumption in and around the 
range of the Okaloosa darter are presently served by wells that tap the 
Floridan Aquifer, which is declining in the most populated areas near 
the coast (Pascale 1974, pp. 1-2). At this time, there is no evidence 
that pumping from that aquifer has reduced flows in darter streams 
(USFWS 2017, p. 13). To the extent that the darter drainages are spring 
fed (by and large they are fed by seepage), the springs are from the 
shallow sand and gravel aquifer that is not currently used for human 
consumption. Additionally, the low permeability of the Pensacola Clay 
confining bed likely severely limits hydraulic connectivity between the 
two aquifers (Schumm et al. 1995, p. 288). As long as withdrawals from 
the sand and gravel aquifer are minimal, local human population growth 
should not adversely affect water flows in the drainages occupied by 
the darter (USFWS 2017, p. 13). This criterion has been met.
    Delisting Criterion 6: Water quality and riparian habitat have been 
significantly improved and maintained. Water quality in Okaloosa darter 
streams has been monitored consistently throughout the past 25 years. 
At each monitoring site, standard water quality parameters are measured 
and recorded and up to 20 sites per year are surveyed using the FDEP 
rapid Biorecon and Stream Condition Index (SCI) methods (FDEP 2017). In 
general, streams originating on Eglin exhibit pristine water quality 
and high to very high scores on Biorecon and SCI surveys (Jordan and 
Jelks 2022, p. 11; USFWS 2023, unpublished data). Streams under 
anthropogenic pressure exhibit lower Okaloosa darter numbers or local 
extirpations, however these anthropogenic pressures are limited to less 
than 15 percent of the historic ranges and only 5 percent of the 
currently occupied range (USFWS 2019, p. 15). Water Quality in Deer 
Moss Creek and Shaw Still Branch continue to be negatively influenced 
by treated sewage effluent applied to sprayfields adjacent to those 
streams and the Niceville wastewater treatment facility was upgraded in 
2010, to reduce nutrients in sprayfield effluent. Recent studies at 
Eglin AFB have found that groundwater transport in the Deer Moss Creek 
watershed is approximately 12 to 18 years (Landmeyer et al. 2022, 
9(5):69), so we expect to observe water quality changes in upcoming 
years. This criterion is partially fulfilled, and progress is ongoing.
    Delisting Criterion 7: Cooperative and enforceable agreements are 
in place to protect habitat and water quality and quantity for the 
historical range outside of Eglin AFB ((2)(a), above), and management 
plans that protect and restore habitat and water quality and quantity 
have been effective and are still in place for the 90 percent of the 
historical range currently managed by Eglin AFB ((2)(b), above).
    About 90 percent of the 51,397 hectares (127,000 acres) that 
represent the drainage basins of darter streams are managed by Eglin 
AFB. Eglin AFB will continue to include management for the Okaloosa 
darter in the Eglin AFB's integrated natural resources management plan 
(INRMP), changes to which are reviewed and approved by both the Service 
and by FWC as specified under the Sikes Act. Eglin AFB has no plans to 
remove management from the INRMP or limit management within Okaloosa 
darter watersheds (Hagedorn 2020, pers. comm.). In fact, Eglin AFB is 
working with the Service to shift prescribed fire management to reduce 
canopy cover in Okaloosa darter streams to further bolster darter 
numbers and stabilize monitoring sites with observed declines. 
Additionally, Eglin AFB has placed protective buffers on Okaloosa 
darter streams to prevent land use changes and management actions that 
might adversely affect Okaloosa darter or its habitat, thus protecting 
90 percent of the darter's watershed area from impacts (Felix 2020, 
pers. comm.).
    Outside the Eglin AFB boundary, the remaining 485.6 hectares (1,200 
acres) of Okaloosa darter habitat are situated in the Niceville-
Valparaiso urban complex. Okaloosa darters are found at reduced levels 
or absent from much of this area. Current stream impacts include 
erosion, non-point discharge of nutrients and pollutants, impoundment, 
alteration of flow, and culverting. Conservation agreements and habitat 
buffering on private property further prevent adverse impacts to an 
additional 3 to 4 percent

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of the historical range (Ruckel Properties 2018, entire). In total, 90 
to 95 percent of the watershed area has established protections, and 
monitoring will ensure this criterion continues to be met.
    Delisting Criterion 8: Management plans that protect and restore 
habitat and water quality and quantity have been effective and are 
still in place for the 90 percent of the historical range currently 
managed by Eglin AFB. This criterion is largely fulfilled through 
Eglin's 2007 INRMP.
    Delisting Criterion 9: Okaloosa darter populations at monitoring 
sites consist of two or more age-classes and remain stable or 
increasing in all six streams over a period of 20 consecutive years.
    Monitoring for Okaloosa darter has been conducted annually at 21 
core sites distributed throughout the range since 1995. In 2005, 2014, 
and 2020, expanded monitoring efforts of 58 sites were conducted to 
estimate the population size and inform the status review and species 
status assessment. Additional monitoring has been conducted to support 
specific research projects. In general, Okaloosa darter numbers 
increased in the late 1990s through early 2000s, at which time declines 
were observed at a subset of sites (Jordan and Jelks 2020, p. 11). 
Multiple year-classes have been recorded in each of the six watersheds 
in all years of study, regardless of declines (USFWS 2022, unpublished 
data). Although declines have been identified in portions of the range, 
the majority of the declines could be associated with dense canopy 
cover limiting vegetation and primary productivity in the stream 
(Jordan and Jelks 2020, p. 10). Eglin AFB natural resource managers are 
working to shift habitat management activities such as prescribed fire, 
vegetative spraying, or mechanical timber stand improvement to limit 
excessive riparian growth along Okaloosa darter streams. Monitoring 
data will continue to be collected and used to assess and inform 
management actions in Okaloosa darter watersheds.
    Regardless of declines, the overall population estimate for 
Okaloosa darter was greater than 500,000 individuals in 2020 (Jordan 
and Jelks 2021, p. 11) and rangewide densities generally remain above 2 
darters per meter of inhabited stream (Jordan and Jelks 2021). 
Maintaining multiple viable populations substantially reduces the risk 
of species extinction, and future scenario modelling suggests that 
resiliency and redundancy will remain sufficient to support the 
viability of the species into the foreseeable future (USFWS 2019, pp. 
70-72). This criterion has been fully met.
    Delisting Criterion 10: No foreseeable threats exist that would 
impact the survival of this species.
    Potential future threats to the Okaloosa darter are to its habitat, 
particularly in three of the smaller basins: Mill, Swift, and Deer Moss 
Creeks. Human activity has degraded physical and chemical habitat 
quality in these basins, though only the Deer Moss Creek population 
exhibits declines. Mill Creek is almost entirely within the Eglin AFB 
golf course, which sponsored a major stream restoration in 2007 that 
nearly doubled the inhabited stream in this watershed. The golf course 
has also implemented best management practices (BMPs) for herbicide and 
pesticide application that limit impacts to Mill Creek. The lower 
portions of Swift Creek are nearly completely urbanized, but our models 
show that the restoration of College Pond would nearly double the 
population size. Stream restoration at College Pond would not only add 
substantial habitat to the watershed, it would also remove a fish 
passage barrier to multiple tributaries that are currently unoccupied 
by the Okaloosa darter. Eglin AFB is currently working with the 
Service, FWC, and community partners to begin engineering designs for 
this project.
    The portions of Deer Moss Creek outside Eglin AFB are currently 
subject to development pressure; however, during the FWC endangered 
species permit process, developments and other actions must show a net 
benefit to the species before approval by the State. In the case of 
Deer Moss Creek, a conservation plan was developed that prevents 
construction in all wetlands, adds an upland buffer that requires 
bridges that completely span all wetlands, and requires the removal of 
two fish passage barriers within the watershed, among other provisions 
(Ruckel Properties 2014, entire). In addition to protections from 
urbanization in lower Deer Moss Creek, the Niceville wastewater 
treatment facility was upgraded in 2010, to reduce nutrients in 
sprayfield effluent. Recent studies at Eglin AFB have found that 
groundwater transport in the Deer Moss Creek watershed is approximately 
12 to 18 years (Landmeyer 2022, 9(5):69), so we expect to observe water 
quality changes in upcoming years.
    Because the range of the Okaloosa darter is almost entirely on 
Federal lands, nearly all actions in this area were subject to the 
interagency cooperation requirements of section 7. Following delisting, 
the protections under section 7 will no longer apply; however, Eglin 
AFB plans to maintain protections for the Okaloosa darter by 
maintaining a buffer around Okaloosa darter streams during 
infrastructure and mission planning (USAF 2022d, appendix K) and by 
developing enhanced BMPs to limit erosion during construction projects 
and continuing to monitor stream health (Felix 2020, pers. comm.). 
Additionally, any action on Federal or private lands that impact 
wetlands would require permits under the Clean Water Act (33 U.S.C. 
1251 et seq.). Eglin AFB protection and restoration of Okaloosa darter 
streams is a substantial component of natural resources management on 
Eglin AFB. Approximately 90 percent of the species' range is under the 
management of Eglin AFB; urbanization will have little to no future 
effect. Because the Okaloosa darter occurs in multiple stream systems, 
which provides redundancy, and no long-term threats are presently 
impacting the Okaloosa darter at the species level within the 
foreseeable future, this criterion has been met.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for endangered 
species. In 2019, jointly with the National Marine Fisheries Service, 
the Service issued a final rule that revised the regulations in 50 CFR 
424 regarding how we add, remove, and reclassify endangered and 
threatened species and the criteria for designating listed species' 
critical habitat (84 FR 45020; August 27, 2019). On the same day, the 
Service also issued final regulations that, for species listed as 
threatened species after September 26, 2019, eliminated the Service's 
general protective regulations automatically applying to threatened 
species the prohibitions that section 9 of the Act applies to 
endangered species (84 FR 44753; August 27, 2019).
    The Act defines an ``endangered species'' as a species that is in 
danger of extinction throughout all or a significant portion of its 
range, and a ``threatened species'' as a species that is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range. The Act requires that we 
determine whether any species is an endangered

[[Page 41840]]

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

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the species, including an assessment of the potential 
stressors to the species. The SSA report does not represent a decision 
by the Service on whether the species should be proposed for delisting. 
However, it does provide the scientific basis that informs our 
regulatory decisions, which involve the further application of 
standards within the Act and its implementing regulations and policies. 
In this discussion, we summarize the key conclusions from the SSA 
report; the full SSA report can be found on the Service website at 
https://ecos.fws.gov/ecp/species/E00H/ and at https://www.regulations.gov under Docket No. FWS-R4-ES-2021-0036.
    To assess the Okaloosa darter's viability, we used the three 
conservation biology principles of resiliency, representation, and 
redundancy (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency 
describes the ability of the species to withstand environmental and 
demographic stochasticity (for example, wet or dry, warm or cold 
years), redundancy supports the ability of the species to withstand 
catastrophic events (for example, droughts, large pollution events), 
and representation supports the ability of the species to adapt over 
time to long-term changes in the environment (for example, climate 
changes). In general, the more redundant and resilient a species is, 
and the more representation it has, the more likely it is to sustain 
populations over time, even under changing environmental conditions. 
Using these principles, we identified the species' ecological 
requirements for survival and reproduction at the individual, 
population, and species levels, and described the beneficial and risk 
factors influencing the species' viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated individual species' life-history 
needs. The next stage involved an assessment of the historical and 
current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to sustain populations in the 
wild over time. We use this information to inform our regulatory 
decision.

