[Federal Register Volume 65, Number 106 (Thursday, June 1, 2000)]
[Proposed Rules]
[Pages 35033-35040]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-13706]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AGO4


Endangered and Threatened Wildlife and Plants; Proposed 
Endangered Status for the Buena Vista Lake Shrew

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 
list the Buena Vista Lake shrew, Sorex ornatus relictus, as endangered 
pursuant to the Endangered Species Act of 1973, as amended (Act). Prior 
to 1986, this subspecies had not been observed since it was first 
described in 1932. In 1986, three Buena Vista Lake shrews were observed 
at a permanent pond located within a former preserve, approximately 26 
kilometers (km) (16 miles (mi)) south of Bakersfield, CA. No more than 
38 individuals have been observed since they were rediscovered in 1986. 
The only known extant Buena Vista Lake shrew population is threatened 
primarily by agricultural activities, modifications and potential 
impacts to local hydrology, uncertainty of water delivery, possible 
toxic effects from selenium poisoning, and random naturally occurring 
events. This proposal, if made final, would implement the Federal 
protection and recovery provisions afforded by the Act for the Buena 
Vista Lake shrew.

DATES: We must receive comments from all interested parties by July 31, 
2000. Public hearing requests must be received by July 17, 2000.

ADDRESSES: Send your comments and materials concerning this proposal to 
the Field Supervisor, Sacramento Fish and Wildlife Office, U.S. Fish 
and Wildlife Service, 2800 Cottage Way, Rm W-2605, Sacramento, 
California 95825. Comments and materials received, as well as the 
supporting documentation used in preparing the rule, will be available 
for public inspection, by appointment, during normal business hours at 
the above address.

FOR FURTHER INFORMATION CONTACT: Dwight Harvey, Sacramento Fish and 
Wildlife Office (see ADDRESSES section) (telephone 916/414-6600; 
facsimile 916/414-6710).

SUPPLEMENTARY INFORMATION:

Background

    The Buena Vista Lake shrew, Sorex ornatus relictus, is one of nine 
subspecies within the ornate shrew Sorex ornatus species complex known 
to occur in California (Hall 1981; Owen and Hoffmann 1983; Maldonado 
1992). Sorex ornatus belongs to the order Insectivora and family 
Soricidae, subfamily Soricinae, and the tribe Soricini, with three 
subgenera (Owen and Hoffmann 1983; Junge and Hoffmann 1981).
    Sorex ornatus relictus are primarily insectivorous mammals that are 
the approximate size of a mouse. They have a long snout, tiny bead-like 
eyes, ears that are concealed, or nearly concealed, by soft fur, and 
five toes on each foot (Ingles 1965; Burt and Grossenheider 1964). 
Sorex ornatus relictus are active day or night. When they are not 
sleeping, they are searching for food. These shrews eat more than their 
own weight each day (Burt and Grossenheider 1964) to withstand 
starvation and maintain their body weight at high rates of metabolism 
(McNab 1991). Sorex ornatus relictus can have an impact on surrounding 
plant communities by consuming large quantities of insects, slugs, and 
other invertebrates that can influence such things as plant succession 
and control the irruptions of pest insects (Maldonado 1992; Williams 
1991). Sorex ornatus relictus also may be an important prey species for 
raptors, snakes, and carnivores (Maldonado 1992).
    Grinnell (1932) was the first to describe Sorex ornatus relictus. 
According to Grinnell's description, the Buena Vista Lake shrew's back 
is predominantly black with a buffy-brown speckling pattern, its sides 
are more buffy-brown than the upper surface, and its underside is 
smoke-gray. The tail is faintly bicolor and blackens toward the end 
both above and below. The Buena Vista Lake shrew weighs approximately 4 
grams (g) (0.14 ounces (oz)) (Kathy Freas, Stanford University, pers. 
comm. 1994) and has a total length ranging from 98 to 105 millimeters 
(mm) (3.85 to 4.13 inches (in.)) with a tail length of 35 to 39 mm 
(1.38 to 1.54 in.) (Grinnell 1932). The Buena Vista Lake shrew differs 
from its geographically closest subspecies, the ornate shrew Sorex 
ornatus spp. ornatus, by having darker, grayish-black coloration, 
rather than brown. In addition, S. o. ssp. relictus has a slightly 
larger body size; shorter tail; skull with a shorter, heavier rostrum; 
and a higher and more angular brain-case in dorsal view than S. o. ssp. 
ornatus (Grinnell 1932).
    Ornate shrews, on the average, rarely live longer than 12 months, 
and evidence indicates that the normal

[[Page 35034]]

