Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for Santa Ana Sucker, 77962-78027 [2010-30447]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 239 (Tuesday, December 14, 2010)]
[Rules and Regulations]
[Pages 77962-78027]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-30447]



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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Revised Critical Habitat 
for Santa Ana Sucker; Final Rule

Federal Register / Vol. 75 , No. 239 / Tuesday, December 14, 2010 / 
Rules and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2009-0072; 92210-1117-0000-B4]
RIN 1018-AW23


Endangered and Threatened Wildlife and Plants; Revised Critical 
Habitat for Santa Ana Sucker

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), designate 
critical habitat for Santa Ana sucker (Catostomus santaanae) under the 
Endangered Species Act of 1973, as amended. In total, approximately 
9,331 acres (3,776 hectares) of habitat in the Santa Ana River in San 
Bernardino, Riverside, and Orange Counties and the San Gabriel River 
and Big Tujunga Creek in Los Angeles County in southern California fall 
within the boundaries of the critical habitat designation. This final 
revised designation constitutes an overall increase of approximately 
1,026 acres (415 hectares) from the 2005 designation of critical 
habitat for Santa Ana sucker.

DATES: This rule becomes effective on January 13, 2011.

ADDRESSES: This final rule and the associated final economic analysis 
are available on the Internet at https://www.regulations.gov and https://www.fws.gov/carlsbad/. Comments and materials received, as well as 
supporting documentation used in preparing this final rule are 
available for public inspection, by appointment, during normal business 
hours, at the U.S. Fish and Wildlife Service, Carlsbad Fish and 
Wildlife Office, 6010 Hidden Valley Road, Suite 101, Carlsbad, CA 
92011; telephone 760-431-9440; facsimile 760-431-5901.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, U.S. 
Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, 6010 
Hidden Valley Road, Suite 101, Carlsbad, CA 92011; telephone 760-431-
9440; facsimile (760) 760- 431-5901. If you use a telecommunications 
device for the deaf (TDD), call the Federal Information Relay Service 
(FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

    It is our intent to discuss only those topics directly relevant to 
the development and designation of revised critical habitat for Santa 
Ana sucker in this final rule. In the proposed rule (74 FR 65056; 
December 9, 2009) and the document that made available the draft 
economic analysis (DEA) (75 FR 38441; July 2, 2010), we stated that 
there was new information on the distribution of Santa Ana sucker and 
its habitat within the Santa Ana River that we did not discuss in the 
2005 final critical habitat designation for this species (70 FR 425; 
January 4, 2005). As a result of public comments on this new 
information, we are providing clarification of this information in the 
Habitat and Geographic Range and Status sections of this final rule. 
Additionally, we incorporated information from recent surveys in the 
Santa Ana River (see Geographic Range and Status section) and new 
information on the hydrology and flow regime of the Santa Ana River 
(see Sites for Breeding, Reproduction, and Rearing (or Development) of 
Offspring section). No new information pertaining to the species' 
description, life history, or ecology was received following the 2009 
proposed revised rule and the document that made available the DEA. For 
more information on Santa Ana sucker, refer to the final listing rule 
published in the Federal Register on April 12, 2000 (65 FR 19686); the 
designation and revision of critical habitat published in the Federal 
Register on February 26, 2004 (69 FR 8839), and on January 4, 2005 (70 
FR 425), respectively; the proposed revised critical habitat published 
in the Federal Register on December 9, 2009 (74 FR 65056); and the 
document that made available the DEA published in the Federal Register 
on July 2, 2010 (75 FR 38441).

Habitat

    As discussed in detail in the Habitat section of the proposed 
revised critical habitat rule (74 FR 65056; December 9, 2009), Santa 
Ana sucker requires various substrate types throughout different stages 
of its life. The presence of coarse substrates, including gravel, 
cobble, and a mixture of gravel or cobble with sand, and a combination 
of shallow riffle areas and deeper runs and pools provide optimal 
stream conditions (Haglund et al. 2001, p. 60; Haglund and Baskin 2003, 
p. 55). Areas of shifting sandy substrates are less suitable for 
development of algae, an important food source for suckers (Saiki et 
al. 2007, p. 98). Therefore, an integrated water system that contains 
and provides the appropriate quantity of coarse substrates such as 
gravel, larger cobbles, or boulders that provide the space for 
reproductive development and growth of algae as a primary food source 
is important for a viable population of Santa Ana suckers.
    Saiki et al. (2007, p. 98) indicates that the San Gabriel River 
supports higher body condition Santa Ana suckers (as described by their 
higher length-weight relationship) and greater availability of various 
habitat types than the Santa Ana River. They state that the San Gabriel 
River generally contains a higher abundance of Santa Ana suckers and 
larger individuals, which may be attributed to more suitable habitat 
characters such as cooler water temperature, intermediate water 
velocities, and commonality of pools and riffles with coarser bottom 
substrates, all of which may contribute to a better functioning system 
and more suitable habitat for Santa Ana suckers (Saiki et al. 2007, pp. 
99-100).
    In the San Gabriel River, there are some distinct differences 
between the three forks of the river (north, west, and east), which 
seem to correlate with both fish abundance and life stage occupancy 
(Tennant 2006, pp. 4-5, 9). Overall, the water condition (i.e., lower 
temperature, lower specific conductance, and lower turbidity) and 
habitat available in the San Gabriel River system appear to be primary 
reasons that Santa Ana suckers are in higher abundance and better 
condition compared to those in the Santa Ana River, although other 
variables (i.e., stream width or depth) may also influence the species' 
abundance and condition. For example, in the Santa Ana River, the 
predominate riparian vegetation is the nonnative species Arundo donax 
(giant reed). In Big Tujunga Creek, A. donax can be common in the lower 
reaches (Baskin and Haglund 1999, p. 11; Saiki 2000, pp. 62-80). In the 
San Gabriel River, this nonnative plant is rarely found, and the 
riparian vegetation consists of primarily native vegetation or may be 
bare due to the steeper, mountainous terrain (Saiki 2000, pp. 18-19; 
Saiki et al. 2007, p. 90). Native riparian vegetation provides cover 
and shelter from predators, which is essential for juvenile and adult 
Santa Ana suckers (see Primary Constituent Elements--Cover and Shelter 
and Primary Constituent Elements for Santa Ana Sucker below). Arundo 
donax is an aquatic plant in the genus of perennial reed-like grasses 
(Poaceae) and is often found growing along lakes, streams, and other 
wetted areas. Compared to other riparian vegetation, it is known to use 
excessive amounts of water to supply its exceptionally high growth 
rates (Bell 1997, p. 104) and could crowd out native riparian 
vegetation or possibly lower the water table (Zembal and Hoffman 2000, 
p. 66). In areas where A.

