Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Jollyville Plateau salamander (Eurycea tonkawae) as Endangered With Critical Habitat, 71040-71054 [E7-23757]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 239 (Thursday, December 13, 2007)]
[PROR]
[Pages 71040-71054]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-23757]



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Part VI





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; 12-Month Finding on a 
Petition To List the Jollyville Plateau salamander (Eurycea tonkawae) 
as Endangered With Critical Habitat; Proposed Rule

Federal Register / Vol. 72, No. 239 / Thursday, December 13, 2007 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List the Jollyville Plateau salamander (Eurycea 
tonkawae) as Endangered With Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
12-month finding on a petition to list the Jollyville Plateau 
salamander (Eurycea tonkawae) as endangered and to designate critical 
habitat under the Endangered Species Act of 1973, as amended (Act). 
After review of all available scientific and commercial information, we 
find that listing the Jollyville Plateau salamander as threatened or 
endangered is warranted. Currently, however, listing of the Jollyville 
Plateau salamander is precluded by higher priority actions to amend the 
Lists of Endangered and Threatened Wildlife and Plants. Upon 
publication of this 12-month petition finding, we will add Jollyville 
Plateau salamander to our candidate species list. We will develop a 
proposed rule to list this species as our priorities allow. We will 
make any determination on critical habitat during development of the 
proposed listing rule.

DATES: We made the finding announced in this document on December 13, 
2007.

ADDRESSES: The supporting file for this finding is available for public 
inspection, by appointment, during normal business hours at the Austin 
Ecological Services Office, U.S. Fish and Wildlife Service, 10711 
Burnet Road, Suite 200, Austin, TX 78758. The finding is available via 
the Internet at www.fws.gov/endangered/. Please submit any new 
information, materials, comments, or questions concerning this finding 
to the above address or via electronic mail (e-mail) at fw2_
jps@fws.gov.

FOR FURTHER INFORMATION CONTACT: Adam Zerrenner, Field Supervisor, 
Austin Ecological Services Office (see ADDRESSES); by telephone at 512-
490-0057; or by facsimile at 512-490-0974. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Background

    Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires 
that, for any petition to revise the Lists of Endangered and Threatened 
Wildlife and Plants that contains substantial scientific and commercial 
information indicating that listing may be warranted, we make a finding 
within 12 months of the date of our receipt of the petition on whether 
the petitioned action is: (a) Not warranted, (b) warranted, or (c) 
warranted, but the immediate proposal of a regulation implementing the 
petitioned action is precluded by other pending proposals to determine 
whether any species is threatened or endangered. Such 12-month findings 
are to be published promptly in the Federal Register. Section 
4(b)(3)(C) of the Act requires that we treat a petition for which the 
requested action is found to be warranted but precluded as though 
resubmitted on the date of such finding, and we must make a subsequent 
finding within 12 months.

Previous Federal Action

    On June 13, 2005, we received a petition, dated June 10, 2005, from 
Save Our Springs Alliance (SOSA), requesting that the Jollyville 
Plateau salamander (Eurycea tonkawae) be listed as an endangered 
species in accordance with section 4 of the Act.
    Action on this petition was precluded by court orders and 
settlement agreements for other listing actions that required all of 
our listing funds for fiscal year 2005 and a substantial portion of our 
listing funds for fiscal year 2006. On September 29, 2005, we received 
a 60-day notice of intent to sue from SOSA for failing to make a timely 
90-day finding. On December 1, 2005, we sent a letter to SOSA informing 
them that we would not likely make a petition finding during fiscal 
year 2006 due to higher priority actions.
    Subsequently, in fiscal year 2006, funding became available to act 
on the petition. We began working on the 90-day finding at that time. 
On August 10, 2006, SOSA filed a complaint against the Service for 
failure to issue a 90-day petition finding under section 4 of the Act 
for the Jollyville Plateau salamander. In our December 11, 2006, motion 
for summary judgment, we informed the court that based on current 
funding and workload projections, we believed that we could complete a 
90-day finding by February 6, 2007, and if we determined that the 
petition provided substantial scientific or commercial information, we 
could make a 12-month warranted or not warranted finding by December 1, 
2007. On February 13, 2007, we published a 90-day petition finding (72 
FR 6699) in which we concluded that the petition presented substantial 
information indicating that listing may be warranted. This notice 
constitutes the 12-month finding on the June 10, 2005, petition to list 
the Jollyville Plateau salamander as endangered.

Taxonomy and Species Description

    The Jollyville Plateau salamander was recently described as Eurycea 
tonkawae by Chippendale, et al. (2000, pp. 1-48), based on morphology 
and mitochondrial DNA tests. The Jollyville Plateau salamander is a 
neotenic (does not transform into a terrestrial form) member of the 
family Plethodontidae. As neotenic salamanders, they retain external 
gills and inhabit aquatic habitats (springs, spring-runs, and wet 
caves) throughout their lives (City of Austin (COA) 2001, p. 3). Water 
for the salamanders is provided by infiltration of surface water 
through the soil into the aquifer which discharges from springs as 
groundwater (Schram 1995, p. 91). Juvenile Jollyville Plateau 
salamanders are less than 1.5 inches (3.8 centimeters); adults are 
typically 1.5 to 2 inches ( 3.8-5 centimeters) long (COA 2001a, p. 5). 
Those salamanders occurring in spring habitat have large, well-
developed eyes; wide, yellowish heads; blunt, rounded snouts; dark 
greenish-brown bodies; and bright yellowish-orange tails (Chippendale, 
et al. 2000, pp. 33-34). Some cave forms of Jollyville Plateau 
salamanders exhibit cave-associated morphologies, such as eye 
reduction, flattening of the head, and dullness or loss of color 
(Chippendale, et al. 2000, p. 37).
    Genetic analysis suggests that Jollyville Plateau salamanders 
occurring in caves may actually be separate species from the surface-
dwelling forms, but more study is needed to confirm this, because 
sample sizes from the caves were small (Chippendale, et al. 2000, pp. 
36-37). For the purposes of this finding, we are considering all of the 
Jollyville Plateau salamanders described in Chippendale, et al. (2000, 
pp. 32-37) as one species.

Distribution

    The Jollyville Plateau salamander occurs in the Jollyville Plateau 
and Brushy Creek areas of the Edwards Plateau in Travis and Williamson 
Counties, Texas (Chippendale, et al. 2000, pp. 35-36; Bowles, et al. 
2006, p. 112; Sweet 1982, p. 433). Upon classification as a species, 
Jollyville Plateau salamanders were known from Brushy Creek and, within 
the Jollyville Plateau, from Bull Creek, Cypress Creek,

[[Page 71041]]

Long Hollow Creek, Shoal Creek, and Walnut Creek drainages 
(Chippendale, et al. 2000, p. 36). Since it was described, the 
Jollyville Plateau salamander has been documented within the Lake Creek 
watershed (COA 2006, p. 1).
    Cave dwelling Jollyville Plateau salamanders are known from 1 cave 
in the Cypress Creek drainage and 12 caves in the Buttercup Creek cave 
system in the Brushy Creek drainage (Chippendale, et al. 2000, p. 49; 
Russell 1993, p. 21; Service 1999, p. 6; HNTB 2005, p. 60). While the 
entrances to these caves are located within particular watersheds, the 
subsurface waters could move in a different direction from the surface 
waters. For example, dyes injected into three of the Buttercup Creek 
caves later surfaced at one spring (proving subsurface connection of 
these caves) to the south in the Long Hollow Creek drainage (Hauwert 
and Warton 1997, pp. 11, 13), rather than to the east where Brushy 
Creek flows. No further subsurface flow studies have been completed in 
caves inhabited by Jollyville Plateau salamanders.