lifespan does not exceed 16 months (Rudd 1955). In montane woodlands, 
shrews have a well-defined reproductive season that lasts from mid-May 
through August (Williams 1991). They give birth to up to two litters 
per year containing four to six young. The number of litters depends on 
how early or late in the year the young are born and can become 
sexually active (Owen and Hoffmann 1983). The Buena Vista Lake shrew 
has a breeding season that begins in February or March, and may either 
extend later in the year, based on habitat quality and availability of 
water, or end with the onset of the dry season in May or June (Jesus 
Maldonado, University of California-Los Angeles, pers. comm. 1998).
    The Buena Vista Lake shrew was originally described by Grinnell 
(1932) as a new subspecies, Sorex ornatus relictus, based on the type 
specimen and two other specimens collected around the old Buena Vista 
Lake bed. On October 21, 1909, a single specimen of S. o. ssp. relictus 
was collected at Buttonwillow, a town approximately 40 km (25 mi) 
northwest of Buena Vista Lake (Williams 1986; Doug Long, California 
Academy of Sciences, pers. comm. 1998). Grinnell (1932) noted evidence 
that integration between the subspecies Sorex ornatus ornatus and S. o. 
ssp. relictus occurred in areas of geographic overlap. This integration 
prompted Freas (1990) to question the legitimacy of the Buena Vista 
Lake shrew's status as a distinct subspecies. Currently, the entire 
Sorex ornatus complex (consisting of eight subspecies in California and 
one in Baja California) is undergoing additional genetic and 
morphological evaluation (J. Maldonado, pers. comm. 1998). Preliminary 
results from strictly morphological measurements for this group were 
equivocal throughout California. However, mitochondrial DNA and micro-
satellite nuclear sequences and allozyme data have aided in determining 
subspecies ranges. From these data, researchers determined that the 
Buena Vista Lake shrew is a distinct subspecies from other S. ornatus 
subspecies; it is unlike any other sampled throughout the southern San 
Joaquin Valley (J. Maldonado, pers. comm. 1998).
    Based on Grinnell's (1933) records in the Museum of Vertebrate 
Zoology at Berkeley (three museum specimens and related field notes), 
the distribution of the Buena Vista Lake shrew was historically limited 
to the marshlands of the southern San Joaquin Valley south from 
approximately where the waters of the Kings River divide toward the San 
Joaquin River and bed of Tulare Lake, with the animals living in the 
swampy margins of Kern, Buena Vista, Goose, and Tulare Lakes. However, 
by the time the shrew was discovered, Grinnell stated that the beds of 
these lakes were already dry and mostly cultivated with only sparse 
remnants of the original fauna (Grinnell 1932). Williams (1986) stated 
that nearly all of the valley floor in the Tulare Basin is cultivated 
and that most of the lakes and marshes had been drained and cultivated.
    The Buena Vista Lake shrew was likely historically distributed in 
the marshlands of the San Joaquin Valley throughout most of the Tulare 
Basin (Grinnell 1933; U.S. Fish and Wildlife Service 1997). The Buena 
Vista Lake shrew occurs on property owned by the J.R. Boswell Company 
(Company), formerly known as the Kern Lake Preserve (Preserve), on the 
old Kern Lake bed, in Kern County, California (California Natural 
Diversity Data Base (CNDDB)1986). This property totals about 33.5 
hectares (ha) (83 acres (ac)), and the only known viable population of 
Buena Vista Lake shrews inhabits a small 1.2-ha (3-ac) wetland area 
that exists there. Although the Preserve has remained relatively 
unchanged since the Buena Vista Lake shrew was detected at this site in 
1986, the future management of the Preserve and the future existence of 
this subspecies is uncertain.
    Water is a necessary component of the Buena Vista Lake shrew's 
environment. Moisture is required to support a diverse insect fauna, 
which is the primary food source needed to maintain the shrew's high 
metabolism. During surveys conducted on the Preserve in 1988 and 1990, 
Freas (1990) found a clear trend in preference of moderately moist 
(mesic) habitats over drier (xeric) habitats by the shrew, with 25 
animals being captured in the mesic environments and none in xeric 
habitat. Maldonado (1992) also acknowledged this type of habitat 
preference, stating that the shrew is closely associated with dense, 
riparian understories that provide food, cover, and moisture.
    The permanent pond where the subspecies occurs is located within 
the Preserve, called Gator Pond, which is not an artesian system. It is 
dry for many years, filling only when there is adequate flood runoff, 
or as in 1986, when the Company used the area for storage of excess 
water (The Nature Conservancy (TNC) in litt. 1986; Rick Hewett, TNC, in 
litt. 1987). The Rim Ditch forms the southern border of the Preserve, 
and another ditch was installed by the Company to convey irrigation 
flows to agricultural land north of the Rim Ditch. The land in and 
around the pond has a high (perched) water table because it is 
underlined with a natural hardpan soil layer that is somewhat 
impervious to water. In the past, this hardpan soil layer kept the area 
very wet and prevented it from being productively farmed. In 1982, the 
company installed a system of perforated tile line (drain pipes), which 
drains water from west to east under the Preserve, then northeast to 
the South Sump. Within 1 year, the perched water table began to 
subside, and the pond remained dry for the next 3 years (CNDDB 1986). 
As a result of the installation of the tile line, the areas northeast 
of the pond and southwest of the South Sump became arable allowing 
wheat and sorghum to be grown in these areas (TNC, in litt. 1986). The 
land west of the pond has never been farmed, but weeds are cleared off 
once a year. The land around the pond was disked annually until 1985, 
when TNC signed a lease and took over the management of the 33.5-ha 
(83-ac) Preserve. Only about 12 ha (30 ac) around the pond is now 
suitable habitat for the shrew (J. Maldonado, pers. comm. 1994).
    All water that runs north from the Rim Ditch into the tile lines 
ends up in the South Sump. The water, referred to as tail water, is 
pumped back to the Rim Ditch. The Company agreed they could supply the 
excess tail water to the Preserve in the early fall for the TNC leased 
area. June through August are the critical irrigation months for the 
Company's cotton and alfalfa production. During that period, all 
available water is presumably used for these purposes. In 1986, the 
Company allowed TNC to install a separate pipe from the Rim Ditch 
directly to the pond as a way of providing water to this area. Three 
Buena Vista Lake shrew were discovered during the digging of a ditch 
for this pipe. (CNDDB 1986).
    The Company originally supplied sufficient water to maintain the 
marshes on the Preserve. This water was sold to TNC through a lease 
agreement (Company, in litt. 1995). The Company committed to supplying 
water only during the years when quantities would be available in 
excess of that required for other corporate uses, primarily 
agriculture. Without this supplemental water supply, the remaining 
marshlands will dry up (J. Maldonado, pers. comm. 1994). In 1994, the 
Fish and Wildlife Service asked the Company to commit to a conservation 
agreement that would support the long-term maintenance of the Preserve 
and the survival of the Buena Vista Lake shrew, but the Company 
declined. (Edward Gierman, J.G. Boswell Company, in litt. 1995). TNC 
was concerned about the long-term health of the Preserve, but 
considered it

