Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the Santa Ana Sucker (Catostomus santaanae, 65056-65087 [E9-29024]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 74, Number 235 (Wednesday, December 9, 2009)]
[Proposed Rules]
[Pages 65056-65087]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-29024]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2009-0072]
[92210-1117-0000-B4]
[RIN 1018-AW23]


Endangered and Threatened Wildlife and Plants; Revised Critical 
Habitat for the Santa Ana Sucker (Catostomus santaanae); Proposed Rule

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
revise the designated critical habitat for the Santa Ana sucker 
(Catostomus santaanae). The areas identified in this proposed rule 
constitute a revision of the areas designated as critical habitat for 
the Santa Ana sucker on January 4, 2005. In the 2005 final rule, we 
designated 8,305 ac (3,361 ha) of critical habitat in Los Angeles 
County. Approximately 9,605 acres (ac) (3,887 hectares (ha)) of habitat 
in the Santa Ana River (San Bernardino, Riverside, and Orange Counties) 
and the San Gabriel River and Big Tujunga Creek (Los Angeles County) in 
southern California fall within the boundaries of the proposed revised 
critical habitat designation.

DATES: We will consider comments we receive on or before February 8, 
2010. We must receive requests for public hearings, in writing, at the 
address shown in the FOR FURTHER INFORMATION CONTACT section by January 
25, 2010.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments to Docket No. FWS-R8-
ES-2009-0072.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R8-ES-2009-0072; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see the Public Comments section below for more information).

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) 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:

Public Comments

    We intend any final action resulting from this proposal to be as 
accurate and as effective as possible. Therefore, we request comments 
or suggestions on this proposed rule. We particularly seek comments 
concerning:
    (1) The reasons we should or should not revise the designation of 
habitat as ``critical habitat'' under section 4 of the Endangered 
Species Act of 1973, as amended (Act; 16 U.S.C. 1531 et seq.), 
including whether the benefit of designation would outweigh any threats 
to the species caused by the designation, such that the designation of 
critical habitat is prudent.
    (2) Specific information on:
     Areas that provide habitat for the Santa Ana sucker that 
we did not discuss in this proposed critical habitat rule,
     Areas within the geographical area occupied by the species 
at the time of listing that contain the physical and biological 
features essential to the conservation of the species which may require 
special management considerations or protection, that we should include 
in the designation and reason(s) why (see Physical and Biological 
Features section below for further discussion.), and
     Areas outside the geographical area occupied by the 
species at the time of listing that are essential for the conservation 
of the species and why.
     (3) Specific information on our proposed designation of City Creek 
and the Santa Ana River above Seven Oaks Dam to provide habitat for 
future reintroduction of the Santa Ana sucker to augment the Santa Ana 
sucker population in the Santa Ana River. See Critical Habitat Units 
section below.
     (4) Specific information on the Santa Ana sucker, habitat 
conditions, and the presence of physical and biological features 
essential for the conservation of the species in Subunit 1B below Prado 
Dam.
     (5) Specific information on the sediment contribution from 
tributaries to the Santa Ana River below Prado Dam (Subunit 1B).
     (6) Specific information on the Santa Ana sucker, habitat 
conditions, and the presence of potential permanent barriers to 
movement in Big Tujunga Wash (Subunit 3A), particularly between the Big 
Tujunga Canyon Road Bridge and the Big Tujunga Dam. See Critical 
Habitat Units section below.
     (7) Specific information on in-stream gradient (slope) limitations 
of the species. In this proposed revised rule, we assume that Santa Ana 
suckers are unable to occupy stream sections where the in-stream slope 
exceeds 7 degrees. See Primary Constituent Elements (PCEs) section 
below.
     (8) Land-use designations and current or planned activities in the 
areas proposed as critical habitat, as well as their possible effects 
on proposed critical habitat.
    (9) Comments or information that may assist us in identifying or 
clarifying the PCEs. See Primary Constituent Elements section below for 
further discussion of PCEs.
    (10) How the proposed revised critical habitat boundaries could be 
refined to more closely circumscribe the areas identified as containing 
the features essential to the species' conservation.
     (11) Any probable economic, national-security, or other impacts of 
designating particular areas as critical habitat, and, in particular, 
any impacts on small entities (e.g., small businesses or small 
governments), and the benefits of including or excluding areas that 
exhibit these impacts.
     (12) Whether any specific areas being proposed as critical habitat 
should be excluded under section 4(b)(2) of the Act, and whether the 
benefits of potentially excluding any particular area outweigh the 
benefits of including that area under section 4(b)(2) of the Act. See 
Exclusions section below for further discussion.
    (13) The potential exclusion of Subunits 1B and 1C under section 
4(b)(2) of the Act based on the benefits to the species provided by 
implementation of the Santa Ana Sucker Conservation Program and whether 
the benefits of exclusion of this area outweigh the benefits of 
including this area as critical habitat, and why. See Exclusions 
section below for further discussion.
    (14) Information on any quantifiable economic costs or benefits of 
the proposed revised designation of critical habitat.
    (15) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and

