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United States Department of the Interior
FISH AND WILDLIFE SERVICE
10711 Burnet Road, Suite 200
Austin, Texas 78758
512 490-0057
June 2, 2021
In Reply refer to:
Consultation No. 02ETAU00-2021-FC-1230
MEMORANDUM
To: Regional Director, Region 2, U.S. Fish and Wildlife Service, Albuquerque,
New Mexico (Attn: Marty Tuegel, Branch Chief Environmental Review)
From: Adam Zerrenner, Field Supervisor, Austin Ecological Services Field Office,
Austin, Texas
Subject: Intra-Service Section 7 Conference Opinion on the Proposed Issuance of a
Section 10(a)(1)(A) Permit for the Balcones spike (Fusconaia iheringi) and
Texas fawnsfoot (Truncilla macrodon) for the Proposed Implementation of
the Candidate Conservation Agreement with Assurances for the Balcones
Spike and Texas Fawnsfoot in the Brazos River Basin
This transmits the U.S. Fish and Wildlife Service’s (Service) conference opinion pursuant to
section 7 of the Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et seq.) for
the issuance of a 10(a)(1)(A) Enhancement of Survival Permit (permit) to the Brazos River
Authority (BRA, Applicant) authorizing incidental take of the Balcones spike
(Fusconaia iheringi) and Texas fawnsfoot (Truncilla macrodon). The BRA will be responsible
for implementing the proposed Candidate Conservation Agreement with Assurances (CCAA) for
the Balcones Spike and Texas Fawnsfoot in the Brazos River basin, dated 2020. This conference
opinion analyzes the effects of the proposed issuance of the permit and implementation of the
CCAA. We have determined that this action “may affect” the Balcones spike and Texas
fawnsfoot. We have further determined that this action will have no effect on any threatened or
endangered species, or adversely modify any critical habitat, as no listed species or designated
critical habitat occur within the action area that would be affected by the action. Assurances
provided do not apply to any species other than Balcones spike and Texas fawnsfoot.
This conference opinion is based on information provided in the 2020 final CCAA, the
categorical exclusion/low-effect evaluation form, telephone conversations with the Applicant,
field investigations, and other sources of information including the December 2019 draft Species
Status Assessment report for six species of Central Texas Mussels (Service 2019, entire).
Literature cited in this conference opinion is not a complete bibliography of all literature
available on the species of concern, activities related to managing surface water and operating
02ETAU00-2021-FC-1230
water supply systems and its effects, or on other subjects considered in this opinion. A complete
administrative record of this consultation is on file at the Austin Ecological Services Field
Office.
CONSULTATION HISTORY
August 20, 2020 Applicant submits section 10(a)(1)(A) enhancement of survival permit
application and draft CCAA to the Service.
Aug. - Sept. 2020 Personnel from the Department of Interior’s Office of the Solicitor, the
Service’s Southwest Regional Office and Austin Ecological Services Field
Office review the draft CCAA, and the Service provides comments to the
Applicant.
Sept. - Oct. 2020 The Applicant and the Service revise the draft CCAA and prepare it for
public comment.
October 5, 2020 Notice announcing availability of the draft CCAA and low-effect
evaluation form for public review and comment is published in the Federal
Register.
November 5, 2020 Public comment period for the draft CCAA and low-effect evaluation
form closes.
Nov. - Dec. 2020 The Applicant and the Service review public comments received during
the public comment period.
December 3, 2020 The Applicant and the Service meet to discuss public comments.
March 4, 2021 The Applicant prepares a response to comments received.
March 17, 2021 The Applicant and the Service meet to discuss the response to comments
letter.
March 30, 2021 The Service provides final comments on the draft CCAA to the Applicant.
April 13, 2021 The Applicant submits final, revised 508-compliant CCAA to the Service.
2
02ETAU00-2021-FC-1230
CONFERENCE OPINION
DESCRIPTION OF THE PROPOSED ACTION
Regulations implementing the Act (50 CFR 402.02) define “action” as “all activities or programs
of any kind authorized, funded, or carried out, in whole or in part, by federal agencies of the
United States or upon the high seas.”
The BRA manages the State of Texas water resources of the Brazos River basin (Figure 1); the
BRA develops and distributes water supplies, provides water and wastewater treatment, and
monitors water quality (BRA 2020, p. 1). The proposed action is issuance of a section
10(a)(1)(A) enhancement of survival permit to the BRA for implementation of the CCAA, which
covers the BRA’s ongoing surface water supply and delivery operations, and develops a
comprehensive conservation strategy for freshwater mussels, including the Balcones spike and
Texas fawnsfoot, in the Brazos River basin.
Figure 1. Map depicting Brazos River Authority Water Supply System (Source: BRA 2020, p.
2).
302ETAU00-2021-FC-1230
Ongoing BRA Water Supply and Delivery Operations
The BRA System is comprised of multiple components including physical operation and
maintenance of reservoirs and associated diversion, storage, and delivery of surface water, as
well as compliance with water right permits and contract requirements. Routine operation and
maintenance activities generally include: water releases from reservoirs; inspections, cleaning,
and repairs to intake structures and pump stations; inspecting, cleaning, repairing, or replacing
dam gates and other mechanical structures on dams; dewatering concrete stilling basins below
reservoirs for dam safety inspection and repairs; and replacing or adding riprap for erosion
control on the river banks immediately downstream of dams but within the dam’s footprint (BRA
2020, p.60).
The water rights associated with the BRA System equate to about 38% of the total permitted
diversions within the basin. The 11 existing reservoirs authorize a total collective impoundment
storage volume of 2,222,949 acre-feet, or approximately 53% of the total permitted storage
within the entire basin (BRA 2020, p. 60). It is important to note that the BRA does not have
control over all the water or impoundment structure operations in the Brazos River basin.
Conservation Strategy for Freshwater Mussels
The BRA’s conservation strategy includes a suite of conservation measures that will avoid and
minimize possible effects of their covered activities, and provide a net conservation benefit to the
Balcones spike and Texas fawnsfoot over the 20-year term of the CCAA and permit. The BRA’s
conservation strategy is based on the Freshwater Mollusk Conservation Society’s National
Strategy for the Conservation of Native Freshwater Mollusks (FMCS 2016, entire), which
identifies 10 priorities for freshwater mollusk conservation (BRA 2020, p.16). Appendix 1
(excerpted from BRA 2020, pp. 18-20) provides a list of these 10 priorities, a summary of the
goals provided in the strategy, and how BRA’s conservation measures address each goal,
providing a net conservation benefit to the Balcones spike and Texas fawnsfoot.