[[Page 35035]]

a ``non-defensible parcel'' because the land surrounding the Preserve 
has been converted to cotton (Reed Tollefson, TNC, pers. comm. 1994). 
Water diverted away from the Preserve for agricultural purposes has 
caused a drop in the already shallow water table, thereby eliminating 
most of the habitat that historically supported the shrew (R. Hewett, 
in litt. 1987). TNC staff estimated that proper management of the 
Preserve would require 1.9-2.5 hectare-meters (15-20 acre-feet) of 
water per year (R. Tollefson, pers. comm. 1995). Without a reliable 
water source, TNC declined to renew the lease and terminated their 
arrangement with the Company to maintain the Preserve (Sabin Phelps, 
TNC, pers. comm. 1995).
    Since the rediscovery of the Buena Vista Lake shrew at the 
Preserve, the subspecies has been found only three other times. In 
1992, one shrew was found alive under a sprinkler cover, and another 
was found dead in a manager's residence at the Kern National Wildlife 
Refuge (Refuge), Kern County, California (Morgan Cook, Service, pers. 
comm. 1995). One additional shrew was found dead in 1994 within the 
same residence on the Refuge. This residence is currently the Refuge 
headquarters and is one of two buildings located on a 4-ha (10-ac) 
compound surrounded by lawns and trees (Jack Allen, Service, pers. 
comm. 1998). The Refuge is located approximately 80 km (50 mi) 
northwest of the Preserve (Joseph Engler, Service, in litt. 1994).
    Water management practices at the Refuge have focused on waterfowl, 
and riparian habitat has not received adequate water over the years to 
maintain riparian diversity (J. Engler, in litt. 1994). If Sorex 
ornatus relictus still exists, it would probably be found around a 323-
ha (800-ac) marsh unit located on the south side of the Refuge where 
emergent vegetation, such as willows and cottonwoods exist. The marsh 
unit also remains moist longer than most other marshes on the Refuge 
(J. Allen, pers. comm. 1998). The constant lawn, shrub, and tree 
watering and the ponds at the Refuge headquarters may be sufficient to 
maintain any potential shrew populations (J. Engler, in litt. 1994).
    Recent genetic data have confirmed that the shrews found at the 
Refuge were Buena Vista Lake shrews (J. Maldonado, pers. comm. 1998). 
No additional Buena Vista Lake shrews, nor any other shrew species, 
have been found at the Refuge.
    The elimination of most of the riparian vegetation with associated 
marsh habitat that once occurred in the southern San Joaquin Valley has 
drastically reduced the amount of suitable habitat available to the 
shrew, and may have restricted the animal to the Preserve. Rapid 
agricultural, urban, and energy developments since the early 1900s have 
severely reduced and fragmented native habitats. Historically, the 
Tulare Basin, including the former Tulare, Buena Vista, Goose, and Kern 
Lakes with their respective overflow marshes, provided 19 percent of 
the Tulare Basin valley floor habitat (Werschkull et al. 1992). Around 
the turn of the 20th century, the Tulare Basin had 104,890 ha (259,189 
ac) of valley fresh water marsh, 177,005 ha (437,388 ac) of valley 
mixed riparian forests, and 105,333 ha (260,283 ac) of valley sink 
scrub, making a total of 387,229 ha (956,860 ac) of potentially 
suitable Buena Vista Lake shrew habitat. By the early 1980s, the 
combined total had been reduced to 19,019 ha (46,996 ac), less than 5 
percent of the original habitat (Werschkull et al. 1992). As of 1995, 
intensive irrigated agriculture comprised 1,239,961 ha (3,064,000 ac) 
or about 96 percent of the total lands within the Tulare Basin. Cotton, 
grapes, and alfalfa represented the top three crops (California 
Department of Water Resources (DWR) 1998).
    All of the natural plant communities in the Tulare Basin have been 
affected by the transformation of this area to production of food, 
fiber, and fuel at the expense of the natural biological diversity 
(Spiegel and Anderson 1992; Griggs et al. 1992). As more canals were 
built, and more water was diverted for irrigation of the floodplains of 
the major rivers of the southern San Joaquin Valley, less water was 
available to keep the riparian forests alive, and less water reached 
the lakes. By the early 1930s, the former Tulare, Buena Vista, Goose, 
and Kern Lakes were virtually dry and open for cultivation (Griggs 
1992).
    Irrigation, combined with subsurface drainage, have caused 
naturally occurring selenium to be leached from agricultural soils in 
the San Joaquin Valley. Elevated concentrations of selenium are 
believed to have caused major wildlife mortalities in places like the 
Kesterson National Wildlife Refuge (Kesterson) (Moore et al. 1989). The 
leaching of selenium has increased in recent times due to the increased 
supply of irrigation water for the cultivation of crops in the Tulare 
Basin. In 1984, elevated selenium levels in the blood and liver were 
measured in several small and large mammals from Kesterson (Clark 1987; 
Clark et al. 1989). Ornate shrews captured around Kesterson showed 
selenium concentrations (parts per million (ppm) dry weight) 3 to 25 
times greater than those found for any other small mammal at the same 
site (Clark 1987). As with other forms of wildlife, selenium toxicity 
represents a serious threat to the continued existence of the Buena 
Vista Lake shrew.