Habitat

    The Jollyville Plateau salamander's spring-fed tributary habitat is 
typically characterized by a depth of less than 1 foot (0.3 meters) of 
cool, well oxygenated water (COA 2001a, p. 128; Bowles, et al. 2006, p. 
118) supplied by the underlying Edwards Aquifer (Cole, et al. 1995, p. 
33). Jollyville Plateau salamanders are typically found near springs or 
seep outflows, and are thought to require constant temperatures (Sweet 
1982, pp. 433-434; Bowles, et al. 2006, p. 117). Salamander densities 
are higher in pools and riffles and in areas with rubble, cobble, or 
boulder substrates rather than on solid bedrock (COA 2001a, p. 128; 
Bowles, et al. 2006, pp. 114-116).
    Surface-dwelling Jollyville Plateau salamanders also occur in 
subsurface habitat within the underground aquifer (COA 2001a, p. 65; 
Bowles, et al. 2006, p. 118). While no one has physically observed 
these salamanders in the aquifer, there are observations that support 
this behavior. For example, City of Austin biologists have observed 
Jollyville Plateau salamanders at spring sites where the springs and 
associated spring runs had previously ceased flowing, particularly 
during the 2006 drought, and the surrounding area dried (COA 2006, pp. 
5-6). Additionally, City of Austin biologists have noted low counts for 
small juveniles followed by high counts for large (presumably older) 
juveniles at several monitoring sites, indicating small juveniles spent 
time within the subsurface habitat (COA 2001a, pp. 65-66).

Biology

    Jollyville Plateau salamander breeding events have not been 
observed. Eggs have also not been observed in or around springs or in 
spring runs, indicating egg laying and early development likely occurs 
in the subsurface aquifer (COA 2001a, p. 4). Bowles, et al. (2006, p. 
114) observed gravid females (those with eggs visible through the 
abdominal wall) between November and February and noted the number of 
juvenile salamanders was higher from March to August. In an effort to 
learn more about the reproductive biology of Jollyville Plateau 
salamander, the City of Austin collected salamanders from the wild to 
start a captive breeding program (COA 2006, pp. 17-18).
    Eurycea species in Texas have been found to eat a variety of 
benthic macroinvertebrates (insects in their larval stage that are 
found at the bottom of a body of water), such as amphipods and 
chironomid larvae (midges) (COA 2001a, pp. 5-6). These small 
invertebrates are also dependant on aquatic habitats for their survival 
(Price, et al. 1999, p. 2).

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations at 50 CFR 424 set forth procedures for adding species to 
the Federal List of Endangered and Threatened Wildlife. In making this 
finding, we summarize below information regarding the status and 
threats to this species in relation to the five factors in section 
4(a)(1) of the Act. In making our 12-month finding, we considered all 
scientific and commercial information in our files, including 
information received during the comment period that ended April 16, 
2006 (72 FR 6699).
    This status review found threats to the Jollyville Plateau 
salamander related to Factors A, C, and D. The primary threat to the 
species is from habitat modification (Factor A) in the form of 
declining water quality due to the effects of current and future urban 
development. Other less significant threats to the species' habitat 
include declining water quantity in groundwater aquifers that support 
spring flows, direct habitat alterations from human disturbance, and 
habitat modification from nonnative feral pig activity. Some threats 
exist from predation by fish and infections of chytrid fungus on 
salamander appendages (Factor C), but neither of these threats appears 
to result in a substantial negative response by the species overall. In 
addition, State regulations and local ordinances intended to protect 
water quality integrity are not currently adequate to prevent habitat 
degradation in the aquatic environments occupied by the salamander 
(Factor D).

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of the Species' Habitat or Range

    Habitat modification, in the form of degraded water quality, is the 
primary threat to the Jollyville Plateau salamander. The range of the 
salamander is largely within the urban environment of the Austin, 
Texas, metropolitan area (Cole 1995, p. 28; COA 2006, pp. 45-50). Urban 
development upstream of salamander habitat provides sources of various 
pollutants from construction and maintenance of residential and 
commercial structures and associated roads and pipelines. These sources 
contribute pollutants such as sediments, fertilizers, pesticides, and 
petroleum products into salamander habitat. During rainstorms, water 
runs off these urban areas, mobilizing and transporting pollutants into 
the aquatic habitat of the Jollyville Plateau salamander decreasing 
water quality. Degraded water quality has been linked to deformities in 
salamanders in some locations (COA 2006, p. 26) and declines in 
abundance and lower densities of salamanders in some locations with 
developed watersheds, compared to areas that are undeveloped.
    Water quality degradation in salamander habitat has been cited as a 
substantial concern in several studies (Chippendale, et al. 2000, p. 
36; Bowles, et al. 2006, pp. 118-119; COA 2006, pp. 45-50). The 
majority of the discussion under factor A will focus on evaluating the 
nature and extent of decreased water quality and its correlation to the 
level of urban development, the primary source of this threat. 
Additionally, we will address the possible threat due to declining 
water quantity (loss of spring flows) in Jollyville Plateau salamander 
habitat. Although lack of water quantity is a concern, there is not 
sufficient information currently available to determine how significant 
the threat to the salamander from spring flow losses may be, other than 
this threat likely exacerbates threats from degraded water quality. 
Other minor threats to habitat include direct alteration from human 
disturbance and activities by non-native feral hogs (Sus scrofa).

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City of Austin Monitoring Data

    We relied heavily on data provided by the City of Austin in this 
status review of the Jollyville Plateau salamander. The City of Austin 
has been monitoring this species' abundance at many locations since 
1996. At the same time, the City of Austin has been measuring various 
water quality and flow parameters within the salamander's habitats. In 
June 2001, they published a comprehensive report of the initial results 
of their monitoring efforts between 1996 and 1999 (COA 2001a). The City 
of Austin continued to collect information on the Jollyville Plateau 
salamander and its habitat and produced other interim reports. 
Following publication of our 90-day finding for the salamander, the 
City of Austin completed a report that summarized monitoring efforts 
from 1996 through 2006 (COA 2006).
    We particularly focused on the results of the data collected by the 
City of Austin on salamander abundance and water quality at long-term 
monitoring sites. We found this dataset robust in evaluating the 
abundance of salamanders based on visual counts at nine locations 
representative of the salamander's range. Overall, the dataset 
contained 357 independent counts of salamanders between December 1996 
and January 2007 (10 years). The results show that 4 of the 9 sites had 
statistically significant declines in salamander abundance over the 
last 10 years (COA 2006, p. 4). The average number of salamanders 
counted at these 4 sites declined from 27 salamanders counted during 
surveys from 1996 to 1999 to an average of 4 salamanders counted during 
surveys from 2004 to 2007. The City reports that these declines are 
related to degraded water quality from urban development in the 
contributing watersheds of the monitoring sites (COA 2006, p. 48). 
Quantifying the nature and extent of the impacts from urban development 
was a key part of this status review because it characterizes the 
extent and magnitude of the primary threats to Jollyville Plateau 
salamander.

