Endangered and Threatened Wildlife and Plants; Removal of the Nashville Crayfish From the Federal List of Endangered and Threatened Wildlife, 65098-65112 [2019-25548]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 84, Number 228 (Tuesday, November 26, 2019)]
[Proposed Rules]
[Pages 65098-65112]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-25548]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2018-0062; FXES11130900000-189-FF0932000]
RIN 1018-BD02


Endangered and Threatened Wildlife and Plants; Removal of the 
Nashville Crayfish From the Federal List of Endangered and Threatened 
Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
remove the Nashville crayfish (Orconectes shoupi), a relatively large 
crayfish native to the Mill Creek watershed in Davidson and Williamson 
Counties, Tennessee, from the Federal List of Endangered and Threatened 
Wildlife (List). This determination is based on the best available 
scientific and commercial data, which indicate that the threats to the 
species have been eliminated or reduced to the point that the species 
has recovered and no longer meets the definition of an endangered or a 
threatened species under the Endangered Species Act of 1973, as amended 
(Act). We also announce the availability of a draft post-delisting 
monitoring (PDM) plan for the Nashville crayfish. We seek information, 
data, and comments from the public regarding this proposal to remove 
the Nashville crayfish from the List (i.e., ``delist'' the species) and 
regarding the draft PDM plan.

DATES: We will accept comments received or postmarked on or before 
January 27, 2020. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for 
public hearings, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by January 10, 2020.

ADDRESSES: Written comments: You may submit comments on this proposed 
rule by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter FWS-R4-ES-2018-0062, 
which is the docket number for this rulemaking. Then, click on the 
Search button. On the resulting page, in the Search panel on the left 
side of the screen, under the Document Type heading, click on the 
Proposed Rule box to locate this document. You may submit a comment by 
clicking on ``Comment Now!''
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R4-ES-2018-0062; U.S. Fish and Wildlife 
Service, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Information Requested, below, for more information).
    Document availability: This proposed rule, the draft PDM plan, and 
supporting documents (including the species status assessment (SSA) 
report, references cited, and the 5-year review) are available at 
https://www.regulations.gov under Docket No. FWS-R4-ES-2018-0062.

FOR FURTHER INFORMATION CONTACT: Lee Andrews, Field Supervisor, U.S. 
Fish and Wildlife Service, Tennessee Ecological Services Field Office, 
446 Neal Street, Cookeville, TN 38506; telephone 931-528-6481. Persons 
who use a telecommunications device for the deaf (TDD) may call the 
Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Information Requested

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments and information from other concerned governmental agencies, 
Native American tribes, the scientific community, industry, or any 
other interested party concerning this proposed rule. Because we will 
consider all comments and information we receive during the comment 
period, our final determination may differ from this proposal. We 
particularly seek comments on:
    (1) Information concerning the biology and ecology of the Nashville 
crayfish;
    (2) Relevant data concerning any threats (or lack thereof) to the 
Nashville crayfish, particularly any data on the possible effects of 
climate change as it relates to habitat, and the extent of State 
protection and management that would be provided to this crayfish as a 
delisted species;
    (3) Current or planned activities within the geographic range of 
the Nashville crayfish that may negatively impact or benefit the 
species; and
    (4) The draft PDM plan and the methods and approach detailed in it.
    Please include sufficient information (such as scientific journal 
articles or other publications) to allow us to verify any scientific or 
commercial information you include. All comments submitted 
electronically via https://www.regulations.gov will be presented on the 
website in their entirety as submitted. For comments submitted via hard 
copy, we will post your entire comment--including your personal 
identifying information--on https://www.regulations.gov. You may request 
at the top of your document that we withhold personal information such 
as your street address, phone number, or email address from public 
review; however, we cannot guarantee that we will be able to do so.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Tennessee Ecological Services Field Office (see FOR 
FURTHER INFORMATION CONTACT).
    Please note that submissions merely stating support for or 
opposition to the listing action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act (16 U.S.C. 
1531 et seq.) directs that determinations as to whether any species is 
an endangered or a threatened species must be made ``solely on the 
basis of the best scientific and commercial data available.''

Public Hearing

    Section 4(b)(5)(E) of the Act provides for a public hearing on this 
proposal, if

[[Page 65099]]

requested. Requests must be received within 45 days after the date of 
publication of this proposed rule in the Federal Register (see DATES). 
Such requests must be sent to the address shown in FOR FURTHER 
INFORMATION CONTACT. We will schedule a public hearing on this 
proposal, if requested, and announce the date, time, and place of the 
hearing, as well as how to obtain reasonable accommodations, in the 
Federal Register at least 15 days before the hearing.

Previous Federal Actions

    On September 26, 1986, we published a final rule in the Federal 
Register (51 FR 34410) listing the Nashville crayfish as endangered due 
to siltation, stream alterations, and water quality deterioration 
resulting from urban development pressures. On February 8, 1989, we 
released a recovery plan for the Nashville crayfish (USFWS 1989, 
entire). The latest 5-year review for the species, completed in 
February 2017, recommended reclassifying the Nashville crayfish to a 
threatened species due to recovery (USFWS 2017a, entire). Based on this 
recommendation, a species status assessment (SSA) was initiated and 
completed. Six peer reviewers were requested to review the SSA and 
provide feedback. Reviewers were selected based on their knowledge of 
the species' biology and habitat. Two peer reviewers submitted 
feedback. One of the commenters informed us that Nashville crayfish 
have been observed to be active on the surface diurnally during certain 
times of the year and suggested we add otters as predators to the 
crayfish. Another commenter asked about the conservation work being 
done by two Tennessee agencies. This information was incorporated into 
the final SSA and this proposed rule.