Previous Federal Action

    The September 18, 1985, Notice of Review (50 FR 37958), included 
the Buena Vista Lake shrew as a category 2 candidate species for 
possible future listing as threatened or endangered. Category 2 
candidates were those taxa for which listing as threatened or 
endangered might be warranted, but for which adequate data on 
biological vulnerability and threats were not available to support 
issuance of listing proposals.
    We received a petition dated April 18, 1988, from Ms. Doris Dixon 
of The Interfaith Council for the Protection of Animals and Nature to 
list the Buena Vista Lake shrew and three additional shrew species as 
endangered species. We determined that the petition presented 
substantial information indicating that the requested action may be 
warranted. We announced this finding in the Federal Register on 
December 30, 1988 (53 FR 53030). The Buena Vista Lake shrew remained a 
category 2 candidate in the January 6, 1989, Notice of Review (54 FR 
554). In the November 21, 1991, Notice of Review (56 FR 58804), the 
Buena Vista Lake shrew was elevated to category 1 status based on new 
information received by us. Category 1 taxa were those taxa for which 
we had on file sufficient information on biological vulnerability and 
threats to support preparation of a listing proposal.
    The processing of this proposed rule conforms with our listing 
priority guidance published in the Federal Register on October 22, 1999 
(64 FR 57114). This guidance clarifies the order in which we will 
process future rulemakings. The highest priority is processing 
emergency listing rules for any species determined to face a 
significant and imminent risk to its well-being (Priority 1). The 
second priority (Priority 2) is processing final determinations on 
proposed additions to the lists of endangered and threatened wildlife 
and plants. The third priority is processing new proposals to add 
species to the lists. The processing of administrative petition 
findings (petitions filed under section 4 of the Act) is the fourth 
priority. This proposed rule ranks as a Priority 3 action.

[[Page 35036]]

Summary of Factors Affecting the Species

    Section 4 of the Endangered Species Act (Act) of 1973, as amended 
(16 U.S.C. 1533 et seq.), and regulations (50 CFR part 424) promulgated 
to implement the listing provisions of the Act set forth the procedures 
for adding species to the Federal List of Endangered and Threatened 
Wildlife. A species may be determined to be endangered or threatened 
based on one or more of the five factors described in section 4(a)(1) 
of the Act. These factors and their application to the Buena Vista Lake 
shrew, Sorex ornatus relictus, are as follows:

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

    The amount of suitable habitat for the Buena Vista Lake shrew has 
been significantly reduced over time due to the systematic drainage of 
land and shallow lakes for the purpose of agricultural crop production. 
As a result, over 95 percent of the riparian vegetation and associated 
marsh habitat of the southern San Joaquin Valley has been eliminated. 
The Buena Vista Lake shrew appears to be restricted to the Preserve 
location.
    Clark et al. (1982) were unsuccessful in capturing any Buena Vista 
Lake shrews in suitable habitat found on TNC's Paine Wildflower 
Preserve or at the Voice of America site west of Delano. The Paine 
Wildflower Preserve is about 13 km (8 mi) south of the Kern National 
Wildlife Refuge and 72 km (45 mi) northwest of the Preserve. The Voice 
of America site is located 40 km (25 mi) due east of the Kern Refuge 
and 80 km (50 mi) north of the Preserve. No Buena Vista Lake shrews 
were found after conducting surveys for small mammals along the Kern 
River Parkway in 1987 (Beedy et al. 1992). This area supports 68 ha 
(168 ac) of riparian woodlands, as well as 9 ha (22 ac) of freshwater 
marshes, and it is located 30 km (19 mi) due north of the Preserve. In 
1991, surveys were conducted in suitable habitat on the Tule Elk State 
Reserve, 32 km (20 mi) northwest of the Preserve. No shrews were 
captured in these surveys (Maldonado 1992). In a 1995 survey at the 
Preserve, a total of 10 individuals were trapped (Maldonado 1998).
    The only known remaining population of Buena Vista Lake shrews 
exists on the Preserve. Water delivery to maintain the Preserve and 
support the Buena Vista Lake shrew habitat cannot be assured because 
the natural water table has been lowered by past and present 
agricultural practices on and around the Preserve. Despite available 
water supplies, the Company supplies water to the Preserve only during 
years of high runoff, at times when excess water is available at the 
end of the growing season, and after commercial crop needs are met. 
This process occurs through an informal agreement between the Company 
and the lease holder of the property. Without a dependable water supply 
of approximately 1.9-2.5 hectare-meters (15-20 acre-feet) required to 
maintain the Preserve's marshes, the continued existence of the Buena 
Vista Lake shrew is unlikely.
    Other remnant patches of suitable habitat that might support the 
Buena Vista Lake shrew include areas within the Buena Vista Lake 
Aquatic Recreation Area, the Buena Vista Golf Course, and along the 
Buena Vista Slough, Goose Lake Slough, and the Kern River west of 
Bakersfield, CA (Maldonado 1994; J. Maldonado, pers. comm. 1998; U.S. 
Fish and Wildlife Service 1997). Additional areas of suitable moist 
locations that might provide remnant shrew habitat occur within the 
Pixley National Wildlife Refuge west of the former Tulare Lake bed, as 
well as around the former Goose Lake bed. However, small habitat 
patches within these areas are marginal at best and would not likely 
support a significant number of animals (J. Maldonado, pers. comm. 
1998). In addition, these areas represent highly disjunct and 
fragmented habitat that may not be reconnected in the foreseeable 
future.