[[Page 65057]]

understanding, or to better accommodate public concerns and comments.
    Our final determination concerning critical habitat for the Santa 
Ana sucker will take into consideration all written comments we receive 
during the comment period, including comments we have requested from 
peer reviewers, comments we receive during a public hearing should we 
receive a request for one, and any additional information we receive 
during the 60-day comment period. Our final determination will also 
consider all written comments and any additional information we receive 
during the comment period for the draft economic analysis. All comments 
will be included in the public record for this rulemaking. On the basis 
of peer reviewer and public comments, we may, during the development of 
our final determination, find that areas within those proposed do not 
meet the definition of critical habitat, that some modifications to the 
described boundaries are appropriate, or that some areas may be 
excluded from the final determination under section 4(b)(2) of the Act 
based on Secretarial discretion.
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section.
    We will post your entire comment--including your personal 
identifying information--on https://www.regulations.gov. If you provide 
personal identifying information, you may request at the top of your 
document that we withhold this information from public review. However, 
we cannot guarantee that we will be able to do so. We will post all 
hardcopy comments on https://www.regulations.gov. Please include 
sufficient information with your comment to allow us to verify any 
scientific or commercial data you submit.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Ventura Fish and Wildlife Office (see the FOR FURTHER 
INFORMATION CONTACT section).
    You may obtain copies of this proposed revised rule by mail from 
the Carlsbad Fish and Wildlife Office (see the FOR FURTHER INFORMATION 
CONTACT section) or by visiting the Federal eRulemaking Portal at 
https://www.regulations.gov.

Background

    It is our intent to discuss only those topics directly relevant to 
the revised designation of critical habitat in this proposed rule. This 
rule incorporates new information on the distribution of the 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. No new information pertaining to the species' description, 
life history, or ecology was received following the 2005 final critical 
habitat designation for this species; summary information relevant to 
this species critical habitat is provided below. For more information 
on the Santa Ana sucker, refer to the final listing rule published in 
the Federal Register on April 12, 2000 (65 FR 19686), and the 
designation and revision of critical habitat for the Santa Ana sucker 
published in the Federal Register on February 26, 2004 (69 FR 8839), 
and on January 4, 2005 (70 FR 426), respectively.

Species Description

    The Santa Ana sucker is a small, short-lived member of the sucker 
family of fishes (Catostomidae), named so primarily because of the 
downward orientation and anatomy of their mouth-parts which allow them 
to suck up small invertebrates, algae, and other organic matter with 
their fleshy, protrusible lips (Moyle 2002, p. 179). Santa Ana suckers 
are generally less than 6.3 inch (in) (16 centimeters (cm) in length, 
are silvery-white below and darker along the back, with irregular 
dorsal blotches on the sides and faint patterns of pigmentation 
arranged in lateral stripes, and the membranes connecting the rays of 
the caudal (tail) fin are pigmented (Moyle 2002, p. 182). Spawning 
tubercles, or raised growths on sexually mature fish, particularly at 
the beginning of the breeding season, are present on most parts of the 
body of breeding males and are heaviest on the anal fin, caudal fin, 
and lower half of the caudal peduncle. Female suckers grow tubercles on 
the caudal fin and caudal peduncle (Moyle 2002, pp. 182-183).