Summary of Threats and Conservation Measures That Affect the Species

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability.
    Stressors to Okaloosa darter stem from two main sources: land use 
and management practices on Eglin AFB and urbanization around the lower 
reaches of streams outside of Eglin AFB. Urbanization is the greatest 
threat to the Okaloosa darter, as development leads, through multiple 
pathways, to pollution, erosion, and sedimentation; altered water 
flows; and dispersal barriers. Land use and management practices such 
as road building, timber harvesting, and fire suppression can affect 
abundance of Okaloosa darters on Eglin AFB. The effects of a changing 
climate, such as increasing stream temperatures, could become a threat 
to the Okaloosa darter throughout its geographic range in the future; 
however,

[[Page 41841]]

the degree and magnitude of any impacts are uncertain at this time. 
Impending development along Deer Moss Creek would likely be completed 
in 20 years; however, a conservation plan is in place to minimize 
impacts to Deer Moss Creek.

Sedimentation and Erosion

    Sediment loading is perhaps the primary factor continuing to impact 
the Okaloosa darter. The primary sources of sediment to aquatic 
ecosystems on Eglin AFB are accelerated streamside erosion, borrow pits 
(areas where clay, sand, or gravel are removed for use at other 
locations), developed areas, weapon test ranges, silviculture, and 
roads (Rainer et al. 2005, p. 1-1). Sedimentation can result from 
unpaved roads, road crossings, and road or development projects (e.g., 
solar power grids); sedimentation can also result from poor stormwater 
control or runoff during heavy, localized rains. Even though the 
species has been impacted by these threats, the current population 
estimate is approximately 500,000 darters across its range.
    Management for the Okaloosa darter is outlined in Eglin AFB's 
INRMP, which includes specific goals and objectives to improve Okaloosa 
darter habitat, and Eglin AFB has demonstrated a commitment to recovery 
of the species. Therefore, management and other conservation actions 
are much more likely to occur on Eglin AFB than surrounding properties 
(USFWS 2007, p. 5). These streams on Eglin AFB flow mostly through 
forested, natural settings, whereas off-installation, they interface 
mostly with urban and suburban areas. Eglin AFB personnel have 
implemented this effective habitat restoration program to control 
erosion from roads, borrow pits, and cleared test ranges. Since 1995, 
Eglin AFB personnel have restored 317 sites covering 196.2 hectares 
(484.8 acres) that were eroding into Okaloosa darter streams, including 
borrow pits and other non-point sources (pollution created from larger 
processes and not from one concentrated point source, like excess 
sediment from a construction site washing into a stream after a rain) 
of stream sedimentation (76 FR 18087, April 1, 2011, p. 18090). Erosion 
into the streams has been reduced to background levels, nearly all fish 
passage barriers on Eglin AFB have been removed, several restoration 
projects have been completed to restore and reconnect stream habitat, 
and conservation agreements with local landowners (on 3 to 4 percent of 
potential Okaloosa darter range) have been put in place on private 
lands to protect stream and floodplain habitat (Wetland Sciences 2011, 
entire).
    Eglin AFB personnel estimate that these and other restoration 
efforts have reduced soil loss from roughly 69,000 tons per year in 
Okaloosa darter watersheds in 1994 to approximately 2,500 tons per year 
in 2010 (Pizzolato 2018, pers. comm.). While soils will always be 
highly susceptible to disturbance and sedimentation and erosion could 
impact the species, habitat restoration work has improved Okaloosa 
darter habitat within the base. Improvements such as bottomless 
culverts, bridges over streams, and bank restoration and revegetation 
have resulted in increased clarity of the water, stability of the 
channel and its banks, and expansion of Okaloosa darter into new areas 
within drainages (USFWS 2011, 76 FR 18087, April 1, 2011, p. 18090). 
Poorly designed silviculture programs can result in accelerated soil 
erosion and stream sedimentation, but Eglin AFB personnel have designed 
their program within Okaloosa darter habitat to avoid and minimize 
impacts to the aquatic ecosystems such that the program is not likely 
to adversely affect Okaloosa darters (USAF 2022, pp. 4-23; USFWS 2017, 
pp. 11-12).
    Forest and timber management in Okaloosa darter drainages is 
generally directed toward habitat management for the red-cockaded 
woodpecker (Picoides borealis) or fuel reduction near military test 
ranges and in the urban interface, which involve the use of prescribed 
fire, mechanical or chemical timber stand improvement, and traditional 
forestry practices for timber harvest and fuel-wood. Recently timbered 
areas may leave exposed sandy patches, which can be susceptible to wind 
erosion. However, erosion has been reduced to background levels; all of 
these habitat management programs are coordinated through Eglin AFB and 
are conducted in accordance with State and Federal BMPs (USAF 2022, p. 
77, INRMP forestry component plan).

Road Development Projects

    Unpaved roads, their low-water stream crossings, and subsequent 
bank erosion probably have the greatest impact because of their 
distribution on Eglin AFB, relative permanence as base infrastructure, 
and long-term soil disturbance characteristics. The largest remaining 
source of sediment input to Okaloosa darter streams is the unpaved road 
network, which allows sediment to be washed off the road and into 
nearby streams, especially where they cross the stream itself. As of 
2005, 87 percent (4,348 km) of the roads in Eglin AFB's road network 
were unpaved, and remain so currently (Felix 2018, pers. comm.).
    Road crossings can be detrimental to Okaloosa darter depending on 
their design. Pipe culverts alter stream flow and impede movement of 
Okaloosa darter, whereas bridges and bottomless culverts do not. Of the 
153 road crossings that previously existed in Okaloosa darter 
drainages, 57 have been eliminated--28 in Boggy Bayou streams and 29 in 
Rocky Bayou streams. Although many road crossings have been removed and 
restored through road closures and restoration efforts over the last 
few years, others remain and pose a threat to the Okaloosa darter and 
its habitat. For example, five road crossings in the Turkey Creek 
drainage have repeatedly exceeded State water quality standards for 
turbidity (USFWS 2017, p. 11).
    Road development projects also present potential threats that may 
negatively impact the Okaloosa darter. The Mid-Bay Bridge Authority's 
Mid-Bay Connector Road (Connector Road), a road constructed from the 
terminus of the Mid-Bay Bridge to SR 85 north of Niceville, was 
completed in February 2014 (USFWS 2017, p. 13). We completed 
consultation on this project under section 7(a)(2) of the Act. Although 
the Connector Road crosses Okaloosa darter drainages, conservation 
measures included 19 stipulations to minimize impacts to darter 
drainages. For example, the project used environmentally sensitive 
bridge construction techniques and measures to minimize erosion and 
ground disturbance at each stream crossing and to maintain channel 
stability. Because the bridges were designed to maintain natural stream 
geomorphology and were built using appropriate methods to stabilize 
stream banks and provide erosion control along the stream, long-term 
erosion and degradation of Okaloosa darter habitat is not anticipated. 
Monitoring before, during, and after construction detected no 
significant project-related changes in abundance of Okaloosa darters 
above or below any of the new stream crossings (Jordan and Jelks, 
unpublished data). However, the project impacted multiple areas of 
Okaloosa darter streams via erosion associated with large storm events 
and, in 2012, violated erosion controls. One of the stream crossings 
required a full stream restoration within the project limits and 
downstream from the project area. Erosion-related issues were also 
reported in 2013 (USFWS 2017, p. 13). As part of further mitigation of 
the Connector Road's accumulated negative impacts on the Okaloosa 
darter, to date the Mid-Bay

[[Page 41842]]

Bridge Authority has improved road crossings of Okaloosa darter streams 
at seven sites on Eglin AFB and at one site off of Eglin AFB. As of 
February 2019, the Mid-Bay Bridge Authority has no plans for future 
corridors. The existing corridor could be widened to four lanes if 
future traffic projections justify the need. The corridor has already 
been cleared and grassed, so no additional sedimentation or erosion-
related impacts are anticipated should an expansion to four lanes 
occur. Any future road projects will require consultation under section 
7(a)(2) of the Act (USFWS 2017, p. 13).
    The construction of the Connector Road created several relatively 
small ``orphaned'' parcels of Eglin AFB-owned property, whereby the 
road effectively separated those parcels from the natural resources 
management practices employed elsewhere over the contiguous Eglin AFB 
reservation properties. Three of these orphan parcels lie within the 
Okaloosa darter's geographic range (approximately 740, 170, and 260 
acres) and surround segments of four occupied streams (Mill, Swift, 
Turkey, and Deer Moss Creeks). Eglin AFB has historically considered 
orphan parcels candidates both for leasing through enhanced use 
agreements and for real property transaction or exchange to public and 
private entities in order to maximize the effectiveness of its real 
property in supporting the United States Air Force (USAF) mission. 
Eglin AFB may consider the three parcels mentioned above for such 
transactions. However, the Eglin AFB has indicated its intent to 
coordinate with the Service on the impacts identified in any 
environmental impact analysis for such transactions (Felix 2018, pers. 
comm.).
    In 2012, the Service issued a biological opinion to the Federal 
Highway Administration (FHWA) for widening SR 123 from a two-lane 
undivided roadway to a four-lane divided roadway from SR 85 South to SR 
85 North (USFWS 2017, p. 13). The widening included new two-lane 
bridges at Toms Creek and Turkey Creek, and replacement of the culvert 
at the unnamed tributary to Turkey Creek with two single-span bridges. 
The biological opinion concluded that, while the effects of the project 
included displacement, injury, and mortality to Okaloosa darters 
resulting from construction debris, equipment movement, dredge and fill 
activities, sedimentation, introduction of contaminants, and habitat 
alteration, it would not jeopardize the continued existence of the 
threatened Okaloosa darter if certain measures were implemented.
    In 2015 and 2016, multiple erosion control failures resulted in 
sediment from the project site discharging into streams occupied by 
Okaloosa darters: Toms Creek, Shaw Still Branch, Turkey Creek, and an 
unnamed tributary to Turkey Creek following storm events. The Service 
worked with the U.S. Army Corps of Engineers, FHWA, and the Florida 
Department of Transportation to develop a restoration and compensation 
plan, and implementation of the plan began in 2018. The plan was 
designed to fully offset all impacts and provide a net conservation 
benefit to the species due to unforeseen, but preventable, impacts. In 
summer 2017, the Service identified additional impacts of this highway 
project to steepheads (deep ravines) outside of the initial defined 
action area for this project (Tate 2018, pers. comm.; USFWS 2017, pp. 
13-14). Additionally, a working group including the Service and Eglin 
AFB was formed to develop BMPs that would prevent erosion events and 
that would be applied to base projects during site preparation and 
construction (Tate 2018, pers. comm.). The goal of this effort is to 
prepare BMPs and language/requirements to be included in the real 
estate leasing agreements, to help ensure the species' conservation 
when the Act's protections are removed. The BMPs and any additional 
requirements will be finalized before any projects move forward; to 
date, no such projects have been undertaken.