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

    The subspecies has no known commercial or recreational value. The 
only known extant population of the Buena Vista Lake shrew is on 
private property.

C. Disease or Predation

    Although there are no documented cases of disease related to Buena 
Vista Lake shrews, the possibility of disease and associated threats 
exists. The small population size and restricted distribution increases 
their vulnerability to epidemic diseases. Buena Vista Lake shrews, like 
most small mammals, are host to numerous internal and external 
parasites, such as round worms, mites, ticks, and fleas, that may 
infest individuals and local populations in varying degrees with 
varying adverse effects (J. Maldonado, pers. comm. 1998). However, the 
significance of the threat of disease and parasites to the Buena Vista 
Lake shrew is not known.
    Most carnivores of the Tulare Basin, such as coyotes, foxes, 
weasels, raccoons, feral cats and dogs, as well as certain avian 
predators such as hawks, owls, herons, jays and egrets, are all known 
predators of small mammals (Ingles 1965; J. Maldonado, pers. comm. 
1998).

D. The Inadequacy of Existing Regulatory Mechanisms

    The primary cause of decline of the Buena Vista Lake shrew is the 
loss and fragmentation of habitat due to human activities. Federal, 
State, and local laws have not been adequate in preventing destruction 
of the limited Buena Vista Lake shrew habitat.
    Under section 404 of the Clean Water Act (33 U.S.C. 1344 et seq.), 
the U.S. Army Corps of Engineers (Corps) regulates the discharge of 
fill material into waters of the United States, including wetlands. 
Section 404 regulations require applicants to obtain a permit for 
projects that involve the discharge of fill material into waters of the 
United States. However, many farming activities do not require a permit 
due to their exemption under the Clean Water Act (53 FR 20764; R. 
Wayland III, Environmental Protection Agency (EPA), in litt. 1996). 
Projects that are subject to regulation may qualify for authorization 
to place fill material into headwaters and isolated waters, including 
wetlands, under several nationwide permits. Moreover, these projects 
can normally be permitted with minimal environmental review by the 
Corps. An individual permit may be required by the Corps if a project 
otherwise qualifying under a nationwide permit would have greater than 
minimal adverse environmental impacts. No activity that is likely to 
jeopardize the continued existence of a threatened or endangered 
species, or that is likely to destroy or adversely modify the critical 
habitat of such species, is authorized under any nationwide permit.
    However, the Corps typically confines its evaluation of impacts 
only to those areas under its jurisdiction (i.e., wetlands and other 
waters of the United States). Impacts to uplands and mitigation for 
upland habitat losses are not typically addressed by the Corps unless 
such actions affect a listed species. More importantly, the termination 
of water sales to the Preserve does not fall under Corps jurisdiction. 
The lack of a guaranteed water supply is one of the major reasons TNC 
determined that the habitat on the Preserve could not remain viable and 
led to TNC's refusal to renew the lease

[[Page 35037]]