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donax is common, flows may become diminished and sandy pools may form. 
Slow-moving flows and formation of pools are preferred habitat for 
nonnative predators such as largemouth bass (Micropterus salmoides) and 
green sunfish (Lepomis cyanellus), which have been suggested to prey 
heavily on Santa Ana suckers. The effects of A. donax presence may 
negatively affect Santa Ana sucker by altering the instream habitat 
and, may also provide habitat for nonnative predators. However, these 
types of impacts would need to be evaluated within the context of 
potential threats to the Santa Ana sucker.
    The unmodified and unpolluted habitat in the San Gabriel River 
supports what appears to be a healthier and more viable population of 
Santa Ana sucker. Habitat assessments conducted throughout the Big 
Tujunga Creek indicate that the habitat suitability is variable 
throughout the system; however, the river does contain areas that are 
suitable for all Santa Ana sucker life stages (LACDPW 2009, Google 
Earth kmz file). It is likely that because of the variability in 
habitat suitability, the density of Santa Ana suckers in the Big 
Tujunga Creek is patchy and often low (Ecorp Consulting 2010a, p. 5; 
Haglund and Baskin 2010, pp. 5-6).
    Santa Ana sucker habitat may be impacted as a result of wildfires. 
Impacts associated with wildfires may occur immediately or may not 
become apparent until much later. Immediate impacts may include the 
loss of upland and riparian vegetation and creation of roads for fire-
fighting, which may allow greater access to streambeds and facilitate 
increased Off Highway Vehicle (OHV) use, resulting in further habitat 
degradation (USGS 2009, p. 7). Excessive debris flows and changes to 
water quality are anticipated to occur during seasonal rains over the 
next several years in the Big Tujunga Creek and surrounding San Gabriel 
Mountains (USGS 2009, p. 7). Anticipated post-fire impacts to streams 
within the critical habitat designation for Santa Ana sucker include 
ash and debris deposition that may physically alter streambeds and 
pools, increased scouring of riparian and aquatic vegetation, and 
increased water temperature from the short-term loss of canopy shading 
(USFS 2009, p. 5). Post-fire impacts to water quality (such as 
increased turbidity) are also anticipated along with release and 
mobilization of toxic chemicals such as gas, oil, and building 
materials from burned structures and their contents (USFS 2009, p. 6). 
The impacts associated with post-fire winter flows include but are not 
limited to changes in sediment composition, high flows that flush Santa 
Ana suckers into unsuitable habitats, and changes in water quality 
(such as increased turbidity and the introduction of chemicals from 
debris and fire retardant).
    Recreational uses of streams may pose significant impacts to Santa 
Ana sucker habitat. Throughout the drainage systems where Santa Ana 
suckers persist, there are varying levels of recreational use. On U.S. 
Forest Service lands, recreational pressures may be considerable. 
Permanent or intermittent dams are frequently created for recreational 
purposes, such as those used for suction dredging or bathing. These 
dams may degrade instream and bank habitat, decrease water quality by 
increasing turbidity (affect PCE 4), disrupt sediment transport (affect 
PCEs 1 and 2), impede upstream movement, degrade habitat by slowing 
water velocities (affect PCE 3), increase water temperatures (affect 
PCE 5), and encourage excessive growth of algae (Ally 2003, p. 3). In 
addition, presumably, since water depths increase and velocities 
decrease, these areas may harbor nonnative predators (Ally 2003, p. 1; 
Chambers Group 2004, p. 6-4). Recreational residences located within 
the riparian area of the San Gabriel River and Big Tujunga Creek may 
impact Santa Ana sucker because of the improperly functioning septic 
systems at these residences which can degrade water quality conditions 
by increasing water turbidity (PCE 4) as a result of the increased 
nutrient loads in the water (USFS 2007, p. 18), which lead to excessive 
algal growth.

Geographic Range and Status

    As discussed in detail in the Geographic Range and Status section 
of the proposed revised rule (74 FR 65056; December 9, 2009), genetic 
introgression (when a hybrid breeds with one of the parent species) has 
been detected in both Santa Ana sucker and Owens sucker (Catostomus 
fumeiventris) within the Santa Clara River (Ferguson 2009, p. 1; Chabot 
et al. 2009, p. 24), indicating that hybridization between these two 
species has occurred. Moyle (2002, p. 184) and Chabot et al. (2009, p. 
1) recently described hybridization of Santa Ana sucker with Owens 
sucker in the lower Santa Clara River in the vicinity of Fillmore and 
Sespe Creek. As stated in the proposed revised critical habitat rule 
(74 FR 65056; December 9, 2009), a genetic analysis of the populations 
in all four watersheds would provide information on the status of the 
fish throughout the range, including whether the Santa Clara population 
is native, introduced, or hybridized. However, this analysis has not 
been completed to date. Researcher and species' expert opinions on the 
status of the population in the Santa Clara River vary widely. 
Additional research is needed to determine the impact and extent of 
hybridization on genetically pure Santa Ana sucker in the Santa Clara 
River. Given the lack of new genetic information to help us determine 
whether Santa Ana suckers in the Santa Clara River are native or 
introduced, as well as a lack of information on the impact and extent 
of hybridization on genetically pure Santa Ana sucker, we continue to 
adhere to our 2000 decision not to include the Santa Clara River 
population of the Santa Ana sucker as part of the listed entity. 
Therefore, the Santa Clara River area was not included in the proposed 
revision to critical habitat or this final rule.
    The Santa Ana sucker is considered a listed species in the Los 
Angeles, San Gabriel, and Santa Ana River drainages (Service 2000, pp. 
19686-19687). Additionally, the listing rule states that Arroyo 
Tesquesquite, Sunnyslope Creek, Anza Park Drain, and the lower outlet 
of Hidden Valley Drain are used for spawning and nurseries (Service 
2000, p. 19687), and therefore Santa Ana sucker in those areas are 
considered part of the listed entity. The historical survey records for 
this species are not considered complete, and the precise areas 
occupied by the species are difficult to determine with certainty 
because not all areas were surveyed exhaustively and distribution 
literature states that the Los Angeles, San Gabriel, and Santa Ana 
River drainages as a whole were occupied (Moyle 2002, p. 183; 
Greenfield et al. 1970, p. 166; Smith 1966, pp. 53-56). In particular, 
the upper limit of habitat occupied by the Santa Ana sucker within each 
of the Los Angeles, San Gabriel, and Santa Ana River drainages is 
difficult to determine. However, as we note in our analysis of criteria 
used to define critical habitat (see Criteria Used To Identify Critical 
Habitat section below), Santa Ana suckers have not been observed in 
streams or rivers where the instream gradient exceeds 7 degrees. Even 
in areas where the stream gradient is less than 7 degrees, the upper 
limits of occupied habitat within the drainages likely have varied 
through time because of the dynamic nature of these drainage systems. 
Portions of streams may dry out in some years while the same area may 
become occupied by Santa Ana suckers in subsequent years due to the