Habitat

    The Santa Ana sucker occurs in the watersheds draining the San 
Gabriel and San Bernardino Mountains of southern California. Their 
historical distribution extended from upper watershed areas to the 
Pacific Ocean; hence, they are capable of living in habitats as diverse 
as mountain streams and rivers in alluvial floodplains (Moyle 2002, p. 
183; Swift et al. 1993, pp. 119-121). Sediment loads are high in the 
San Gabriel and San Bernardino Mountains (National Research Council 
1996, p. 29). The streams that this species inhabits are generally 
perennial streams with water ranging in depth from a few inches to 
several feet and with currents ranging from slight to swift (Haglund 
and Baskin 2003, p. 2). They are also naturally subject to periodic, 
severe flooding (Moyle 2002, p.183). However, decades of groundwater 
extraction have lowered subsurface groundwater levels within the 
historical range of the Santa Ana sucker (California Regional Water 
Quality Control Board 1995, pp. 1-4 to 1-5). In conjunction with 
periodic reductions in stream flows during extended periods of drought 
typical of southern California climate cycles, all streams that support 
the Santa Ana sucker experience less perennial flow (California 
Regional Water Quality Control Board 1995, p. 1-4). Flows also 
fluctuate artificially, either increasing or decreasing in an unnatural 
manner as a result of dam operations and, in some areas, discharges 
from wastewater treatment plants.
    Santa Ana suckers are most abundant in unpolluted, clear water that 
is typically less than 72 degrees Fahrenheit ([deg]F) (22 degrees 
Celsius ([deg]C)) in temperature (Moyle and Yoshiyama 1992, p. 203). 
Santa Ana suckers appear to tolerate the relatively warmer water 
temperatures and turbid water conditions that occur in the Santa Ana 
River (Chadwick and Associates, Inc. 1992, p. 37; Moyle and Yoshiyama 
1992, p. 203; Saiki 2000, p. 25). Santa Ana suckers prefer streams that 
contain coarse substrates, including gravel, cobble, and mixtures of 
gravel or cobble with sand and a combination of shallow riffle areas 
and deeper runs and pools (Haglund and Baskin 2003, p. 55; Haglund et 
al. 2001, p. 60). This species also prefers habitat containing in-
stream or bank-side riparian vegetation that provides shade/cover; 
however, vegetation becomes less important where larger, deeper pools 
and riffles are present (Moyle 2002, p. 183). Open stream reaches with 
shifting sandy substrates typically lack an accumulation of woody 
debris and are less suitable for the development of an aquatic 
invertebrate community (Leidy et al. 2001, p. 5-3). Areas of shifting 
sandy substrates are also less suitable for development of algae, an 
important food source for suckers (Saiki et al. 2007, p. 98).
    Tributaries, particularly near their confluence with occupied areas 
of the mainstem of the river, may also provide important habitat for 
the Santa Ana sucker (Chadwick and Associates, Inc.

[[Page 65058]]

1992, p. 49; Chadwick Ecological Consultants, Inc. 1996, p. 16; Haglund 
et al. 2002, pp. 54-60), providing shallow-water refuge for larvae and 
fry from larger predatory fish and acting as refuge for juvenile and 
adult Santa Ana suckers during storms. Additionally, the species may be 
attracted to tributaries due to the relatively colder water 
temperatures found there (Swift 2001, p. 26).