and manage the Preserve (S. Phelps, pers. comm. 1995).
    The California Environmental Quality Act (CEQA) (Public Resources 
Code Sec. 21000-21177) requires a full disclosure of the potential 
environmental impacts of proposed projects. The public agency with 
primary authority or jurisdiction over a project is designated as the 
lead agency and, therefore, is responsible for conducting a review of 
the project and consulting with the other agencies concerned with the 
resources affected by the project. Section 15065 of the CEQA 
Guidelines, as amended, requires a finding of significance if a project 
has the potential to ``reduce the number or restrict the range of a 
rare or endangered plant or animal.'' Once significant effects are 
identified, the lead agency has the option to require mitigation for 
effects through changes in the project or to decide that overriding 
considerations make mitigation infeasible (CEQA Sec. 21002). In the 
latter case, projects may be approved that cause significant 
environmental damage, such as destruction of listed endangered species 
and/or their habitat. Protection of listed species through CEQA is, 
therefore, dependent upon the discretion of the agency involved.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    As stated previously, selenium toxicity represents a serious threat 
to the continued existence of the Buena Vista Lake shrew. No cases of 
widespread selenium poisoning (selenosis) among native mammals in 
nature have been well documented. The lowest dietary threshold for 
mammalian toxicity was 1.4 parts per million (ppm) (dry weight) as 
associated with sublethal effects from lifetime exposure in rats 
(Eisler 1985). Longevity was reduced at 3 ppm in the lifetime diet. 
Olson (1986) reports a minimum dietary exposure associated with 
reproductive selenosis in rats of 3 ppm. Although stomach content data 
for the Buena Vista Lake shrew is lacking, aquatic insects such as 
brine flies Diptera ephydridae, damselflies Odonata zygoptera, and 
midge flies Diptera chironomidae, have been found in the stomachs of 
other shrew species (Churchfield 1991), and could be a dietary source 
for the highly insectivorous Buena Vista Lake shrew. Selenium 
concentrations have been measured in the above species of flies 
collected at agricultural drainage evaporation ponds throughout the 
Tulare Basin (Moore et al. 1989). Concentrations of selenium have been 
measured from 1.4 to 26.9 ppm (dry weight) in these flies from six 
evaporation ponds located a few miles west of the Preserve to the 
northern border of the Kern National Wildlife Refuge (Moore et al. 
1989). The potential dietary selenium concentration levels are well 
within the known range that is toxic to small mammals (Olsen 1986), and 
could potentially adversely affect the Buena Vista Lake shrew. Such 
effects could include, but may not be limited to, reduced reproductive 
output or premature death (Eisler 1985).
    Some of the highest selenium levels (greater than 200 parts per 
billion) have been measured from ground water throughout the historic 
range of the Buena Vista Lake shrew within the Tulare Basin, and 
specifically, in evaporation ponds within the agricultural lands 
immediately surrounding the only known population of shrews at the 
Preserve (DWR 1997). The increased supply of imported water and little 
or no exported drain water has resulted in the raising of the ground 
water table throughout the Tulare Basin (DWR 1997). Water table levels 
have been measured at 1.5 to 3 m (5 to 10 ft) beneath the Preserve and 
have steadily moved upwards since 1988 (DWR 1997). As selenium and 
other dissolved salts move upward with the elevated water table 
(perched water table), the surface vegetation takes up selenium with 
the water via root transpiration and enters the food chain of the shrew 
by becoming concentrated in insects that forage on the vegetation or 
reside in aquifers that concentrate these salts (Saiki and Lowe 1987; 
Moore et al. 1989).
    Due to the hardpan soil layer beneath the Preserve, the water table 
is high and frequently floods despite the installation of tile drains. 
In dry years, the water supply is controlled by a single ditch or small 
pipe. These unpredictable variables limit the maintenance of suitable 
moist habitat for this population of Buena Vista Lake shrews. These 
conditions restrict alternative land management practices for shrews on 
the Preserve in the event of drought, flooding, harsh winter 
conditions, or human-induced environmental impacts.
    The only known population of Buena Vista Lake shrews is vulnerable 
to the risks associated with small, restricted populations. Impacts to 
species populations that can lead to extinction include the loss or 
alteration of essential elements, such as habitat or food, the 
introduction of limiting factors into the environment, such as poison 
or predators, and catastrophic random changes or environmental 
perturbations, such as floods, droughts, or disease (Gilpin and Soule 
1986). Many extinctions are the result of a severe reduction of 
population size by some deterministic event, followed by a random 
natural event that extirpates the species. The smaller a population is, 
the greater its vulnerability to such perturbations (Terbough and 
Winter 1980; Gilpin and Soule 1986; Shaffer 1987). The elements of risk 
that are amplified in very small populations include: (1) The impact of 
high death rates or low birth rates; (2) the effects of genetic drift 
(random fluctuations in gene frequencies) and inbreeding; and (3) 
deterioration in environmental quality (Gilpin and Soule 1986). When 
the number of individuals in the sole population of a species or 
subspecies is sufficiently low, the effects of inbreeding may result in 
the expression of deleterious genes in the population (Gilpin 1987). 
Deleterious genes reduce individual fitness in various ways, most 
typically by decreasing survivorship of young. Genetic drift in small 
populations decreases genetic variation due to random changes in gene 
frequency from one generation to the next. This reduction of 
variability within a population limits the ability of that population 
to adapt to environmental changes.
    One scenario where loss of habitat may lead to extinction is when 
the species is a local endemic (because of its isolation and restricted 
range) (Gilpin and Soule 1986). The Buena Vista Lake shrew is a limited 
local endemic subspecies (Williams and Kilburn 1992), which has never 
been found to be locally abundant, and lives in very restricted areas 
of marshy wetland habitat (Bradford 1992). Because the sole population 
is small (only 10 known individuals as of 1995) and occurs in a single 
small location (12 ha (30 ac)), the Buena Vista Lake shrew is extremely 
vulnerable to natural or human-caused environmental impacts. No known 
viable populations of Buena Vista Lake shrews exist outside the former 
Kern Lake Preserve for recolonization if a catastrophic event were to 
occur at this site. While the subspecies still occurs within its 
limited range, whether the population is declining, how habitat 
conditions may be affecting the population, or how small population 
size may be affecting genetic and behavioral stability is unknown. 
Based on the vulnerability of this small population in its limited 
range and the extremely limited potential for suitable habitat outside 
this range, we believe that threats to currently occupied or potential 
habitat and individuals put this subspecies at a high risk for 
extinction.
    In developing this proposed rule, we have carefully assessed the 
best

[[Page 35038]]