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presence of water (Baskin et al. 2005, pp. 1-2).
    The current status of Santa Ana sucker in the Santa Ana River 
appears to be declining. In 2009, the lowest Santa Ana sucker density 
since sampling began in 2001was reported by the Santa Ana Sucker 
Conservation Program Team (Team). Although densities of Santa Ana 
sucker have been variable from year to year, the overall density trend 
in the Santa Ana River is decreasing (SMEA 2009, p. 2). Recent research 
conducted by Thompson et al. (2010, pp. 321-332) indicates that the 
areas in the Santa Ana River with the highest quality habitat (gravel 
and cobbles) available for adult, juvenile, and larval stages of Santa 
Ana sucker occur just downstream of Riverside Avenue near the 
Riverside-San Bernardino County line. Further, they believe Santa Ana 
sucker abundance is directly related to the abundance of cobbles and 
gravel and that the lower portion of the survey area contains little to 
no suitable substrates (Thompson et al. 2010, pp. 328-331). Monitoring 
and research results from both the Team (SMEA 2009, pp. 1-5) and 
Thompson et al. (2010, pp. 328-330) show that low abundance of suitable 
habitat is correlated with low Santa Ana sucker abundance, indicating 
that altered fluvial processes (i.e., diminished transport of water and 
coarse sediments), lack of suitable substrate, and impediments to 
movement continue to fragment much of the current distribution of Santa 
Ana sucker in the Santa Ana River watershed.
    Recent survey reports from the West Fork of the San Gabriel River 
indicate that there may be a decreasing trend in Santa Ana sucker 
population (Ecorp Inc. 2007, p. 9; Ecorp Inc. 2010b, p. 9). Monitoring 
of the West Fork of the San Gabriel River within and outside of the 
off-highway vehicle (OHV) area has indicated that Santa Ana sucker is 
generally more abundant at the control sites than in the OHV area 
(Haglund and Baskin 2002, pp. 9-15; Ecorp Inc. 2007, p. 9; Ecorp Inc. 
2010b, p. 9). However, during the 2009 monitoring period, very low 
numbers of Santa Ana suckers and hundreds of nonnative predators were 
captured at all sites within the study area (Ecorp Inc. 2010b, p. 9). 
The report postulates that the flood basin of the San Gabriel Dam was 
full and flooded into areas where Santa Ana suckers are normally 
present; however, water quality measurements do not indicate any 
measureable change (Ecorp Inc. 2010b, p. 7). It is possible that the 
operations of the Cogswell and San Gabriel Dams have impacted the 
habitat suitability for Santa Ana sucker, and, in turn, abundance has 
decreased in the West Fork of the San Gabriel River. More information 
is needed to evaluate the status of Santa Ana sucker in the West Fork 
of the San Gabriel River.

Previous Federal Actions

    Santa Ana sucker was listed as a threatened species under the 
Endangered Species Act of 1973, as amended (Act; 16 U.S.C. 1531 et 
seq.) on April 12, 2000 (65 FR 19686), in the Los Angeles River basin, 
San Gabriel River basin, and Santa Ana River basin. A fourth population 
in the Santa Clara River was not listed because it was presumed to be 
introduced into that watershed. Critical habitat was designated on 
January 4, 2005 (70 FR 425).
    On November 15, 2007, California Trout, Inc., the California-Nevada 
Chapter of the American Fisheries Society, the Center for Biological 
Diversity, and the Friends of the River filed suit against the Service 
alleging the 2005 final designation of critical habitat violated 
provisions of the Act and Administrative Procedure Act [(California 
Trout, Inc., et al., v. United States Fish and Wildlife, et al., Case 
No. 07-CV-05798 (N.D. Cal.) transferred Case No. CV 08-4811 (C.D. 
Cal.)]. We entered into a stipulated settlement agreement with 
plaintiffs that was approved by the district court on January 21, 2009.
    The stipulated agreement required that we submit a proposed revised 
critical habitat for the Santa Ana sucker to the Federal Register by 
December 1, 2009, and a final revised critical habitat by December 1, 
2010. On December 9, 2009, we published in the Federal Register a 
proposed revised critical habitat for the Santa Ana sucker (74 FR 
65056). On July 2, 2010, we published a notice in the Federal Register 
reopening the comment period on the proposed rule and making available 
the DEA (75 FR 38441). With this final rule, we are submitting a final 
revised critical habitat designation to the Federal Register by 
December 1, 2010, in accordance with the stipulated agreement. For 
additional information, please see the Previous Federal Actions section 
of the proposed rule (74 FR 65056; December 9, 2009).

Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (i) The specific areas within the geographical area occupied by a 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (I) Essential to the conservation of the species and
    (II) That may require special management considerations or 
protection; and
    (ii) Specific areas outside the geographical area occupied by a 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means the use 
of all methods and procedures that are necessary to bring any 
endangered or threatened species to the point at which the measures 
provided under the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, transplantation, and in the extraordinary case where 
population pressures within a given ecosystem cannot otherwise be 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7(a)(2) of the 
Act through the prohibition against Federal agencies carrying out, 
funding, or authorizing the destruction or adverse modification of 
critical habitat. Section 7(a)(2) of the Act requires consultation on 
Federal actions that may affect critical habitat. The designation of 
critical habitat does not affect land ownership or establish a refuge, 
wilderness, reserve, preserve, or other conservation area. Such 
designation does not allow the government or public to access private 
lands. Such designation does not require implementation of restoration, 
recovery, or enhancement measures by private landowners. Where a 
landowner requests Federal agency funding or authorization for an 
action that may affect a listed species or critical habitat, the 
consultation requirements of section 7(a)(2) of the Act would apply, 
but even in the event of a destruction or adverse modification finding, 
the landowner's obligation is not to restore or recover the species, 
but to implement reasonable and prudent alternatives to avoid 
destruction or adverse modification of critical habitat.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time it was listed 
must contain the physical and biological features essential to the 
conservation of the species, and be included if those features may 
require special

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management considerations or protection. Critical habitat designations 
identify, to the extent known using the best scientific and commercial 
data available, habitat areas that provide essential life cycle needs 
of the species (areas on which are found the physical and biological 
features laid out in the appropriate quantity and spatial arrangement 
essential to the conservation of the species). Under the Act and 
regulations at 50 CFR 424.12, we can designate critical habitat in 
areas outside the geographical area occupied by the species at the time 
it is listed only when we determine that those areas are essential for 
the conservation of the species and that designation limited to those 
areas occupied at the time of listing would be inadequate to ensure the 
conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. 
Further, our Policy on Information Standards Under the Endangered 
Species Act (published in the Federal Register on July 1, 1994 (59 FR 
34271), the Information Quality Act (section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658), and our associated Information Quality Guidelines 
provide criteria, establish procedures, and provide guidance to ensure 
that our decisions are based on the best scientific data available. 
They require our biologists, to the extent consistent with the Act and 
with the use of the best scientific data available, to use primary and 
original sources of information as the basis for recommendations to 
designate critical habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge.
    Habitat is often dynamic, and species may move from one area to 
another over time. Furthermore, we recognize that critical habitat 
designated at a particular point in time may not include all habitat 
areas that we may later determine are necessary for the recovery of the 
species. For these reasons, a critical habitat designation does not 
signal that habitat outside the designated area is unimportant or may 
not be required for recovery of the species.
    Areas that are important to the conservation of the species, but 
are outside the critical habitat designation, will continue to be 
subject to conservation actions we implement under section 7(a)(1) of 
the Act. Areas that support populations are also subject to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available scientific 
information at the time of the agency action. Federally funded or 
permitted projects affecting listed species outside their designated 
critical habitat areas may still result in jeopardy findings in some 
cases. Similarly, critical habitat designations made on the basis of 
the best available information at the time of designation will not 
control the direction and substance of future recovery plans, habitat 
conservation plans (HCPs), or other species conservation planning 
efforts if information available at the time of these planning efforts 
calls for a different outcome.