Background

    A thorough review of the taxonomy, life history, ecology, and 
overall viability of the Nashville crayfish is presented in the SSA 
report (USFWS 2017b; available at https://www.fws.gov/southeast/ and at 
https://www.regulations.gov under Docket No. FWS-R4-ES-2018-0062).
    The Nashville crayfish is endemic to the Mill Creek watershed south 
of Nashville in Davidson and Williamson Counties, Tennessee. The 
species is currently known to occur in Mill Creek and its tributaries, 
including Collins Creek, Owl Creek, Edmonson Branch, Sims Branch, 
Sevenmile Creek, Sorghum Branch, Whittemore Branch, Turkey Creek, 
Indian Creek, Holt Creek, four unnamed tributaries to Mill Creek, and 
one unnamed tributary to Owl Creek (USFWS 2017b, p. 5). There has been 
no change in the distribution of the species within its historical 
range (USFWS 2016, unpublished data).
    Biologists conducting the pre-listing status survey for the species 
surveyed 148 streams in the following central Tennessee drainages 
(Korgi and O'Bara 1985, entire): Collins River, Stones River, Caney 
Fork River, Cumberland River, Red River, Mill Creek, Harpeth River, and 
Elk River. Nashville crayfish were only found in Mill Creek and its 
tributaries.
    Nonetheless, at the time of listing in 1986, the species was 
thought to have occurred historically in several locations outside of 
the Mill Creek watershed, including Big Creek in Giles County (Elk 
River drainage), the South Harpeth River in Davidson County (Harpeth 
River drainage), and Richland Creek in Davidson County (Cumberland 
River drainage) (USFWS 1987, entire). The Service now believes that the 
Big Creek and South Harpeth River records are the result of accidental 
introduction by anglers using the species as bait and are no longer 
thought to be historical locations for the crayfish (USFWS 2017b, p. 
4). The Service originally believed that the Richland Creek occurrence 
had been displaced by a more competitive crayfish species (USFWS 2017b, 
p. 4). However, it was later determined that specimens of Nashville 
crayfish (Orconectes shoupi) collected from Richland Creek were 
misidentified, and the collections were subsequently correctly 
identified as the bigclaw crayfish (Orconectes placidus) (USFWS 1989, 
entire). In short, we now conclude that Mill Creek and its tributaries 
constitute both the historical and current ranges of the species.
    The Nashville crayfish is a relatively large crayfish ranging from 
young-of-the-year at about 0.6 centimeters (cm) (0.24 inches (in)) 
total length (TL) to adults at about 17.8 cm (7 in) (TDNA 2009, p. 11; 
O'Bara et al. 1985, entire). Other Orconectes species reported from the 
Mill Creek watershed, including O. rhoadesi and O. durelli, can easily 
be distinguished from the Nashville crayfish by gonopod (reproductive) 
structure and body coloration. However, even young-of-the-year crayfish 
from the Mill Creek watershed often can be identified as the Nashville 
crayfish, as no other saddle-bearing species are present in the system. 
The saddle-bearing features include elongate pincers with red tips and 
adjacent narrow black banding, a usually light-colored ``saddle'' on 
the carapace extending from the posterior to the anterior and 
terminating as lateral stripes on both sides, and distinctive gonopods 
markedly different from any of its congeners.
    The Nashville crayfish has been found in a wide range of 
environments, including gravel and cobble runs, pools with up to 10 cm 
(3.9 in) of settled sediment, and in small pools with intermittent flow 
(Stark 1986, 44 pp; Miller and Hartfield 1985, entire). The species has 
also been found in impoundments that include overflow pools and 
retention ponds adjacent to Mill Creek and its tributaries (Cook and 
Walton 2008, p. 121; Service 2011, entire). It is estimated that 
approximately 54 percent (104 stream miles) of the 192 stream miles of 
the Mill Creek watershed that have the potential to support Nashville 
crayfish is currently occupied by the species (USFWS 2017b, p. 30).
    Population estimates from surveys are limited to the mainstem of 
Mill Creek and Sevenmile Creek, although surveys in other streams have 
detected Nashville crayfish and indicate consistent presence over time 
(USFWS 2017, pp. 29-30, 35-40). Between 1999 and 2001, surveys 
conducted within the mainstem and Sevenmile Creek led to overall 
estimates of 1,854 to 3,217 individuals and 404 to 1,425 individuals 
per 100 linear meters, respectively. (USFWS 2017b, p. 29). Long-term 
monitoring, conducted between 2011 and 2015, has documented a total of 
1,763 crayfish per 100 linear meters at five main stem Mill Creek 
sampling sites. This long-term monitoring, conducted by the Nashville 
Zoo, found Nashville crayfish to be the predominant species, comprising 
more than 90 percent of all crayfish documented at all five sites 
surveyed. According to these surveys, the Nashville crayfish has 
remained stable throughout the Mill Creek watershed.

Summary of Biological Status and Threats

    The Act directs us to determine whether any species is an 
endangered or a threatened species because of any factors affecting its 
continued existence. The SSA report documents the results of our 
comprehensive biological status review for the Nashville crayfish, 
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 listed as an endangered or a threatened species under 
the Act. It does, however, provide the scientific basis for our 
regulatory decision, which involves the further application of 
standards within the Act and its implementing regulations and policies. 
The following is a summary of the key results and conclusions from the 
SSA

[[Page 65100]]

report; the full SSA report can be found on the Southeast Region 
website at https://www.fws.gov/southeast/ and at https://www.regulations.gov under Docket No. FWS-R4-ES-2018-0062.

Summary of SSA Report

    To assess the Nashville crayfish's viability, we used the three 
conservation biology principles of resiliency, representation, and 
redundancy (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency 
supports the ability of the species to withstand environmental and 
demographic stochasticity (for example, wet or dry, warm or cold 
years); representation supports the ability of the species to adapt 
over time to long-term changes in the environment (for example, climate 
changes); and redundancy supports the ability of the species to 
withstand catastrophic events (for example, droughts, hazardous 
spills). 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 divided into three sequential stages. During 
the first stage, we use the conservation biology principles of 
resiliency, redundancy, and representation (together, the 3Rs) to 
evaluate individual life-history needs. The next stage involves an 
assessment of the historical and current condition of species' 
demographics and habitat characteristics, including an explanation of 
how the species arrived at its current condition. The final stage of 
the SSA involves making predictions about the species' responses to 
positive and negative environmental and anthropogenic influences. This 
process uses the best available information to characterize viability 
as the ability of a species to sustain populations in the wild over 
time. We used this information to inform our decision in this proposed 
rule.