Source of Water

    Jollyville Plateau salamanders are dependent upon a constant supply 
of clean water from the northern segment of the Edwards Aquifer (COA 
2001a, p. 3). This segment of the Edwards Aquifer extends from the 
Colorado River in Travis County north to the Lampasas River in southern 
Bell County (TWD 2003, p. 3). Water quality at springs that provide 
habitat for Jollyville Plateau salamanders is influenced by both 
groundwater and surface water interdependently. Surface water can 
directly supply water to salamander habitats during storm water runoff 
and also serves as the source for recharge to groundwater aquifers that 
later discharge to the surface through springs. The northern segment of 
the Edwards Aquifer where these salamanders occur is not well-studied 
compared to other parts of the Edwards Aquifer (TWDB (Texas Water 
Development Board) 2003, p. 1) and, therefore, the recharge areas and 
flow paths have not been thoroughly described.
    Groundwater recharge in the Jollyville Plateau area is described as 
occurring primarily by filtration of water through the surface soils 
(rather than through larger, more direct faults and fissures as in 
other segments of the Edwards Aquifer) (Schram 1995, p. 91). This 
recharge mechanism was predicted to result in urbanization impacts to 
water quality over long-term periods (as opposed to short-term 
responses as in other segments of the Edwards Aquifer), depending on 
the extent and type of development patterns that occur in the area 
(Schram 1995, p. 91). Our analysis of threats to habitat focuses on the 
status of urban development and, therefore, the potential sources for 
pollutants, in the surface watersheds that drain into stream segments 
where salamanders occur. The base flow issuing from springs in these 
stream segments (that is, the portion of stream flow not directly 
resulting from storm water runoff) is supported by aquifer-dependent 
spring flows. Groundwater in this area can move in directions 
independent of surface water flows (Hauwert and Warton 1997, pp. 11, 
13). Although specific aquifer sources and recharge areas for the 
groundwater are not well documented, information available has shown 
that both groundwater (based on analysis of water from immediate spring 
discharge) (COA 2001a, pp. 54-56) and surface water (based on 
observations of increased sedimentation) (COA 2006, pp. 37, 45-47) are 
affected by urban development.

Urban Development as a Source of Pollutants

    The range of the Jollyville Plateau salamander is limited to 
northwest Travis County and southwest Williamson County, Texas, an area 
of rapid human population growth. For example, the population of the 
City of Austin grew from 251,808 people in 1970 to 656,562 people in 
2000. By 2007, the population had grown to 735,088 people (COA 2007a, 
p. 1). This represents a 192 percent increase over the 37-year period. 
Within the range of the areas that contribute storm water runoff to 
salamander habitats, urban development has included residential and 
commercial structures, golf courses, and the associated roads and 
utility pipelines (Cole 1995, p. 28; COA 2001a, pp.10-12).
    As development increases (see Extent of Development in the 
Foreseeable Future below) more opportunities exist for the chronic, 
long-term introduction of non-point source pollutants into the 
environments. For example, the ongoing application of pesticides and 
fertilizers to lawns is a constant source of pollutants (Menzer and 
Nelson 1980, pp. 663, 637-652). Petroleum products are also inherent 
components of urban environments from automobile operation and 
maintenance (Van Metre, et al. 2000, p. 4069). During rain events, 
these chemical pollutants, which accumulate in soils and on impervious 
surfaces (such as roofs, parking lots, and roads) during dry periods, 
are transported by water downstream into areas where salamanders occur. 
This process can occur either through direct surface water runoff or 
through infiltration into groundwater that later discharges through 
springs (Schram 1995, p. 91). Elevated mobilization of sediment (soils 
of sand, silt, or clay) also occurs as a result of increased velocity 
of water running off impervious surfaces in the urban environment 
(Schram 1995, p. 88; Arnold and Gibbons 1996, pp. 244-245). Increased 
rates of storm water runoff causes erosion by scouring in headwater 
areas and sediment deposition in downstream channels (Booth 1991, pp. 
93, 102-105; Schram 1995, p. 88).
    Acute short-term increases in pollutants, particularly sediments, 
can occur during construction of new development. When vegetation is 
removed and rain falls on unprotected soils, large discharges of 
suspended sediments result and can have immediate effects of increased 
sedimentation in downstream drainage channels (Schueler 1987, p. 1.4; 
COA 2003, p. 24).
    A number of point-sources of pollutants exist in the range of the 
salamander and result in accidental discharges from utility structures 
such as storage tanks or pipelines (particularly gas and sewer lines). 
Leaking underground storage tanks have been documented as a problem 
within the salamander's range (COA 2001a, p. 16). Sewage spills from 
pipelines have been documented in watersheds supporting the salamander 
(COA 2001a, pp. 16, 21, 74). As an example, during this status review, 
a sewage line overflowed an estimated 50,000 gallons

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(190,000 liters) of raw sewage into the Stillhouse Hollow drainage area 
of Bull Creek (COA 2007b, pp. 1-3). The location of the spill was a 
short distance downstream of currently known salamander locations, and 
no salamanders were thought to be affected.