Conservation Measures
The following conservation measures will be implemented to avoid and minimize adverse effects
to the Balcones spike and Texas fawnsfoot resulting from the BRA’s proposed actions. These
conservation measures will be planned and executed in close coordination with the Service and
other key partners. Appendix 2 (excerpted from BRA 2020, p. 60) provides BRA’s anticipated
timeline for implementation of each conservation measure.
1) Implement comprehensive freshwater mussel surveys to fill existing data gaps to
inform current and future implementation of conservation strategy and covered
activities;
2) Perform additional hydrologic modeling to inform current and future management of
environmental flows to provide for the needs of covered species;
3) Coordinate with agencies through interagency workgroups to encourage collaboration
and reduce conflicts and threat of over-collection;
402ETAU00-2021-FC-1230
4) Increase awareness of freshwater mussels and foster community engagement;
5) Manage environmental flows;
6) Support environmental flows by managing water supply operations, including the
proposed Allen’s Creek Reservoir, when built;
7) Evaluate controlled releases to minimize erosion of stream banks and river beds;
8) Avoid and minimize disturbances to Balcones spike and Texas fawnsfoot and their
habitats, through the establishment and management of Mussel Conservation Zones;
9) Develop a habitat quantification tool;
10) Develop environmental flow methodologies specific to freshwater mussels;
11) Evaluate reintroduction techniques and opportunities;
12) Analyze physiological tolerances of Balcones spike and Texas fawnsfoot;
13) Investigate groundwater-surface water interactions to inform flow management;
14) Implement site-specific and reach-scale monitoring for Balcones spike and Texas
fawnsfoot, other mussels, and host fish;
15) Implement water quality monitoring targeted to important habitats for Balcones spike
and Texas fawnsfoot;
16) Implement long-term monitoring at instream flow monitoring locations to assess
changes in substrate composition and channel morphology;
17) Monitor invasive species and implement measures to prevent future infestations;
18) Support contingency planning and establishment of short-term refugia; and,
19) Support efforts to develop captive propagation of Balcones spike and Texas fawnsfoot.
Finally, the BRA will implement a comprehensive adaptive management process that considers
the responses of the Balcones spike, Texas fawnsfoot, and their host fish to changes in flow,
water quality, and substrate conditions.
Action Area
The action area is defined at (50 CFR 402.02) as “all areas to be affected directly or indirectly by
the federal action and not merely the immediate area involved in the action.”
The general CCAA action area is shown in Figure 2, indicating the maximum extent of the
BRA’s operations or operational influence in the Brazos River basin covered by the CCAA.
Conservation measures will be prioritized for five Mussel Conservation Zones (Figure 3),
proposed by the BRA and located in stream reaches known to be occupied by or have potential
habitat for Balcones spike or Texas fawnsfoot. Zones A through D are those zones categorized
as having suitable or potentially suitable habitat for the Balcones spike (Zone A), Texas
fawnsfoot (Zones B and C), and other freshwater mussels within the action area (Zone D).
502ETAU00-2021-FC-1230
Figure 2. CCAA action area (Source: BRA 2020, p. 16).
Mussel Conservation Zone A - defined as all stream reaches where Balcones spike is currently
known to be present within the action area. Balcones spike has a limited distribution within the
Brazos River basin and is relatively rare where it occurs. This includes portions of the Little
River, San Gabriel River, and Brushy Creek in Milam and Williamson counties, Texas.
Mussel Conservation Zone B - defined as stream reaches where Texas fawnsfoot is most
abundant. Since Texas fawnsfoot is more widely distributed within the action area, abundance
was used to stratify conservation priority within the species’ range. Zone B includes portions of
the mainstem Brazos River and Navasota River in Brazos, Grimes, Washington, Waller, Austin,
and Fort Bend counties, Texas.
Mussel Conservation Zone C - defined as stream reaches where Texas fawnsfoot is present, but
is not as abundant as in Zone B, or where abundance data is lacking. Portions of Zone C include
Texas fawnsfoot populations which are isolated by reservoirs, and therefore, are of high
conservation concern. Given differences in population abundance and isolation, conservation
actions may differ between Zone B and Zone C. Zone C includes portions of the lower Brazos
River mainstem in McLennan, Falls, Milam, Robertson, Burleson, and Brazos counties, as well
as portions of the middle Brazos River mainstem in Palo Pinto and Parker counties, Texas. Zone
602ETAU00-2021-FC-1230
C in the Clear Fork Brazos River extends from FM 600 in Jones County to the confluence with
the Brazos River in Young County.
Mussel Conservation Zone D - defined as stream reaches where Balcones spike and Texas
fawnsfoot are absent, but other substantial freshwater mussel populations currently exist.
Although these mussel populations are of lower conservation priority, this zone is of
conservation significance since abundant mussel populations are known in these areas. Although
currently not occupied by Balcones spike and Texas fawnsfoot, some of the areas in Zone D
were historically occupied by these species, and they represent potential areas for habitat
restoration and natural population expansion. Zone D includes portions of the Leon River in
Comanche, Hamilton, and Coryell counties; portions of the Navasota River in Robertson, Leon,
Brazos, Madison, and Grimes counties; portions of Yegua Creek in Burleson and Washington
counties; and portions of the Little River in Milam County, Texas.
Mussel Conservation Zone E - defined as stream reaches where no substantial mussel
populations exist based on currently available data. These areas are currently of lowest
conservation priority. It should be noted that not all of Zone E has been surveyed for mussels.
Figure 3. Map of the five proposed Mussel Conservation Zones (red, orange, yellow, green, blue
stream segments) in the Brazos River basin, Texas (Source: BRA 2020, p.24).
702ETAU00-2021-FC-1230
STATUS OF THE SPECIES
The false spike and Texas fawnsfoot were among fifteen mussel species added to the list of
Texas state threatened species by the Texas Parks and Wildlife Department (TPWD) in 2009
(TPWD 2009, pp. 1-2). False spike and Texas fawnsfoot were petitioned for listing by
WildEarth Guardians on October 9, 2008, and the Service published a substantial 90-day finding
for those species on December 15, 2009 (74 FR 66260). The Service published a 12-month
finding on October 6, 2011 for the Texas fawnsfoot, finding that listing was warranted but
precluded by higher priority actions, and adding it to the candidate list (76 FR 62166).