Species Needs

    For the Nashville crayfish to maintain viability, its populations 
or some portion thereof must be resilient. Stochastic factors that have 
the potential to affect Nashville crayfish include impacts to water 
quality, particularly phosphorus loading, sedimentation, and 
significant alterations to dissolved oxygen.
    Silt deposition in streams contributes to several of the 
impairments in the Mill Creek watershed, and can also be a risk factor 
for crayfish. Stream channelization and silt deposition has been 
reported to be directly responsible for the permanent loss of some 
crayfish populations (Reynolds et al. 2013, p. 197-218). As crayfish 
are primarily active at night, the chief requirement of all size 
classes is for hiding spaces during the daytime. Where loss of hiding 
spaces occurs through bank reconstruction or siltation from natural or 
human causes, the habitat's carrying capacity for crayfish diminishes 
(Reynolds et al. 2013, p. 197-218). Therefore, good quality habitat for 
Nashville crayfish has minimal silt deposition such that availability 
of vital hiding spaces, and thus carrying capacity, are maximized.
    Dissolved oxygen (DO) levels are an important water quality 
parameter for all aquatic life, including crayfish. Oxygen is dissolved 
into the water in streams through diffusion, aeration, and as the waste 
product of plants that are photosynthesizing. The amount of DO found in 
water can vary due to several factors including water temperature, 
level of pollutants and water velocity. Extended periods of 
supersaturation can occur in highly aerated waters, often near 
hydropower dams and waterfalls, or due to excessive photosynthetic 
activity. Algae blooms can cause air saturations of over 100% due to 
large amounts of oxygen as a photosynthetic byproduct. This is often 
coupled with higher water temperatures, which also affects saturation 
(Fondriest 2013, entire). High levels of DO may be stressful to 
crayfish because of physiological effects, such as gas bubble disease, 
or because higher oxygen levels allow invasion of invasive crayfish 
species, who better tolerate higher DO concentrations. If DO levels are 
very low, it is harder for individual crayfish to take in oxygen, and 
in extreme cases the lack of DO results in death. Although the 
tolerance level of Nashville crayfish for DO is not known, levels below 
2.0 mg/L typically result in invertebrates abandoning the area 
(Fondriest 2013, entire).
    Other factors that influence the resiliency of Nashville crayfish 
populations include population size and the presence of slab rock (TDNA 
2009, entire). Influencing those factors are elements of Nashville 
crayfish ecology (e.g., dispersal and reproductive success) that 
determine whether populations can grow to maximize habitat occupancy, 
thereby increasing resiliency of populations (USFWS 2017b, p. 22). Slab 
rock is defined as moderately to large sized rocks in the stream 
channel, typically limestone, found on top of bedrock, cobble, or 
gravel. Adult Nashville crayfish occur in various habitats in streams 
with slab rocks or other debris for cover. Adults tend to be solitary, 
seeking cover under large rocks, logs, debris, or rubble; the largest 
individuals generally selected the largest cover available (USFWS 1987, 
entire). Cover, particularly presence of large rocks, is also important 
to Nashville crayfish (Cook and Walton 2008, p. 121). Nashville 
crayfish were found half of the time in runs, using rocks with a 
surface area of 0.05 m\2\ (0.54 ft\2\) as cover, and half of the time 
in pools, when cover rock area increased to 0.10 m\2\ (1.1 ft\2\). 
Larger rock areas may be needed in pools to decrease risk of predation, 
whereas smaller rock areas would provide adequate protection in runs 
(Cook and Walton 2008, p. 121). Reproductive females are typically 
found under large slab rocks. Females seek out large slab rocks when 
they are carrying eggs and young, and these secluded places are also 
needed for molting. Cover rocks of at least 0.02 m\2\ (2.15 ft\2\) may 
be important habitats for females releasing broods and for protection 
during molting after releasing broods (USFWS 1987, entire). Gravel-
cobble substrate provided good cover for juveniles (Stark 1986, Miller 
and Hartfield 1985, entire).
    Representation can be measured by the breadth of genetic or 
environmental diversity within and among populations, and gauges the 
probability that a species is capable of adapting to environmental 
changes. In the absence of species-specific genetic and ecological 
diversity information, we evaluated representation based on the extent 
and variability of habitat characteristics across the geographical 
range of the species.
    For the Nashville crayfish to maintain viability, the species as a 
whole also needs to exhibit some degree of redundancy. We measured 
redundancy for Nashville crayfish in terms of the number and 
distribution of resilient populations across the range of the species. 
It is important to note that Nashville crayfish has a naturally limited 
range, so measures of redundancy reflect the distribution within a 
relatively small area.

Current Condition

Resiliency
    The Nashville crayfish is restricted to the Mill Creek watershed, 
which we now understand to represent the species' historical range. For 
this assessment, we measured resiliency at

[[Page 65101]]

the population segment level, but also reported resiliency in total 
stream miles across the species' range. Because resiliency is a 
population-level attribute, key to assessing it is the ability to 
delineate populations. Because there is insufficient information on 
dispersal and genetics to accurately delineate demographic populations 
for Nashville crayfish, we delineated population segments. These were 
delineated based on habitat quality (i.e., presence of slab rock and 
qualitative assessments of water quality) and species occurrence data 
from natural heritage data of the Tennessee Department of Environment 
and Conservation (TDEC) and opinions of species experts. We identified 
174 stream segments based on watershed features, stream 
characteristics, and expert opinion (USFWS 2017b, p. 19). This resulted 
in delineation of 10 population segments within 3 representative units: 
Upper Mill Creek, Middle Mill Creek, and Lower Mill Creek watershed 
catchments (Table 1; and Figure 1).

  Table 1--List of Delineated Population Segments of Nashville Crayfish
------------------------------------------------------------------------
                                   Middle Mill Creek   Lower Mill Creek
    Upper Mill Creek (MCW-A)            (MCW-B)             (MCW-C)
------------------------------------------------------------------------
Upper Mill Creek Streams........  Middle Mill Creek   Lower Mill Creek
                                   Streams.            Streams.
Upper Mill Creek and Tributaries  Owl Creek.........  Sevenmile Creek
                                                       and Tributaries.
Mainstem Mill Creek *...........  Holt Creek........  Mainstem Mill
                                                       Creek .*
                                  Indian Creek......
                                  Collins Creek.....
                                  Mainstem Mill
                                   Creek *.
------------------------------------------------------------------------
* Mainstem Mill Creek runs through all three watershed catchments.

[GRAPHIC] [TIFF OMITTED] TP26NO19.000

    Element Occurrence (EO; an area of land or water where a species is 
or was present) data were available through TDEC Natural Heritage Data 
shapefiles. These data represent survey detections for Nashville 
crayfish conducted since

[[Page 65102]]