Physical and Biological Features

    In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and 
the regulations at 50 CFR 424.12, in determining which areas within the 
geographical area occupied by the species at the time of listing to 
designate as critical habitat, we consider the physical and biological 
features essential to the conservation of the species which may require 
special management considerations or protection. These include, but are 
not limited to:
    1. Space for individual and population growth and for normal 
behavior;
    2. Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    3. Cover or shelter;
    4. Sites for breeding, reproduction, and rearing (or development) 
of offspring; and
    5. Habitats that are protected from disturbance or are 
representative of the historic, geographical, and ecological 
distributions of a species.
    We consider the specific physical and biological features essential 
to the conservation of the species laid out in the appropriate quantity 
and spatial arrangement for the conservation of the species. We derive 
the specific physical and biological features for Santa Ana sucker from 
the biological needs of this species as described in the Critical 
Habitat section of the proposed rule to designate critical habitat for 
Santa Ana sucker, which published in the Federal Register on December 
9, 2009 (74 FR 65056).
    Based on the needs and our current knowledge of the life-history, 
biology, and ecology of the species and the habitat requirements for 
sustaining the essential life history functions of the species, we 
determined that Santa Ana sucker's physical and biological features 
consist of flowing stream habitat (see Primary Constituent Elements 
section for further discussion). However, some portions of this habitat 
may experience significant reductions in, or an absence of, surface 
flows during certain portions of the year (such as during summer 
months) or under certain conditions (such as during severe droughts or 
when artificial sources of water are temporarily suspended). Some areas 
that we consider essential to the conservation of Santa Ana sucker may 
not experience flows except during major storms events. However, these 
areas are critically important components of naturally occurring 
hydrologic and geologic processes because they provide a connected 
hydrologic system within the historical range of this species. We have 
attempted to capture the dynamic nature and importance of these 
processes in identifying the habitat upon which Santa Ana sucker 
depends.

Habitats That Are Representative of the Historic Geographical and 
Ecological Distribution of the Species

    Santa Ana sucker inhabits flowing streams, and has not been 
collected from reservoirs (Swift 2001, p. 15; Moyle 2002, p. 184). 
Water depths and velocities, as well as bed substrates, vary over the 
reaches of these streams creating various habitat features including:
    1. Moderate currents over a uniform, unbroken stream bottom (i.e., 
runs);
    2. Water flowing over gravel and cobble substrates that causes 
ripples to form on the surface of the water (i.e., riffles); and
    3. Deep water areas created by submerged boulders where water is 
cool and relatively still (i.e., pools).
    Streams in southern California are subject to periodic, severe 
flooding that alters channel configuration, instream habitat 
conditions, and vegetation structure (Moyle 2002, p. 183). Hence, as 
stream conditions change, the characteristics of stream and bank 
habitats and their suitability for Santa Ana sucker change, influencing 
the distribution of the fish over time. Therefore, even stream reaches 
where flows may periodically be interrupted or dewatered become 
essential during periods of high flows to allow Santa

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Ana suckers to move between other habitat areas necessary for breeding, 
feeding, and sheltering.
    Gravel beds in shallow, but clear, flowing stream reaches are 
needed for spawning. Shallow areas with sandy substrates and 
overhanging vegetation are needed to support larvae and fry. Juvenile 
and adult Santa Ana suckers require deeper pools of water for foraging, 
shelter during storms, and cover.
    Santa Ana sucker prefers cool water temperatures but has been found 
in waters between 59 and 82 [deg]Fahrenheit (F) (15 and 28 [deg]Celsius 
(C)) in the Santa Ana River (Swift 2001, p. 18). Cooler water 
temperatures are only maintained in some areas by the upwelling of 
cooler groundwater, tributary flows, or shade from overhanging 
vegetation. Overhanging and instream vegetation are also needed for the 
development of an aquatic invertebrate community to supply food for 
adult suckers as well as for protective cover, and shade, which reduces 
water temperature during summer and fall months. Therefore, a complex 
and integrated stream system is needed that: (1) Encompasses sand, 
gravel, cobble, and rock substrates; (2) harbors diverse bed 
morphologies found in deep canyons and alluvial floodplains; (3) 
provides varying water depths and velocities; (4) contains tributaries 
that provide fish with areas of refuge (refugia) from predators and 
during floods and that can also provide suitable breeding habitat; and 
(5) harbors sources of coarse sediment for renewal of substrate in 
occupied areas. The primary constituent elements (PCEs; see Primary 
Constituent Elements for Santa Ana Sucker section for detailed 
discussion) and the resulting physical and biological features 
essential to the conservation of Santa Ana sucker are derived from 
studies of this species' habitat, ecology, and life history as 
described below, in the Background section of the proposed revised rule 
published in the Federal Register on December 9, 2009 (74 FR 65056), in 
the final listing rule published in the Federal Register on April 12, 
2000 (65 FR 19686), in the final critical habitat designation published 
in the Federal Register on February 26, 2004 (69 FR 8839), and in the 
final revised critical habitat designation published in the Federal 
Register on January 4, 2005 (70 FR 425).