Water Quality Degradation and Jollyville Plateau Salamander Responses

    As early as 1995, water quality deterioration, including increases 
in nutrient levels as a product of urban development, was cited for the 
Bull Creek watershed, where half of the drainage areas with Jollyville 
Plateau salamanders occur (Schram 1995, p. 87). The pollutants 
considered most problematic in Jollyville Plateau salamander habitats 
(discussed in more detail below) include sediments, ions (such as 
chlorides and sulfates) and dissolved solids (as measured by 
conductivity), nutrients (particularly nitrates and ammonia), and 
petroleum compounds (primarily polycylic aromatic hydrocarbons). Other 
pollutants such as heavy metals are also possible sources causing water 
quality degradation from urban runoff, but have not been documented as 
elevated in the salamander's habitat.
    Amphibians, especially their eggs and larvae (which are usually 
restricted to a small area within an aquatic environment), are 
sensitive to many different aquatic pollutants (Harfenist, et al. 1989, 
pp. 4-57). Contaminants found in aquatic pollutants may interfere with 
a salamander's ability to develop, grow, or reproduce (Burton and 
Ingersoll 1994, pp. 120, 125). In addition, macroinvertebrates, such as 
small freshwater crustaceans, that the Jollyville Plateau salamander 
feeds on are especially sensitive to water pollution (Phipps, et al. 
1995, p. 282; Miller, et al. 2007, p. 74). Studies in the Bull Creek 
watershed found a loss of some sensitive macroinvertebrate species, 
potentially due to nutrient enrichment and sediment accumulation (COA 
2001b, p. 15).
    Excess sedimentation is a form of water pollution found in 
Jollyville Plateau salamander habitats (COA 2006, p. 46). Sediments are 
mixtures of silt, sand, clay, and organic debris that are washed into 
streams or aquifers during storm events either as deposited sediment 
layers or suspended sediments (Ford and Williams 1989, p. 537; Mahler 
and Lynch 1999, p. 13). Sediment derived from soil erosion has been 
cited by Menzer and Nelson (1980, p. 632) as the greatest single source 
of pollution of surface waters by volume. Due to high organic carbon 
content, sediments eroded from contaminated soil surfaces can 
concentrate and transport contaminants (Mahler and Lynch 1999, p. 1). 
Sediment can affect aquatic organisms in a number of ways. Sediments 
suspended in water can clog gill structures, which impairs breathing of 
aquatic organisms, and can reduce their ability to avoid predators or 
locate food sources due to decreased visibility (Schueler 1987, p. 
1.5).
    Excessive deposition of sediment in streams will physically reduce 
the amount of available habitat and protective cover for aquatic 
organisms, by filling in the interstitial spaces of the larger 
substrates (such as gravel and rocks) surrounding the spring outlets 
that offer protective cover and an abundant supply of well-oxygenated 
water for respiration. As an example, a California study found that 
densities of two salamander species were significantly lower in streams 
that experienced a large infusion of sediment from road construction 
after a storm event. The vulnerability of the salamander species in 
this California study was attributed to their reliance on interstitial 
spaces in the streambed habitats (Welsh and Ollivier 1998, p. 1,128). 
The loss of interstitial spaces in stream substrates can be measured as 
the percent embeddedness. Embeddedness reflects the degree to which 
rocks (which provide cover for salamanders) are surrounded or covered 
by fine sediment. Increased sedimentation from urban development is a 
major water quality threat to the Jollyville Plateau salamander because 
it fills interstitial spaces and eliminates resting places and also 
reduces habitat of its prey base (small aquatic invertebrates) (COA 
2006, p. 34).
    Excess sedimentation may have contributed to declines in Jollyville 
Plateau salamander populations in the past. The City of Austin 
monitoring found that, as sediment deposition increased at several 
monitoring sites, salamander abundances significantly decreased (COA 
2001a, pp. 101, 126). As an example, the City of Austin found that 
sediment deposition and embeddedness estimates have increased 
significantly along one of the long-term monitoring sites as a result 
of recent construction activities upstream (COA 2006, p. 34). This site 
has had significant declines in salamander abundance, based on 10 years 
of monitoring, and the City of Austin attributes this decline to the 
increases in sedimentation (COA 2006, pp. 34-35). The location of this 
monitoring site is within a large preserved tract. However, the 
headwaters of this drainage are outside the preserve and the 
development in this area increased sedimentation downstream and 
impacted salamander habitats.
    One practical measure of water quality in freshwater springs, such 
as those where the Jollyville Plateau salamanders occur, is 
conductivity. Conductivity is a measure of the electrical conductivity 
in water and is used to approximate salinity in terrestrial and aquatic 
environments. Water salinity reflects the concentration of dissolved 
inorganic solids (that is, salts such as chlorides or sulfates) in 
water that can affect the internal water balance in aquatic organisms. 
As ion concentrations such as chlorides, sodium, sulfates, and nitrates 
rise, conductivity will increase. These compounds are the chemical 
products, or byproducts, of many common pollutants that originate from 
urban environments as fertilizers and pesticides (Menzer and Nelson 
1980, p. 633).
    Conductivity measurements by the City of Austin between 1997 and 
2006 found that conductivity measurements averaged between 550 and 650 
[mu]S/cm (microsiemens per centimeter) at rural springs with low or no 
development and averaged between 900 and 1000 [mu]S/cm at monitoring 
sites in watersheds with urban development (COA 2006, p. 37). These 
results indicate that developed watersheds contribute to higher levels 
of water pollution in habitats of the Jollyville Plateau salamander.
    High conductivity has been associated with declining salamander 
abundance. For example, 3 of the 4 sites with statistically 
significantly declining salamander abundance over the last 10 years are 
cited as having high conductivity readings (COA 2006, p. 37). Similar 
correlations were shown in studies comparing developed and undeveloped 
sites from 1996 to 1998 (Bowles, et al. 2006, pp. 117-118). This 
analysis found significantly lower numbers of salamanders and 
significantly higher measures of specific conductance at developed 
sites as compared to undeveloped sites (Bowles, et al. 2006, pp. 117-
118). However, developed sites also had a higher proportion of bedrock 
substrate, which is not used by salamanders and may have also 
contributed to the results of lower salamanders in this study. Poor 
water quality, as measured by high specific conductance and elevated 
levels of ion concentrations, is cited as one of the likely factors 
leading to the statistically significant declines in salamander 
abundance at City of Austin long-term monitoring sites (COA 2006, p. 
46).

[[Page 71044]]