Life History

    Santa Ana suckers feed on algae, zooplankton (such as diatoms), and 
detritus that they scrape from the surfaces of rocks and other hard 
substrates. These food sources constitute approximately 98 percent of 
their diet, with the remainder consisting of aquatic insect larvae, 
fish scales, and fish eggs (Greenfield et al. 1970, p. 174). While 
smaller, younger Santa Ana suckers feed primarily on algae, diatoms, 
and detritus, insects appear to become a more significant part of the 
diet of larger individuals (Greenfield et al. 1970, p. 174).
    Santa Ana suckers typically live about 3 years, although, based on 
size, some may live longer than 4 years (Drake 1988, p. 56). Male and 
female Santa Ana suckers grow at approximately the same rate 
(Greenfield et al. 1970, p. 174). Spawning typically occurs in the 
spring, generally beginning in mid-March, peaking in April, and 
concluding by early July (Moyle 2002, p. 183). However, juveniles less 
than 1 inch (in) (25 millimeters (mm)) in length have been collected in 
the Santa Ana River as early as February (Haglund et al. 2003, p. 103) 
and as late as August (Chadwick and Associates, Inc. 1992, pp. 51, 54). 
In the San Gabriel River, juveniles less than 1 in (25 millimeters 
(mm)) have been collected in both December (Saiki 2000, p. 54) and 
August (Tennant 2006, p. 2). These data indicate spawning may be 
protracted and the timing highly variable, depending on local 
conditions in each watershed (such as water temperature, stream size, 
or pattern of seasonal runoff).
    Santa Ana suckers become reproductively mature during spring 
following hatching (Greenfield et al. 1970, p. 172). Females deposit 
eggs in gravel substrate without constructing any type of nest; 
however, eggs are well-camouflaged in the gravel. The eggs are demesal 
and adhesive, meaning they adhere to the substrate rather than floating 
and dispersing on the surface of the water (Greenfield et al. 1970, p. 
169). Eggs deposited in ambient stream temperatures of 55 [deg]F (13 
[deg]C) have been found to hatch larvae approximately 0.3 in (7 mm) in 
total length within 360 hours (approximately 15 days) of fertilization. 
When larvae are approximately 0.6 in (16 mm) long, the mouth becomes 
sub-terminal and the larva transform into fry (Greenfield et al. 1970, 
p. 169).
    Fecundity in the Santa Ana suckers is exceptionally high relative 
to that of other suckers (Moyle 2002, p. 183). Females can lay between 
4,400 and 16,000 eggs at a given time with larger females laying 
greater numbers of eggs than smaller females (Greenfield et al. 1970, 
p. 170). Hence, average overall growth of fish likely affects 
population fitness. The combination of early sexual maturity, 
protracted spawning period, and high fecundity allows the Santa Ana 
sucker to quickly repopulate streams following periodic flood events 
that can otherwise decimate populations (Greenfield et al.1970, pp. 
166, 177, 178), provided that there is a refuge available to fish 
within the stream. Winter flood events may contribute to catastrophic 
decreases in abundance by transporting Santa Ana suckers downstream to 
areas with unsuitable habitat. Such floods, when of sufficient 
magnitude, also disrupt the aquatic invertebrate community, thereby 
reducing habitat quality for the Santa Ana sucker until stream bed 
conditions stabilize and the diversity and abundance of this forage 
source is re-established (Haglund and Baskin 1992, p. 45, 56; Leidy et 
al. 2001, p. 5-3). Conversely, summer droughts may strand Santa Ana 
suckers in isolated pools where they are exposed to unsuitable water-
quality conditions or an increased probability of predation. Both 
conditions highlight the importance of refuge areas with more stable 
habitat conditions for the conservation of the Santa Ana sucker.