Space for Individual and Population Growth and for Normal Behavior

    Santa Ana suckers use various water depths, depending on their 
life-history stage and activity, and do not occupy all reaches of their 
habitat at any one time (Saiki 2000, p. 19; Haglund and Baskin 2003, p. 
53). Larval- and early-stage juvenile Santa Ana suckers prefer the 
shallow margins of streams in water of 2 to 4 inches (in) (5 to 10 
centimeters (cm) in depth; as fish mature, they move into deeper water. 
Adults prefer deep pools for feeding and seeking refuge, riffles of 
varying depths for spawning, and riffles and runs of varying depths for 
movement between pools (Haglund et al. 2003, p. 102). For example, in 
the Santa Ana River, adult Santa Ana suckers have been found in diverse 
habitat areas, including shallow runs of less than 4 in (10 cm) in 
depth, in flowing water up to 5 feet (ft) (150 cm) deep (Saiki 2000, p. 
19; Swift 2001, p. 66), and in pools 6 to 10 ft (200 to 300 cm) deep 
(Allen 2004). They have been found in similarly varying water depths in 
the San Gabriel River (Saiki 2000, p. 48), and Saiki speculates that 
their capture in these various depths is reflective of their ability to 
take advantage of a variety of habitat conditions (2000, p. 25). Flows 
within occupied habitat areas may occasionally become very shallow due 
to seasonal reductions in flow volumes or be interrupted as a result of 
dam operations or releases from wastewater treatment plants (such as in 
the Santa Ana River) in some portions of a stream reach. When stream 
depth is significantly reduced, deep pools become a critically 
important refuge for fish.
    Surface water flows must be present within the stream, but water 
velocities where Santa Ana suckers occur can vary from slight to swift 
(Haglund and Baskin 2003, p. 2). Larvae and fry congregate exclusively 
in almost-still waters, not moving into swifter currents until they 
have matured into later juvenile stages (Swift 2001, pp. 17-18). Swift 
(2001, p. 61) suggests that juvenile fish prefer areas with less water-
velocity than do adults because they can expend less energy maintaining 
their position in the stream. Adult and juvenile Santa Ana suckers in 
the San Gabriel River have been found in waters with bottom velocities 
ranging from 0.17 to 0.51 ft per second (0.05 and 0.15 m per second) 
and mid-column velocities reaching 1.95 ft per second (0.6 m per 
second) (Haglund and Baskin 2002, pp. 38-39). Haglund and Baskin (2003, 
pp. 39 and 53) concluded that there was no evident pattern in the 
locations Santa Ana suckers selected relative to water velocity and 
suggested that they preferentially seek out locations that provide the 
best combination of habitat parameters. In the Santa Ana River, Santa 
Ana suckers have been found in areas with water velocities of up to 2.4 
ft per second (0.74 m per second) where wastewater discharges and 
channelization of the river bed increase water velocity (Saiki 2000, 
pp. 18-19).
    Stream beds containing the mosaic of rock, cobble, and gravel 
preferred by Santa Ana suckers are most prevalent in the San Gabriel 
River (Saiki 2000, pp. 18-19). Within the Santa Ana River, shifting 
sands are the primary substrate constituent upstream of the Prado 
Basin. In the Santa Ana River bed, substrates containing at least 10 
percent gravel, cobble, and rock were documented for a distance of 7 mi 
(12.3 km) downstream from the Rialto Drain in 1999 and 2000 (Swift 
2001, pp. 4, 68-75). Habitat assessments conducted between 2006 and 
2008 indicated that these substrates fluctuated from 2.6 to 6.0 mi (4.2 
to 9.6 km) downstream of the Rialto Drain (Thompson et al. 2010, p. 
328).
    The distribution of Santa Ana suckers across streams varies 
depending upon bed conditions and stream depth. Santa Ana suckers 
within the San Gabriel River are often found mid-channel adjacent to 
submerged cobble, boulders, or manmade structures such as culverts. In 
the Santa Ana River where the streambed is sandier, they are rarely 
found mid-channel, but rather adjacent to shoreline areas near rooted 
vegetation (Saiki 2000, pp. 25, 27). Where preferred habitat conditions 
are absent, Santa Ana suckers make use of available habitats that 
provide some of the same functions provided by preferred habitats 
(Saiki 2000, p. 19).
    The distribution of Santa Ana suckers is also likely dependent on 
instream gradient. While several authors have acknowledged that this 
species cannot access high gradient areas, we are not aware of any 
research quantifying the maximum slope passable by Santa Ana suckers. 
In an attempt to estimate the maximum slope passable by the species, we 
used GIS to analyze the slopes associated with Santa Ana sucker 
occurrence polygons and points in our database for the Santa Ana River, 
San Gabriel River, and Big Tujunga Creek. Based on our analysis, Santa 
Ana suckers have not been found in areas where the instream slope 
exceeds 7 degrees. This could be due to the species' inability to swim 
up these higher gradients or due to the lack of suitable habitat in 
these areas as a result of higher water velocity and a subsequent lack 
of suitable spawning and feeding substrates or both. Also, the 
probability of encountering vertical barriers (such as waterfalls) 
increases as the overall slope across a given distance increases; 
therefore, even if habitat is suitable upstream, it may be inaccessible 
to the species. However,

[[Page 77967]]

more extensive analysis is needed to determine the gradient limitations 
of the species.
    A comparative analysis of suckers within the Santa Ana and San 
Gabriel Rivers revealed that only two cohorts are generally present 
within the Santa Ana River, compared with three in the San Gabriel 
River, indicating that few individual suckers live beyond their second 
year of life in the Santa Ana River (Saiki 2000, p. 13). No 
investigations have occurred to determine the relative lifespan or 
fecundity of Santa Ana suckers as they relate to habitat conditions. 
However, overall habitat conditions for Santa Ana suckers are generally 
better in the San Gabriel River than in the Santa Ana River, which is 
reflected in the overall greater abundance of fish and their better 
body condition in the San Gabriel River (Saiki 2000, pp. 18-28).

Food, Water, Air, Light, Minerals, or Other Nutritional or 
Physiological Requirements