Stormwater Control

    Development and construction activity in residential areas outside 
of Eglin AFB and primarily in the downstream-most portion of the 
Okaloosa darter's range pose a threat due to poor stormwater runoff 
control and pollution prevention measures that degrade habitat and 
sometimes create barriers to movement between basins. Although this 
threat is greater in urban areas, recent failures in erosion control 
and stormwater management on Eglin AFB highlight the importance of 
thoroughly understanding how proposed activities contribute to erosion 
and stormwater management problems and implementing practices to 
minimize those effects (USFWS 2017, p. 11).
    For example, in June 2017, a significant stormwater retention pond 
failure occurred on Eglin AFB property leased to Gulf Power and run by 
Gulf Coast Solar Center I, LLC (Coronal Energy), for a solar energy 
project. This failure caused extensive soil loss both on the leased 
site and offsite on Eglin AFB property. Okaloosa darter habitat in an 
unnamed tributary to Toms Creek was completely lost to sedimentation, 
and additional sediment is still located throughout the floodplain. 
However, this event impacted less than 0.1 percent of the estimated 
populations involved, and design changes have been made that are 
expected to fully offset all impacts and provide a net conservation 
benefit to the species due to unforeseen, but preventable, impacts 
(USFWS 2017, p. 14).

Borrow Pits

    Borrow pits were a major source of sediment loading to Okaloosa 
darter streams cited in the 1998 darter recovery plan. At that time, 29 
of 39 borrow pits located within or immediately adjacent to Okaloosa 
darter drainages had been restored. As of 2004, all borrow pits within 
Okaloosa darter drainages had been restored (59.3 ha; 146.5 ac) (USAF 
2022b, pp. 3-18; USFWS 2017, p. 11).

Pollution

    Pollution, other than sedimentation, poses a potential threat to 
darters. One stream in the darter's range, lower Turkey Creek, is on 
the Florida Department of Environmental Protection's (2018) Verified 
List as impaired, listing iron from a closed landfill as the pollutant 
(USFWS 2018, entire). Using aquatic insect sampling methods, the 
Service (Thom and Herod 2005, entire) found 12 sites out of 42 sampled 
within the darter's range to be impaired. One notable source of 
pollution in Shaw Still Branch and Deer Moss Creek results from 
wastewater treatment sprayfields (the Niceville-Valparaiso Regional 
Effluent Land Application Sprayfield) (USFWS 2017, pp. 12-13). 
Abundance declines from about 45 Okaloosa darter per 20 meters in the 
headwaters just above the sprayfield down to 1 or fewer Okaloosa darter 
per 20 meters in the remaining 4 kilometers or so of stream downstream 
from the sprayfield (Jordan 2017, pp. 5-7; Jordan 2018, unpublished 
data, figure 8). The actual pollutant has yet to be determined, but 
impacted streams have high conductivity compared to the relatively 
sterile, ion-poor, and slightly acidic streams that are typical of the 
area and likely similar to streams where the Okaloosa darter evolved. 
Contaminants found in the portions of Deer Moss Creek exposed to 
sprayfield effluent were shown to affect the biological processes of 
other species of fish in those streams (Weil et al. 2012, p. 185). 
Municipal wastewater with increased conductivity has been shown to 
negatively affect other species of

[[Page 41843]]

darters (Hitt et al. 2016, entire; Fuzzen et al. 2016, entire).

Water Withdrawals

    Water withdrawals for human consumption in and around the range of 
the Okaloosa darter are presently served by wells that tap the Floridan 
Aquifer, which is declining in the most populated areas near the coast 
(Pascale 1974, pp. 1-2). At this time, there is no evidence that 
pumping from that aquifer has reduced flows in darter streams (USFWS 
2017, p. 13). To the extent that the darter drainages are spring fed 
(by and large they are fed by seepage), the springs are from the 
shallow sand and gravel aquifer that is not currently used for human 
consumption. Additionally, the low permeability of the Pensacola Clay 
confining bed likely severely limits hydraulic connectivity between the 
two aquifers (Schumm et al. 1995, p. 288). As long as withdrawals from 
the sand and gravel aquifer are minimal, local human population growth 
should not adversely affect water flows in the drainages occupied by 
the darter (USFWS 2017, p. 13).

Effects of Climate Change

    The Intergovernmental Panel on Climate Change (IPCC) concluded that 
warming of the climate system is unequivocal (IPCC 2014, entire). 
Numerous long-term changes have been observed including changes in 
arctic temperatures and ice, and widespread changes in precipitation 
amounts, ocean salinity, wind patterns, and aspects of extreme weather 
including droughts, heavy precipitation, heat waves, and the intensity 
of tropical cyclones (IPCC 2014, entire). While continued change is 
certain, the magnitude and rate of change is unknown in many cases 
(USFWS 2017, p. 14).
    The current occupied range of the darter is restricted to 
approximately 402 kilometers of streams in Walton and Okaloosa 
Counties, Florida. While science shows that global-scale increases in 
stream temperatures have occurred (Kaushal et al. 2010, entire; Song et 
al. 2018, entire), streams within the Okaloosa darter's range are 
seepage and spring-fed, and thus thought to be thermally moderated 
(USFWS 2017, p. 14). However, thermal mediation varies among nearby 
Okaloosa darter streams, and streams that support Okaloosa darter are 
strongly affected by increases in air temperature (Jordan 2018, 
unpublished data). Information required to evaluate whether increased 
temperatures in streams will adversely affect the Okaloosa darter is 
lacking; however, declines in abundance following the impoundment of 
small stream reaches are likely due in part to increased temperatures, 
and the loss of darters below larger impoundments, such as Brandt Pond 
and Swift Creek, are generally assumed to be due to temperature change 
(Jordan 2018, pers. comm.). Because the distribution of the Okaloosa 
darter is limited, and individuals cannot expand northward, stream 
temperature increases or sea level rise that would cause stream 
inundation could pose a threat to the Okaloosa darter by isolating the 
populations. The National Oceanographic and Atmospheric Administration 
(NOAA) (2017, entire; NOAA Sea Level Rise Viewer 2018) projects sea 
level rise will be around 1.84 feet by year 2050 (Sweet et al. 2017, 
Intermediate High scenario). While this increase will not inundate much 
of the darter's stream systems due to topography, it could isolate the 
stream systems from each other, limiting genetic exchange (Tate 2018, 
pers. comm.; NOAA Sea Level Rise Viewer 2018). However, the species has 
maintained genetic exchange among populations despite current and 
historical saltwater isolation (Austin et al. 2011, p. 987).

Impoundments

    Many streams within the range of the Okaloosa darter have a history 
of impoundment. These impoundments were either deliberately created to 
produce recreational ponds or unintentionally formed following 
installation of a poorly designed road crossing. Culverts and other 
installations can also facilitate the creation of permanent 
impoundments by North American beavers (Castor canadensis), which take 
advantage of human-made alterations (Nicholson 2009, p. 5; Reeves et 
al. 2016, p. 1376). Okaloosa darters do not occupy impounded stream 
reaches (Mettee et al. 1976, p. 2; Nicholson 2009, p. 6) due to their 
depth and low flow rates, variable water temperatures, more 
accumulation of organic substrates, and higher numbers of predatory 
fishes than free-flowing stream reaches (Nicholson 2009, pp. 3-4; 
Reeves et al. 2016, p. 1376). Okaloosa darters living downstream of 
impoundments are also negatively affected, sometimes for a considerable 
distance. For instance, the roughly 3 kilometers (60 percent) of Swift 
Creek below College Pond and roughly 2 kilometers (100 percent) of 
Foxhead Branch below Brandt Pond currently lack Okaloosa darters 
(Jordan 2018, pers. comm.). In the absence of predators, beaver 
populations can become overpopulated (Nicholson 2009, p. 5). Eglin AFB 
currently traps and relocates nuisance beavers and removes beaver 
impoundments in order to improve stream habitats for Okaloosa darters 
and plans to continue this work indefinitely (USAF 2022, pp. 5-12).

Barriers to Dispersal

    All of the aforementioned threats could pose barriers to dispersal. 
Road crossings and impoundments, however, create the most obvious 
barriers, and many of these barriers have been removed. In 2011, when 
the Okaloosa darter was downlisted to threatened status, 4 of the 153 
road crossings and 25 impoundments that were barriers to fish passage 
remained. A few of these road crossings were culverts with the 
downstream end perched above the stream bed, precluding the upstream 
movement of fish during normal and low-flow conditions. However, some 
of these barriers were determined to have little to no adverse 
consequence to darter habitat connectivity because they occurred on the 
outskirts of the current range or were immediately adjacent to another 
barrier or impoundment.
    To date, all but three of the problematic road crossings have been 
removed. One of these, located at the headwaters of Rocky Creek, is 
scheduled for removal in upcoming funding cycles (USAF 2022d, appendix 
K). Additionally, 13 impoundments still exist, 4 of which are caused by 
beaver activity. Beavers that remain are primarily in the headwater 
reaches where the Okaloosa darter is either not present or would be in 
very low density. Nuisance beavers are managed under a cooperative 
agreement with the U.S. Department of Agriculture. USFWS is currently 
working with Eglin and other partners to secure funding for the 
restoration of Swift Creek via removal of College Pond (Tate 2020, 
pers. comm.). Since the time of listing, most of the barriers to 
dispersal have been removed, and most of the problematic ones that 
remain are scheduled to be removed, contributing to improved habitat 
and reduced population fragmentation.