    Excessive nutrient input to Jollyville Plateau salamander habitat 
is another form of pollution. Sources of nutrients (which are elements 
or compounds, such as phosphorus or nitrogen, that fuel abnormally high 
organic growth in aquatic ecosystems) in water include human and animal 
wastes, municipal sewage treatment systems, decaying plant material, 
and fertilizers used on croplands (Garner and Mahler, p. 29). Excessive 
nutrient levels typically cause algal blooms that ultimately die back 
and cause progressive decreases in dissolved oxygen concentration in 
the water from decomposition (Schueler 1987, pp. 1.5-1.6). Increased 
nitrate levels, which are often associated with fertilizer use, have 
been known to affect amphibians by altering feeding activity and by 
causing disequilibrium and physical abnormalities (Marco, et al. 1999, 
p. 2837). Elevated nutrient levels, particularly nitrogen in the forms 
of nitrates and ammonia, have been documented by the City of Austin in 
both surface water (COA 2006, p. 37) and groundwater (COA 2001a, pp. 
54-56) at several salamander locations with high levels of development.
    Water quality monitoring in streams occupied by the Jollyville 
Plateau salamander has shown that, overall, streams with developed 
watersheds have statistically significant higher levels of pollutants 
compared with rural watersheds (COA 2001a, p. 59). The City of Austin 
defines rural sites as streams draining watersheds with less than 10 
percent impervious cover (impervious cover defined below in the Current 
Impervious Cover Analysis section); developed sites had impervious 
cover greater than 10 percent (COA 2001a, p. 12). Similar analysis of 
samples from seven springs also found water quality measures of 
pollutants in groundwater significantly higher in developed sites 
compared to rural sites (COA 2001a, pp. 54-56). Developed tributary 
streams also experienced significantly lower mean adult and juvenile 
Jollyville Plateau salamander abundances per square meter of wetted 
surface when compared to undeveloped tributary streams (COA 2001a, p. 
99).
    An assessment of water quality trends also found that measures of 
sodium had significant increases between 1997 and 2006 at one site and 
significant increases in conductivity measurements at three other sites 
(COA 2006, p. 29). The drainage areas to each of these sites have high 
levels of urban development (COA 2001a, pp. 29-33; COA 2006, pp. 3, 
46).
    Poor water quality, particularly elevated nitrates, may also be a 
cause of morphological deformities in individual Jollyville Plateau 
salamanders. The City of Austin has documented very high levels of 
nitrates (averaging over 6 mg/L with some samples exceeding 10 mg/L) 
and high conductivity at two monitoring sites in the Stillhouse Hollow 
drainage area (COA 2006, pp. 26, 37). For comparison, nitrate levels in 
undeveloped Edwards Aquifer springs (watersheds without high levels of 
urbanization) are typically close to 1 mg/L (milligram per liter) (COA 
2006, p. 26). Salamanders observed at the Stillhouse Hollow monitoring 
sites have shown high incidences of deformities, such as curved spines, 
missing eyes, missing limbs or digits, and eye injuries (COA 2006, p. 
26). The Stillhouse Hollow location was also cited as having the 
highest observation of dead salamanders (COA 2001a, p. 88). Although no 
statistical correlations were found between the number of deformities 
and nitrate concentrations (COA 2006, p. 26), environmental toxins are 
the suspected cause of salamander deformities (COA 2006, p. 25). 
Nitrate toxicity studies have indicated that salamanders and other 
amphibians are sensitive to these pollutants (Marco, et al. 1999, p. 
2837).
    In an effort to reduce the high nitrate levels within the 
Stillhouse Hollow drainage, City of Austin staff have been working with 
community residents upstream of Stillhouse Hollow and Barrow Springs in 
efforts to improve water quality at the spring (COA 2007c, p. 38). The 
goal of the conservation program, which started in 2001, is to educate 
more than 250 residents on environmentally appropriate fertilizer use. 
While the program has resulted in changes to fertilizer use in the 
targeted community, there have been no changes in water quality 
detected to date as a result of these efforts (COA 2007c, p. 40).
    Polycyclic aromatic hydrocarbons (PAHs) are another form of aquatic 
pollution that may be affecting Jollyville Plateau salamanders, their 
habitat, or their prey. PAHs can originate from petroleum products, 
such as oil or grease, or from atmospheric deposition from the 
byproducts of combustion (for example, vehicular combustion). These 
pollutants are widespread and can contaminate water supplies through 
sewage effluents, urban and highway runoff, and chronic leakage or 
acute spills of petroleum and petroleum products (Van Metre, et al. 
2000, p. 4067, Albers 2003, p. 345). Petroleum and petroleum byproducts 
can adversely affect living organisms by causing direct toxic action, 
altering water chemistry, reducing light, and decreasing food 
availability (Albers 2003, p. 349). PAH exposure can cause impaired 
reproduction, reduced growth and development, and tumors or cancer in 
species of amphibians, reptiles, and other organisms (Albers 2003, p. 
354). PAHs are also known to cause death, reduced survival, altered 
physiological function, inhibited reproduction, and changes in species 
populations and community composition of freshwater invertebrates 
(Albers 2003, p. 352).
    Limited sampling by the City of Austin has detected PAHs at 
concentrations of concern at three sites in the range of the Jollyville 
Plateau salamander. Most notable, were the elevated levels of nine 
different PAH compounds at the Spicewood Springs site in the Shoal 
Creek drainage area (COA 2005, pp. 16-17). This is also one of the 
sites where salamanders have shown a significant decline in abundance 
during the City of Austin long-term monitoring studies (COA 2006, p. 
47).
    In summary, the best available information indicates that habitat 
destruction, in the form of water quality degradation, is occurring in 
the majority of the range of the Jollyville Plateau salamander, as 
evidenced by elevated levels of sedimentation, ions, nutrients, and 
PAHs documented in salamander habitats. The primary threat from water 
quality stressors is, therefore, at a significant level of exposure and 
is imminent because detrimental effects are already being manifested. 
Probable negative responses by Jollyville Plateau salamanders to 
habitat degradation from water quality declines include mortalities and 
deformities of individual salamanders at several sites and significant 
declines in abundance at four monitoring sites over the last 10 years. 
In addition, sedimentation results in physical loss of available 
habitat and changes macroinvertebrate communities, which are the prey 
(food sources) for the salamander. These habitat modifications are most 
likely the result of urban development in the drainage areas where 
salamanders occur. Overall, the information available provides 
compelling evidence that urban development has led to decreases in 
water quality caused by higher levels of aquatic pollutants and 
increased sedimentation in habitats of Jollyville Plateau salamanders. 
Such habitat destruction or modification (in the form of decreased 
water quality) has shown to significantly lower salamander abundance.

Extent of Existing and Future Development

    We used two quantitative measures to assess the extent of urban 
development

[[Page 71045]]