    Suckers (Family Catostomidae) are primarily bottom feeders, sucking 
up algae, small invertebrates, and organic detritus from gravel, 
cobble, rock, and other hard surfaces (Moyle 2002, p. 179). Forage for 
adult Santa Ana suckers is also found in pools (Allen 2003, p. 6). 
Riparian vegetation and emergent aquatic vegetation provide additional 
sources of detritus and aquatic invertebrates such as insects (Leidy et 
al. 2001, p. 5-2). Insects may provide a high energy source of food for 
adult Santa Ana suckers (Saiki 2000, p. 23). In a comparative analysis 
of Santa Ana suckers in the Santa Ana and San Gabriel Rivers, Saiki 
(2000, pp. 27, 98) found that body condition (length-weight 
relationship) of Santa Ana suckers in the San Gabriel River was better 
than that of fish in the Santa Ana River, possibly due to a greater 
abundance of food resources (including algae and insects) found on the 
rocky substrate in the San Gabriel River relative to the sandy 
substrate in the Santa Ana River.
    Although the specific tolerances to water quality variables have 
not been evaluated for Santa Ana sucker, water temperature, dissolved 
oxygen content, and turbidity (such as excessive detritus in the water 
column or protracted suspension of fine-grained sediments) are all 
important aspects of water quality that affect the physiology of fish 
(California Regional Water Quality Control Board (CRWQCB) 1995, pp. 4-
1--4-15). This species has been found in waters between 59 and 82 
[deg]F (15 and 28 [deg]C) in the Santa Ana River (Swift 2001, p. 18). 
Swift (2001, p. 34) states that although a lethal limit for water 
temperature is unknown, water temperatures much above 86 [deg]F (30 
[deg]C) likely limit distribution and movement of this species. Santa 
Ana suckers are generally more abundant in the cooler waters of the San 
Gabriel River than they are in the warmer waters of the Santa Ana River 
(Saiki 2000, pp. 27-28). Researchers conclude that in addition to 
having poor habitat conditions such as sandy substrate and lack of 
instream cover, areas of the Santa Ana River may be devoid of Santa Ana 
suckers due to higher water temperatures (Chadwick and Associates, Inc. 
1992, p. 37).
    Adequate dissolved oxygen is necessary for aquatic life and as 
water warms, its concentration of dissolved oxygen drops, stressing 
fish (CRWQCB 1995, p. 4-3). In general, waters occupied by Santa Ana 
suckers are high in dissolved oxygen (Saiki 2000, pp. 18-19).
    Santa Ana suckers are more abundant in clear rather than in turbid 
(cloudy or hazy) water conditions (Saiki 2000, pp. 28, 52; 2007, p. 
95). This is most likely because suspended sediments interrupt light 
penetration through the water column, causing a reduction in algal 
growth and thus limiting the primary food source of Santa Ana sucker. 
However, while Santa Ana suckers likely avoid turbid waters when 
possible, they have been documented in turbid conditions on occasion 
(Haglund et al. 2002, p. 11). One measurement of turbidity is 
Nephelometric Turbidity Units (NTU), where turbidity level of 1.0 NTU 
equals 1 milligram of particulate per liter of water. Saiki et al. 
(2007, pp. 95-96) found that Santa Ana suckers were more abundant in 
the San Gabriel River where turbidity averaged 5.9 NTUs (ranging from 
4.3 to 8.2 NTUs), and less abundant but not absent in more turbid areas 
of the Santa Ana River where turbidity averaged 29 NTUs (ranging from 
10.1 to 83.4 NTUs). However, Santa Ana suckers have been found in the 
Santa Ana River in an area where turbidity was measured between 85 and 
112 NTUs (Baskin and Haglund 2001, p. 6). Saiki (2000, p. 25) 
speculates that fish occur under less-than-optimal ambient conditions 
because they are using whatever habitat is available to them and cites 
these conditions as a possible reason for reduced abundance of Santa 
Ana suckers in the Santa Ana River relative to their abundance in the 
San Gabriel River.
    Multiple wastewater treatment plants discharge into the Santa Ana 
River and its tributaries and account for most of the dry-season flows 
within the river (CRWQCB 1995, pp. 1-7). The City of San Bernardino 
Municipal Water District's Rapid Infiltration and Extraction Facility, 
Rialto Treatment Plant, and the City of Riverside Regional Water 
Quality Control Plant all discharge into the Santa Ana River. As a 
result of rising groundwater, nonpoint source urban runoff, and these 
wastewater discharges, perennial flows are maintained from the vicinity 
of the Rialto Drain and downstream. Although these discharges contain 
contaminants not found in natural runoff, there is no evidence that the 
concentrations of regulated compounds found in Santa Ana suckers in 
this river exceed mean concentrations found in freshwater fish in other 
areas of the United States (Saiki 2000, p. 24). However, research has 
indicated that anthropogenic chemicals introduced into riverine systems 
may have lasting negative impacts on fish reproductive success (Service 
2008, p. 3). The specific impacts of residual chemicals in discharged 
treated wastewater (such as inorganic compounds, hydrocarbons, 
solvents, steroids, and hormones) are the subject of investigation for 
Santa Ana suckers (Service 2008, p. 2).

Cover or Shelter

    Instream emergent and overhanging riparian vegetation along the 
banks of stream courses provide shade, shelter, and cover for fry, 
juvenile, and adult Santa Ana suckers. Shading is very important to 
Santa Ana suckers that inhabit shallow waters because it reduces water 
temperatures during periods of high summer ambient temperatures. A 
complex stream system including tributaries that contain submerged 
boulders, deep pools, and undercut banks provides cover and shelter for 
juvenile and adult Santa Ana suckers (Saiki et al. 2007, p. 99; Moyle 
et al. 1995, p. 202). Tributaries may provide important shallow-water 
refugia for larvae and fry from larger, predatory fish and act as 
refugia for juvenile and adult Santa Ana suckers during storms.

Sites for Breeding, Reproduction, and Rearing (or Development) of 
Offspring

    Adult Santa Ana suckers spawn over gravel beds in flowing water 
(riffles) where the female deposits the eggs in fine gravel substrate. 
Substrate collected from two spawning locations in tributaries to the 
Santa Ana River consisted of gravel-sized particles ranging in diameter 
from 0.04 to 1.6 in (1.0 to 41.5 mm) (Haglund et al. 2001, p. 47). The 
presence of appropriately sized substrate allows for water flow around 
eggs to prevent sediment from depositing on and smothering the eggs. 
Eggs deposited on sand or silt are likely

[[Page 77968]]