Canopy Closure

    Overhead canopies range from open to fully closed depending on 
stream width and fire history (Jordan 2018, pers. comm.). Okaloosa 
darters thrive in reaches with relatively open canopies, likely due to 
either increased abundance of submerged vegetation that is used 
preferentially for spawning or increased secondary production of insect 
prey (Ingram 2018, p. 11). During the past 25 years, several monitored 
stream sections have changed from open with submerged vegetation to 
closed canopies with no vegetation. Closed

[[Page 41844]]

canopy may reduce densities of the Okaloosa darter. Once canopy is 
removed, Okaloosa darter densities increase quickly and dramatically 
(USFWS 2019, p. 30). In addition to increased riparian density along 
the streams, the use of low-intensity fire for forest management as 
opposed to historically high-intensity wildfires could have cascading 
negative effects on the watershed through changes in nutrient cycling, 
hydrology (evapotranspiration), or simply charcoal buffering (changes 
in pH levels) of water chemistry in the creeks. The Eglin AFB fire 
management program may shift, if needed, toward the use of higher 
intensity prescribed fires in the growing season along stream margins 
to control growth of canopy trees.

Invasive Species

    The introduction and colonization by nonnative, invasive species 
that could compete with or prey on the Okaloosa darter is a potential 
threat. The Okaloosa darter recovery plan lists competitive exclusion 
by the then-thought-to-be invasive brown darter (Etheostoma edwini) to 
be a threat to the Okaloosa darter. The brown darter is native to 
Okaloosa darter watersheds (Austin 2011, unpublished data) and is not 
altering the distribution or abundance of the Okaloosa darter where 
they coexist (USFWS 2019, p. 23). Flathead catfish (Pylodictis 
olivaris) are already present in the surrounding river systems, and 
conditions could become suitable for several cichlid species to 
successfully reproduce in Okaloosa darter habitat (Jelks 2018, pers. 
comm.). Tilapia (Oreochromis niloticus), for instance, are highly 
invasive and are well documented to cause local extinctions of native 
species through resource competition, predation, and habitat alteration 
(Canonico et al. 2005, pp. 467-474; Zambrano et al. 2006, pp. 1906-
1909). Release of aquarium species also remains a possibility. While 
this threat is speculative and dependent on an intentional release of 
an unknown invasive species, introduction of a highly competitive 
predator could lead to severe population depression or potential 
extirpation of the Okaloosa darter. Dispersal of an invasive species 
among Okaloosa darter's watersheds, however, would likely be limited by 
saltwater, giving managers time to take control measures within a 
single population. Eglin AFB and Service personnel have long-
established invasive species monitoring programs, and both agencies are 
committed to routine monitoring, early detection, and control of 
aquatic invasive species (USAF 2022d, appendix K). Early detection and 
targeted management of invasive species will minimize or eliminate this 
threat to the Okaloosa darter in the future (Tate 2019, pers. comm.).

Summary of Factors Influencing Viability

    The vast majority of the range of the Okaloosa darter is located on 
Eglin AFB, where many conservation and restoration actions have been 
successful in restoring the Okaloosa darter to regions from which it 
had previously been extirpated and increasing darter densities since 
the time of its listing in 1973. Much progress has been made in 
implementing conservation actions since the Okaloosa darter was 
downlisted to threatened in 2011. For example, Eglin AFB has restored 
more than 534 acres of erosional sites and completed multiple stream 
restoration projects to reconnect fragmented populations. Stream 
erosion levels have been reduced, and most of the fish passage barriers 
have been removed. Many restoration projects have been completed, and 
conservation agreements have been implemented. Collectively, the 
habitat restoration programs have restored Okaloosa darter habitat, and 
management agreements will secure the habitat into the future (USAF 
2022, p. 94; Wetland Sciences 2011, entire).
    However, portions of the Okaloosa darter's range still face 
threats, mostly from urbanization. The sedimentation, pollution, and 
water quality impacts, as well as changes to water flow from 
impoundments that can result from urbanization, can lead to a decrease 
in Okaloosa darter numbers. In areas where there is development, either 
on Eglin AFB main base or the surrounding cities, darters decrease in 
abundance or disappear (USFWS 2019, p. 23). Darters also still face 
threats from canopy closure, accidental spills, or other severe events. 
However, the vast majority of the Okaloosa darter's range is expected 
to remain under the management of the Air Force, limiting the impacts 
from urbanization to less than 10 percent of the historical range for 
the species.
    Okaloosa darters react quickly to restoration activities. For 
instance, erosion control and other restoration activities began 
earlier in the Boggy Bayou drainages, progressing to the Rocky Bayou 
drainages (Pizzolato 2018, pers. comm.). Accordingly, darter numbers 
increased in the Boggy Bayou drainages earlier than in the Rocky Bayou 
drainages (Jordan and Jelks 2021, p. 9). Okaloosa darters have also 
been shown to quickly recolonize restored streams (Reeves et al. 2016, 
entire) and reclaim beaver impoundments (Nicholson 2009, entire).
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the factors that may be 
influencing the species, including threats and conservation efforts. 
Because the SSA framework considers not just the presence of the 
factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.

Current Condition

Resiliency

    For the Okaloosa darter to maintain viability and withstand 
stochastic disturbance events, its populations must be sufficiently 
resilient, which is associated with population size, growth rate, and 
habitat quality. Stochastic events that have the potential to affect 
the Okaloosa darter include temperature changes, drought, localized 
pollutants/contaminants or other disturbances, or severe weather events 
such as hurricanes, which can impact individuals or the habitat they 
require for critical life functions such as breeding, feeding, and 
sheltering.
    Sufficiently resilient Okaloosa darter populations need quality 
habitat. Okaloosa darters require clear, clean, flowing water provided 
by deep layers of sand that regulate temperature and flow, with aquatic 
vegetation, root mats, leaf snags, and other substrates that provide 
cover. This habitat is maintained by land management practices on 
adjacent land that limit sedimentation and pollution. Streams that 
support Okaloosa darter should be free of impoundments created as 
human-made retention ponds, by poorly designed road crossings that 
impede flow and genetic exchange, or by beaver dams. Okaloosa darter 
also benefit from open riparian canopies that allow sunlight to reach 
the stream below (Ingram 2018, p. 11).

[[Page 41845]]

    For analysis purposes, we delineated resiliency units for the 
Okaloosa darter based on genetic analysis and obvious barriers to 
dispersal. Genetic variation exists between the six stream systems 
(Austin et al. 2011, p. 987). Because limited genetic exchange occurs 
between streams, the population in each stream is likely to be 
demographically independent; therefore, we used abundance data for each 
of the six stream systems to assess resiliency.
    Additionally, we assessed barriers to dispersal within each stream 
system that would indicate a further breakdown into additional 
populations. However, Eglin AFB has been effective in removing 
impoundments and poorly designed road crossings that served as barriers 
to dispersal, so the remaining impoundments occur at the headwaters or 
the lower reaches of each stream, leaving each stream's population 
mostly intact, allowing genetic exchange to occur within each stream 
system. Outside of Eglin AFB, Shaw Still Branch has Okaloosa darters 
that are isolated from other Okaloosa darters in the upper reaches of 
Swift Creek by College Pond; however, the numbers of darters in this 
small stream are likely fewer than 150. Therefore, we considered this 
population separately. The watersheds of each of the bayous (Toms, 
Boggy, and Rocky) where the species has been historically found 
constitute the three resiliency units for the purposes of this 
analysis. The Toms representative unit consists only of the Toms 
population; the Boggy unit consists of the Turkey and Mill populations; 
and the Rocky unit consists of the Swift, Deer, and Rocky populations.
    Habitat metrics, such as conductivity, other water quality metrics, 
and management, influence darter presence and abundance, but due to a 
lack of explained variation within the data, no quantitative predictive 
model has been successfully used. However, numerous data exist that 
draw causal relationships between habitat metrics and darter presence 
and abundance, such that we can draw some conclusions. First, it is 
clear that the Okaloosa darter does not inhabit impounded stream 
reaches. Further, when an impounded stream is restored, Okaloosa darter 
will quickly colonize the restored habitat, often at higher densities 
than initially found (Jordan and Jelks 2018, p. 29). When water 
conductivity gets too high, Okaloosa darter abundance drops (USFWS 
2019, p. 33).
    We assess current resiliency for the Okaloosa darter in terms of 
population factors, including the species' presence and density. To 
estimate a population size, we multiplied the estimated average 
abundance per meter by the estimated meters occupied (USFWS 2019, table 
5). The average abundance was derived from annual sampling at each of 
the 21 core monitoring sites over the past 20 years. In populations 
with multiple core sites, a grand mean was calculated for the entire 
population by averaging the long-term means within the population. Due 
to statistical constraints, population estimates using the expanded 
monitoring data from 2005 and 2014 only estimate the population of 
darters present in stream reaches between monitoring sites (USFWS 2019, 
p. 23) and do not include headwaters and tributary systems known to be 
inhabited. The calculations made during the SSA and used for this 
assessment apply the average abundance to all known inhabited stream 
reaches, generally producing a larger but more complete population 
estimate.
    Using this method, the total rangewide population estimate of the 
Okaloosa darter is approximately 500,000 (see table 1, below). The 
Rocky Creek population is the largest, comprising 713,458 darters, or 
57 percent of this total, followed by the Turkey Creek population, 
comprising 490,456 darters, or 39 percent. The other four resiliency 
units (Toms, Mill, Swift, and Deer Moss Creeks) together total only 4 
percent of the estimate: Toms Creek has an estimated 23,099 darters; 
Mill Creek, 1,317; Swift Creek, 18,810; and Deer Moss Creek, 2,353.
    These numbers reflect a significant (40 percent) decline between 
2005 and 2014. However, the population is still significantly greater 
than when the species was originally listed. Our professional judgment 
is that the reduction was caused by an increase in the canopy cover and 
that more aggressive clearing of the canopy cover will result in 
rebounding population numbers. This conclusion is consistent with 
experimental data, in which darter populations increased within months 
after canopy removal.

               Table 1--Resiliency Scores for the Okaloosa Darter Based on Estimated Population Size, Population Trends, and Vulnerability
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Population trend
              Population                      Estimated       slope (avg. count/      Population trend              Resiliency             Population
                                             population             year)                                                              vulnerability (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Toms..................................        23,099 (7,610)
Turkey................................       490,456 (90,045)
Mill..................................         1,317 (288)
Swift.................................        18,810 (9,875)
Deer Moss.............................         2,353 (1,658)
Rocky.................................       713,458 (130,006)
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We classified resiliency by species' presence, density, and 
population sizes. Population sizes of fewer than 10,000 Okaloosa 
darters are considered ``low,'' 10,000 to 50,000 are ``moderate,'' and 
more than 50,000 are ``high'' resiliency. Based on the population 
numbers presented above, the results of the resiliency analysis are as 
follows: Two of the populations (Turkey and Rocky) currently have high 
resiliency, two (Toms and Swift) have moderate resiliency, and two 
(Deer Moss and Mill) are considered to have low resiliency.