Balcones spike (Fusconaia iheringi)
Species Description
Until recently, Balcones spike and false spike were considered to be a single species. False spike
was originally described as a species (Unio mitchelli) by Charles T. Simpson in 1895, from the
Guadalupe River in Victoria County, Texas (Dall 1896, pp. 5-6), and is currently recognized as
Fusconaia mitchelli (Williams et al. 2017, pp. 35, 39). The false spike, a medium-sized
freshwater mussel (to 132 mm) with a yellow-green to brown, to black, elongate shell,
sometimes with greenish rays (Howells et al. 1996, pp. 127-8; Howells 2014, p. 85), was
previously thought to occur in the Brazos, Colorado, and Guadalupe River basins of Texas
(Howells 2010, p. 4; Randklev et al. 2017, p. 12). However, Smith et al. 2020 (entire) used
taxon sampling, multi-locus DNA sequence data, and traditional morphometrics to re-evaluate
species boundaries for F. mitchelli, finding genetic divergence between populations in the
Guadalupe and those in the Brazos and Colorado drainages. Based upon this analysis, Smith et
al. 2020 (pp. 12-14) resolved that the false spike is restricted to the Guadalupe drainage (F.
mitchelli), while the Balcones spike (F. iheringi) is found in the Brazos and Colorado drainages.
Balcones spike have obligate associations with specific host fish, although host fish species and
reproductive timing remain unidentified (Smith et al. 2020, p. 14). Host fish for the false spike, a
congenor of the Balcones spike, include red shiner (Cyprinella lutrensis) and blacktail shiner
(Cyprinella lutrensis); female false spike are gravid and brood their young (glochidia) during the
months of March and April (Dudding et al. 2019, p. 16). Although it is possible Balcones spike
shares one or more of the host fish used by false spike, additional investigation is required to
confirm the species of fish used by the Balcones spike for reproduction. Glochidia attach to and
infect host fish, which provide both nutrition and locomotion necessary for the dispersal of
juvenile mussels to favorable habitat sites. Balcones spike, like the false spike, occurs in larger
creeks and rivers with sand, gravel, or cobble substrates, and with slow to moderate flows, and is
not known from impoundments, nor from deep water such as reservoirs (Howells 2014, p. 85).
Status and Distribution
The Service is currently aware of three known populations of Balcones spike: Lower San Saba
River (Colorado Basin), Llano River (Colorado Basin), and Little River (Brazos Basin) (Service
2019, pp. 76-78).
802ETAU00-2021-FC-1230
Population Trends
Balcones spike populations appear to be in decline, with the largest number of individuals found
in recent years located in the Little River (Service 2019, pp. 71-73). Randklev et al. (2017, p.11)
surveyed 130 sites in the Brazos, Colorado, and Guadalupe River drainages for false spike, and
found a total of 31 live false spike individuals from eight locations; 22 of these individuals were
from the Little River, and are now recognized as Balcones spike.
Threats
Balcones spike populations are currently or have historically been, influenced by: increased fine
sediment, reducing habitat quality; water quality degradation; hydrological alterations that
inundate habitats; hydrological alterations that result in flow losses or scour of habitats;
predation, collection, disease and invasive species; barriers to fish movement that fragment and
isolate populations; and climate change, which exacerbates the effects of other stressors (Service
2019, pp. 116-123).
Texas fawnsfoot (Truncilla macrodon)
Species Description
The Texas fawnsfoot was originally described as the species Unio macrodon by Isaac Lea in
1859 from a location near Rutersville, Fayette County, Texas (Lea 1859, pp. 154-155); with shell
morphology described by Lea (1862, pp. 192-3). Strecker (1931, p. 48) recognized Texas
fawnsfoot as Truncilla macrodon and noted it “is an abundant shell in the Colorado and Brazos
rivers” with “largest examples from Austin and Waco” and that “adult shells from many of the
tributary streams average much smaller” and provided locations in the Brazos River in Brazos
and Robertson Counties, Colorado River in Burnet, Colorado, Travis (at Austin) and Wharton
Counties, Leon River in Coryell County, Aquilla Creek in McLennan County, Bosque River in
McLennan County, North Bosque River in McLennan County, and Llano River in Mason
County. The recognized scientific name for Texas fawnsfoot is Truncilla macrodon (Williams et
al. (2017, pp. 35, 44). Texas fawnsfoot is a small- to medium-sized (60 mm) mussel with a
compressed, elongate oval shell that is “dull green, tan, yellow-brown, reddish-brown with
patterns of broken rays, often with irregular blotches, inverted [chevrons] or zig-zag markings,
sometimes between rays” (Howells 2014, p. 111). Texas fawnsfoot is currently known to occur
in the Brazos, Colorado, and Trinity River basins of Texas.
Texas fawnsfoot have obligate associations with specific host fish including freshwater drum
(Aplodinotus grunniens; Howells 2014, p. 111). Freshwater drum are specially adapted for
feeding on larger mussels with large muscular pharyngeal plates that are capable of crushing
shells (McMahon and Bogan 2001, p. 385) and can eat adult mussels, including gravid females.
This strategy of host infestation may limit population size, as reproductively successful females
are sacrificed. Texas fawnsfoot are found in medium- to large-sized streams and rivers with
flowing waters and mud, sand, and gravel substrates (Howells 2014, p. 111), and adults are most
often found in bank habitats and occasionally in backwater, riffle, and point bar habitats with low
to moderate velocities that appear to function as flow refuges during high flow events (Randklev
et al. 2017, p. 137). Texas fawnsfoot are also reported from run edge, pool edge, and backwater
902ETAU00-2021-FC-1230
habitats (Bonner et al. 2018, p. 10). Texas fawnsfoot is relatively small bodied and mobile, with
reported observed movement ranging between 1 and 20 m (Bonner et al. 2018, pp. 10-11).
Status and Distribution
The Service is currently aware of seven populations of Texas fawnsfoot: Clear Fork Brazos
River, Upper Brazos River, Lower Brazos River, Lower San Saba River (Colorado Basin),
Lower Colorado River, East Fork Trinity River, and Trinity River (Service 2019, pp. 94-96).