scientific and commercial information available regarding the past, 
present, and future threats facing this subspecies. The Buena Vista 
Lake shrew is threatened primarily by agricultural activities, 
modifications and potential impacts to local hydrology, uncertainty of 
water delivery to the Preserve, possible toxic effects from selenium 
poisoning, and by random naturally occurring events. Only one known 
population exists, and any decrease in its numbers could result in 
decreased genetic variability. Because of the high potential that these 
threats, if realized, will result in the extinction of the Buena Vista 
Lake shrew, the preferred action is to list the subspecies as 
endangered. Not listing the subspecies or listing it as threatened 
would not provide adequate protection and would not be consistent with 
the Act.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: (i) The 
specific areas within the geographical area occupied by the species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection and; (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. ``Conservation'' means the use of all methods and 
procedures needed to bring the species to the point at which listing 
under the Act is no longer necessary.
    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, we designate critical habitat at the time the species 
is determined to be endangered or threatened. Our regulations (50 CFR 
424.12(a)(1)) state that the designation of critical habitat is not 
prudent when one or both of the following situations exist--(1) the 
species is threatened by taking or other human activity, and 
identification of critical habitat can be expected to increase the 
degree of threat to the species, or (2) such designation of critical 
habitat would not be beneficial to the species.
    We propose that critical habitat is prudent for Sorex ornatus 
relictus. In the last few years, a series of court decisions have 
overturned Service determinations regarding a variety of species that 
designation of critical habitat would not be prudent (e.g., Natural 
Resources Defense Council v. U.S. Department of the Interior 113 F. 3d 
1121 (9th Cir. 1997); Conservation Council for Hawaii v. Babbitt, 2 F. 
Supp. 2d 1280 (D. Hawaii 1998)). Based on the standards applied in 
those judicial opinions, we believe that designation of critical 
habitat would be prudent for Sorex ornatus relictus.
    In the absence of a finding that critical habitat would increase 
threats to a species, if any benefits would result from critical 
habitat designation, then a prudent finding is warranted. In the case 
of this species, designation of critical habitat may provide some 
benefits. The primary regulatory effect of critical habitat is the 
section 7 requirement that Federal agencies refrain from taking any 
action that destroys or adversely modifies critical habitat. While a 
critical habitat designation for habitat currently occupied by this 
species would not be likely to change the section 7 consultation 
outcome because an action that destroys or adversely modifies such 
critical habitat would also be likely to result in jeopardy to the 
species, in some instances, section 7 consultation might be triggered 
only if critical habitat is designated. Examples could include 
unoccupied habitat or occupied habitat that may become unoccupied in 
the future. Designating critical habitat may also provide some 
educational or informational benefits. Therefore, we find that critical 
habitat is prudent for the Buena Vista Lake shrew.
    As explained in detail in the Final Listing Priority Guidance for 
FY 2000 (64 FR 57114), our listing budget is currently insufficient to 
allow us to immediately complete all of the listing actions required by 
the Act. We plan to employ a priority system for deciding which 
outstanding critical habitat designations should be addressed first. We 
will focus our efforts on those designations that will provide the most 
conservation benefit, taking into consideration the efficacy of 
critical habitat designation in addressing the threats to the species, 
and the magnitude and immediacy of those threats. Deferral of the 
critical habitat designation for the Buena Vista Lake shrew will allow 
us to concentrate our limited resources on higher priority critical 
habitat and other listing actions, while allowing us to put in place 
protections needed for the conservation of the Buena Vista Lake shrew 
without further delay. We will make the final critical habitat 
determination with the final listing determination for the shrew. If 
this final critical habitat determination is that critical habitat 
designation is prudent, we will develop a proposal to designate 
critical habitat for the Buena Vista Lake shrew as soon as feasible, 
considering our workload priorities.

Available Conservation Measures

    Conservation measures provided for species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation actions by Federal, State, and local agencies, private 
organizations, and individuals. The Act provides for possible land 
acquisition and cooperation with the States, and requires that recovery 
actions be carried out for all listed species. The protection required 
by Federal agencies and the prohibitions against certain activities are 
discussed, in part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened, and with respect to its critical 
habitat, if any is being designated. Regulations implementing this 
interagency cooperation provision of the Act are codified in 50 CFR 
part 402. Section 7(a)(2) of the Act requires Federal agencies to 
ensure that activities they authorize, fund, or carry out are not 
likely to jeopardize the continued existence of a listed species or 
destroy or adversely modify its critical habitat. If a Federal action 
may affect a listed species or its critical habitat, the responsible 
Federal agency must enter into formal consultation with us.
    Federal agency actions that may require conference and/or 
consultation as described in the preceding paragraph include the U.S. 
Army Corps of Engineers and their authorization of projects such as the 
construction of drainage diversions, roads, bridges, and dredging 
projects subject to section 404 of the Clean Water Act.
    The Buena Vista Lake shrew has been included as a candidate species 
in the Recovery Plan for Upland Species of the San Joaquin Valley of 
California (Recovery Plan) (U.S. Fish and Wildlife Service 1998). 
Historically, the Buena Vista Lake shrew was most common in wetland 
habitat, and all of its extant and potential habitat is included within 
the habitats of the listed species that use alkali sink and associated 
communities. Because the subspecies is not federally listed as 
endangered or threatened, the recovery actions are identified as 
conservation actions and are designed to ensure long-term conservation. 
The recovery actions include additional surveys in areas of potentially 
suitable

[[Page 35039]]