Redundancy

    Redundancy describes the ability of a species to withstand 
catastrophic events. Measured by the number of populations, their 
resiliency, and their distribution (and connectivity), redundancy 
gauges the probability that the species has a margin of safety to 
withstand or to bounce back from catastrophic local events such as 
collapse of a restored borrow pit, infestation by beavers, or spill of 
toxic chemicals that affect part or all of one population. We report 
redundancy for the Okaloosa darter as the total number of populations 
and the resiliency of population segments and their distribution within 
and among representative units. Also, there are

[[Page 41846]]

multiple populations in two of the stream systems.
    Six populations comprise the vast majority of the historical range 
of the Okaloosa darter within the three representative units. 
Redundancy is demonstrated through the darter's presence in multiple 
tributaries within most watersheds, and representation is demonstrated 
through the genetic structure of the populations. All six extant 
populations exhibit genetic differentiation, and the species is extant 
across all three representation units. Adequate redundancy is 
demonstrated through the darter's presence in multiple tributaries 
within most watersheds encompassing its historical range.

Representation

    Representation can be characterized by genetic variability within 
the range of the species. These three representative units, each 
identified as containing unique and significant historical variation 
(Austin et al. 2011, pp. 983, 987), have not been reduced over time. 
The Toms Bayou representative unit comprises just the Toms population, 
which is currently considered moderately resilient. However, the Toms 
population is vulnerable to upstream impacts, which could affect the 
representation of this unit were a major impact to occur. The Boggy 
Bayou representative unit comprises the Turkey and Mill populations, of 
which Turkey is considered highly resilient and has low vulnerability. 
The Rocky Bayou unit comprises the Swift, Deer Moss, and Rocky 
populations, of which Swift is considered moderately resilient and 
Rocky is considered highly resilient with low vulnerability. Given that 
each unit still contains at least one population that is moderately or 
highly resilient (>10,000 individuals), the Okaloosa darter has 
sufficient genetic variability. Representation is demonstrated through 
the genetic structure of the populations.

Future Condition

    The biggest potential threat to the Okaloosa darter in the future 
is development on and off Eglin AFB. Neighborhoods, roads, commercial 
structures, and associated utilities such as sprayfields are potential 
sources of sedimentation, pollution, and altered stream flow throughout 
the range of this species. Natural factors resulting from long-term 
forest management practices (e.g., prescribed fire) could also have 
potentially negative impacts on the Okaloosa darter. For instance, 
excessive canopy closure over streams might limit Okaloosa darter 
abundance by shading out aquatic vegetation preferred for spawning, 
refuge, or foraging (USFWS 2019, p. 23). The effects of canopy closure 
were built into all the future scenarios through general population 
increases or declines. For instance, in the ``ideal management'' 
scenario, we would expect that prescribed fire or other management 
limits excessive canopy cover and contributes to increases in darter 
numbers. The opposite would be expected in the ``poor'' and ``worst'' 
scenarios. Because we have not established a quantitative relationship 
between darter numbers and canopy closure, we decided to incorporate 
this factor into a general increase or decrease in populations over 
time.
    While there are several restoration activities, developments, or 
other proposed activities that have anticipated locations and 
quantifiable outcomes, specific information on the location, and 
therefore the effects to the Okaloosa darter, of other potential 
threats are unknown. Therefore, because it is impossible to predict the 
specific locations or impacts of future developments or other 
management decisions that could impact Okaloosa darter streams, we 
assess the future resiliency of each population based on general 
management and development scenarios. Accordingly, to assess the future 
viability of the Okaloosa darter, we considered four future scenarios 
that account for some degree of future development and restoration 
activities, considering effects of whether these activities are 
implemented or not; we also considered general impacts from unknown 
future management or land use changes or impacts, at varying levels 
with positive or negative impacts to each population. For each 
population, we consider its current condition, including the length of 
each stream that is unimpounded, the length considered occupied, and 
the average abundance per meter, to assess the future viability under 
each of these scenarios. Please see the SSA report (USFWS 2019, entire) 
for a more detailed discussion of these considerations.
    We projected these future scenarios both over 20 years and 50 
years. Any planned restoration efforts, should they be realized, as 
well as the impending development along Deer Moss Creek, would likely 
be completed in 20 years. Okaloosa darters respond very quickly to 
habitat changes, both good and bad. Improved conditions would result in 
an increase in Okaloosa darters, possibly within the same year (Reeves 
et al. 2016, pp. 1379-1382), but areas can also lose Okaloosa darters 
equally quickly if habitat conditions worsen. In some cases where 
habitat is restored in areas without nearby Okaloosa darters, 20 years 
would be sufficient to ensure that they would recolonize that area. Not 
only would 20 years encompass several generations of Okaloosa darter, 
but it is the time period outlined in the recovery plan for delisting. 
We projected to 50 years as it is considered the outer limit that 
projections of base realignment, hydrologic cycles, and climate 
alteration may be relied upon, based on expert opinion, and will 
encompass a timeframe in which projected sea level rise as a result of 
climate change could have realized impacts.
    To account for the uncertainty in the management implications of 
some proposed actions (Deer Moss Creek development and cleanup of the 
sprayfields) and other unforeseen/unknown future conditions (future 
land management/development and accidents), we generalize the future 
stream conditions/management in four categories: status quo (current 
conditions continue), ideal, poor, and worst. The ``ideal,'' or ``best-
case,'' scenario assumes that all potential stream habitat is colonized 
at normal densities. ``Poor'' management assumes that accidents 
stemming from errors in management may occur but are unlikely to affect 
the population in the worst possible place or are unlikely to have a 
high-magnitude impact; however, over time, these accidents add up and 
eventually have a larger impact. ``Worst'' management assumes that 
accidents stemming from errors in management occur and affect the 
population in a location that will affect the largest portion of the 
stream or will be of such a magnitude to have a similar effect. In all 
long-term scenarios, we anticipate the potential negative impacts of 
climate change by applying reductions in population estimates of 0.5 
standard deviations from the current population mean abundance.
    Below, we assess the future resiliency of Okaloosa darter 
populations both in the short (20-year) and long term (50-year) for the 
four different scenarios. Of the four scenarios, the status quo and the 
ideal scenario are the most likely to occur. The poor and worst 
management are the least likely to occur. Because these four scenarios 
encompass the broad changes to management, which would encompass water 
quality and render land ownership irrelevant, we model future 
resiliency based on how each scenario would affect the amount of 
occupied habitat and average abundance estimates within each 
population. Please see the SSA report (USFWS 2019, entire) for further 
description of the methodologies we

[[Page 41847]]

used to model these scenarios and their impacts to the Okaloosa darter.

Scenario 1: Status Quo

    In this scenario, we modeled current management coupled with both 
no restoration efforts (1a) and with restoration of the beaver dams on 
Toms Creek and College Pond on Swift Creek (1b). Under scenario 1a, 
nothing changed by way of management or restoration, meaning the 
impounded stream and abundance estimates stayed the same as the current 
estimates. The development of Deer Moss Creek did not affect the 
resiliency of this population because the section of stream that would 
be developed is currently, and remains, unoccupied. For the species as 
a whole, population estimates did not change much in the short term but 
decreased in the long term due to a loss of potential habitat (due to 
sea level rise resulting in stream inundation) and other possible 
climate-related threats, which we modeled as a 0.5 standard deviation 
reduction for each population. Not surprisingly, the smallest and most 
fragmented populations, Mill, Deer Moss, Toms, and Swift Creeks, are 
potentially susceptible to climate change impacts alone. Habitat 
restoration in Toms and Swift Creeks (scenario 1b) would offset our 
modelled impacts from climate change. Even though saltwater inundation 
will fragment about 5 percent of the two large populations in Turkey 
and Rocky Creeks, our models exhibited minimal loss of resiliency as a 
result of climate change under this scenario.
    For the species as a whole, our modelling suggested that, under 
current management conditions, there are likely to be nearly 1 million 
Okaloosa darters beyond the 50-year timeframe. In the long term under 
this scenario, Mill Creek would lose over 30 percent of its population 
(dropping below 1,000), as would Deer Moss and Toms Creek, unless 
restoration occurs. Swift Creek would lose almost 60 percent of its 
population unless habitat restoration occurs, but if restoration occurs 
(scenario 1b), the population would more than double in the short term 
and still increase by nearly 60 percent in the long term. Saltwater 
inundation in the long term would cause the Rocky, Turkey, and Swift 
populations to split into three streams each. While Rocky and Turkey 
would see about 5 percent of their populations cut off from the main 
segment, the inundation of Swift Creek would also cut off that 
population from the current location in the absence of restoration 
efforts. With no restoration, we can expect that 70 percent of the 
population in Swift Creek will be above College Pond in Swift Creek, 
with fewer than 100 in Shaw Still Branch, although neither of these 
populations are unlikely to remain at all in 50 years. With 
restoration, about 83 percent of the population would remain in the 
Swift Creek population and about 17 percent in a Shaw Still Branch 
population, with likely no dispersal between them (see table 2, below). 
Due to the continued impacts of urbanization in the watershed within 
the city of Niceville, we estimated population sizes as if inhabited 
under moderate management conditions (long-term average minus one 
standard deviation). Sanders Branch would remain unoccupied.