Geographic Range and Status

    As discussed in the final rule (65 FR 19686; April 12, 2000), 
listing the Santa Ana sucker as threatened, this species' historical 
range includes the rivers and larger streams emanating from the San 
Gabriel and San Bernardino Mountains in Ventura, Los Angeles, Orange, 
Riverside, and San Bernardino Counties. The species is currently known 
to occur in the Santa Ana River (San Bernardino, Riverside, and Orange 
Counties) and the San Gabriel River and Big Tujunga Creek (Los Angeles 
County). However, information about the distribution of the Santa Ana 
sucker in many tributaries within its historical range is incomplete. 
For example, Santa Ana suckers were recently found in San Dimas Creek, 
a tributary to the San Gabriel River that is isolated from remaining 
occupied habitat in the San Gabriel River by development (Chambers 
Group 2008, pp. 1-3). See the final listing rule for a detailed 
discussion of this species' historical range.
    A population of the Santa Ana sucker is also found in the Santa 
Clara River. However, we determined at the time of listing that there 
was sufficient evidence to conclude that this population of Santa Ana 
sucker is not native to this river and hence, we did not include the 
Santa Clara River population in the geographic range of the listed 
Santa Ana Sucker (65 FR 19686; April 12, 2000). We have no new 
information that clarifies the status of this species as native or 
nonnative to this river. A genetic analysis of the populations in all 
four watersheds (Santa Clara, Santa Ana, San Gabriel, and Los Angeles) 
would assist in determining the origin of the species in the Santa 
Clara River; however, this analysis has not been completed at this 
time.
    In addition to a lack of information clarifying the status of this 
species as native or nonnative, hybrids between the Santa Ana sucker 
and the Owens sucker have been collected in the lower Santa Clara River 
in the vicinity of Fillmore and within Sespe Creek (Moyle 2002, p. 
182). The Owens sucker (Catostomus fumeiventris), which is endemic to 
the Owens River watershed in southeastern California, has been 
documented in the Santa Clara River since the 1930s (Hubbs et al. 1943, 
p. 47). This species was apparently introduced to the Santa Clara River 
through transfers of Owens River water via the Owens Aqueduct (Bell 
1978, p. 14). Recently, genetic introgression (which is the 
backcrossing of hybrid offspring with one of its parent species) has 
been detected in both Santa Ana and Owens suckers within the Santa 
Clara River (Ferguson 2009, p.1; Chabot et al. 2009, p. 24), indicating 
that hybridization between these two species has occurred. However, 
additional research is needed to determine the impact of hybridization 
on genetically ``pure'' Santa Ana sucker in the Santa Clara River.
    Therefore, given the lack of new information on the status of this 
species as native or nonnative as well as a lack of information on the 
impacts 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. 
As a consequence, the Santa Clara River area has not been included in 
this proposed revision to critical habitat.
    The current distribution of the listed Santa Ana sucker is 
delimited by dams

[[Page 65059]]

or other impassable structures that preclude further dispersal or 
migration of fish (Cogswell Reservoir on the West Fork; the ``Bridge-
of-No-Return'' on the North Fork of the San Gabriel River; the Big 
Tujunga Dam on Big Tujunga Creek; and the La Cadena drop structure in 
the Santa Ana River). Additionally, decades of water diversion and 
water withdrawal have permanently altered the natural watershed flows 
within the Los Angeles and Santa Ana watershed region (California 
Regional Water Quality Control Board 1995, pp. 1-2 to 1-4). The current 
distribution is also delimited by dams (Hansen Dam on Big Tujunga 
Creek, San Gabriel Dam on San Gabriel River, and a series of rubber 
dams just below Weir Canyon Road on the Santa Ana River) and the 
permanent loss of suitable downstream habitat areas as a result of 
urban development (Moyle 2002, p. 184). Altered fluvial processes and 
impediments to movement fragment much of the current range of the Santa 
Ana sucker within each watershed. In its remaining habitat, severe 
restriction of natural water flows causes impacts to populations of the 
Santa Ana sucker including stranding and reduction in usable habitat 
areas when tributaries run dry (Moyle 2002, p. 184). See the final 
listing rule (65 FR 19686; April 12, 2000) and the Special Management 
Considerations or Protection section below for additional discussion of 
the current threats to the species in areas included in this proposed 
revised critical habitat designation.