within areas draining to stream segments where Jollyville Plateau 
salamanders are known to occur. This analysis provided a tool for 
assessing the scope (geographic extent), immediacy (potential future 
effects), and the intensity (strength of stressor) of the habitat 
stressors that originate from urban development (the source of water 
quality threats). For this status review, we assumed that, as the 
amount of urban development increases, as quantified by these two 
measurements, the extent (that is the scope, immediacy, and intensity) 
of the source of water quality threats also increases.
    The first measure is the estimated percent of impervious cover and 
the second is the overall percent of land area that is currently 
developed, undeveloped, or open space (these terms are defined below). 
Impervious cover is any surface material, such as roads, rooftops, 
sidewalks, patios, paved surfaces, or compacted soil, that prevents 
water from filtering into the soil (Arnold and Gibbons 1996, p. 244). 
Developed areas are land tracts that have structures already built on 
the property including, for example, tracts with land use designations 
of residential, commercial, industrial, civic (public), utilities, and 
roads. Undeveloped tracts were those that have not been dedicated as 
open space, and have not yet had any construction on the land. Open 
space includes lands set aside for either low-use recreation (some 
recreational parks are included) or as wildlife preserves.
    To calculate impervious cover and land use, the City of Austin 
delineated the surface drainage area flowing into 20 distinct stream 
segments with all currently known salamander localities. Then, for each 
of these drainage areas, they calculated the percent of impervious 
cover using the area of the building and transportation footprints. For 
the land use calculations, they determined which parcels fell into each 
of 15 categories (Single-Family Residential, Mobile Home, Large-Lot 
Single-Family Residential, Multi-Family Residential, Commercial, 
Office, Industrial, Civic, Open Space, Golf Course, Transportation, 
Streets and Roads, Utilities, Undeveloped, and Water) based upon land 
usages. We summarized these data by calculating the total area of the 
parcels designated as ``undeveloped'' and ``open space'' and adding all 
the other categories together, with the exception of ``water'', to 
create our ``developed'' category. ``Water'' was only found in one 
polygon in the Walnut Creek watershed and was not added to any land use 
category.
    Current Impervious Cover Analysis. We evaluated the current (2006 
and 2007) levels of impervious cover in the areas that drain to 
salamander locations, which include undeveloped tracts and open spaces 
in the calculation. Once natural vegetation in a watershed is replaced 
with impervious cover, rainfall is converted to surface runoff instead 
of filtering through the ground (Schueler 1991, p. 114). Citing a 
number of other studies, Bowles, et al. (2006, p. 111) state that 
impervious cover in watersheds elevates the frequency and intensity of 
storm flows (water draining watersheds immediately following rain 
events) and reduces baseflow (flows from spring flows not directly 
influenced by rain events) in receiving streams, increases erosion and 
down cutting (lowering the elevation of stream channels by moving 
substrates downstream), and contributes nutrient and toxic pollutant 
loads. Also, Schueler (1994, p. 104) found that sites receiving runoff 
from high impervious cover drainage areas had sensitive aquatic 
macroinvertebrate species replaced by species more tolerant of 
pollution and hydrologic stress (high rate of changes in discharges 
over short periods of time).
    Various levels of impervious cover within watersheds have been 
cited as having detrimental effects to water quality within streams. 
The threshold of measurable degradation of stream habitat and loss of 
biotic integrity consistently occurs with 6 to 15 percent impervious 
cover in contributing watersheds (Bowles, et al. 2006, p. 111; Miller, 
et al. 2007, p. 74). A review of relevant literature by Schueler (1994, 
p. 100-102) indicates that stream degradation occurs at impervious 
cover of 10 to 20 percent, a sharp drop in habitat quality is found at 
10 to 15 percent impervious cover, and watersheds above 15 percent are 
consistently classified as poor, relative to biological condition. 
Schueler (1994, p. 102) also concluded that even when water quality 
protection practices are widely applied, 35 to 60 percent impervious 
cover exceeds a threshold beyond which we cannot maintain 
predevelopment water quality.
    The 20 drainage areas within the range of the Jollyville Plateau 
salamander have impervious cover estimates ranging from 0 percent to 45 
percent. For the purposes of our analysis, we categorized each of the 
20 drainage areas (based on overall drainage areas, which incorporate 
undeveloped tracts and open spaces) as either low (less than 6 percent 
impervious cover), moderate (between 6 and 15 percent impervious 
cover), high (between 16 and 34 percent impervious cover), or very high 
(35 percent impervious cover or greater) to assess the intensity of 
development. Five of the areas had overall low levels of impervious 
cover (less than six percent). Eight areas had moderate levels of 
impervious cover (6 to 15 percent). Five areas had high levels of 
impervious cover (16 to 34 percent). Two drainage areas had very high 
levels of impervious cover (35 percent or greater). We expect the 
levels of impervious cover to increase as undeveloped areas are 
developed in the future (discussed in more detail below in the Extent 
of Development in the Foreseeable Future section). In summary, based on 
the best available information we found that 15 of the 20 drainage 
areas evaluated have levels of impervious cover (greater than 5 
percent) that may be detrimental to salamander habitats. Therefore, the 
Jollyville Plateau salamander has a significant level of exposure to 
threats from water quality degradation originating in urban development 
because a majority of populations are potentially affected.
    Current Land Use Analysis. We also evaluated the extent of the 
potential pollution sources from urban areas affecting Jollyville 
Plateau salamander habitat by quantifying the land use designation in 
all upstream areas that drain to stream segments where salamanders have 
been documented to occur. Overall, we found that the 20 drainage areas 
upstream of salamander locations encompass 15,485 ac (6,267 ha), 
ranging in size from 44 to 2,063 ac (18 to 835 ha). Of the overall 
total, 8,464 ac (3,425 ha) (55 percent) are already developed, 2,432 ac 
(984 ha) (16 percent) are currently undeveloped, and 4,586 ac (1,856 
ha) are dedicated as open space (30 percent).
    A substantial portion of the land area categorized as open space is 
protected as part of the Balcones Canyonlands Preserve (BCP). The BCP 
is managed as mitigation lands by the City of Austin, Travis County, or 
others under the authority of an Endangered Species Act Section 
10(a)(1)(B) permit and Habitat Conservation Plan for the protection of 
endangered birds and karst invertebrates. Of the 4,586 acres (ac) 
(1,856 hectares (ha)) in the drainage areas designated as open space, 
an estimated 3,999 ac (1,618 ha) (87 percent) is within areas managed 
under the BCP. Although the permit that created the BCP did not include 
the Jollyville Plateau salamander, the BCP land management strategies 
provide strong protections for salamander habitats on lands within the 
preserve. Water quality in salamander sites

[[Page 71046]]