                         Table 2--Scenario 1 of Management for Okaloosa Darter Recovery
     [Total stream lengths in meters (m) that would be unimpounded, the occupied meters and the percent that
 represents, abundance estimates per meter, and the projected population size, both with and without restoration
efforts on Toms and Swift Creeks, in both the short term and long term. Scenario 1b shown for Toms (r) and Swift
                        (r) assume restoration of uninhabited portions of the watershed.]
----------------------------------------------------------------------------------------------------------------
                                                       Total
                                                    unimpounded    Occupied (m)     Abundance/m     Population
                                                    streams (m)                                        size
----------------------------------------------------------------------------------------------------------------
                                                   Short Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,936          11,300             2.0          23,011
Turkey..........................................         150,040         147,911             3.3         486,243
Mill............................................           1,993             846             1.6           1,317
Swift...........................................          21,130           5,292             3.5          18,631
Deer Moss.......................................           8,396           5,780             0.4           2,354
Rocky...........................................         282,068         276,683             2.6         707,791
Toms (r)........................................          16,336          12,360             2.0          25,167
Swift (r).......................................          22,276          14,767             3.5          46,622
----------------------------------------------------------------------------------------------------------------
                                                    Long Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,111           9,265             1.7          15,759
Turkey..........................................         149,063         132,041             3.0         394,227
Mill............................................           1,993             647             1.4             896
Swift...........................................          19,533           2,939             2.6           7,631
Deer Moss.......................................           7,981           4,696             0.3           1,239
Rocky...........................................         280,096         246,739             2.3         573,683
Toms (r)........................................          15,511          11,736             1.7          19,960
Swift (r).......................................          20,679          11,031             2.6          20,509
----------------------------------------------------------------------------------------------------------------

Scenario 2: Ideal Restoration, Good Management

    This scenario represented the highest population size that the 
species could attain. Under this scenario, all impoundments were 
removed, and management removed most existing threats, increasing the 
occupied lengths of each stream to almost all of the inhabitable area. 
In other words, we modelled the potential population for all streams as 
if they were completely free-flowing by applying our current population 
estimates to the entire potential length of stream habitat in the 
watershed. This scenario represented the ``best case scenario'' for the 
species. Because of this, we modelled an expected population expansion 
of 1.0 standard deviation from the current mean abundance for each 
population.

[[Page 41848]]

As expected, short-term estimates increased for all populations, with 
the highest relative increases in fragmented populations (Swift and 
Toms Creeks) or those impaired by urbanization (Deer Moss and Mill 
Creeks). Because we apply the same negative influence of climate change 
to the long-term models in this scenario, the long-term population 
estimates are dampened but still increasing in the four smaller 
populations with a very slight (<1 percent) reduction in Turkey and 
Rocky Creeks due to fragmentation and saltwater inundation. Under this 
scenario, our model indicated there will be more than 1.3 million 
Okaloosa darters and increased resiliency in all of the smaller 
populations, even when negative impacts of climate change are applied 
in the long term.
    In the short term, the population would increase for all stream 
systems, although by a much higher percent in Mill and Swift Creeks 
than in Rocky and Turkey Creeks. In the long term, all populations 
except Turkey and Rocky Creeks still see an increase from current 
conditions, though not quite as large. Turkey and Rocky Creeks would 
decrease slightly from the current situation (see table 3, below). 
Saltwater inundation in the long term would cause the Rocky, Turkey, 
and Swift stream systems to split into three streams each. While Rocky 
and Turkey Creeks would see about 5 percent of their populations cut 
off from the main segment, the inundation of Swift Creek in the long 
term, given ideal restoration and management, would split the 
population such that about 15 percent would be cut off into a Shaw 
Still Branch population, and about 11 percent would be cut off into a 
Sanders Branch population.

                         Table 3--Scenario 2 of Management for Okaloosa Darter Recovery
     [Total stream lengths in meters (m) that would be unimpounded, the occupied meters and the percent that
  represents, abundance estimates per meter, and the projected population size in both the short term and long
    term. Saltwater inundation in the long term causes the Swift stream systems to split into three streams.]
----------------------------------------------------------------------------------------------------------------
                                                       Total
                                                    unimpounded    Occupied (m)     Abundance/m     Population
                                                    streams (m)                                        size
----------------------------------------------------------------------------------------------------------------
                                                   Short Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          18,510          18,247             2.7          49,397
Turkey..........................................         152,692         150,525             3.9         585,687
Mill............................................           4,555           4,490             1.9           8,520
Swift...........................................          24,510          24,162             5.4         129,717
Deer Moss.......................................           8,396           8,277             0.7           5,746
Rocky...........................................         282,731         278,719             3.0         842,921
----------------------------------------------------------------------------------------------------------------
                                                    Long Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          17,685          15,666             2.4          37,153
Turkey..........................................         151,715         134,390             3.6         482,352
Mill............................................           4,555           4,035             1.7           6,968
Swift...........................................          22,913          14,816             4.4          65,852
                                                  ..............           3,146             4.4          13,982
                                                  ..............           2,334             4.4          10,374
Deer Moss.......................................           7,981           7,070             0.6           3,894
Rocky...........................................         280,759         248,699             2.8         694,169
----------------------------------------------------------------------------------------------------------------

Scenario 3: Poor Management

    To model what the future effect of poor management decisions, 
developments, or other habitat impacts would be in terms of a decrease 
in average Okaloosa darter abundance per meter, we considered the 
configuration (or geography) of each stream system for each population. 
In streams that are complex (have many branching tributaries) or are 
generally large, a severe negative impact (such as a chemical spill or 
source of chronic sedimentation) at any of the headwaters would be more 
likely to impact a smaller percentage of the population compared to a 
similar impact in the headwaters of a low-complexity (few tributaries) 
or small stream system. For scenarios 3 and 4, we first assessed the 
effects of an impact that might occur at the worst possible placement 
within each watershed by finding the longest length of stream that 
could be affected by a major impact at the headwaters; in other words, 
the longest possible downstream distance that could be affected by a 
single upstream impact. We calculated this distance for each stream 
(USFWS 2019, figure 14) and then took that distance and calculated the 
percent of the total unimpounded streams it would affect (USFWS 2019, 
table 7). This percent represents the maximum percent of the stream 
system that could be affected by one management decision or 
development. In real-world terms, if one of the outlying airfields that 
are located in the upper reaches of these stream systems (USFWS 2019, 
figure 14) were to be reactivated for military or other uses, the 
amount of stream impacted could come close to or meet these estimates 
of ``largest percent affected.''
    For both the ``poor'' and ``worst'' management scenarios, we used 
this ``largest percent affected'' to model declines in Okaloosa darter 
abundances based on whether management was considered ``poor'' or 
``worst,'' and whether we were assessing the scenario in the long or 
short term (USFWS 2019, table 8).
    For management that was ``poor,'' looking at the short term, we 
considered a management decision or set of decisions or impacts that 
would decrease the average abundance by 1.0 standard deviation across 
this ``largest percent affected'' (this percent of the occupied 
meters). The remainder of the occupied stream length stayed at current 
Okaloosa darter abundances. In the long term, we proposed that 
management impacts could continue to affect these streams either in 
unfortunate locations or in great magnitude and, coupled with

[[Page 41849]]

unknown impacts of climate change and the associated warming over that 
time span, will decrease all abundance estimates an additional 0.5 
standard deviation (USFWS 2019, table 8). As with the ``status quo'' 
scenario, we modeled poor management coupled with either no restoration 
efforts or removal of beaver dams on Toms Creek and restoration of 
College Pond on Swift Creek.
    Under this scenario (see table 4, below), all population sizes 
decreased. In the long term, the Swift population dropped below 10,000 
individuals unless College Pond is restored, in which case the 
population almost doubled in the short term and still maintained 15 
percent more than current in the long term. In the long term, the Swift 
Creek population dropped below 10,000 individuals without restoration, 
and the populations in both Deer Moss and Mill Creeks dropped below 
1,000 individuals. Even so, long-term resiliency in Toms, Turkey, 
Swift, and Rocky Creeks remained relatively unchanged from the ``status 
quo'' models.

                         Table 4--Scenario 3 of Management for Okaloosa Darter Recovery
     [Total stream lengths in meters (m) that would be unimpounded, the occupied meters and the percent that
 represents, abundance estimates per meter, and the projected population size, both with and without restoration
                    efforts on Toms and Swift Creeks, in both the short term and long term.]
----------------------------------------------------------------------------------------------------------------
                                                       Total
                                                    unimpounded    Occupied (m)   Avg. abundance/   Population
                                                    streams (m)                          m             size
----------------------------------------------------------------------------------------------------------------
                                                   Short Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,936          11,300             1.8          20,333
Turkey..........................................         150,040         147,911             3.2         474,298
Mill............................................           1,993             846             1.3           1,057
Swift...........................................          21,130           5,292             3.1          16,321
Deer Moss.......................................           8,396           5,780             0.2           1,075
Rocky...........................................         282,068         276,683             2.5         692,277
Toms (r)........................................          16,336          12,360             1.8          21,913
Swift (r).......................................          22,276          14,767             2.8          41,688
----------------------------------------------------------------------------------------------------------------
                                                    Long Term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,111           9,265             1.5          13,563
Turkey..........................................         149,063         132,041             2.9         383,564
Mill............................................           1,993             647             1.1             698
Swift...........................................          19,533           2,939             2.2           6,348
Deer Moss.......................................           7,981           4,696             0.1             284
Rocky...........................................         280,096         246,739             2.3         559,848
Toms (r)........................................          15,511          10,184             1.4          14,640
Swift (r).......................................          20,679          13,290             1.9          25,238
----------------------------------------------------------------------------------------------------------------

Scenario 4: Worst Management

    This scenario is very pessimistic. We considered a management 
decision or set of decisions or impacts that would decrease the average 
abundance by 2.0 standard deviations across the ``largest percent 
affected,'' described above. The remainder of the occupied stream 
length in Scenario 4 was then considered to be occupied at the ``poor'' 
Okaloosa darter abundances (a reduction of 1.0 standard deviation). As 
with other scenarios, we modeled climate change impacts as an 
additional reduction of 0.5 standard deviations from the long-term mean 
and considered the impact of restoration in Toms and Swift Creeks in a 
separate model.
    This is the only scenario where we modelled an extirpation. All 
populations were reduced by at least 20 percent, even in the short term 
(see table 5, below). Under this scenario, Mill and Deer Moss Creeks 
dropped below 1,000 individuals in the short term, and Deer Moss Creek 
became extirpated in the long term. We estimated a population decline 
in Toms Creek to approximately half the population estimate of the 
``status quo'' scenario. Our model projected that Swift Creek could 
drop to approximately one quarter of the population anticipated under 
the ``status quo''; however, the restoration of College Pond would 
prevent this population from dropping below 10,000 individuals in the 
short term and more than quadruple the population estimate in the long 
term. The Turkey and Rocky Creeks' populations would maintain high 
resiliency, above 300,000 individuals, even in the long term.