Previous Federal Actions

    The Santa Ana sucker was listed as a threatened species on April 
12, 2000 (65 FR 19686), in the Santa Ana River, San Gabriel River, and 
Big Tujunga Creek. A fourth population in the Santa Clara River was not 
listed because it was presumed to be introduced into that watershed 
(see Geographic Range and Status section above). Pursuant to a 
settlement agreement with California Trout, Inc., the California-Nevada 
Chapter of the American Fisheries Society, the Center for Biological 
Diversity, and the Friends of the River (plaintiffs) [California Trout, 
et al. v. Norton, et al. (Case No. 97-3779, N.D. Cal)], we published a 
proposed and final critical habitat designation in the Federal Register 
on February 26, 2004, that encompassed 21,129 ac (8,551 ha) in the 
Santa Ana River, San Gabriel River, and Big Tujunga Creek. To give the 
public an opportunity to comment on the critical habitat designation, 
including the opportunity for a public hearing, and to enable the 
Service to complete and circulate for public review an Economic 
Analysis of the critical habitat designation, we published and 
solicited comment on the proposed rule (69 FR 8911). Subsequently, we 
published a notice in the Federal Register on August 19, 2004 (69 FR 
51416), announcing the reopening of a 30-day comment period on the 
proposed rule and the holding of a public hearing on September 9, 2004, 
in Pasadena, California. A final revised critical habitat rule was 
published in the Federal Register on January 4, 2005, designating a 
total of 8,305 ac (3,361 ha) in the San Gabriel River and Big Tujunga 
Creek in San Bernardino County. On July 20, 2007 (Service 2007, pp. 1-
2), we announced that we would review the January 4, 2005, final 
critical habitat rule after questions were raised about the integrity 
of scientific information used and whether the decision made was 
consistent with the appropriate legal standards. Based on our review of 
the 2005 final critical habitat designation, we determined it was 
necessary to revise critical habitat and this rule proposes those 
revisions.
    On November 15, 2007, the parties listed above 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.)]. The plaintiffs alleged that our January 4, 2005, final 
revised critical habitat designation for the Santa Ana sucker was 
insufficient for various reasons and should include the Santa Clara 
River population. We entered into a stipulated settlement agreement 
with plaintiffs that was approved by the district court on January 21, 
2009. Pursuant to the district court order, we committed to submit a 
proposed revised critical habitat designation for the Santa Ana sucker 
to the Federal Register by December 1, 2009, and submit a final revised 
critical habitat designation to the Federal Register by December 1, 
2010.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as:
    (1) 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:
    (a) essential to the conservation of the species and
    (b) that may require special management considerations or 
protection; and
     (2) 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) 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 of listing 
must contain physical or biological features that are essential to the 
conservation of the species, and be included only if those features may 
require special management considerations or protection. Critical 
habitat designations identify, to the extent known using the best 
scientific data available, habitat areas that provide essential life 
cycle needs of the species (i.e., areas on which are found the primary 
constituent

[[Page 65060]]

elements (PCEs) laid out in the appropriate quantity and spatial 
arrangement essential to the conservation of the species). Under the 
Act, we can designate critical habitat in areas outside the 
geographical area occupied by the species at the time it is listed as 
critical habitat only when we determine that those areas are essential 
for the conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific 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 determine 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 designation of 
critical habitat may not include all habitat areas that we may 
eventually 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 promote 
the recovery of the species.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the Act. They are also 
subject to the regulatory protections afforded by section 9 of the Act 
and 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.

Methods

    As required by section 4(b) of the Act, we used the best scientific 
and commercial data available in determining areas occupied at the time 
of listing that contain the features essential to the conservation of 
the Santa Ana sucker. We reviewed the approach to the conservation of 
the Santa Ana sucker provided in the 2004 final critical habitat 
designation for the Santa Ana sucker (69 FR 8839; February 26, 2004); 
the 2005 final revised critical habitat designation (70 FR 426; January 
4, 2005); information from State, Federal, and local government 
agencies; and information from academia and private organizations that 
collected scientific data on the species. Other information we used for 
this proposed revised critical habitat includes: published and 
unpublished papers, reports, academic theses, species and habitat 
surveys; Geographic Information System (GIS) data (such as species 
occurrence data, habitat data, land use, topography, digital aerial 
photography, and ownership maps); correspondence to the Service from 
recognized experts; site visits by Service biologists; and other 
information as available. Mapping for this proposed revised critical 
habitat designation was completed using ESRI ArcMap 9.3.1 (ESRI, Inc. 
2009).

Physical and Biological Features

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR Sec.  424.12(b), in determining which areas occupied by the 
species at the time of listing to propose as critical habitat, we 
consider those physical and biological features that are essential to 
the conservation of the species that may require special management 
considerations or protection. We consider the physical and biological 
features to be the PCEs laid out in the appropriate quantity and 
spatial arrangement for the conservation of the species. The PCEs 
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 historical, geographical, and ecological 
distributions of a species.
    We derived the PCEs required for the Santa Ana sucker from its 
biological needs. The areas proposed as revised critical habitat 
consist of flowing stream habitat, although 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, when artificial sources of water are temporarily suspended). 
Some areas that we consider essential to the conservation of the Santa 
Ana sucker may not experience flows except during major storms events. 
However, these areas are critical important components of naturally-
occurring hydrologic and geologic processes in the historical range of 
this species. We have attempted to capture the dynamic nature and 
importance of these processes to the ecological function upon which the 
Santa Ana sucker depends.