Population Trends
Texas fawnsfoot populations appear to be in decline: its range has been reduced; some
populations in previously occupied habitats appear to have been extirpated; and a few of the
remaining populations are classified as unhealthy, while the remainder are considered
moderately healthy or healthy (Service 2019, pp. 87-94).
Threats
Texas fawnsfoot populations are currently, or have historically been, influenced by: increased
fine sediment, reducing habitat quality; water quality degradation; hydrological alterations that
inundate habitats; hydrological alterations that result in flow losses or scour of habitats;
predation, collection, disease and invasive species; barriers to fish movement that fragment and
isolate populations; and climate change, which exacerbates the effects of other stressors (Service
2019, pp. 116-123).
Previous Related Consultations within the Action Area
This action represents the first consultation (a conference opinion) on the Balcones spike and
Texas fawnsfoot in the Brazos River basin. The Texas fawnsfoot was included in a conference
report (informal consultation) with NRCS for the Working Lands for Wildlife Project in the
Lower Colorado River basin of Texas.
ENVIRONMENTAL BASELINE
Regulations implementing the Act (50 CFR 402.02) define the environmental baseline as the
condition of the listed species or its designated critical habitat in the action area, without the
consequences to the listed species or designated critical habitat caused by the proposed action.
The environmental baseline includes the past and present impacts of all Federal, State, or private
actions and other human activities in the action area, the anticipated impacts of all proposed
Federal projects in the action area that have already undergone formal or early section 7
consultation, and the impact of State or private actions which are contemporaneous with the
consultation in process. The consequences to listed species or designated critical habitat from
ongoing agency activities or existing agency facilities that are not within the agency’s discretion
to modify are part of the environmental baseline.
1002ETAU00-2021-FC-1230
Status of the Species within the Action Area
Balcones spike (Fusconaia iheringi)
In the Brazos River basin, historical records document the occurrence of Balcones spike in the
Little River system and the Brazos River. The species has historically been collected from the
Leon River, a tributary of the Little River, in Bell County and Coryell Counties (Strecker 1931
pp. 18-19; Randklev et al. 2017, p. 12) and from the Lampasas River, another tributary of the
Little River (Randklev et al. 2017, p. 12). In the Brazos River, the species has been collected
from the boundary of Brazos and Burleson Counties (Randklev et al. 2017, p. 12). Balcones
spike is currently known to occur within the Brazos River basin only in the Little River and two
tributaries, Brushy Creek and the San Gabriel River (Service 2019, p. 71). The species is
presumed to be extirpated from the entire mainstem Brazos River (reviewed in Randklev et al.
2017, pp. 12-13). The CCAA action area includes the only known population of Balcones spike
in the Brazos River basin (i.e., the Little River watershed).
Texas fawnsfoot (Truncilla macrodon)
In the Brazos River basin, Texas fawnsfoot historically occurred from Fort Bend County
upstream to the lower reaches of the Clear Fork of the Brazos River in Shackelford County, as
well as in the Leon, Little, Navasota, and San Gabriel Rivers, and Deer and Yegua Creeks
(Howells 2010, pp. 87-88; Randklev et al. 2017, p. 137). Texas fawnsfoot is known to currently
occur within the Brazos River basin only from the Clear Fork of the Brazos River, in the Brazos
River between Possum Kingdom and Granbury reservoirs, and in the Brazos River from below
Waco to near Sugar Land, Texas (Service 2019, pp. 89-90). The CCAA action area includes all
three known populations of Texas fawnsfoot in the Brazos River basin; however, no activities
are anticipated to occur in stream reaches occupied by the Clear Fork Brazos River population.
The amount of potential Balcones spike and Texas fawnsfoot habitat (in stream miles), present in
the Mussel Conservation Zones in the Brazos River basin, is summarized in Table 1.
Table 1. Amount of potential Balcones spike and Texas fawnsfoot habitat (in stream miles)
present in the CCAA area, in Mussel Conservation Zones A, B, C, and D (Source: BRA 2020,
pp. 23-29).
Mussel Zone Potential Balcones spike habitat Potential Texas fawnsfoot
present (stream miles) habitat present (stream miles)
A 56.4 0
B 0 181.6
C 0 417.2
D 0 355.1
Total 56.4 953.9
1102ETAU00-2021-FC-1230
EFFECTS OF THE ACTION
In accordance with 50 CFR 402.02, effects of the action are all consequences to listed species or
critical habitat that are caused by the proposed action, including the consequences of all other
activities that are caused by the proposed action. A consequence is caused by the proposed
action if it would not occur but for the proposed action and it is reasonably certain to occur.
Effects of the action may occur later in time and may include consequences occurring outside the
immediate area involved in the action (see §402.17).
The proposed action is the issuance of a section 10(a)(1)(A) enhancement of survival permit to
the Applicant for Balcones spike and Texas fawnsfoot in association with the implementation of
BRA’s CCAA in the Brazos River basin of Texas.
Ongoing BRA Water Supply and Delivery Operations
Adverse effects to the Balcones spike or Texas fawnsfoot could occur in the form of death,
injury, and reproductive failure during the implementation of water management operations, due
to changes in water quality, water levels, or flows. Balcones spike or Texas fawnsfoot may be
inadvertently injured or killed by the downstream effects of: releases of water from stilling
basins that is of high temperature, low dissolved oxygen or otherwise degraded; or through
sediments transported downstream following maintenance of reservoir infrastructure including
dams, rip-rap, and stilling basins. Although considered unlikely, Balcones spike or Texas
fawnsfoot may also be killed or injured during routine water management activities (i.e.,
delivering water from the BRA reservoirs to downstream customers via the bed and banks of the
Brazos River or built infrastructure).
Balcones spike or Texas fawnsfoot individuals may be killed or injured due to infrastructure
maintenance or upgrades associated with the BRA’s surface water supply and delivery
operations, or catastrophic failure. The BRA maintains and makes repairs to its water supply and
delivery infrastructure during routine, flood management, and emergency operations. However,
because the known mussel populations are not located in close proximity to the BRA’s dam and
intake structures, direct injury or mortality to downstream mussels resulting from maintenance
and repair is expected to be minimal.
Dam and intake structures are mechanically cleaned on a periodic basis, resulting in water
having degraded quality (i.e., having low dissolved oxygen, high temperature, or low levels of
contaminants) released downstream of the infrastructure. Degraded water quality negatively
affects freshwater mussels and may cause death or injury to Balcones spike and Texas fawnsfoot.