[[Page 41850]]



                      Table 5--Scenario 4 of Worst Management for Okaloosa Darter Recovery
     [Total stream lengths in meters (m) that would be unimpounded, the occupied meters and the percent that
 represents, abundance estimates per meter, and the projected population size, both with and without restoration
                    efforts on Toms and Swift Creeks, in both the short term and long term.]
----------------------------------------------------------------------------------------------------------------
                                                       Total
                                                    unimpounded    Occupied (m)   Avg. abundance/   Population
                                                    streams (m)                          m             size
----------------------------------------------------------------------------------------------------------------
                                                   Short term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,936          11,300             1.1          12,752
Turkey..........................................         150,040         147,911             2.6         385,027
Mill............................................           1,993             846             0.9             769
Swift...........................................          21,130           5,292             1.3           6,760
Deer Moss.......................................           8,396           5,780             0.0             159
Rocky...........................................         282,068         276,683             2.0         563,304
Toms (r)........................................          16,336          12,360             1.1          13,622
Swift (r).......................................          22,276          14,767             1.0          15,377
----------------------------------------------------------------------------------------------------------------
                                                    Long term
----------------------------------------------------------------------------------------------------------------
Toms............................................          14,111           9,265             0.8           7,348
Turkey..........................................         149,063         132,041             2.3         303,870
Mill............................................           1,993             647             0.7             478
Swift...........................................          19,533           2,939             0.6           1,680
Deer Moss.......................................           7,981           4,696             0.0               0
Rocky...........................................         280,096         246,739             1.8         444,833
Toms (r)........................................          15,511          11,736             0.8           8,998
Swift (r).......................................          20,679          13,290             0.5           6,192
----------------------------------------------------------------------------------------------------------------

Future Resiliency

    Our projections of how resiliency will change in the future are 
based on the completion or success of specific restoration efforts, 
nonspecific changes to the management of Okaloosa darter streams or 
other unforeseen impacts, and the effects of climate change, including 
unknown effects to the streams from temperature increases, drought, 
frequent or heavy rainfalls, or invasive species. Our models showed 
population increases only under ``ideal restoration, good management,'' 
with the exception of restoration efforts on Swift Creek, which 
increase the population even under the ``poor'' management scenario. We 
also took a pessimistic approach to climate change impacts by applying 
population reductions to all populations in the long-term models. 
Accordingly, population numbers declined in the long-term models across 
all stream systems in the absence of future management efforts. Both 
Mill Creek and Deer Moss Creek remained at low resiliency and decreased 
to fewer than 1,000 individuals or became extirpated in the long term 
under the ``poor'' and ``worst'' scenarios. Toms Creek maintained a 
moderate resiliency in all but the ``worst'' scenario. Swift Creek 
would see a huge benefit from the removal of beaver impoundments in 
College Pond, which even under ``poor'' management conditions, would 
almost double its population size in the short term. In the long term, 
restoring College Pond resulted in the most robust population gains, 
roughly quadrupling population estimates under ``poor'' and ``worst'' 
scenarios. Even under the worst projected management or impact 
scenario, the estimated sizes of Rocky and Turkey populations did not 
drop below 300,000, and resiliency in these populations remained 
exceptionally high.
    In general, in our scenarios, the larger populations were more 
resilient and more likely than small populations to maintain resiliency 
in the future. The Deer Moss population is considered to have a low 
resiliency in comparison to the other populations; however, even under 
ideal conditions, our models suggested that this population can 
increase to only about 4,000 individuals, which remains below our 
designation of moderate resiliency. So, even under ``ideal'' 
conditions, this population will always have low resiliency. 
Regardless, the Deer Moss Creek population has persisted over time, 
even with a much lower resiliency than the other populations. When 
comparing model outcomes to the most likely future scenario, ``status 
quo,'' we do not see shifts in resiliency categorization for any of the 
populations. Only under the ``worst'' scenario were the resiliency for 
Toms and Swift Creeks depressed, indicating that the two large 
populations, Turkey and Rocky, should maintain high to very high 
resiliency in perpetuity. From a population standpoint, a reduction of 
2.5 standard deviations from the long-term mean is massive and highly 
unlikely, indicating the ``worst'' scenario is a depiction of a truly 
catastrophic decline. Even under this scenario, five of the six 
populations remain. At the species level, Okaloosa darter exhibits 
moderate to high resiliency even under the worst-case scenario.

Future Redundancy

    Determined by the number of populations, their resiliency, and 
their distribution (and connectivity), redundancy describes the 
probability the species has a margin of safety to withstand or recover 
from catastrophic events (such as a rare destructive natural event or 
episode involving many populations). The Okaloosa darter has a 
constrained range, limited to just six populations in six streams, and 
redundancy is naturally low. However, the Okaloosa darter inhabits its 
historical range almost completely, exhibiting documented resiliency to 
natural phenomena such as hurricanes and drought (USFWS 2019, p. 23).
    Four of the populations, the ones with the lowest current 
resiliency, are considered highly vulnerable to catastrophic events due 
to their stream configuration. We determined the ``largest percent 
affected'' in Mill Creek to be 90 percent (USFWS 2019, table 7).

[[Page 41851]]

Thus, a major impact like a toxic chemical spill in the upper watershed 
could result in drastic population declines. Further, climate change 
could have consequences that make the streams uninhabitable to Okaloosa 
darter; temperature rise is one potential threat, but other impacts are 
possible. Invasive species could also extirpate an entire population 
were a highly competitive predator to be introduced; tilapia, for 
instance, are highly invasive and are well documented to cause local 
extinctions of native species through resource competition, predation, 
and habitat alteration (Canonico et al. 2005, pp. 467-474; Zambrano et 
al. 2006, pp. 1906-1909). Given the species' limited range, 
catastrophic events, the invasion of a nonnative species, or steady 
changes such as increased stream temperatures due to climate change 
could impact one or more populations. Even so, our modeling resulted in 
only one population completely failing in the long term under our 
``worst'' management scenario, and that scenario assumed drastic 
declines across all six populations. Thus, loss of redundancy is 
unlikely in all but the most extreme circumstances. Accordingly, we do 
not expect the Okaloosa darter's viability to be characterized by a 
loss in redundancy unless management fails dramatically in the coming 
years, or a major impact occurs.

Future Representation

    All representative units are predicted to retain the same number of 
populations at least 50 years into the future, except in the scenario 
where management is particularly bad (``worst'' scenario). In the 
``worst'' scenario, the Deer Moss population becomes extirpated, and 
the Mill population experiences heavy declines. In both the ``poor'' 
and ``worst'' scenarios, each representative unit will have populations 
with decreased resiliency, both within the next 20 years (short term) 
and next 50 years (long term); however, even under the ``worst'' 
scenario, the two large populations (Turkey Creek and Rocky Creek) will 
maintain resiliency. The Toms Creek population, being the only 
population in its representative unit, will see decreased resiliency in 
the short term in two (``poor'' and ``worst'') of the scenarios, and in 
the long term in three scenarios (all except ``ideal restoration, good 
management'').

Determination of Species Status

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species meets the definition of an endangered species or a 
threatened species. The Act defines an ``endangered species'' as a 
species that is in danger of extinction throughout all or a significant 
portion of its range, and a ``threatened species'' as a species that is 
likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range. For a more 
detailed discussion on the factors considered when determining whether 
a species meets the Act's definition of an endangered species or a 
threatened species and our analysis on how we determine the foreseeable 
future in making these decisions, please see Regulatory and Analytical 
Framework, above.

Status Throughout All of Its Range

    The Okaloosa darter is a narrow endemic, occurring in six stream 
systems in Walton and Okaloosa Counties, Florida. Okaloosa darters 
currently occur within all six historical watersheds. Populations in 
two of those watersheds are currently highly resilient, two are 
moderately resilient, and two have low resiliency. While the 
populations have been affected by impoundments, urbanization (on the 
lower ends of the streams), and land use impacts (e.g., sedimentation), 
current population estimates show approximately more than 500,000 
darters across the species' range. Redundancy is demonstrated through 
the darter's presence in multiple tributaries within most watersheds, 
and representation is demonstrated through the genetic structure of the 
populations. All six extant populations exhibit genetic 
differentiation, and the species is extant across all three 
representative units. Overall, the populations are robust. Because 
approximately 90 percent of the species' range is under the management 
of Eglin AFB, urbanization will have little to no future effect. The 
Okaloosa darter occurs in multiple stream systems, which provides 
redundancy, and no long-term threats are presently impacting the 
Okaloosa darter at the species level. Accordingly, we conclude that the 
species is not currently in danger of extinction, and thus does not 
meet the Act's definition of an endangered species, throughout its 
range.
    In considering whether the species continues to meet the Act's 
definition of a threatened species (likely to become an endangered 
species within the foreseeable future) throughout its range, we 
identified the foreseeable future for the Okaloosa darter to be 20 to 
50 years based on our ability to reliably determine that the threats 
are likely and predict the species' response to current and future 
threats. Over 90 percent of the darter's range is located on Eglin AFB 
and will continue to benefit from the conservation protections 
resulting from the Eglin AFB INRMP. Overall, while there may be some 
loss of resiliency due to climate change, in all but the worst-case 
scenario, all extant populations will remain. Redundancy will remain 
the same except under the worst-case scenario, as will representation. 
Under all four management scenarios, two darter populations (Turkey 
Creek and Rocky Creek) are expected to continue to be highly resilient. 
Toms Creek will continue to be moderately resilient in all but the 
worst-case scenario, in which case its resilience will fall to low. The 
currently uninhabited tributaries in the Swift Creek watershed will 
continue to be isolated due to sea level rise, and without restoration, 
Swift Creek itself will be the only occupied tributary in this 
population; however, the upper Swift Creek population will continue to 
serve as a source for recolonization if restoration occurs. Deer Moss 
Creek is the only population with potential for extirpation, and then 
only under the worst-case scenario. Further, this population exhibits 
low resiliency even under ``ideal'' conditions, and its extirpation 
would not compromise the resiliency of the Rocky Creek representative 
unit. In other words, while some populations may decline or even become 
extirpated under the two negative scenarios, under all scenarios the 
Okaloosa darter will exhibit sufficient resiliency, redundancy, and 
representation to maintain viability for the foreseeable future. 
Accordingly, we conclude that the species is not likely to become in 
danger of extinction in the foreseeable future throughout all of its 
range.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. Having determined that the Okaloosa darter is not in danger 
of extinction or likely to become so throughout all of its range in the 
foreseeable future, we proceed to evaluating whether it may be in 
danger of extinction or likely to become so in the foreseeable future 
in a significant portion of its range--that is, whether there is any 
portion of the species' range for which it is true that both (1) the 
portion is significant; and (2) the species is in danger of extinction 
now or likely