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

    The 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, in-stream 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 
the Santa Ana sucker changes, influencing the distribution of

[[Page 65061]]

the fish over time. Therefore, even stream reaches where flows may 
periodically be interrupted or dewatered become important during 
periods of high flows to allow Santa 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 forage, 
shelter during storms, and cover.
    The Santa Ana sucker prefers cool water temperatures and 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). These cooler water temperatures 
are only maintained in some areas by the upwelling of cooler 
groundwater, tributary flows, or shade from overhanging vegetation. 
Overhanging and in-stream 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 
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 sediment 
for renewal of substrate in occupied areas. The PCEs and the resulting 
physical and biological features essential for the conservation of the 
Santa Ana sucker are derived from studies of this species' habitat, 
ecology, and life history as described below, in the Background section 
in this proposed rule, in the final listing rule published in the 
Federal Register on April 12, 2000 (65 FR 19686), in the designation of 
critical habitat published in the Federal Register on February 26, 2004 
(69 FR 8839), and in the final revised critical habitat published in 
the Federal Register on January 4, 2005 (70 FR 426).

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 in (5 to 10 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 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 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 
concluded that there was no evident pattern in the locations the Santa 
Ana sucker selected relative to water velocity and suggested that 
suckers preferentially seek out locations that provide the best 
combination of habitat parameters (Haglund and Baskin 2003, pp. 39 and 
53). 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). In the Santa Ana 
River, suckers have historically been found at the Imperial Highway 
Bridge in Orange County (Chadwick and Associates, Inc. 1992, p. 45). 
However, Saiki (2000, p. 28) failed to detect Santa Ana suckers there 
in 1999 and believes the numbers of fish found at this site may have 
declined and become extirpated from the area.
    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. 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. 2009, p. 11).
    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 man made 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 
in-stream 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 the Santa Ana 
sucker. In an attempt to estimate the maximum slope passable by the 
species, we used GIS to analyze the slopes associated with the 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 sucker have not been found in areas where the in-
stream slope exceeds 7 degrees. This could be due to the species' 
inability to swim up these higher gradients and/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

[[Page 65062]]

and feeding substrates. 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, more 
extensive analysis is needed to determine the gradient limitations of 
the species and we are seeking additional information on this topic 
(see Public Comments section above).
    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 life-span 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 better body 
condition of suckers in the San Gabriel River (Saiki 2000, pp. 18-28).

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

    Suckers 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 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 the 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 1995, pp. 4-1 
to 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 in-
stream 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 (California Regional Water Quality Control Board, Santa Ana Region 
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, reducing algal growth that is the 
primary forage of the Santa Ana sucker. One measurement of turbidity is 
Nephelometric Turbidity Units (NTU). Saiki (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 in 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). Therefore, 
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). 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 (California Regional Water Quality Control Board 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).

Cover or Shelter

    In-stream 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 due to high summer ambient temperatures. A complex stream 
system containing 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 to be washed downstream or be 
smothered. In addition to appropriate substrate, adequate water 
velocities are necessary to oxygenate eggs. Santa Ana sucker spawning 
has been reported in streams with bottom velocities of 0.65

[[Page 65063]]

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 (Haglund et al. 2003, p. 11; Haglund et 
al. 2002, pp. 69-71; Swift 2001, p. 17). This type of habitat is 
usually found along the margins of streams in proximity to emergent 
vegetation. Fry are found almost exclusively 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 restoration may be 
required to maintain substrate conditions over time (Orange County 
Water District (OCWD) 2009, pp. 6-4 - 6-5).