1985, and each EO has an associated EO viability score. The EO 
viability scores provide a succinct assessment of the estimated 
viability of the species, or an estimation of the likelihood that, if 
current conditions prevail, a species occurrence will persist for a 
period of time. The EO viability scores for Nashville crayfish were 
delineated by Service biologists following NatureServe descriptions 
(Hammerson et al. 2008) as follows:
     Excellent--species occurrence exhibits optimal or at least 
exceptionally favorable characteristics with respect to population size 
and/or quantity and quality of occupied habitat, and if current 
conditions prevail, the occurrence is very likely to persist for the 
foreseeable future (i.e., at least 20-30 years).
     Good--species occurrence exhibits favorable 
characteristics with respect to population size and/or quantity and 
quality of occupied habitat, and if current conditions prevail, the 
occurrence is very likely to persist for the foreseeable future (i.e., 
at least 20-30 years).
     Fair--species occurrence characteristics (size, condition, 
and landscape context) are non-optimal such that occurrence persistence 
is uncertain under current conditions, but may persist for the 
foreseeable future with appropriate management or protection.
     Poor--If current conditions prevail, occurrence has a high 
risk of extirpation because of small population size or area of 
occupancy, deteriorated habitat, poor conditions for reproduction, or 
other factors.
    We looked at EO viability scores based on the element occurrence 
data, and elicited the opinions of Nashville crayfish experts as to how 
we should characterize resiliency of that population segment. The EO 
viability scores provided a succinct assessment of the estimated 
viability of the species, or an estimation of the likelihood that, if 
current conditions prevail, a species occurrence will persist for a 
period of time.
    The EO data, combined with other survey efforts and expert opinion 
resulted in the delineation of 174 stream segments. These stream 
segments were scaled up to the population segment scale based on 
watershed features such as physical hydrology and stream 
characteristics, and species expert opinion, resulting in 
identification of 10 population segments. We categorized resiliency for 
each of these population segments using stream segment viability scores 
(e.g., excellent, good, fair, poor, and uncertain) and expert opinion. 
We considered stream segment viability scores of excellent and good as 
a single category, with fair, poor, and uncertain being the other three 
stream viability scores used in the resilience categorization. We 
considered populations to be high resiliency when more than 50 percent 
of its stream segments had EO viability scores of Excellent or Good. 
Populations where greater than 50 percent of stream segments had EO 
viability scores of Fair were considered to be moderate resiliency. We 
considered populations to be low resiliency if more than 50 percent of 
its stream segments had Poor EO viability scores. Finally, for 
populations where over 50 percent of stream segment viability scores 
were uncertain, we used a combination of EO viability scores (where 
this was available) and expert opinion to determine whether they were 
high, moderate, or low resiliency. Within each of the 10 population 
segments, we calculated the total stream miles within each stream 
segment viability category to determine the proportion of various 
viability ranks represented (USFWS 2017b, p. 21).
    Of the 10 population segments, currently six (145 stream miles; 76 
percent of the total range) display high resiliency (likely to persist 
for at least 20 to 30 years); two (20 stream miles; 10 percent of the 
total range) display moderate resiliency (may persist for at least 20 
to 30 years); and two (26.5 stream miles; 14 percent of the total 
range) display low resiliency (high risk of extirpation in 20 to 30 
years).
Representation
    We lack genetic and ecological diversity data to characterize 
representation for Nashville crayfish. In the absence of this 
information, we evaluated representation based on the extent and 
variability of habitat characteristics across the species' geographical 
range. For the Nashville crayfish, we characterized representative 
units by using physical stream hydrology, and measured representation 
as the number of resilient populations within three delineated 
representative units as originally proposed in Jones (2006, p. 6)--MCW-
A or Upper, MCW-B or Middle, and MCW-C or Lower (see discussion and 
Table 1 above). The three units have different stream and watershed 
characteristics, such as stream order, surrounding drainage landscapes, 
depth, and flow, but are primarily delineated based on amount of 
development. The landscape in unit MCW-A is primarily agricultural, 
unit MCW-B encompasses the suburban subwatersheds, and unit MCW-C is 
primarily urban (Jones 2006, p. 6). The representative units are 
catchments created by using flow direction, flow accumulation, and a 3-
meter resolution digital elevation model (Jones 2006, entire).
    Differences in hydrology in these three areas could result in 
differences in how the species may adapt to changing environmental 
conditions. Because the mainstem population segment crosses 
representative unit boundaries, we report representation as the 
percentage of stream miles categorized as low, moderate, and high 
within each representative unit:
     Upper (MCW-A): There are 61.8 total stream miles within 
this unit. Of those, 49.6 miles (80 percent) are portions of population 
segments classified as high resiliency; 12.2 miles (20 percent) are 
classified as low resiliency.
     Middle (MCW-B): There are 72.6 total stream miles within 
this unit. Of those, 43.6 miles (60 percent) are portions of population 
segments classified as high resiliency; 19.7 miles (27 percent) are 
classified as moderate resiliency; and 9.3 miles (13 percent) are 
classified as low resiliency.
     Lower (MCW-C): There are 57.1 total stream miles within 
this unit. Of those, 52.1 miles (91 percent) are portions of population 
segments classified as high resiliency; 5.0 miles (9 percent) are 
classified as low resiliency.
    For the Nashville crayfish, our expert noted that the sub-
watersheds we used were a good way to spatially delineate adaptive 
capacity. In fact, our spatial analysis was confirmed by a dissertation 
done previously that looked at variability within that watershed 
discussed in the SSA (Jones 2006, entire). From north to south the 
species clearly showed some adaptive capacity, as evidenced by the 
differences in habitat from north to south. Because of this we 
established the three representative units (upper, middle, lower).
    To measure representation we then looked at the number of resilient 
stream segments and their resiliency score, assuming that a high number 
of stream segments in a high resiliency status means there is 
sufficient representation in that unit. If, for example, we had a 
representative unit with a majority of low resiliency stream segments 
we would then be concerned the species may lose some of its 
representation. As this was not the case, we believe that 
representation is not limiting the species' ability to maintain 
resilient populations. We therefore conclude that representation is 
high because the

[[Page 65103]]

majority of stream miles in each segment are highly resilient.
Redundancy
    For the Nashville crayfish to maintain viability, the species needs 
to exhibit some degree of 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 return from catastrophic events (such 
as a rare destructive natural event or episode involving many 
populations). We report redundancy for Nashville crayfish as the total 
number of population segments and their distribution within and among 
representative units.
    As discussed above, there are 10 population segments distributed 
across the range of the Nashville crayfish between the three 
representative units. Six of these population segments are highly 
resilient; two population segments are moderately resilient; and two 
population segments are of low resiliency. As also discussed above, 
there is adequate redundancy based on the distribution in the three 
representative units for the Nashville crayfish to withstand 
catastrophic events. The catastrophic events likely to affect the 
Nashville crayfish are spills associated with increasing human 
population and urbanization (see Summary of Threats below). However, 
the likelihood of such events occurring is not equal across the three 
units: They are far more likely to occur in the lower, highly urbanized 
unit MCW-C (the farthest downstream) and much less likely to occur in 
the middle (MCW-B) and upper (MCW-A) units because these units are less 
developed. Therefore, if a spill were to occur, it is more likely to 
affect only one unit and not all three.
    In any case, even in the unlikely circumstance a catastrophic event 
would impact the entire range of the species, the Nashville crayfish 
has demonstrated a high degree of resistance to disturbance. In the 
Mill Creek watershed, there have been frequent spills/releases of raw 
sewage and hazardous substances, particularly in the lower reaches 
(USFWS 2018, p. 50-51). However, despite these events, the species has 
been found in large numbers at several locations that are already 
heavily developed. Although the Metropolitan Nashville area is 
experiencing significant growth, with numerous residential, commercial, 
utility, and other infrastructure developments occurring in the 
watershed, Nashville crayfish populations have been documented to be 
stable or increasing in size.
    Based on our analysis of these three factors, the species 
demonstrates high viability, indicating that it is likely to persist in 
the future. Since the Nashville crayfish was listed, individuals have 
been found in large numbers at several locations in the watershed that 
are heavily developed and subjected to consistent storm water and 
sediment inputs, as well as frequent spills and releases of raw sewage 
and hazardous substances. Despite these stressors, Nashville crayfish 
density has increased in all three representative units (McGinnity 
2016, p. 3)