to be washed downstream or be smothered. In addition to appropriate 
substrate, adequate water velocities are necessary to oxygenate eggs. 
Observations of Santa Ana sucker spawning have been reported in streams 
with bottom velocities of 0.65 and 0.77 ft per second (0.20 and 0.23 m 
per second) (Haglund et al. 2003, p. 63).
    Once emerged from the eggs, Santa Ana sucker larvae congregate in 
shallow, slow-moving waters from 1 to 5.5 in (3 to 14 cm) deep over 
very soft sand or mud substrate (Swift 2001, p. 17; Haglund et al. 
2002, pp. 69-71; Haglund et al. 2003, p. 11). This type of habitat is 
usually found along the margins of streams in proximity to emergent 
vegetation. Fry are found almost exclusively found in edgewater 
habitats over silt or sand in water depths of less than 7 in (17 cm) 
where there is little measurable flow; Haglund and Baskin (2003, p. 47) 
speculate this reduces access by larger predatory fish and, because 
shallow waters are warmer, may increase the growth rates of developing 
suckers. Juvenile fish move away from edgewater habitats and congregate 
at the interface of the almost-still waters at the adjacent bank-edge 
and the main stream flows (Swift 2001, pp. 17-18). By the end of their 
first summer, juvenile Santa Ana suckers move into deeper water 
habitats with adults, presumably because they are large enough to 
compete with adult suckers for forage (Swift 2001, p. 18).
    Tributaries may provide essential spawning habitat for the Santa 
Ana sucker, particularly in the Santa Ana River (Chadwick and 
Associates, Inc. 1992, p. 49; Chadwick Ecological Consultants, Inc. 
1996, p. 16; Haglund et al. 2002, pp. 54-60). An abundance of juvenile 
fish has been recorded in multiple tributaries in the Santa Ana River 
(such as the Tequesquite Arroyo and the Evans and Anza drains), and, 
hence, these have been considered possible spawning sites (Chadwick and 
Associates, Inc. 1992, p. 49). However, Swift (2001, p. 26) concluded 
that the species may be attracted to tributaries due to the relatively 
colder water temperatures found there. He stated that most tributaries 
to the Santa Ana River lack either suitable substrates or water 
velocities to support successful spawning. Swift (2001, p. 26) 
considered that only the Rialto Drain and Sunnyslope Creek provided 
habitat conditions suitable to support spawning. These sites are two of 
the few remaining areas containing gravel beds, and management may be 
required to maintain substrate conditions over time (Orange County 
Water District (OCWD) 2009, pp. 6-4--6-5).
    In the hydrologically altered systems in which Santa Ana suckers 
exist, tributaries provide another essential function through 
contribution of water and coarse sediments into the mainstem of rivers. 
In typical unaltered stream systems periodic high flow events not only 
remove fine sand and silt that have covered up coarse sediments that 
are essential for breeding and foraging of Santa Ana sucker, they also 
deliver and replenish coarse sediments (i.e., gravel and cobble) to 
occupied areas from upstream sources. Historical records indicate that 
the upper Santa Ana River above Seven Oaks Dam was a principle 
contributor of sediment to the lower reaches of the Santa Ana River 
(Humphrey et al. 2004, p. 3). However, much of the input of gravel and 
cobble substrate to the lower reaches of the river has decreased since 
the construction and operation of the Seven Oaks Dam in the upper Santa 
Ana River. Therefore, tributaries are of even greater importance to 
ensure flow velocities that clear out silt and other fine sediments 
from occupied areas, and to replenish essential coarse sediment to the 
lower reaches of the Santa Ana River. A sediment transport study of the 
Santa Ana River (Humphrey et al. 2004, p. 2) indicates that 
historically the upper Santa Ana River (above Seven Oaks Dam), City 
Creek, Plunge Creek, and Mill Creek were significant contributors of 
coarse sediment to the occupied reaches of the Santa Ana River. 
However, currently City Creek and Mill Creek are the remaining 
contributors of coarse sediment into the occupied reaches of the Santa 
Ana River since the coarse sediment that was historically delivered by 
the upper Santa Ana River has been trapped behind Seven Oaks Dam and 
Plunge Creek now contains a settling basin that has been modified for 
mining. Therefore, these two tributaries are the only remaining 
significant sources of essential coarse sediment into the mainstem of 
the Santa Ana River below the Seven Oaks Dam, which supplies coarse 
sediment downstream to the occupied reaches of the river.
    Presumably there has been a reduction in transported cobble and 
gravel from the upper Santa Ana River because periodic high flow events 
have been controlled by Seven Oaks Dam, which has also trapped coarse 
sediment behind it. However, there has not been a similar reduction in 
fine sediments, such as silt and sand, to the lower reaches of the 
Santa Ana River (Humphrey et al. 2004, p. 5; Warrick and Rubin 2007, p. 
3). Gravel and cobbles are essential coarse sediments for Santa Ana 
sucker spawning habitat (Moyle 2002, pp. 182-185). Fine sand and silt 
may be deposited on top of suitable coarse spawning sediment because 
flows have declined due to the altered fluvial process in the Santa Ana 
River. Tributaries and lower order streams (upstream areas) provide a 
source of water and coarse sediments that are transported downstream 
(to higher order streams) where the presence of water and coarse 
sediments are essential to the conservation of the species. Therefore, 
flows to clear out fine sand and silt from suitable spawning substrate 
(i.e., gravel and cobble) and flows to transport suitable materials 
from upstream sources for maintenance of spawning substrate are 
essential to the conservation of Santa Ana sucker.
    In the Santa Ana River, Humphrey et al. (2004, p. 7) states a 
critical flow of water of 4,000 cubic feet per second (cfs) or more is 
necessary to transport gravel and cobbles downstream and lower velocity 
flows (500-4,000 cfs) have the ability to move silt and other fine 
sediment that accumulates on top of suitable spawning substrates. The 
critical velocity necessary to move gravel and cobbles is variable 
depending on the conditions and location within the system. For 
example, during a test release of water from behind Seven Oaks Dam of 
approximately 2,500 cfs, boulder-sized rocks were observed moving 
within several hundred feet of the plunge pool (Wood 2010, pers. 
comm.). United States Geological Survey gauging stations along the 
Santa Ana River and City Creek indicate that there are flows sufficient 
to clear out fine sand and silt, and also flows that reach 
approximately 4,000 cfs and above that would deliver essential gravel 
and cobble substrates from upstream sources to downstream to occupied 
areas. These coarse sediments are a component of the physical and 
biological features essential to the conservation of the species (see 
Primary Constituent Elements for the Santa Ana Sucker below). In all 
three of the watersheds where Santa Ana sucker persists, the existence 
of dams has regulated flows and trapped sediments from being 
transported downstream. Therefore, sources of water and coarse 
sediments and the transport of these materials to occupied areas to 
create and maintain habitat conditions suitable for Santa Ana sucker 
breeding and foraging within these tributaries and lower order streams 
is essential to the conservation of the species.

[[Page 77969]]

Primary Constituent Elements (PCEs) for Santa Ana Sucker

    Under the Act and its implementing regulations, we are required to 
identify the physical and biological features within the geographical 
area occupied by Santa Ana sucker at the time of listing that are 
essential to the conservation of the species and which may require 
special management considerations or protection. The physical and 
biological features are those PCEs laid out in a specific spatial 
arrangement and quantity determined to be essential to the conservation 
of the species. We are designating critical habitat in areas within the 
geographical area that were occupied by the species at the time of 
listing that continue to be occupied, and that contain the PCEs in the 
quantity and spatial arrangement to support life-history functions 
essential to the conservation of the species. We are also designating 
areas outside the geographical area occupied by the species at the time 
of listing that are not occupied but are essential for the conservation 
of the species. See Criteria Used To Identify Critical Habitat section 
below for a discussion of the species' geographic range.
    We believe conservation of Santa Ana sucker is dependent upon 
multiple factors, including the conservation and management of areas to 
maintain suitable ecological functions where existing populations 
survive and reproduce. The areas we are designating as critical habitat 
provide some or all of the physical or biological features essential 
for the conservation of this species. Based on the best available 
information, the PCEs essential to the conservation of Santa Ana sucker 
are the following:
    1. A functioning hydrological system within the historical 
geographic range of Santa Ana sucker that experiences peaks and ebbs in 
the water volume (either naturally or regulated) that encompasses areas 
that provide or contain sources of water and coarse sediment necessary 
to maintain all life stages of the species, including adults, 
juveniles, larvae, and eggs, in the riverine environment;
    2. Stream channel substrate consisting of a mosaic of loose sand, 
gravel, cobble, and boulder substrates in a series of riffles, runs, 
pools, and shallow sandy stream margins necessary to maintain various 
life stages of the species, including adults, juveniles, larvae, and 
eggs, in the riverine environment;
    3. Water depths greater than 1.2 in (3 cm) and bottom water 
velocities greater than 0.01 ft per second (0.03 m per second);
    4. Clear or only occasionally turbid water;
    5. Water temperatures less than 86 [deg]F (30 [deg]C);
    6. Instream habitat that includes food sources (such as 
zooplankton, phytoplankton, and aquatic invertebrates), and associated 
vegetation such as aquatic emergent vegetation and adjacent riparian 
vegetation to provide: (a) Shading to reduce water temperature when 
ambient temperatures are high, (b) shelter during periods of high water 
velocity, and (c) protective cover from predators; and
    7. Areas within perennial stream courses that may be periodically 
dewatered, but that serve as connective corridors between occupied or 
seasonally occupied habitat and through which the species may move when 
the habitat is wetted.
    All occupied units designated as critical habitat contain the PCEs 
in the appropriate quantity and spatial arrangement essential to the 
conservation of this species and support multiple life processes for 
Santa Ana sucker.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the specific 
areas within the geographical area occupied by the species at the time 
of listing contain the physical and biological features that are 
essential to the conservation of the species and may require special 
management considerations or protection.
    All areas included in this final critical habitat designation will 
require some level of management to address the current and future 
threats to the physical and biological features essential to the 
conservation of Santa Ana sucker. Special management considerations or 
protection may be required to minimize habitat destruction, 
degradation, and fragmentation associated with the following threats, 
among others: Water diversion; alteration of stream channels and 
watersheds; reduction of water quantity associated with urban 
development and human recreational activities, including swimming, and 
construction and operation of golf courses; and OHV use. For discussion 
of the threats to Santa Ana sucker and its habitat, please see the 
Summary of Comments and Recommendations and Summary of Factors 
Affecting the Species sections of the final listing rule (65 FR 19686; 
April 12, 2000) and the Public Comments and Critical Habitat Unit 
Descriptions sections of the 2005 final critical habitat rule (70 FR 
425; January 4, 2005). Please also see Critical Habitat Units section 
below for a discussion of the threats in each critical habitat unit.
    In addition to the threats to Santa Ana sucker and its habitat 
described in the final listing and previous critical habitat rules, the 
physical and biological features essential to the conservation of Santa 
Ana sucker may require special management considerations or protection 
to minimize habitat destruction, degradation, and fragmentation 
associated with the construction of dams, the operation of recreational 
residences, the construction of road crossings and bridges across 
waterways, nonnative vegetation and predators, the impacts of wildfires 
to riparian and instream conditions, and the degradation of water 
quality.