Primary Constituent Elements for the Santa Ana Sucker

    Pursuant to the Act and its implementing regulations, we are 
required to identify the physical and biological features within the 
geographical area occupied by the 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 proposing to designate critical 
habitat in areas within the geographical area that were occupied by the 
species at the time of listing that are and continue also currently to 
be occupied today, and that contain the PCEs in the quantity and 
spatial arrangement to support life history functions essential for the 
conservation of the species. We are also proposing to designate areas 
outside the geographical area occupied by the species at the time of 
listing that are not occupied but are essential to 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 the Santa Ana sucker is dependent upon 
multiple factors, including the conservation and management of areas to 
maintain ``normal'' ecological functions where existing populations 
survive and reproduce. The areas we are proposing 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 primary constituent elements essential for the 
conservation of the sucker are the following:
    (1) A functioning hydrological system within the historical 
geographic range of the Santa Ana sucker that experiences peaks and 
ebbs in the water volume (either naturally or regulated) necessary to 
maintain all life stages of the species, including adults, juveniles, 
larva, 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, larva, 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) In-stream 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 proposed 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 
the Santa Ana sucker.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the physical 
and biological features within the geographical area occupied by the 
species at the time of listing that are essential to the conservation 
of the species may require special management considerations or 
protection.
    All areas included in our proposed revision of critical habitat 
will require some level of management to address the current and future 
threats to the physical and biological features essential to the 
conservation of the 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, 
construction and operation of golf courses; and off-highway vehicle 
(OHV) use. For discussion of the threats to the 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 final critical habitat rule 
(70 FR 439; January 4, 2005). Please also see Critical Habitat Units 
section below for a discussion of the threats in each proposed critical 
habitat unit.
    In addition to the threats to the Santa Ana sucker and its habitat 
described in the final listing and critical habitat

[[Page 65064]]

rules, the physical and biological features essential to the 
conservation of the Santa Ana sucker may require special management 
considerations or protection to minimize habitat destruction, 
degradation, and fragmentation associated with the construction of 
recreational dams, the operation of recreational residences, and the 
construction of road crossings and bridges across waterways.

Recreational Dams

    People construct artificial dams from boulders, logs, and trash to 
create pools within these rivers for fishing, swimming, wading, and 
bathing (Ally 2003, p. 1). The construction of ``recreational'' dams 
degrades in-stream 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. When dams 
exist during the spawning season, these in-stream disruptions 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).

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 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 nutrient loads into the water (USFS BA 
2007, p. 18) and increasing water turbidity (PCE 4).

Road Crossings and Bridges

    Road crossings and bridges constructed across waterways can impact 
the Santa Ana sucker by creating semi permanent barriers to upstream 
movement and fragmenting connective corridors between areas of occupied 
habitat. 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. 
However, the extent to which these structures constitute permanent or 
temporary 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.

Criteria Used To Identify Critical Habitat

    Using the best scientific and commercial data available as required 
by section 4(b)(1)(A) of the Act, we identified those areas to propose 
for revised designation as critical habitat that, within the 
geographical area occupied by the species at the time of listing (see 
Geographic Range and Status section), possess those physical and 
biological features essential to the conservation of the Santa Ana 
Sucker and which may require special management considerations or 
protection. We also considered the area outside the geographical area 
occupied by the species at the time of listing for any areas that are 
essential for the conservation of the Santa Ana Sucker.
    At the time the Santa Ana sucker was listed in 2000, the 
geographical area occupied by the species was considered to include the 
Los Angeles, San Gabriel, and Santa Ana River basins (65 FR 19686; 
April 12, 2000). Specifically, the listing rule identifies the 
following areas in each river basin as being within the geographic 
range occupied by the species: (1) The Santa Ana River basin including 
the Santa Ana River below Prado Dam, the Santa Ana River above Prado 
Dam to the City of Riverside, and the following tributaries: 
Tequesquite Arroyo, Sunnyslope Channel, and Anza Park Drain; (2) the 
San Gabriel River basin, including the West, North, and East forks of 
the San Gabriel River and Bear [Canyon] Creek, which is a tributary of 
the West Fork of the San Gabriel River; and (3) the Los Angeles River 
basin, including Big Tujunga Creek, between Big Tujunga Dam and Hansen 
Dam, and Hain