Summary of Threats and Conservation Measures That Affect the Species

    Section 4(a)(1) of the Act directs us to determine whether any 
species is an endangered species or a threatened species because of any 
of the following factors: (A) The present or threatened destruction, 
modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence.
    In the assessment report, we reviewed the factors (i.e., threats, 
stressors) that could be affecting the Nashville crayfish now or in the 
future. However, in this proposed rule, we will focus our discussion on 
those factors that could meaningfully impact the status of the species. 
The primary risk factor affecting the status of the Nashville crayfish 
is development in the Mill Creek watershed that results in destruction 
or alteration of habitat. This was a primary factor in our decision to 
list the species in 1986. Specifically, increased development in the 
watershed leads to increased impervious cover, which in turn often 
leads to water quality deterioration. This takes the form of siltation, 
stream alteration, and urban runoff (particularly of phosphorus), 
resulting from development in Nashville and surrounding urbanized 
areas, all of which have the potential to negatively impact the 
Nashville crayfish. Secondary risk factors include the species' limited 
distribution, which makes it vulnerable to catastrophic events, such as 
chemical spills or other contamination sources. Development in the 
watershed can also increase the probably of catastrophic spills as well 
as increase road density and create new contaminant sources. 
Competition with invasive crayfish species could also be problematic, 
but presently, this is not a known threat for the species. Similarly, 
climate change and its associated effects will not have a negative 
impact on the Nashville crayfish now or in the foreseeable future.

Factor A. Present or Threatened Destruction, Modification, or 
Curtailment of Habitat or Range

    The primary threat to the continued existence of the Nashville 
crayfish is still development in the Mill Creek watershed that results 
in destruction or alteration of the aquatic habitat. The population of 
Davidson County grew by 5.1 percent between 2010 and 2013. Adjacent 
Williamson County grew by 8.6 percent in the same time period (USFWS 
2017a, p. 12). As Nashville and the surrounding areas have grown, 
commercial and residential development has increased within the Mill 
Creek watershed. Areas in the upper reaches of the Mill Creek watershed 
that were once rural agricultural areas are now being developed for 
residential purposes. Development often results in removal of riparian 
vegetation and canopy cover over the stream that may result in bank 
collapse. Runoff from denuded areas can result in heavy input of 
sediment into the stream, excessive in-stream sediment deposition, and 
increased water turbidity and temperatures. Sediment has been shown to 
break down and or suffocate bottom-dwelling algae and other organisms 
by clogging gills and reducing aquatic insect diversity and abundance 
(Waters 1995, p. 251). We anticipate population growth in the Nashville 
metropolitan area to continue, with associated increases in 
development. Five of the ten counties in Tennessee with the highest 
projected growth rates through 2040--Williamson, Rutherford, Wilson, 
Robertson, and Sumner--are in the Nashville metropolitan area. 
Approximately 69 percent of the population growth in Tennessee from 
2010 to 2040 is expected to occur in 10 counties across the state, 
including Davidson and Williamson counties (Boyd Center 2015, entire). 
However, despite the increased development, the species has been found 
in several locations and in large numbers.
    Highway and road construction, as well as utility line construction 
and right-of-way maintenance, within and adjacent to streams, may also 
alter or destroy habitat. Additionally, short-term dewatering to 
excavate trenches for utility lines could also result in temporary loss 
of habitat. The settling

[[Page 65104]]

and filling in of crevices and interstitial spaces with sediment under 
slab rocks is likely to result in increased biological oxygen demand 
and longer term or permanent loss of habitat for crayfish (Cook and 
Walton 2008, p. 121). These are all potential impacts to crayfish 
habitat. We know that these actions result in degradation of riparian 
areas and stream health, but there is uncertainty regarding how 
tolerant the Nashville crayfish is to such changes. The only area where 
we know the species was negatively impacted was near the airport where 
toxic releases caused abandonment of that stream reach. However, years 
later, the area was recolonized, albeit at a lower abundance (USFWS 
2017b, p. 51).
    To avoid direct adverse impacts to the crayfish and its habitat, 
developers increasingly use directional boring under the stream as a 
means of accomplishing crossings for utility and communication lines; 
however, if not done properly, boring can cause fracturing of the 
stream bottom. This can result in release of bentonite and other 
slurries as well as toxic materials from the bore hole into the stream. 
Dewatering of short or long reaches of the stream channel downstream 
from the fracture may also occur. Dewatering can be permanent if the 
fracture causes the entire surface flow to go underground. Materials 
released into the stream from bore holes range from inert slurries to 
potentially toxic chemicals and lubricants; however, inert slurry, if 
released in large amounts, could result in mortality to crayfish and 
other benthic fauna by smothering adults and juveniles. In 2000, during 
installation of fiber optic cables in the Mill Creek drainage, several 
incidents of fracturing occurred resulting in the release of large 
amounts of bentonite slurry into the streams. In 2013, a Piedmont 
Natural Gas Pipeline boring under Sevenmile Creek impacted its 
tributary, releasing a bentonite slurry that resulted in mortality of 
six individual crayfish. Due to these incidents, areas where known 
bedrock fracturing potential exists are now being trenched (surface 
cut) for projects involving utility line crossings (USFWSb 2017, p. 
52).
    Another potential threat to the species' continued existence is the 
improper use or overuse of lawn pesticides and fertilizers. Intentional 
or inadvertent application of chemicals to the stream or runoff from 
yards after application has resulted in significant mortality of 
aquatic organisms, including Nashville crayfish. We have received 
periodic reports of mortality of stream fauna that likely resulted from 
input of pesticides into streams in the Mill Creek watershed. This 
threat is likely to increase in the future as residential development 
increases (USFWS 2017b, p. 50).
    Additionally, there have been consistent stormwater and sediment 
inputs to the Mill Creek watershed, as well as frequent spills/releases 
of raw sewage and hazardous substances, yet the Nashville crayfish 
persists in high numbers. The species exhibits a high degree of 
resistance to disturbance, indicating that the species has a low 
susceptibility to threats and high degree of stability (USFWS 2017a, p. 
16).
    As of 2014, numerous stream segments in Mill Creek and its 
tributaries were listed as impaired on the State of Tennessee's 303(d) 
list (TDEC 2018, entire). Impairment of stream reaches in the drainage 
is the result of low dissolved oxygen, siltation, removal of riparian 
vegetation, nutrient enrichment and high bacteria levels from 
stormwater discharges, sewage collection system failures, land 
development, and unrestricted cattle access (TDEC 2018, entire).
    Our analysis of threats and risk factors, as well as the past, 
current, and future influences on what the Nashville crayfish needs for 
long term viability revealed that the most risk to future viability of 
the species is posed by water quality issues: The risk of a 
catastrophic spill and impairment of water quality associated with 
increasing human populations and urbanization. However, the species has 
been found in large numbers at several locations that are already 
heavily developed, and the species has been found in several additional 
tributaries to Mill Creek since its original listing under the ESA 
(USFWSb 2017, p. 73). Although the Metropolitan Nashville area is 
experiencing significant growth, with numerous residential, commercial, 
utility, and other infrastructure developments occurring in the 
watershed, Nashville crayfish populations have been documented to be 
stable or increasing in size (USFWS 2017b, entire). Additionally, there 
have been consistent stormwater and sediment inputs to the Mill Creek 
watershed, as well as frequent spills/releases of raw sewage and 
hazardous substances, yet the Nashville crayfish persists in high 
numbers. The species exhibits a high degree of resistance to 
disturbance, indicating the species has a low susceptibility to threats 
and a high degree of stability.