Weeds growing on the dams are sprayed with a glyphosate-based herbicide that is approved by
EPA for use in or near water. Glyphosate-containing compounds have been found to be acutely
toxic to early life stage freshwater mussels even while technical-grade glyphosate has not
(Bringolf et al 2007, pp. 2097-2099).
Individuals may experience reproductive failure and reduced growth rates associated with being
handled during relocation events, or from environmental stress associated with short-term
periods of reduced flows. Injury or death of individuals could lead to decreases in population
1202ETAU00-2021-FC-1230
size, or loss of a demographic cohort (in the case of an interrupted recruitment event).
Disturbance of habitat could lead to decreases in range and stream miles occupied, or
fragmentation of habitats occupied by Balcones spike or Texas fawnsfoot.
In addition to potential negative effects, the CCAA and associated operational changes designed
to protect freshwater mussels are expected to have beneficial effects and will likely decrease
injury or death of Balcones spike and Texas fawnsfoot due to ongoing operations. Operational
changes and conservation measures proposed as part of the CCAA are expected to increase
protection of Balcones spike and Texas fawnsfoot during water supply and delivery operations.
The anticipated adverse effects are expected to affect not more than 10% of the total potential
habitat available for the Balcones spike and Texas fawnsfoot within the Action Area over the 20
year period of the permit, and those effects are expected to be transient (i.e., temporary),
localized (i.e., affecting individual to few mussel beds or occupied reaches at any given time),
and diffuse (i.e., distributed across the landscape of potential habitats). Table 2 provides a
summary of the amount of potential Balcones spike and Texas fawnsfoot habitat present in the
covered area, and the maximum amount of habitat (stream miles) that the Service estimates
would be affected by actions covered by the CCAA and permit, for Mussel Conservation Zones
A, B, C, and D
Table 2. Maximum amount of potential Balcones spike and Texas fawnsfoot habitat (in stream
miles) present and likely to be affected during implementation of the CCAA, by Mussel
Conservation Zone (Source: BRA 2020, pp. 23-29).
Mussel Potential Potential Texas Potential Potential Texas
Zone Balcones spike fawnsfoot habitat Balcones spike fawnsfoot habitat
habitat present present (stream habitat affected affected (stream
(stream miles) miles) (stream miles) miles)
A 56.4 0 5.64 0
B 0 181.6 0 18.16
C 0 417.2 / 246.2 1 0 24.621
D 0 355.1 0 35.51
Total 56.4 782.9 2 5.64 78.29
1
The entire coverage area in Zone C in the CCAA includes 171 stream miles of the Clear Fork Brazos River that is
not anticipated to be impacted by BRA activities. Therefore, only 246.2 of the total 417.2 stream miles in Zone C
are used to calculate potential Texas fawnsfoot habitat that could be affected, resulting in a total of 24.62 stream
miles of Texas fawnsfoot habitat that could be affected.
2
The calculated total stream mileage excludes the 171 stream miles located in the Clear Fork Brazos River as part of
Zone C.
1302ETAU00-2021-FC-1230
Conservation Strategy for Freshwater Mussels
Conservation activities described in the proposed CCAA are expected to provide net
conservation benefits for the Balcones spike and Texas fawnsfoot by reducing threats associated
with physical destruction of habitats and dewatering of habitats during critical dry periods, and
include conservation actions which would allow Balcones spike and Texas fawnsfoot
populations to expand naturally, or through reintroductions sponsored by the Service and/or the
TPWD. The applicant would work cooperatively with the Service, the TPWD, and others to
implement conservation actions designed to benefit the Balcones spike, Texas fawnsfoot, and
other freshwater mussels.
Implementation of the CCAA is likely to support the breeding, feeding, and sheltering of the
Balcones spike and Texas fawnsfoot within the Action Area. As the conservation measures are
implemented, increased growth, survival, reproduction, dispersal, and recruitment of individuals,
and increased population sizes and extent throughout the Covered Area is possible.
The purpose of the CCAA is to protect Balcones spike and Texas fawnsfoot habitat areas, and to
reduce threats so habitat areas can expand; therefore, the Service expects that the conservation
activities covered by the CCAA and permit will increase the amount and quality of suitable
Balcones spike and Texas fawnsfoot habitat.
Along with the expected beneficial effects, adverse effects to the Balcones spike or Texas
fawnsfoot could occur in the forms of death, injury, and reproductive failure during the
implementation of conservation activities. Balcones spike or Texas fawnsfoot may be
inadvertently killed or injured during population surveys and other long-term monitoring
activities, or during habitat manipulation. In addition, as Covered Species populations naturally
increase in abundance and extent following implementation of the conservation measures and
associated activities, or are otherwise reintroduced, there is an increased likelihood that injury or
death to a Balcones spike or Texas fawnsfoot individual would occur as a result of the BRA’s
ongoing water management and conservation activities.
CUMULATIVE EFFECTS
Cumulative effects are those “effects of future State or private activities, not involving federal
activities, that are reasonably certain to occur within the action area” considered in this Opinion
(50 CFR 402.02). The Service is not aware of any future state, tribal, local, or private actions
that are reasonably certain to occur within the action area at this time; therefore, no cumulative
effects are anticipated.
CONCLUSION
After reviewing the current status of Balcones spike and Texas fawnsfoot, the environmental
baseline for the action area, the effects of the proposed action and the cumulative effects, it is our
biological and conference opinion that the action, as proposed, is not likely to jeopardize the
continued existence of the Balcones spike or Texas fawnsfoot.
1402ETAU00-2021-FC-1230
We base this conclusion on the following:
1. The BRA CCAA, and included Conservation Strategy, is designed to minimize and avoid
injury and mortality of the Balcones spike and Texas fawnsfoot over the 20-year term of
the agreement.
2. The anticipated adverse effects are expected to affect not more than 10% of the potential
habitat available for the Balcones spike and Texas fawnsfoot within the Action Area, and
those effects are expected to be transient (i.e., temporary), localized (i.e., affecting
individual to few mussel beds or occupied reaches at any given time), and diffuse (i.e.,
distributed across the landscape of potential habitats). Further, adverse effects are
expected to become ameliorated naturally as environmental flows are managed and water
quality improves over the 20-year term of the CCAA.
3. The BRA CCAA, and included Conservation Strategy, is expected to provide a net
conservation benefit to the Balcones spike and Texas fawnsfoot as populations of both
mussels are expected to expand in terms of abundance and extent through natural and
artificial processes as the CCAA and Conservation Strategy are implemented over the
next 20 years.