[[Page 41852]]

to become so in the foreseeable future in that portion. Depending on 
the case, it might be more efficient for us to address the 
``significance'' question or the ``status'' question first. We can 
choose to address either question first. Regardless of which question 
we address first, if we reach a negative answer with respect to the 
first question that we address, we do not need to evaluate the other 
question for that portion of the species' range.
    In undertaking this analysis for the Okaloosa darter, we chose to 
address the status question first--we considered information pertaining 
to the geographic distribution of both the species and the threats that 
the species faces, to identify any portions of the range where the 
species is endangered or threatened. We examined whether any threats 
are geographically concentrated in any portion of the species' range at 
a biologically meaningful scale. It is important to note at the outset 
that this is a narrow endemic with a naturally limited range. We 
examined the following threats: urbanization, land use and management 
practices on Eglin AFB, and sea level rise around the southern reaches 
of watersheds.
    Urbanization is the greatest threat to the Okaloosa darter, as 
development leads, through multiple pathways, to pollution, erosion, 
sedimentation, altered water flows, and dispersal barriers. However, 
because over 90 percent of the range of the Okaloosa darter will 
continue to be managed under the Eglin AFB INRMP, we expect management 
to improve overall conditions for the species across its range. Because 
populations of the Okaloosa darter within Eglin AFB will continue to 
benefit from the conservation protections, where urbanization is not 
considered to be a current or future threat, our analysis focuses on 
southern portions of watersheds outside of Eglin AFB as a portion of 
the range that may have a different status. This portion overlaps with 
three populations of Okaloosa darter: Swift, Deer Moss, and Mill 
Creeks. Of these, Swift Creek rangewide currently has moderate 
resiliency with increasing population size now and into the future in 
all scenarios. Both Deer Moss and Mill Creeks rangewide are considered 
to have low resiliency with decreasing population size now, with the 
potential for extirpation in the future without proper management. 
Because of the current and projected future status of the Deer Moss and 
Mill Creeks populations, and because sea level rise will only affect 
the populations of Okaloosa darter within this portion, our analysis 
indicates that the status of this portion of the range (i.e., southern 
portions of watersheds outside of Eglin AFB) may be different than the 
overall range.
    We then proceeded to consider whether this portion of the range 
(Deer Moss and Mill Creeks) is significant. The Service's most recent 
definition of ``significant'' within agency policy guidance has been 
invalidated by court order (see Desert Survivors v. U.S. Department of 
the Interior, 321 F. Supp. 3d 1011, 1070-74 (N.D. Cal. 2018)). In 
undertaking this analysis for the Okaloosa darter, we considered 
whether the Deer Moss and Mill Creeks portion of the species' range may 
be significant based on its biological importance to the overall 
viability of the Okaloosa darter. Therefore, for the purposes of this 
analysis, when considering whether this portion is significant, we 
considered whether the portion may (1) occur in a unique habitat or 
ecoregion for the species; (2) contain high-quality or high-value 
habitat relative to the remaining portions of the range, for the 
species' continued viability in light of the existing threats; (3) 
contain habitat that is essential to a specific life-history function 
for the species and that is not found in the other portions (for 
example, the principal breeding ground for the species); or (4) contain 
a large geographic portion of the suitable habitat relative to the 
remaining portions of the range for the species.
    This portion (Deer Moss and Mill Creeks' populations) represents a 
small portion (approximately 2 and 1 percent, respectively) of the 
Okaloosa darter's range. Although these populations contribute to the 
rangewide representation and redundancy of the darter, this portion 
does not constitute a large geographic area relative to the range as a 
whole. Additionally, this portion does not contribute high-quality 
habitat or constitute high-value habitat (e.g., refugia) for the 
Okaloosa darter. In addition, this portion does not constitute an area 
of habitat that is essential to a specific life-history function for 
the species that is not found in the remainder of the range.
    Overall, we found no substantial information that would indicate 
this portion of the Okaloosa darter's range is significant in terms of 
the above habitat considerations. As a result, we determined that this 
portion does not represent a significant portion of the Okaloosa 
darter's range. Therefore, we conclude that the species is not in 
danger of extinction now or likely to become so in any significant 
portion of its range in the foreseeable future. This finding does not 
conflict with the courts' holdings in Desert Survivors v. U.S. 
Department of the Interior, 321 F. Supp. 3d 1011, 1070-74 (N.D. Cal. 
2018) and Center for Biological Diversity v. Jewell, 248 F. Supp. 3d 
946, 959 (D. Ariz. 2017) because, in reaching these conclusions, we did 
not need to consider whether any portions are significant and therefore 
did not apply the definition of ``significant'' in the Final Policy on 
Interpretation of the Phrase ``Significant Portion of its Range'' in 
the Endangered Species Act's Definitions of ``Endangered Species'' and 
``Threatened Species'' (79 FR 37578; July 1, 2014) that those court 
decisions held was invalid.

Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the Okaloosa darter does not meet the 
definition of an endangered species or a threatened species in 
accordance with sections 3(6) and 3(20) of the Act. Therefore, we are 
delisting (removing) the Okaloosa darter from the Federal List of 
Endangered and Threatened Wildlife.

Effects of This Rule

    This final rule will revise 50 CFR 17.11(h) and 17.44(bb) by 
removing the Okaloosa darter from the Federal List of Endangered and 
Threatened Wildlife and removing the section 4(d) rule for this 
species. The prohibitions and conservation measures provided by the Act 
will no longer apply to this species. Federal agencies will no longer 
be required to consult with the Service under section 7 of the Act in 
the event that activities they authorize, fund, or carry out may affect 
the Okaloosa darter. However, approximately 90 percent of the 457-
square-kilometer (176-square-mile) watershed drainage area that 
historically supported the Okaloosa darter is Federal property under 
the management of Eglin AFB, and about 98.7 percent of the stream 
length in the current range of the Okaloosa darter is within the 
boundaries of Eglin AFB.
    As discussed above, Eglin AFB encompasses the headwaters of all six 
of these drainages. Benefits from conservation protections will 
continue because the Air Force will maintain its INRMP for the benefit 
of other listed species, such as the red-cockaded woodpecker (USAF 
2022c, p. 3-1). Thus, the INRMP will continue to provide for the 
conservation of the Okaloosa darter even if the species is delisted. 
Because the Service is required to approve INRMPs every 5 years, we 
will be able to ensure that this INRMP continues to protect the habitat 
and resources required by the Okaloosa darter into the future. There is 
no critical habitat designated for this

[[Page 41853]]

species, so this rule has no effect on 50 CFR 17.95.

Post-Delisting Monitoring

    Section 4(g)(1) of the Act requires us, in cooperation with the 
States, to implement a monitoring program for not less than 5 years for 
all species that have been delisted due to recovery. Post-delisting 
monitoring (PDM) refers to activities undertaken to verify that a 
species delisted remains secure from the risk of extinction after the 
protections of the Act no longer apply. The primary goal of PDM is to 
ensure that the species' status does not deteriorate, and that if a 
decline is detected, measures are taken to halt the decline so as to 
avoid the need for us to propose listing of the species again. If at 
any time during the monitoring period data indicate that protective 
status under the Act should be reinstated, we can initiate listing 
procedures, including, if appropriate, emergency listing.
    Section 4(g) of the Act explicitly requires that we cooperate with 
the States in development and implementation of PDM programs. However, 
we remain ultimately responsible for compliance with section 4(g) and, 
therefore, must remain actively engaged in all phases of PDM. We also 
seek active participation of other entities that are expected to assume 
responsibilities for the species' conservation after delisting.
    We will coordinate with other Federal agencies, State resource 
agencies, interested scientific organizations, and others as 
appropriate to implement an effective PDM plan for the Okaloosa darter. 
The PDM plan was developed based upon current research and effective 
management practices that have improved the status of the species since 
listing. Ensuring continued implementation of proven management 
strategies that have been developed to sustain the species is a 
fundamental goal for the PDM plan. The PDM plan has identified 
measurable management thresholds and responses for detecting and 
reacting to significant changes in Okaloosa darter's numbers, 
distribution, and persistence. If declines are detected equaling or 
exceeding these thresholds, the Service, in combination with other PDM 
participants, will investigate causes of the declines. The 
investigation will be to determine if the Okaloosa darter warrants 
expanded monitoring or additional protection under the Act.
    We are delisting the Okaloosa darter based on all six extant 
populations exhibiting genetic differentiation and the species being 
extant across all three representation units. Overall, the populations 
are robust. Because approximately 90 percent of the species' range is 
under the management of Eglin AFB, urbanization will have little to no 
future effect. The Okaloosa darter occurs in multiple stream systems, 
and no long-term threats are presently impacting the Okaloosa darter at 
the species level. Since delisting is, in part, due to conservation 
actions taken by stakeholders, we have developed a PDM plan for the 
Okaloosa darter. The PDM plan discusses the current status of the taxon 
and describes the methods that will be implemented for monitoring 
following delisting. The PDM plan: (1) Summarizes the status of the 
Okaloosa darter at the time of delisting; (2) describes frequency and 
duration of monitoring; (3) discusses monitoring methods and sampling 
regimes; (4) defines what potential triggers will be evaluated to 
address the need for additional monitoring; (5) outlines reporting 
requirements and procedures; (6) defines a schedule for implementing 
the PDM plan; and (7) defines responsibilities. It is our intent to 
work with our partners towards maintaining the recovered status of the 
Okaloosa darter.
    The Service prepared this PDM plan in coordination with Eglin AFB, 
based largely on monitoring methods developed by the U.S. Geological 
Survey and Loyola University New Orleans (USFWS 2021, p. 5). The 
Service designed the PDM plan to detect substantial changes in habitat 
occupied by the Okaloosa darter and declines in Okaloosa darter 
occurrences with reasonable certainty and precision. It meets the 
minimum requirement set forth by the Act because it will monitor the 
status of the Okaloosa darter using a structured sampling regime over a 
10-year period.
    The final PDM plan for the Okaloosa darter can be accessed at 
https://www.regulations.gov under Docket No. FWS-R4-ES-2021-0036, and 
through the Service's Environmental Conservation Online System at 
https://ecos.fws.gov/ecp/species/E00H.

Required Determinations

National Environmental Policy Act

    We have determined that we do not need to prepare an environmental 
assessment or environmental impact statement, as defined in the 
National Environmental Policy Act (42 U.S.C. 4321 et seq.), in 
connection with regulations adopted pursuant to section 4(a) of the 
Endangered Species Act. We published a notice outlining our reasons for 
this determination in the Federal Register on October 25, 1983 (48 FR 
49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretary's Order 3207 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. There are no Tribes or Tribal lands 
affected by this final rule.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov under Docket No. FWS-R4-
ES-2021-0036 and upon request from the Field Supervisor, Florida 
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).

Authors

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

List of Subjects in 50 CFR Part 17

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

Regulation Promulgation

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

[[Page 41854]]

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.


Sec.  17.11  [Amended]

0
2. In Sec.  17.11, amend paragraph (h) by removing the entry for 
``Darter, Okaloosa'' under FISHES from the List of Endangered and 
Threatened Wildlife.


Sec.  17.44  [Amended]

0
3. Amend Sec.  17.44 by removing and reserving paragraph (bb).

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-12982 Filed 6-27-23; 8:45 am]
BILLING CODE 4333-15-P