Factor B. Overutilization for Commercial, Sporting, Scientific, or 
Educational Purposes

    We have received reports over the past five years (2010-2015) that 
fish and aquatic invertebrates, including Nashville crayfish, are being 
harvested from Mill Creek for food (USFWS 2016, entire). Although we do 
not know the full impact of harvesting on the species at this time, 
populations are stable or improving across the range, indicating any 
harvesting that is occurring is not affecting population resiliency.

Factor C. Disease or Predation

    This factor was determined to not apply to the Nashville crayfish 
at the time of its 1986 listing. Currently, porcelain disease 
(Thelohania contejeani), known from crustaceans in Australia, may pose 
a threat if infected crustaceans are accidently introduced into the 
Mill Creek watershed from the pet trade (see Factor E discussion, 
below). There is anecdotal evidence that porcelain disease was observed 
in Cambarus sphenoides on the Cumberland Plateau. The Cumberland 
Plateau is the southern part of the Appalachian Plateau in the 
Appalachian Mountains of the United States. It includes much of eastern 
Kentucky, Tennessee, and portions of Alabama and Georgia.
    Although our earlier determination that a population of Nashville 
crayfish was displaced by another crayfish species turned out to be 
incorrect (see Background, above), competition or predation by released 
nonnative crayfish also could potentially pose a threat to the species 
in the future (Bizwell and Mattingly 2010, p. 359). Urbanization may 
result in increased numbers of scavengers, such as raccoons, that might 
prey on aquatic organisms. However, we currently have no information to 
indicate that disease or predation are threats to this crayfish.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

    In our discussions under Factors A, B, C, and E, we evaluate the 
significance of threats as mitigated by any conservation efforts and 
existing regulatory mechanisms. Where threats exist, we analyze the 
extent to which conservation measures and existing regulatory 
mechanisms address the specific threats to the species. Regulatory 
mechanisms, if they exist, may reduce or eliminate the impacts from one 
or more identified threats. The following provides an overview of the 
existing regulatory protections that

[[Page 65105]]

