[Federal Register Volume 63, Number 193 (Tuesday, October 6, 1998)]
[Proposed Rules]
[Pages 53631-53635]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-26735]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AB75


Endangered and Threatened Wildlife and Plants; Withdrawal of 
Proposed Rule to List the Plants Astragalus lentiginosus var. micans 
(shining milk-vetch) and Astragalus lentiginosus var. sesquimetralis 
(Sodaville milk-vetch) as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) withdraws the 
proposed rule to list Astragalus lentiginosus var. micans (shining 
milk-vetch) and Astragalus lentiginosus var. sesquimetralis (Sodaville 
milk-vetch) as threatened, pursuant to the Endangered Species Act of 
1973, as amended (Act). These plants are two of seven desert Astragalus 
taxa from California and Nevada that were included in a proposed rule 
published on May 8, 1992 (57 FR 19844). Since the proposed rule was 
published, management of the lands which support one population of A. 
lentiginosus var. sesquimetralis and both locations where A. 
lentiginosus var. micans occurs, have been transferred to wilderness 
under management of the National Park Service at Death Valley National 
Park. Based on evaluation of this information and public comments, and 
reevaluation of existing data, the Service has determined that evidence 
of sufficient threat warranting the listing of Astragalus lentiginosus 
var. micans and Astragalus lentiginosus var. sesquimetralis is not 
present at this time. The Service will continue to monitor the status 
of these species and may reevaluate the need for their listing at any 
time in the future on the basis of new information and/or actual or 
potential habitat alteration detrimental to the plants' continued 
existence.

ADDRESSES: The complete files for these actions are available for 
inspection, by appointment, during normal business hours. For 
Astragalus lentiginosus var. sesquimetralis contact the Nevada State 
Office, U.S. Fish and Wildlife Service, 1340 Financial Blvd., Suite 
234, Reno, NV 89502. For A. lentiginosus var. micans contact the 
Ventura Fish and Wildlife Office, U.S. Fish and Wildlife Service, 2493 
Portola Road, Suite B, Ventura, CA 93003.

FOR FURTHER INFORMATION CONTACT: Nevada State Office Supervisor, at the 
above address; telephone 702-861-6300 (for Astragalus lentiginosus var. 
sesquimetralis) or Ventura Field Supervisor, above address; telephone 
805-644-1766 (for Astragalus lentiginosus var. micans).

SUPPLEMENTARY INFORMATION:

Background

    On May 8, 1992, the Service published a proposal in the Federal 
Register (57 FR 19844) to list as endangered or threatened seven desert 
plant taxa in the genus Astragalus which occur in California and 
Nevada. The proposed listing was followed by a 60-day comment period 
that closed on July 7, 1992. A final determination on the proposal was 
delayed by other listing priorities, a limited budget, and the Federal 
moratorium on final listing actions. After the proposed rule was 
published, changes in the management of desert lands occurred and new 
conservation activities were initiated in some of the areas where these 
taxa occur. Due to these changes and the amount of time that had 
elapsed since the original publication, the Service reopened a 45-day 
comment period for the proposed listing on September 3, 1996 (61 FR 
46430).
    The Service has considered all available information and withdraws 
its proposal to list these two taxa. The proposal for Astragalus 
lentiginosus var. micans is withdrawn because the Service lacks 
sufficient evidence to indicate that vehicle trespass, visitor use, and 
the presence of Russian thistle (Salsola sp.), an invasive, nonnative 
plant, currently subject this taxon to significant threat. The proposal 
for A. lentiginosus var. sesquimetralis is withdrawn because the 
Service lacks sufficient evidence to indicate that livestock and 
vehicle trespass, or development of its habitat are currently 
threatening this taxon.
    Astragalus lentiginosus var. micans (shining milk-vetch) was 
described by Rupert Barneby (1956) based on two specimens (co-types) 
collected on the lower slopes of sand dunes at the southeast end of 
Eureka Valley, Inyo County, California in 1955. A flowering collection 
was made by Philip Munz and John Roos in April 1955 and a fruiting 
specimen was collected by Roos in May 1955. The plant is an erect 
white-silky perennial with a hardened base. The leaves range from 4.5 
to 9.5 centimeters (cm) (1.8 to 3.7 inches (in.)) in length and consist 
of 11 to 17 leaflets. The flowers are cream to pale yellow with 
lavender or indigo distally, and are arranged in loose, 20-to 35-
flowered racemes. The pods are stiffly papery, inflated, and often 
angled upward to a distinct beak (Barneby 1964).
    Astragalus lentiginosus var. micans is restricted to sands of the 
lower slopes and base of dunes at two sites located about 6 kilometers 
(km) (4 miles (mi)) apart in the Eureka Valley. These two sites, the 
Eureka Dunes and the Saline Spur Dunes, represent the entire known 
historic and the current range of this taxon (Barneby 1956; Spellenberg 
1993; Bruce Pavlik, Mills College, in litt. 1983 and 1996). Potential 
populations from Big Dune, Nevada, erroneously noted in the proposed 
rule as possibly being A. lentiginosus var. micans (57 FR 19845), had, 
in fact, already been identified from past collections as A. 
lentiginosus var. variabilis (Pavlik, in litt. 1980, 1996; R. Barneby, 
New York Botanical Garden, in litt. 1981).
    Of the two sites in the Eureka Valley where this plant occurs, the 
Eureka Dunes, approximately 5 km (3 mi) long and up to 2.4 km (1.5 mi) 
in width, appears to support the most substantial population of 
Astragalus lentiginosus var. micans. As mapped (Bagley 1986), the 
distribution of this taxon on the Saline Spur Dunes, to the east, is 
more restricted. In the 1960s and 1970s, increasing off-highway vehicle 
(OHV) use on the Eureka Dunes destroyed vegetation over the northern 
end of the lower dunes and flats, an area that supports A. lentiginosus 
var. micans (Bureau of Land Management (BLM) 1976, Service 1982). Two 
other taxa endemic to dunes of the Eureka Valley, Oenothera californica 
ssp. eurekensis (Eureka Valley evening primrose, formerly O. avita ssp. 
eurekensis) and Swallenia alexandre (Eureka Valley dune grass), co-
occur with A. lentiginosus var. micans and were federally listed as 
endangered in 1978 (43 FR 17910) as a result of this activity. The BLM 
closed the dunes to OHV use in 1976, although active enforcement of the 
closure wasn't effective until 1980. Since that time, botanists have 
noted that A. lentiginosus var. micans appears to be recolonizing the 
formerly disturbed areas (Pavlik 1979; Service 1982; Mark Skinner, 
California Native Plant Society (CNPS), in litt. 1995), although 
censuses before and after the closure are not available. The dunes were 
managed by the BLM until 1994, when passage of the California Desert 
Protection Act (CDPA) of 1994 transferred the area to the National Park

[[Page 53632]]

Service (NPS) at Death Valley National Park. Both sites are now 
included in wilderness areas within the park.
    The primary threats to Astragalus lentiginosus var. micans 
identified in the proposed rule were illegal off-road vehicle activity 
at the Eureka Dunes and competition with Russian thistle. These issues 
are discussed within this document under factors A, D, and E of the 
``Summary of Factors Affecting the Species'' section of this rule.
    Astragalus lentiginosus var. sesquimetralis (Sodaville milk-vetch) 
was first collected by W.H. Shockley in 1882 near Sodaville, Mineral 
County, Nevada, and described by Per Axel Rydberg as Cystium 
sesquimetrale (Rydberg 1929). The segregate genus Cystium, however, is 
not recognized by other botanists, and in 1945, Barneby reclassified 
the plant as Astragalus lentiginosus var. sesquimetralis. The plant is 
a prostrate perennial with straw-colored stems up to 80 cm (31 in.) 
long and covered with silky hairs. The leaflets are 6 to 18 millimeters 
(mm) (0.2 to 0.7 in.) long. The light purple flowers have white silky 
calyces 7 to 8 mm (0.3 in.) long, arranged on 6-to 12-flowered racemes. 
The pod is moderately inflated, 1.6 to 2.6 cm (0.6 to 1.0 in.) long, 
with an upwardly curved beak.
    Astragalus lentiginosus var. sesquimetralis occurs on powdery clay 
saline soils adjacent to springs. The taxon is known globally from 
three sites that are arrayed along a north-south line through a low 
topographic corridor of the western Great Basin, known as the Lahontan 
Trough. Those sites are Big Sand Spring, Death Valley National Park, 
Inyo County, California; Cold Springs, Nye County, Nevada; and 
Sodaville, Mineral County, Nevada (Morefield 1993).
    The Big Sand Spring site of Astragalus lentiginosus var. 
sesquimetralis, like the Eureka Dunes and Saline Sand Spur localities 
of A. lentiginosus var. micans, was under BLM management until 1994. 
Passage of the CDPA transferred the site to NPS management by inclusion 
within a wilderness area of Death Valley National Park. The site was 
maintained within a cattle grazing allotment and a wild burro Herd 
Management Area by BLM, and it currently retains those designations 
under NPS management. Although a fenced exclosure was constructed 
around the Big Sand Spring site and adjacent spring habitat in 1986 as 
an effort to protect A. lentiginosus var. sesquimetralis, cattle and 
burros continued to access the site on occasion by breaking through the 
fence or by climbing over the fence from the dredge spoils just outside 
of the exclosure (California Department of Fish and Game (CDFG) in 
litt. 1988). In the fall of 1996, NPS tore down and replaced sections 
of the old fence (NPS, in litt. 1996). Population surveys at this 
location has not been completed annually or systematically and 
population size probably varies according to precipitation, as well as 
other environmental factors. Several hundred to a thousand individuals 
have been recorded at this site in the last decade (Constance 
Rutherford, BLM, in litt. 1989, James Morefield, Nevada Natural 
Heritage Program (NNHP), in litt. 1991).
    The privately owned and maintained sites of Astragalus lentiginosus 
var. sesquimetralis at Cold Springs (10 hectares (ha) (25 acres (ac)) 
in Nye County) and Sodaville (10 ha (25 ac) in Mineral County), Nevada 
are adjacent to BLM grazing allotments. Although the sites are subject 
to cattle and burro trespass, the Service has no evidence of grazing or 
trampling damage on either site from cattle and burros (Morefield 
1993). Because both sites are adjacent to highways, potential damage to 
the plants and their habitat by vehicular trespass, commercial 
development, and/or associated roadside activities has been suggested 
(Morefield 1993, 57 FR 19844). To date, however, no permit requests for 
development of either property site or the waters thereon have been 
filed with state or county permitting authorities, and no evidence of 
vehicular trespass has been recorded since 1978 (Morefield 1993). The 
Sodaville property is also the site of a refugia population of Railroad 
Valley Springfish (Chrenichthys nevadae), a federally threatened 
species that occupies adjacent springs (Mike Sevon, Nevada Division of 
Wildlife (NDOW), in litt. 1996). At the time of the last census of 
these sites in 1992, about 600 to 750 plants were known to exist at the 
Sodaville site (Morefield 1993) and about 500 plants at the Cold 
Springs site (Morefield 1993). No population trend data are available 
for these populations and their current population status is unknown. 
Threats to A. lentiginosus var. sesquimetralis identified in the 
proposed rule are discussed further under factors A and E of the 
``Summary of Factors Affecting the Species'' section of this notice.