located within the BCP, however, is influenced by land use practices 
upstream and outside the BCP preserves. For example, important 
headwater areas in Tributaries 5 and 6 of Bull Creek (where significant 
declines in salamander abundance have been found) have affected 
habitats downstream (COA 2006, p. 45).
    One of the drainage areas that have been severely impacted by older 
urban development (in place more than 20 years) is the Walnut Creek 
drainage. In this drainage area, 88 percent of the watershed is 
developed and 7 percent is open space. Overall, it has a very high 
level of impervious cover (36 percent). Only one small spring pool has 
been found in the past to have salamanders within this drainage area 
and the location is within a small recreational park. Despite several 
recent survey efforts, salamanders have not been observed there since 
2005, and the species may be extirpated from this drainage area (COA 
2006, p. 47). This site is likely an example of the extirpation of a 
Jollyville Plateau salamander population as a result of the long-term 
impacts of a highly urbanized watershed.
    Development in Drainage Areas at Monitoring Sites. We also did 
these analyses specifically for the nine long-term monitoring sites. 
For some sites, this required evaluating a subset of the drainage area 
of the stream segment so as to include only areas that are upstream of 
the monitoring site. We found that the drainage areas of the long-term 
monitoring sites with declining salamander abundance had high rates of 
impervious cover. Of the four long-term monitoring sites where the City 
of Austin documented declines in salamander abundance (discussed in 
more detail above in the City of Austin Monitoring Data section), one 
site was in a watershed with very high levels of impervious cover, two 
sites were in watersheds with high levels of impervious cover, and one 
site was in a watershed with moderate levels of impervious cover. Of 
these four sites, the drainage areas were 97 percent, 83 percent, 80 
percent, and 46 percent developed. Three of these sites each had 12 
percent or less of their drainage areas in open space. These data 
support the general conclusion that sites with declining salamander 
abundances have highly developed watersheds.
    One exception is the monitoring site at Tributary 5 of the Bull 
Creek Watershed, which has declining abundance, but only moderate 
levels of impervious cover and only 46 percent of the drainage area 
developed. Tributary 5 is within the BCP (described above in the 
Current Land Use Analysis section). However, this site has substantial 
development (461 ac, 187 ha) within the headwaters of the drainage area 
to this monitoring site, and excessive sedimentation has been observed 
here (discussed in more detail above in the City of Austin Monitoring 
Data section). Since 1997, this site also has seen increases in recent 
development as the reported estimated impervious cover has increased 
from between 5 and 11 percent (COA 2001a, p. 33) to a current estimate 
of 13 percent.
    One of the nine long-term monitoring sites (Wheless site in Long 
Hollow drainage area) had increasing salamander abundance over the 10 
years of study. The drainage area for this site has no development and 
97 percent of the area is within protected lands of the BCP, including 
the headwaters. These results provide correlated evidence that poor 
water quality resulting from the high levels of urban development 
result in a decline in abundance of the Jollyville Plateau salamander 
at specific locations. Therefore, as the intensity of the source of 
threats to habitat (how water quality resulting from urban development) 
increases, a negative response by the salamander at the population is 
apparent.
    We also compared the mean number of salamanders counted during 
recent monitoring surveys (between 2004 and 2006) at the long-term 
monitoring sites (unpublished data provided by the City of Austin) with 
the current level of development within the drainage areas (percent 
developed). Although the sample efforts among sites were not 
standardized, the comparison showed a trend that, as the percent of 
development increased in drainage areas, the mean number of Jollyville 
Plateau salamanders counted decreased. This correlation indicates that 
as development levels increase, the actual abundance of salamanders 
decreases. Urban development results in low water quality and increased 
sedimentation, which negatively impacts salamander abundance. This 
again supports the conclusion that the intensity of urban development 
is inversely related to the population response of the Jollyville 
Plateau salamander. A similar correlation was documented for a species 
of Eurycea salamander in North Carolina. As impervious cover increased 
in drainage areas, salamander abundances in streams significantly 
decreased (Miller, et al. 2007, p. 79).
    Treatment of Cave Locations and Brushy Creek. For the impervious 
cover and land use analysis described above, we did not include the 
caves occupied by Jollyville Plateau salamanders from the Buttercup 
Creek and Cluck Creek drainage areas in the City of Cedar Park as part 
of the 20 drainage areas. Instead, we analyzed these drainage areas 
separately because all of the salamander locations in the Buttercup 
Creek and Cluck Creek drainage areas are within caves (and are the cave 
form of the species, as described above in the Background section). We 
do not have specific information on the extent to which surface 
drainage areas contribute waters to these salamander cave locations; 
subsurface water within the caves is likely originating from other 
surface drainage basins. The Buttercup Creek drainage area (where caves 
occur that contain salamanders) encompasses 689 ac (279 ha) and has 10 
percent impervious cover and is 37 percent developed, 18 percent 
undeveloped, and 45 percent open space. The Cluck Creek drainage area 
(also where caves occur that contain salamanders) encompasses 248 ac 
(100 ha) and has 16 percent impervious cover and is 53 percent 
developed, 27 percent undeveloped, and 20 percent open space. The urban 
development in the drainage areas around these cave locations is at 
moderate to high levels and, depending on hydrogeology of subsurface 
flows, could be affecting water quality in the aquatic habitats in the 
caves.
    We also separately evaluated one Jollyville Plateau salamander 
location along Brushy Creek located approximately 1.5 miles (2.4 
kilometers) east of Interstate Highway 35. This location is 
approximately 5 miles (8 kilometers) northeast of the nearest other 
known salamander location. We are not aware of any surveys for 
salamanders for most of the Brushy Creek drainage (which encompasses 
over 38,000 ac (15,000 ha)) and additional locations could be 
discovered with future surveys (Hillis 2007, p. 1). Salamanders from 
the one site along Brushy Creek mainstem were included in the taxonomic 
study describing the species. Genetic studies confirmed that 
salamanders from this location were Jollyville Plateau salamanders 
(Chippendale, et al. 2000, p. 49). This known salamander habitat is 
isolated at one spring site on private property near an existing office 
complex (Chippendale, et al. 2000, p. 36). The location appears to be 
about 200 feet (61 meters) from the Brushy Creek channel at a spring 
outflow along a steep bank (Hillis 2007, p.1). We do not know if the 
salamander occurs in other parts of Brushy Creek itself, and, 
therefore, we do not know if the species would be

[[Page 71047]]

affected by upstream development in the Brushy Creek watershed.
    We treated the Brushy Creek drainage area separately because of the 
uncertainties of the status of the salamander in this drainage area, 
and because the size of the drainage is more than twice that of all the 
other areas combined and would inaccurately skew the results. The 
Brushy Creek drainage area had an estimated impervious cover of 15 
percent. Current land use analysis showed the Brushy Creek drainage 
area has 46 percent developed, 48 percent undeveloped, and 6 percent 
open space. This drainage area is currently moderately impacted by 
development and, with such a small area of open space and large 
undeveloped area, it is likely to be more heavily impacted by urban 
development in the foreseeable future.
    Conclusion on Existing and Future Development. Based on our 
assessments of impervious cover and current land use, the level of 
development in a drainage area (the primary source of water quality 
degradation and sedimentation loading) can be indicative of the 
abundance and trend of Jollyville Plateau salamander populations within 
the receiving streams downstream. The scope of the threat to water 
quality from urbanization (based on the geographic extent) is 
considered moderate because it occurs in multiple watersheds. The 
strength and the exposure of the threat source are considered moderate 
to high because a majority of the drainage areas are already impacted 
by urban development. We also used this information and relationship of 
land use data to predict the future extent of the threats to salamander 
habitat from urban development.

Extent of Development in the Foreseeable Future

    The amount of developed land within the areas draining to 
salamander habitat is expected to increase in the foreseeable future, 
which as we explain below, we consider to be 20 years. We expect the 
majority of currently undeveloped areas that are not preserved as open 
space (total of 2,432 ac (984 ha)) to be developed as residential or 
commercial structures within the next 20 years. This expectation is 
based on the rapid human population projections for the Austin 
metropolitan area. For example, the 2007 population estimates for the 
City of Austin and the Austin MSA (metropolitan statistical area, which 
includes Bastrop, Caldwell, Hays, Travis, and Williamson Counties) are 
724,111 and 1,501,522, respectively. By 2025 (the year nearest 20 years 
out from present for which population data are available), the 
population projections for the same two areas are 1,041,401 and 
2,603,682, respectively (COA 2007a, p. 1). Between 2007 and 2025, these 
forecasts represent a 44 percent increase in the City of Austin and a 
73 percent increase in the human population in the Austin MSA. The area 
in northwest Austin where salamander habitat occurs has limited lands 
on which to build additional structures to accommodate expected growth. 
Therefore, based on high expected growth and limited areas to build, we 
assume for the purposes of this status review that the remaining 
undeveloped lands in drainage areas of salamander habitat that are not 
located within open space preserves are likely to be developed within 
the next 20 years.
    Using this assumption, we combined the developed and undeveloped 
categories of land use and calculated the total amount of development 
(current and future) in each area draining into the 20 stream segments 
with salamanders. To characterize the scope of development within each 
area, we grouped the drainages into four levels of development (both 
current and future): 0 to 25 percent, 26 to 50 percent, 51 to 75 
percent, and greater than 76 percent developed. This provided us with 
an estimate of the maximum level of future development that can be 
expected. We found that 11 of the 20 drainage areas are likely to have 
greater than 76 percent of their land area developed. There are likely 
to be three drainage areas with 51 to 75 percent developed, four 
drainage areas with 26 to 50 percent developed, and two drainage areas 
with 0 to 25 percent developed. Because the majority of drainage areas 
are likely to be over 75 percent developed, these results support the 
conclusion that threats to Jollyville Plateau salamander habitats from 
urbanization are likely to increase in the foreseeable future.