The conclusions of this conference opinion are based on full implementation of the project as
described in the Description of the Proposed Action section of this document, including any
conservation measures that were incorporated into the project design.
INCIDENTAL TAKE STATEMENT
Section 9 of the Act and Federal regulations pursuant to section 4(d) of the Act prohibit the take
of endangered and threatened species, respectively, without special exemption. “Take” is
defined as to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect, or to attempt
to engage in any such conduct. “Harm” is further defined (50 CFR § 17.3) to include significant
habitat modification or degradation that results in death or injury to listed species by significantly
impairing essential behavioral patterns, including breeding, feeding, or sheltering. “Harass” is
defined (50 CFR § 17.3) as intentional or negligent actions that create the likelihood of injury to
listed species to such an extent as to significantly disrupt normal behavior patterns which
include, but are not limited to, breeding, feeding or sheltering. “Incidental take” is defined as
take that is incidental to, and not the purpose of, the carrying out of an otherwise lawful activity.
In June 2015, the Service finalized new regulations implementing the incidental take provisions
of section 7(a)(2) of the Act. The new regulations also clarify the standard regarding when the
Service formulates an Incidental Take Statement [50 CFR 402.14(g)(7)], from “…if such take
may occur” to “…if such take is reasonably certain to occur.” This is not a new standard, but
merely a clarification and codification of the applicable standard that the Service has been using
and is consistent with case law. The standard does not require a guarantee that take will result;
only that the Service establishes a rational basis for a finding of take. The Service continues to
rely on the best available scientific and commercial data, as well as professional judgment, in
reaching these determinations and resolving uncertainties or information gaps.
1502ETAU00-2021-FC-1230
In August 2019, the Service amended regulations that implement section 7 of the Act (83 FR
35178). The rule addressed alternative consultation mechanisms; the definitions of “destruction
or adverse modification” and “effects of the action”; certainty of measures proposed by action
agencies to avoid, minimize, or offset adverse effects; and other improvements to the
consultation process.
AMOUNT OR EXTENT OF TAKE
The Service anticipates that juvenile and adult Balcones spike and Texas fawnsfoot individuals
will be taken as a result of this proposed action. This incidental take is expected to be in the
form of injury and mortality of adult, sub-adult, juvenile, and larval glochidia live stages. The
incidental take is also expected to be in the form of sublethal effects associated with handling
and monitoring activities that may encounter juvenile or adult mussels, or short-duration
reductions in water quality or water quantity associated with water management activities during
critical dry periods, or maintenance activities) and mortality (lethal effects associated with
handling associated with monitoring activities and rare events associated with long-duration
reductions in water quality or water quantity associated with extended periods of critical low
flows, necessary infrastructure repairs, or catastrophic unexpected events). The incidental take is
expected to occur, usually at low levels, over the 20-year term of the CCAA and permit.
The Service anticipates that the Action is reasonably certain to cause incidental take of individual
Balcones spike and Texas fawnsfoot resulting from the covered activities and conservation
measures. Incidental take that occurs as injury due to sub-lethal effects of the BRA’s water
management operations, which disrupt movement, breeding, feeding, or sheltering of adult or
juvenile Balcones spike and Texas fawnsfoot, or larval glochidia, is likely not detectable or
measurable. Incidental take that occurs as direct injury or death due to the BRA’s actions would
also be difficult to measure. Actual habitat degradation may be detectable, but directly
attributing specific effects of that degradation to individuals would be difficult. Shells and fresh
dead individuals could be recovered, but directly attributing cause of mortality would be
difficult. Incidental take associated with effects to host fish would also be difficult to determine.
Furthermore, there is no practical method to measure the number of Balcones spike and Texas
fawnsfoot adults and juveniles (i.e., larval glochidia) present in any particular stream reach at
any particular time.
Larger individuals would likely to be easier to detect, especially because they are usually found
in spatial aggregations called mussel beds. Larger individuals are more likely to be encountered
during monitoring activities and take associated with such encounters is relatively easy to
quantify, track, and report. Although this agreement does not anticipate large scale dewatering
events of entire mussel beds leading to stranding of adult mussels because of the BRA’s
activities, it is still possible that, in combination with factors outside of the BRA’s control, death
of mature individuals could be visibly detectable if entire riffles or bank habitats are persistently
dewatered or otherwise disturbed. Take can be anticipated by loss of available habitat due to
dewatering, excessive scour, water quality degradation, or other factors associated with the
BRA’s covered activities because the covered species are dependent on stable substrates and
clean flowing water.
1602ETAU00-2021-FC-1230
The Service anticipates incidental take of Balcones spike and Texas fawnsfoot will be difficult to
detect for the following reasons: 1) juveniles of the covered species have a small body size and
finding dead or impaired juveniles is unlikely; 2) the species occur in habitats that are difficult to
sample; 3) losses may be masked by seasonal fluctuations in population size (and detectability)
or by losses associated with actions or events outside of the BRA’s control; 4) losses are most
likely to be sublethal and difficult to measure. Therefore, it is not possible to base the overall
incidental take on numbers of individuals. Instead, the Service will base total overall incidental
take on stream miles of potential habitat affected as a surrogate measure.
The causal link between using stream miles of riverine habitat as a surrogate (50 CFR
402.14(i)(1)(i)) for take of individual mussels is the fact that mussels spend the majority of their
life cycle relatively immobile with most of their bodies buried in sediment of the stream bed.
The BRA’s covered activities include physical disturbance of stream beds as well as possible
changes to water quality, water levels, and flow rates. Activities that disturb stream beds and
alter water quality, water levels, and flow rates could injure or kill Balcones spike and Texas
fawnsfoot (adult mussels, juveniles, larval glochidia) or displace mussels or their host fish
(possibly disrupting reproduction) to unsuitable habitats. Low water levels could expose mussels
to desiccation, heat stress, and predation. Water quality degradation could result in excessive
valve closure, which has been reported to have negative effects on mussel health and
reproduction (through increased energetic costs and reduced feeding rates; Haney et al. 2020, p.
13). In most cases, any damage to habitat associated with the BRA’s actions would not be
expected to be permanent (i.e., habitat will be allowed to recover when streamflows recover from
critical thresholds).