Recreational Dams

    Artificial manmade dams are often constructed from boulders, logs, 
and trash to create pools within these rivers for fishing, swimming, 
wading, and bathing (Ally 2003, p. 1; Chambers Group 2004, p. 6-4). The 
construction of these ``recreational'' dams degrades instream and 
possibly bank habitat, increases turbidity (PCE 4), disrupts sediment 
transport, and impedes upstream movement of Santa Ana suckers, 
especially during droughts (Ally 2003, pp. 1-3), thereby fragmenting 
habitat connectivity within occupied habitat. During the spawning 
season, these dams cause instream disruptions that can bury gravel beds 
(PCE 2) used for spawning (Ally 2003, p. 1). Recreational dams can also 
further degrade habitat by slowing water velocities (PCE 3), increasing 
water temperatures (PCE 5), and encouraging excessive growth of algae 
(Ally 2003, p. 3). In addition, presumably, because water depths 
increase and velocities decrease, these areas may harbor nonnative 
predators. Management activities that could ameliorate these threats 
include patrolling by enforcement officers or rangers throughout the 
accessible recreational areas within the critical habitat designation. 
Prevention of recreational dams will help protect the PCEs by ensuring 
the hydrologic system continues to function (PCE 1) by delivering cool, 
clear water with sufficient food sources (PCEs 2 through 6) that are 
essential to the conservation of Santa Ana sucker.

Recreational Residences

    The U.S. Forest Service (USFS) issues special use permits for the 
operation and maintenance of private recreational residences within the 
boundaries of the

[[Page 77970]]

Angeles National Forest along Big Tujunga Creek and the North and West 
Forks of the San Gabriel River. Improperly functioning septic systems 
at these residences can degrade water quality conditions by increasing 
water turbidity (PCE 4) as a result of the increased nutrient loads in 
the water (USFS 2007, p. 18), which lead to excessive algal growth. 
Management activities that could ameliorate these threats include 
limiting the number of allowable recreational residences and requiring 
that septic systems are properly functioning within areas that are 
hydrologically connected to areas designated as critical habitat. 
Limiting the number of residences and ensuring the proper function of 
their septic systems will help protect PCE 4 by preventing additional 
nutrient loads from entering the water and increasing water turbidity 
(PCE 4) to the detriment of Santa Ana sucker.

Road Crossings and Bridges

    Road crossings and bridges constructed across waterways can impact 
Santa Ana sucker by creating permanent or intermittent barriers to 
upstream movement and fragmenting connective corridors between areas of 
occupied habitat (PCE 7). Bridge footings and pier protections (such as 
concrete aprons that span the waterway) accelerate water velocities 
(PCE 3) and, in the absence of sediment in the water (PCE 2), scour 
sediments from the streambed immediately downstream. With sufficient 
scouring, the elevation of the downstream bed of the stream may become 
so low that Santa Ana suckers cannot swim upstream from that point; 
scouring can also create pools that favor predatory nonnative fish. 
Culverts constructed under road crossings can act as barriers to 
movement when a culvert becomes filled in with sediment, reducing the 
amount of water (PCE 1) and sediment (PCE 2) that could be transported 
downstream. Drop structures that function as a support for road 
crossings or bridges as a result of gradient changes within the river 
may also create a temporary barrier to water and sediment transport and 
Santa Ana sucker movement. The extent, however, to which these 
structures constitute barriers depends on the quantity of water flowing 
and sediment transport in a given year and over time. For example, 
sediment-filled culverts that create a barrier to movement one year may 
be passable in another year if high water flows remove trapped 
sediments. Road crossings and bridges can also impact the species by 
altering the hydrology of the system (PCE 1), rerouting water flow into 
less suitable habitat. Management activities that could ameliorate 
these threats include modifying culverts or drop structures to ensure 
the connective corridor is maintained through a gradient that is 
passable by water and sediment and Santa Ana suckers (i.e., 7 degrees 
as described in the Criteria Used To Identify Critical Habitat section) 
within the critical habitat designation. Maintenance of these corridors 
(PCE 7) and ensuring a passable gradient (PCE 1) will help protect the 
PCEs (2 through 5) that are essential to the conservation of Santa Ana 
sucker.

Water and Sediment Transport or Removal

    The transport of both water and sediment are essential components 
to the conservation of Santa Ana sucker (PCEs 1 through 5). The 
presence of sufficient water and appropriate sediment may be impacted 
by operations attributed, but not limited to, dams operation of 
hydroelectric power facilities, water diversion, sediment removal, or 
flood control activities. Natural flow regimes have inevitably been 
impacted in the Santa Ana River, Los Angeles River, and San Gabriel 
River basins as a result of alterations such as dams, diversions, 
channelization, or other flood control activities. The impacts to Santa 
Ana sucker and its habitat attributable to these activities have yet to 
be fully described or understood. However, as these activities 
continue, there appear to be impacts to Santa Ana sucker and its 
habitat through alteration of the hydrologic system and the function of