Conclusion on Habitat Threats From Water Quality Degradation

    Based on these results, we conclude that the level of impervious 
cover and overall land use are reasonable indicators of the intensity 
and exposure of water quality threats to salamander habitat. The 
intensity (strength of stressor) of the threat and level of exposure 
are considered high because a majority of the drainage areas with 
salamanders currently have levels of urban development (based on 
impervious cover rates and proportion of developed lands) that have 
been shown to cause negative responses by salamanders.

Water Quantity and Spring Flow Declines

    The northern segment of the Edwards Aquifer is the primary supply 
of water for Jollyville Plateau salamander habitat (Cole 1995, p. 33). 
In general, the aquifer has been described as localized, small, and 
highly susceptible to pollution, drying, or draining (Chippendale, et 
al. 2000, p. 36). The portion of the Edwards Aquifer underlying the 
Jollyville Plateau is relatively shallow, with a high elevation, thus 
being likely to not sustain spring flows during periods of drought 
(Cole 1995, pp. 26-27). Increased urbanization in the watershed has 
been cited as one factor, in combination with drought, causing declines 
in spring flows (COA 2006, pp. 46-47). This could occur because of the 
inability of the watershed to allow slow filtration of water through 
soils following rain events. Instead rainfall runs off impervious 
surfaces and into stream channels at higher rates, increasing 
downstream flows and decreasing groundwater recharge (Miller, et al. 
2007, p. 74).
    We found no specific evidence that aquifer declines or spring flow 
losses have occurred as a result of urbanization or the direct use of 
aquifer water by pumping (TWDB 2003, p. 32). Predictions of future 
groundwater use in this area suggest a large drop in pumping as 
municipalities convert from groundwater to surface water supplies (TWDB 
2003, p. 65). However, field studies have shown that a number of 
springs that support Jollyville Plateau salamanders have already gone 
dry periodically and that spring waters resurface following rain events 
(COA 2006, p. 46-47).
    Although water quantity decreases and spring flow declines are 
cited as a threat to the Jollyville Plateau salamander (Bowles, et al. 
2006, p. 111), we did not find evidence that salamander habitats and 
populations are being substantially affected by lack of sufficient 
water quantity. Jollyville Plateau salamanders apparently spend some 
part of their life history in underground aquatic habitats and have the 
ability to retreat underground when surface flows decline. For example, 
one of the City of Austin monitoring sites where the salamanders are 
most abundant undergoes periods where there is no surface water for 
habitat by the salamander (COA 2006, p. 47). Drying spring habitats can 
result in stranding salamanders, resulting in death of individuals (COA 
2006, p. 16).

[[Page 71048]]

    In summary, the intensity and exposure of water quality threats 
posed by potential declining aquifer levels and loss of spring flow to 
the Jollyville Plateau salamander appear to be relatively low. This is 
because the aquifer is not currently used to a large extent as a water 
source for human use, and it is unlikely that it will be in the future. 
Also, we do not have substantial evidence that declining water quality 
is resulting in a negative response by the salamander. However, 
continued future development, which increases runoff and decreases 
aquifer recharge, and the potential use of water from the northern 
segment of the Edwards Aquifer may cause significant threats to the 
species' existence in the future.

Minor Habitat Threats

    Frequent human visitation associated with some habitat of the 
Jollyville Plateau salamander may negatively affect the species and its 
habitat. Documentation from the City of Austin of disturbed vegetation, 
vandalism, and the destruction of travertine deposits (fragile rock 
formations formed by deposit of calcium carbonate on stream bottoms) by 
foot traffic has been documented at one of their salamander monitoring 
sites in the Bull Creek watershed (COA 2001a, p. 21) and may result in 
direct destruction of small amounts of the salamander's habitat. This 
threat is of low magnitude because the negative impacts occur 
infrequently and at limited locations.
    Feral hogs have become abundant in some areas where the Jollyville 
Plateau salamander occurs. Feral hogs can negatively impact salamander 
habitat by physically wallowing in spring heads and destroying 
interstitial spaces and increasing sedimentation downstream (COA 2006, 
p. 34). The City of Austin has addressed this threat in some areas by 
constructing enclosure fences around known salamander locations (COA 
2006, p. 46). Feral hogs are a low magnitude threat (low intensity and 
localized scope) to the salamander.

Conclusion on Threats to Habitat

    The Jollyville Plateau salamander is threatened due to modification 
of the species' habitat (Factor A), both presently and into the 
foreseeable future. The presence of significant urban development in a 
majority of watersheds draining water to salamander locations has 
resulted in the deterioration of the water quality in salamander 
habitats characterized by an increase in sedimentation and pollutant 
loading. This water quality decline has resulted in the physical loss 
of salamander habitat from sedimentation, changes in the composition of 
its macroinvertebrate prey base, death and deformities of individual 
salamanders, and the overall decline in abundance of the salamanders 
over time in areas with urban watersheds.

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

    We are not aware of any information regarding overutilization of 
Jollyville Plateau salamanders for commercial, recreational, 
scientific, or educational purposes and do not consider this a 
significant factor affecting this species (i.e., a threat) now or in 
the foreseeable future.

Factor C. Disease or Predation

    City of Austin biologists found Jollyville Plateau salamander 
abundances were negatively correlated with the abundance of predatory 
centrarchid fish (carnivorous freshwater fish belonging to the sunfish 
family), such as black bass (Micropterus spp.) or sunfish (Lepomis 
spp.) (COA 2001a, p. 102). Predation of a Jollyville Plateau salamander 
by a centrarchid fish was observed during a May 2006, field survey (COA 
2006, p. 38). However, Bowles, et al. (2006, pp. 117-118) rarely 
observed these predators in Jollyville Plateau salamander habitat. 
Jollyville Plateau salamanders have been observed retreating into 
gravel substrate after cover was moved suggesting these salamanders 
display anti-predation behavior (Bowles, et al. 2006, p.117). We have 
no data to indicate whether predation of the Jollyville Plateau 
salamander may increase in the future or is considered a significant 
factor affecting the species and therefore a threat.
    Chytridiomycosis (Chytrid fungus) is a fungal disease that is 
responsible for killing amphibians world wide (Daszak, et al. 2000, p. 
445). The chytrid