Take will be authorized through issuance of an enhancement of survival permit pursuant to
10(a)(1)(A) of the Endangered Species Act. Although we are unable to reasonably anticipate the
actual number of individual adult and juvenile Balcones spike and Texas fawnsfoot that would
be taken by covered activities, we must provide a level at which formal consultation would be
reinitiated. Similarly, the precise amount of stream miles where incidental take could occur as a
result of the Action cannot be known with certainty. However, using stream miles as a proxy for
Balcones spike and Texas fawnsfoot habitat, the Service anticipates that no more than 10% of
stream miles in each of the Mussel Conservation Zones would be affected by BRA’s ongoing
water supply activities and conservation strategy over the 20-year term of the CCAA and permit.
Therefore, if more than: 1) 5.64 miles of stream habitat in Zone A; or 2) 18.16 miles of stream
habitat in Zone B; or 3) 24.62 miles of stream habitat in Zone C; or 4) 35.51 miles of stream
habitat in Zone D is altered or damaged, the BRA must contact the Service immediately and
formal consultation must be reinitiated. Project activities that are likely to cause additional take
should cease during this review period because the exemption provided under section
10(a)(1)(A) would lapse, and any additional take would not be exempt from the section 9
prohibitions.
EFFECT OF THE TAKE
In the accompanying biological and conference opinion, we have determined that the level of
anticipated take is not likely to result in jeopardy to the Balcones spike or Texas fawnsfoot.
Although we anticipate some incidental take to occur, the implementation of the conservation
1702ETAU00-2021-FC-1230
measures proposed in the CCAA should ultimately result in avoidance and minimization of
measureable adverse effects to the covered species and ultimately yield a net conservation
benefit to the Balcones spike and Texas fawnsfoot.
REASONABLE AND PRUDENT MEASURES AND TERMS AND CONDITIONS
The CCAA and associated 10(a)(1)(A) permit contain all measures necessary to avoid, minimize,
and mitigate incidental take of the false spike and Texas fawnsfoot to the maximum extent
practicable and requires that the CCAA be fully implemented. Monitoring will be conducted as
stated in Section 11 (Monitoring and Reporting) of the CCAA. Therefore, no additional
reasonable and prudent measures and terms and conditions are necessary.
Disposition of Dead or Injured Listed Species
Upon locating a dead, injured, or sick listed species (including fresh dead shells but excluding
dead shells with no fleshy materials (i.e., long dead shells, sub-fossil shells, and fossil shells))
initial notification must be made to the Service’s Austin Ecological Services Office, 10711
Burnet Road, Suite 200, Austin, Texas, 78758, phone 512-490-0057, within five working days of
its discovery. Written (or confirmed email) notification must be made within ten calendar days
and include the date, time, and location of the animal, a photograph if possible, and any other
pertinent information. The notification shall be sent to the Austin Ecological Services Field
Office. Care must be taken in handling sick or injured animals to ensure effective treatment and
care, and in handling dead specimens to preserve the biological material in the best possible
state.
CONSERVATION RECOMMENDATIONS
Section 7(a)(1) of the Act directs federal agencies to utilize their authorities to further the
purposes of the Act by carrying out conservation programs for the benefit of endangered and
threatened species. Conservation recommendations are discretionary agency activities to
minimize or avoid adverse effects of a proposed action on listed species or critical habitat, to
help implement recovery plans, or to develop information.
1. The Service recommends the BRA avoid applying glyphosate-containing compounds
where overspray could contaminate surface waters where freshwater mussels could
occur.
2. The Service recommends the BRA work with local, state, and federal partners, as well as
local landowners to promote best land management practices that reduce soil erosion and
contaminant inputs, and improve water quality and quantity in streams throughout the
Brazos River basin.
3. The Service recommends the BRA work with neighboring River Authorities and other
conservation organizations interested in the conservation and management of Balcones
spike and Texas fawnsfoot and other mussels native to the Brazos River basin.
1802ETAU00-2021-FC-1230
The Service requests notification of the implementation of any conservation recommendations so
we may be kept informed of actions minimizing or avoiding adverse effects or benefitting listed
species or their habitats.
REINITIATION NOTICE
This concludes the conference for the issuance of a 10(a)(1)(A) Enhancement of Survival Permit
(permit) to the Brazos River Authority authorizing incidental take of the Balcones spike
(Fusconaia iheringi) and Texas fawnsfoot (Truncilla macrodon). The Service may confirm the
conference opinion as a biological opinion if the proposed species is listed or critical habitat is
designated. If there have been no significant changes in the action as planned or in the
information used during the conference, the Service will confirm the conference opinion as the
biological opinion for the project and no further intra-service section 7 consultation will be
necessary.
The incidental take statement provided in this conference opinion does not become effective
until the species is listed and the conference opinion is adopted as the biological opinion issued
through formal consultation. At that time, the project will be reviewed to determine whether any
take of the proposed species has occurred. Modifications of the opinion and incidental take
statement may be appropriate to reflect that take. No take of the proposed species may occur
between the listing of the species and the adoption of the conference opinion through formal
consultation, or the completion of a subsequent formal consultation.
As provided in 50 CFR §402.16, after listing as threatened or endangered and any subsequent
adoption of this conference opinion, the Service shall re-initiate consultation if: 1) the amount or
extent of incidental take is exceeded; 2) new information reveals effects of the agency action that
may affect the species in a manner or to an extent not considered in the conference opinion; 3)
the agency action is subsequently modified in a manner that causes an effect to the species that
was not considered in this opinion or written concurrences; or 4) a new species is listed or
critical habitat designated that may be affected by the action. In instances where the amount or
extent of incidental take is exceeded, any operations causing such take must cease pending re-
initiation.
Please refer to the consultation number 02ETAU00-2021-FC-1230 in future correspondence
concerning this project. Should you require further assistance or if you have any questions
please contact Mr. Matthew Johnson, Fish and Wildlife Biologist, at 512-490-0057 x253 or
matthew_s_johnson@fws.gov.
Approved:
ADAM Digitally signed by ADAM
ZERRENNER
June 2, 2021
ZERRENNER Date: 2021.06.02 10:17:16
-05'00'
___________________________________ ______________________
Adam Zerrenner, Field Supervisor Date
Austin Ecological Services Field Office
1902ETAU00-2021-FC-1230
LITERATURE CITED
Bonner, T.H., E.L. Oborny, B.M. Littrell, J.A. Stoeckel, B.S. Helms, K.G. Ostrand, P.L. Duncan,
and J. Conway. 2018. Multiple freshwater mussel species of the Brazos River, Colorado
River, and Guadalupe River basins. Final Report to Texas Comptroller of Public
Accounts.