habitat, habitat restoration and creation on private as well as public 
lands, and study of the feasibility of reintroduction at the Tule Elk 
State Reserve near Tupman, California. Also identified as needed 
conservation actions are population genetic studies, as well as the 
continuous monitoring of the only known viable population at the 
Preserve.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all endangered 
wildlife. The prohibitions, codified at 50 CFR 17.21, in part, make it 
illegal for any person subject to the jurisdiction of the United States 
to take (includes harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect; or to attempt any of these), import or export, 
ship in interstate commerce in the course of commercial activity, or 
sell or offer for sale in interstate or foreign commerce any endangered 
wildlife species. It is also illegal to possess, sell, deliver, carry, 
transport, or ship any such wildlife that has been taken illegally. 
Certain exceptions apply to our agents and State conservation agencies.
    Permits may also be issued to carry out otherwise prohibited 
activities involving endangered wildlife under certain circumstances. 
Regulations governing permits are codified at 50 CFR 17.22 and 17.23. 
Such permits are available for scientific purposes, to enhance the 
propagation or survival of the species, and for incidental take in 
connection with otherwise lawful activities.
    As published in the Federal Register on July 1, 1994 (59 FR 34272) 
our policy, to identify to the maximum extent practicable at the time a 
species is listed those activities that would or would not constitute a 
violation of section 9 of the Act. The intent of this policy is to 
increase public awareness of the effect of a proposed listing on 
proposed and ongoing activities within a species' range.
    We believe that, based on the best available information, the 
following actions will not likely result in a violation of section 9, 
provided these actions are carried out in accordance with any existing 
regulations and permit requirements:
    (1) Actions that may affect the Buena Vista Lake shrew that are 
authorized, funded, or carried out by a Federal agency, when the action 
is conducted in accordance with a biological opinion issued by us 
pursuant to section 7 of the Act; and
    (2) Actions that may affect the Buena Vista Lake shrew when the 
action is a part of an approved habitat conservation plan and conducted 
in accordance with an incidental take permit issued by us pursuant to 
section 10(a)(1)(B) of the Act.
    Activities that we believe could likely result in a violation of 
section 9 include, but are not limited to:
    (1) Actions not authorized under section 7 or 10 of the Act that 
lead to the destruction or alteration of occupied Buena Vista Lake 
shrew habitat through the discharge of fill material, draining, 
ditching, tiling, pond construction, rock removal, stream 
channelization, or diversion of ground water flow into or out of 
riparian habitat of this subspecies that are associated with activities 
such as the construction or installation of roads, impoundments, 
discharge or drain pipes, and storm water detention basins;
    (2) Burning, cutting, or mowing of riparian vegetation that results 
in death of injury to Buena Vista Lake shrews or that results in 
degradation of their occupied habitat;
    (3) Application of pesticides that results in death of or injury to 
Buena Vista Lake shrews; and
    (4) Discharging or dumping toxic chemicals or other pollutants 
(such as sewage, oil, or gasoline) that results in death of or injury 
to Buena Vista Lake shrews.
    Direct your questions regarding whether specific activities may 
constitute a violation of section 9 to the Field Supervisor of the 
Sacramento Fish and Wildlife Office (see ADDRESSES section). Requests 
for copies of the regulations concerning listed wildlife and general 
inquiries regarding prohibitions and permits may be addressed to the 
U.S. Fish and Wildlife Service, Ecological Services, Endangered Species 
Permits, 911 NE. 11th Avenue, Portland, Oregon 97232-4181 (telephone 
503/231-2063; facsimile 503/231-6243).

Public Comments Solicited

    We intend that any final action resulting from this proposal will 
be as accurate and as effective as possible. Therefore, comments or 
suggestions from the public, other concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule are hereby solicited. We will follow our 
current peer review policy (59 FR 34270) in the processing of this 
rule. Comments are sought particularly concerning:
    (1) Biological, commercial, or other relevant data concerning any 
threat (or lack thereof) to the Buena Vista Lake shrew;
    (2) The location of any additional populations of this subspecies 
and habitat association (including specific vegetation and soil type), 
and the reasons why any habitat should or should not be determined to 
be critical habitat as provided by section 4 of the Act;
    (3) Additional information concerning the range, distribution, and 
population size and genetics of this subspecies;
    (4) Current or planned activities in the subject area and their 
possible impacts on this subspecies; and
    (5) Additional relevant information concerning the life-history, 
habits, and dispersal of this subspecies.
    A final determination for this subspecies will take into 
consideration the comments and any additional information received by 
us. Such communications may lead to a final determination that differs 
from this proposal.
    The Act provides for one or more public hearings on this proposal, 
if requested. Requests must be received within 45 days of the date of 
publication of the proposal in the Federal Register. Such requests must 
be made in writing and addressed to the Field Supervisor, Sacramento 
Fish and Wildlife Office (see ADDRESSES section).

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined in the National Environmental Policy Act 
of 1969, need not be prepared in connection with regulations adopted 
pursuant to section 4(a) of the Act. We published a notice outlining 
our reasons for this determination in the Federal Register on October 
25, 1983 (48 FR 49244).

Paperwork Reduction Act

    This rule does not contain any new collections of information other 
than those already approved under the Paperwork Reduction Act, 44 
U.S.C. 3501 et seq., and assigned Office of Management and Budget 
clearance number 1018-0094. An agency may not conduct or sponsor, and a 
person is not required to respond to, a collection of information 
unless it displays a currently valid control number. For additional 
information concerning permit and associated requirements for 
endangered species, see 50 CFR 17.21 and 17.22.

References Cited

    A complete list of all references cited herein is available upon 
request from the Field Supervisor, Sacramento Fish

[[Page 35040]]

and Wildlife Office (see ADDRESSES section).

Author

    The primary author of this proposed rule is Dwight Harvey, U.S. 
Fish and Wildlife Service, Sacramento Fish and Wildlife Office (see 
ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulations Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

    1. The authority citation for part 17 continues to read as follows:

    Authority: 6 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.

    2. Section 17.11(h) is amended by adding the following, in 
alphabetical order under ``MAMMALS,'' to the List of Endangered and 
Threatened Wildlife:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
             Mammals
 
                   *                  *                  *                  *                  *                  *                  *
Shrew, Buena Vista Lake..........  Sorex ornatus         U.S.A. (CA)........  Entire.............  E                       699           NA           NA
                                    relictus.
 
                   *                  *                  *                  *                  *                  *                  *
--------------------------------------------------------------------------------------------------------------------------------------------------------


    Dated: May 16, 2000.
Jamie Rappaport Clark,
Director, Fish and Wildlife Service.
[FR Doc. 00-13706 Filed 5-31-00; 8:45 am]
BILLING CODE 4310-55-P