protect the Nashville crayfish ecosystem and the Nashville crayfish.
    Tennessee Wildlife Resources Agency has regulations in place to 
address the collection of baitfish, including amphibians and crayfish, 
which specifically prohibit the taking of and possession of crayfish 
from Mill Creek and its tributaries in Davidson and Williamson Counties 
(TWRA 1994, rule 1660-1-26-.04). The Tennessee Fish and Wildlife 
Commission also issued a proclamation (TFWC 2014, p. 13-15) which 
states that the collection of crayfish from Mill Creek in Davidson and 
Williamson Counties is specifically prohibited. It is also prohibited 
to possess or use crayfish for bait in Mill Creek, which is key to 
preventing accidental introductions of nonnative species.
    Currently there are no State laws that provide specific protection 
for the species' habitat. However, the CWA and the Tennessee Water 
Quality Control Act of 1977 provide water quality protections for 
streams in the State. Agencies implementing these laws routinely issue 
notices of violation (NOVs) when actions are reported that have adverse 
impacts on waters in the State. NOVs are typically issued after the 
fact--i.e., after destruction or alteration of the species and habitat 
has occurred. Agencies are not staffed to oversee, supervise, or 
inspect all of the actions for which permits have been issued. Also, 
penalties levied on violators by the State are likely not severe enough 
to deter future violations. Even if more drastic enforcement action is 
taken by Federal agencies, the time between the violation and 
conclusion of the law enforcement action is likely long enough to 
suppress the deterrent effect of the penalty.
    TDEC and Metropolitan Nashville Water Services (MNWS) routinely 
issue CWA NOVs for incidents in the Mill Creek watershed. Service Law 
Enforcement personnel have assisted the State in numerous 
investigations. As an example, in 2011, a contractor constructing a 
replacement sewage forcemain bypassed a section of an existing sewage 
forcemain by pumping past the section of forcemain to be replaced. The 
pump failed, releasing a significant amount of sewage into Mill Creek. 
Crayfish mortality was observed; however, the Service did not pursue an 
enforcement action under the Act because this was an accidental 
release. The Service will continue to provide technical assistance to 
the state agency to address future incidents within the Mill Creek 
watershed. Mill Creek is currently listed as an impaired stream with 
the U.S. Environmental Protection Agency (EPA).
    Although numerous NOVs have been issued in the Mill Creek watershed 
since 2009, State and Federal water quality laws have not prevented 
pollution from development activities or from municipal and industrial 
sources. Portions of Mill Creek and some of its tributaries are 
currently listed on TDEC's impaired stream list (TDEC 2018, in draft). 
State and Federal agencies have identified impairments to address which 
include low dissolved oxygen, siltation, other anthropogenic habitat 
alterations, Escherichia coli (E. coli), total phosphorus, nitrate-
nitrite, and propylene glycol.
    The CWA makes it unlawful to discharge any pollutant from a point 
source into navigable waters, unless a permit is obtained. Section 404 
of the CWA establishes a program to regulate the discharge of dredged 
or fill material in waters of the United States, including wetlands. 
The basic purpose of the program is that no discharge of dredged or 
fill material may be permitted if: (1) A practicable alternative exists 
that is less damaging to the aquatic environment or (2) the nation's 
waters would be significantly degraded. An individual permit is 
required for potentially significant impacts. Individual permits are 
reviewed by the U.S. Army Corps of Engineers, which evaluates 
applications under a public interest review, as well as the 
environmental criteria set forth in the CWA Section 404(b)(1) 
Guidelines, regulations promulgated by EPA. For the Nashville crayfish, 
the Corps permits would still be applicable and have relevant 
conditions. Furthermore, through our authorities under the Fish and 
Wildlife Coordination Act, the Service will provide technical 
assistance to the Corps during the permit review process. The state 
would also require Aquatic Resource Alteration Permits with conditions 
as well.
    TDEC and the Service conducted a natural resource damage assessment 
(NRDA) and developed specific recommendations for stormwater treatment, 
monitoring, and compliance to the Metropolitan Nashville Airport 
Authority (MNAA). The purpose of the NRDA program is to restore natural 
resources injured as a result of oil spills or hazardous substance 
releases into the environment. The NRDA process evaluates and restores 
wildlife, habitats, and human resources impacted by oil spills, 
hazardous waste sites, and vessel groundings. Damage assessments 
provide the basis for determining the extent of restoration needed to 
address the public's natural resource losses. Should a future oil spill 
or hazardous substance release adversely affect the Nashville crayfish, 
the State, acting as a natural resource trustee, would assess injury 
and determine appropriate restoration. Once the damages are assessed, 
the NRDA Restoration Program negotiates legal settlements or takes 
other legal actions against the responsible parties for the spill or 
release. Funds from these settlements are then used to restore the 
injured resources at no expense to the taxpayer. Settlements often 
include the recovery of the costs incurred in assessing the damages. 
These funds may also be used to fund damage assessments in future 
incidents. Civil penalties were also assessed by TDEC (USFWS 2017b, p. 
51). In cooperation with the Service and our partners, MNAA made 
substantial improvements to the stormwater collection and treatment 
system at the airport. The Service also provided specific 
recommendations to TDEC in the revision of MNAA's national pollutant 
discharge elimination system permit.
Summary of Factor D

Factor E. Other Natural or Man-Made Factors Affecting the Species' 
Continued Existence

    In this section, we will discuss other natural and man-made threats 
affecting the species including limited geographic range, vehicle 
accident spills, introduction of invasive crayfish and climate change.
    The Nashville crayfish's limited geographic range and apparent 
small population size leave the species vulnerable to localized 
extinctions from accidental toxic chemical spills or other stochastic 
disturbances. Species that are restricted in range and population size 
are more likely to suffer loss of genetic diversity due to genetic 
drift, potentially increasing their susceptibility to inbreeding 
depression and decreasing their ability to adapt to environmental 
changes (Allendorf and Luikart 2007, p. 642). However, the Nashville 
crayfish has always occupied a small range. The crayfish is endemic to 
one watershed and still occupies the watershed. Highly resilient 
populations are more than likely to survive stochastic events and there 
are several highly resilient populations spread across the range.
    Potential sources of such spills include accidents involving 
vehicles transporting chemicals over road crossings of streams and 
accidental or intentional release into streams of chemicals used in 
industrial, agricultural, or residential applications. Dead crayfish, 
including Nashville

[[Page 65106]]

crayfish, have been collected downstream from construction sites and 
sewage releases on numerous occasions. For instance, in 2010 and 2011, 
discharges of propylene glycol de-icing fluids from the runways and 
tarmac at the Metropolitan Nashville International Airport adversely 
affected Sims Branch. Response agencies located affected Nashville 
crayfish. An attempt to translocate these individuals to the Cumberland 
River Aquatic Center failed, as the specimens died during transport.
    With regard to the effects of invasive species on Nashville 
crayfish, most crayfish experts believe the introduction of invasive 
crayfish species is not occurring at a rate that could negatively 
impact native species, especially species with small distributions. In 
east Tennessee, there have been several introductions; the most serious 
is the Kentucky River crayfish (O. juvenilis), which has replaced the 
surgeon crayfish (O. forceps) in most of the Holston River system above 
Cherokee Reservoir. Although these water bodies are not within the Mill 
Creek system, it is conceivable that one of these extremely aggressive 
species could be introduced into that system and, once established, 
there is no known method to remove them. A simple aquarium release of a 
single ovigerous (egg bearing) female or other live specimens would be 
detrimental to the Nashville crayfish. However, we have no information 
suggesting the invasive crayfish are utilized in the local pet trade or 
as bait for fishing in the Mill Creek watershed.
    Our analyses under the Act include consideration of ongoing and 
projected changes in climate. A recent compilation of climate change 
and its effects is available from reports of the IPCC (IPCC 2014, 
entire).
    The IPCC concluded that evidence of warming of the climate system 
is unequivocal (IPCC 2014, pp. 2, 40). Numerous long-term climate 
changes have been observed including changes in arctic temperatures and 
ice, widespread changes in precipitation amounts, ocean salinity, and 
aspects of extreme weather including heavy precipitation and heat waves 
(IPCC 2014, pp. 40-44). Since 1970, the average annual temperature 
across the Southeast has increased by about 0.8 degrees Celsius 
([deg]C) with the greatest increases occurring during winter months. 
The geographic extent of areas in the Southeast region affected by 
moderate to severe spring and summer drought has increased over the 
past three decades by 12 and 14 percent, respectively (Karl et al. 
2009, p. 111). These trends are expected to increase. Rates of warming 
are predicted to more than double in comparison to what the Southeast 
has experienced since 1975, with the greatest increases projected for 
summer months. Depending on the emissions scenario used for modeling 
change, average temperatures are expected to increase by 2.5 [deg]C 
(lower emissions scenario, or IPCC SRES B1) to 5 [deg]C (higher 
emissions scenario, or A2) by the 2080s (Karl et al. 2009, p. 111). 
While there is considerable variability in rainfall predictions 
throughout the region, increases in evaporation of moisture from soils 
and loss of water by plants in response to warmer temperatures are 
expected to contribute to increased frequency, intensity, and duration 
of drought events (Karl et al. 2009, p. 112).
    There is also a growing concern that climate change may lead to 
increased frequency of severe storms and droughts (McLaughlin et al. 
2002, p. 6074; Golladay et al. 2004, p. 504; Cook et al. 2004, p. 
1015). Specific effects of climate change to crayfish habitat could 
include changes in stream temperature regimes; the timing and levels of 
precipitation, causing more frequent and severe floods and droughts; 
and alien species introductions. The following systematic changes are 
expected to be realized to varying degrees in the southeastern United 
States (NCILT 2012, p. 27; IPCC 2013, p. 7):
     More frequent drought;
     More extreme heat (resulting in increases in air and water 
temperatures);
     Flooding;
     More intense storms (e.g., frequency of major hurricanes 
increases).
    Despite the recognition of potential climate effects on ecosystem 
processes, there is uncertainty about what the exact climate future for 
the southeastern United States will be and how the ecosystems and 
species in this region will respond. Effects from climate change may 
also result from synergistic effects. That is, factors associated with 
a changing climate may act as risk multipliers by increasing the risk 
and severity of more imminent threats. As a result, impacts from rapid 
urbanization in the region might be exacerbated under long-term climate 
change. However, our approach to assessing the future condition of the 
species (see Future Conditions, below) is focused on a 20- to 25-year 
projection timeframe, because beyond this time, much uncertainty 
remains in both the degree of climate change and the species' response 
to changes in precipitation and temperature. We currently do not have 
information on the effect of future drought on specific stream segments 
the species occupies within the watershed. We also do not know the 
species temperature tolerance in response to long-term temperature 
increases within those streams. While the Nashville crayfish has 
multiple populations, future impacts due to the effects of climate 
change may reduce the resiliency of the species although the long-term 
effects remain unknown.