Brazos River Authority (BRA). 2020. Candidate Conservation Agreement with Assurances for
the Balcones Spike and Texas Fawnsfoot in the Brazos River Basin. 175 pp.
Bringolf, R.B., W.G. Cope, S. Mosher, M.C. Barnhart, and D. Shea. 2007. Acute and chronic
toxicity of glyphosate compounds to glochidia and juveniles of Lampsilis siliquiodea
(Unionidae). Environmental Toxicity and Chemistry 26: 2094-2100.
Dall, W.H. 1896. Diagnoses of new mollusks from the survey of the Mexican boundary.
Proceedings of the United States National Museum. 18:1-6.
Dudding, J., M. Hart, J. Khan, C.R. Robertson, R. Lopez, and C.R. Randklev. 2019. Host fish
associations for two highly imperiled mussel species from the southwestern United
States: Cyclonaias necki (Guadalupe Orb) and Fusconaia mitchelli (False Spike).
Freshwater Mollusk Biology and Conservation 22:12-19.
Freshwater Mollusk Conservation Society (FMCS). 2016. A National Strategy for the
Conservation of Native Freshwater Mollusks. Freshwater Mollusk Biology and
Conservation 19:1-21.
Haney, A., H. Abdelrahman, and J.A. Stoeckel. 2020. Effects of thermal and hypoxic stress on
respiratory patterns of three unionid species: implications for management and
conservation. Hydrobiologia 847: 787-802. https://doi.org/10.1007/s10750-019-04138-4
Howells, R.G., R.W. Neck, and H.D. Murray. 1996. Freshwater Mussels of Texas. Texas Parks
and Wildlife Department, Austin, Texas.
Howells, R.G. 2010. Rare mussels: summary of selected biological and ecological data for
Texas. Six Edwards Plateau Species. Biostudies. Kerrville, Texas. 122 pp.
Howells, R.G. 2014. Field Guide to Texas Freshwater Mussels. BioStudies, Kerrville, TX.
Lea, I. 1859. Description of seven new species of Uniones from South Carolina, Florida,
Alabama and Texas. Proceedings of the Academy of Natural Sciences of Philadelphia
11:154-155.
Lea, I. 1862. New Unionidæ of the United States and Arctic America. Journal of the Academy of
Natural Sciences 5: 193-4. Available at: https://biodiversitylibrary.org/page/35217896
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McMahon, R.F. and A.E. Bogan, 2001. Mollusca: Bivalvia. Chapter 11, pp 331- 429 in Thorp,
J.H. and A.P. Covich (eds). Ecology and Classification of North American Freshwater
Invertebrates. Academic Press, San Diego, CA. 1073 pp.
Randklev, C.R., N.A. Johnson, T. Miller, J.M. Morton, J. Dudding, K. Skow, B. Boseman, M.
Hart, E.T. Tsakiris, K. Inoue, and R.R. Lopez. 2017. Freshwater Mussels (Unionidae):
Central and West Texas Final Report. Texas A&M Institute of Renewable Natural
Resources, College Station, Texas.
Smith, C.H., N.A. Johnson, K. Havlik, R.D. Doyle, and C.R. Randklev. 2020. Resolving species
boundaries in the critically imperiled freshwater mussel species, Fusconaia mitchelli
(Bivalvia: Unionidae). Journal of Zoological Systematics and Evolutionary Research
2020;00:1–18. https://doi.org/10.1111/jzs.12412
Strecker, J.K. 1931. The Naiades or Pearly Freshwater Mussels of Texas. Baylor University
Museum Special Bulletin 2:1-71.
U.S. Fish and Wildlife Service (Service). 2019. Species Status Report for the Central Texas
Mussels, Version 1.5. December 2019. Albuquerque, New Mexico. 244 pp.
Williams, J.D., A.E. Bogan, R.S. Butler, K.S. Cummings, J.T. Garner, J.L. Harris, N.A. Johnson,
and G.T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia:
Unionida) of the United States and Canada. Freshwater Mollusk Biology and
Conservation 20:33-58.
2102ETAU00-2021-FC-1230
Appendix 1. Issues and conservation goals identified in the Freshwater Mollusk Conservation Society’s National Strategy for the
Conservation of Native Freshwater Mollusks (FMCS 2016), along with a brief description of how conservation measures from the
Brazos River basin CCAA address identified conservation goals (Excerpted from BRA 2020, pp.18-20).
Issues Goals Conservation Measure How Measure Addresses Goals
1. Increase knowledge of the Informative Field Surveys will help fill data gaps in distributional
distribution and taxonomy of Understand the status and Investigations and Modeling information.
mollusks at multiple scales over trends of mollusk populations
time and make that information to better manage and conserve. Long-term monitoring will assess trends in existing
Long-term Monitoring
available. populations over time.
Future drought scenario modeling will identify spatial
Informative Field and temporal patterns in drought risk to mussel
Investigations and Modeling populations and assist in prioritizing conservation
actions.
Promotes flow conditions adequate for survival and
2. Address the impacts of past,
Environmental Flow Protection long-term persistence of Covered Species and strives to
ongoing, and newly emerging Minimize threats to mollusks
assure water quantity.
stressors on mollusks and their and their habitats.
Avoids detrimental activities in areas of optimal habitat
habitats. Avoidance
for Covered Species and prevents further fragmentation.
Aids in identifying habitat, water quality, and flow-
related stressors important in structuring populations of
Applied Research
Covered Species and will be used to guide adaptive
management.
Future drought scenario modeling will identify spatial
Informative Field and temporal patterns in drought risk to mussel
Investigations and Modeling populations and assist in prioritizing conservation
actions.
Increase understanding of Aids in identifying habitat, water quality, and flow-
3. Understand and conserve the physical, chemical, and related stressors important in structuring populations of
Applied Research
quantity and quality of suitable biological characteristics of Covered Species. This information will be used to guide
habitat for mollusks over time. habitat to support sustainable adaptive management.
assemblages of mollusks. Habitat utilization surveys will assist in understanding
Long-term Monitoring habitat requirements of the Covered Species. This data
will be essential to the adaptive management process.
Conserves habitat through avoidance of detrimental
Avoidance
activities in areas of optimal habitat.
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