Conservation Measures That Affect the Species

    The Mill Creek Watershed Association (MCWA) was formed in 2009. The 
MCWA was strengthened in 2013 by the Cumberland River Compact with the 
support of the Tennessee Department of Agriculture Division of 
Forestry. The goal of the MCWA is to provide education and support for 
improving and protecting the Mill Creek Watershed. It endeavors to 
clean the water in Mill Creek, eliminate water pollution in local 
neighborhoods, and make the water safe for wildlife and human use. 
Focal activities for the MCWA include adopt a stream, riparian buffers, 
pollution prevention, rain gardens and barrels, and protecting the 
Nashville crayfish.
    The Cumberland River Compact sponsors meetings every other month to 
bring all interested stakeholders together to reach a realistic 
approach to ensure a brighter future for the Mill Creek Watershed. 
These meetings provide stakeholders an opportunity to learn and provide 
perspective on current conditions, recommendations for improvements, 
and plan activities to address the current concerns and needs in the 
watershed. Current participants include Cumberland River Compact, 
Tennessee Department of Agriculture, Tennessee Division of Forestry, 
Metro Water Services, Nashville Zoo at Grassmere, Tennessee Department 
of Environment and Conservation, Tennessee Scenic Rivers Association, 
Tennessee Wildlife Resources Agency, the Corps, and the Service (USFWS 
2017b, p. 57).
    The Tennessee Stream Mitigation Program (TSMP) was established 
under the Tennessee Wildlife Resources Foundation in 2002, as a 
statewide in-lieu fee wetlands mitigation program. The TSMP provides 
mitigation for improving instream and riparian habitat, and overall 
water quality. It funds projects on significantly degraded streams to 
arrest bank erosion, improve water quality, and restore aquatic and 
riparian habitat. The TSMP has implemented 28 projects, restoring over 
45 miles of degraded stream and over 800 acres of riparian habitat. One 
of these projects was initiated in the Mill

[[Page 65107]]

Creek Watershed in 2009. The project encompassed 2,385 feet of Mill 
Creek near Nolensville in Williamson County, in the Upper Mill Creek 
segment (MCW-A). The existing channel was highly degraded due to 
channelization, vegetation removal, and infrastructure including 
roadway fills, and had been listed on the 303(d) list due to impacts 
from unrestricted livestock access. The primary goals of the project 
were to restore riparian buffer function by the excluding of livestock 
from the channel and riparian corridor which would reduce non-point 
source pollutants (such as sedimentation and nutrients). This work 
resulted in improved water quality, channel stability, aquatic habitat, 
and elimination of accelerated bank erosion problems; reestablishment 
of instream habitat by restoring bed form diversity in the form of 
riffles and pools; and enhancement of the riparian zone by planting 
native plants. The restored riparian buffer resulted in decreased 
stream temperatures, which improved water quality for the crayfish. The 
floodplain basins helped improve water quality, decrease peak flows, 
and provide valuable flood plain habitat (USFWS 2017b, p. 58). All of 
the goals of this project were met, which has improved the habitat for 
the Nashville crayfish, thereby increasing the resiliency of the 
species.
    The Nashville Zoo at Grassmere has been heavily involved in 
Nashville crayfish recovery efforts. In March 2017, the zoo, in 
collaboration with the Cumberland River Compact, Tennessee Wildlife 
Resource Agency, and KCI Technologies Inc., removed two dams on Cathy 
Jo Branch in the Lower Mill Creek segment (USFWS 2017b, p. 58). The 
dams, which were located on zoo property, created a barrier to 
crayfish, small fish, and other small aquatic life, preventing the 
migration of aquatic species upstream and reducing the biodiversity of 
the aquatic systems. Dam removal generally allows for the migration of 
aquatic species that were previously blocked by dams within a 
watershed, including the Nashville crayfish, and improves aquatic 
biodiversity. These dam removals opened up 3 miles of habitat and 
restored the stream as a free-flowing system. Nashville crayfish now 
have access to 10 miles of creek and improved habitat and this reach is 
now occupied by a highly resilient population of Nashville crayfish.
    The Nashville Zoo has also implemented a stormwater management 
project that benefits the Nashville crayfish and other aquatic 
organisms. The Nashville Zoo had a stormwater detention pond on the 
edge of its property that captured runoff from a large office park next 
door to the zoo, but several times a year, excess water was discharged 
from the pond's outlet pipe, where it carried sediment and other 
pollutants into Cathy Jo Branch. Runoff from the office park also 
damaged the perimeter fence and carried trash and debris into the pond. 
The project retrofitted the detention pond to modify the two inlet 
structures and expand the water holding capacity. In addition, the 
brushy area below the outfall pipe was transformed into an infiltration 
zone to slow, spread, and soak in the excess water discharges after 
rain events. This project has directly imp