Public Comments on the Proposed Rule

    During the two comment periods in 1992 and 1996, all interested 
parties were requested to submit factual reports or information to be 
considered in making a final listing determination. Appropriate Federal 
and State agencies, the Mexican government, local governments, 
scientific organizations, and other interested parties were notified 
and their comments solicited regarding the 1992 proposed rule and on 
any changes in management or threats that may have occurred since that 
time. Legal notices inviting general public comment were published in 
the appropriate California and Nevada local newspapers.
    Comments specifically relevant to Astragalus lentiginosus var. 
micans or A. lentiginosus var. sesquimetralis are incorporated into 
this withdrawal notice where appropriate. The Service has not prepared 
a discussion or response to several additional comments that were 
received in support of withdrawal of A. lentiginosus var. 
sesquimetralis because these comments did not provide any additional 
relevant information concerning the species' biology, population size, 
numbers or distribution; threats or lack thereof; or conservation 
agreements or other protection instruments and their possible impacts 
to the species.
    Of the parties specifically addressing A. lentiginosus var. micans, 
two expressed concern that NPS does not have adequate funds or staff to 
protect the Eureka Dunes from vehicle trespass, three expressed concern 
about the occurrence of Russian thistle at the base of the Dunes, one 
suggested that Indian rice grass (Oryzopsis hymenoides) might threaten 
A. lentiginosus var. micans in the future, and one requested that the 
final determination on this listing action be delayed until completion 
of the Northern and Eastern Mojave Ecosystem Management Plan (NEMO). 
The issues of vehicle trespass and the occurrence of Russian thistle 
are discussed under factors A, D, and E of the ``Summary of Factors 
Affecting the Species'' section of this notice. In regard to Indian 
rice grass, the Service is not aware of any information to suggest that 
this native species is currently a threat to this taxon. In response to 
the suggestion to delay the final determination of this listing action, 
the Service cannot delay action on a proposed rule, except in 
circumstances where there is substantial disagreement among 
knowledgeable scientists regarding the sufficiency or accuracy of data 
relevant to the determination (50 CFR 424.17).
    Several comments received during the 1992 comment period questioned 
the varietal distinctiveness of Astragalus lentiginosus var. micans. In 
preparing this withdrawal notice, the Service has determined that the 
most recent taxonomic treatment of the genus (Spellenburg 1993) and 
information received from an expert on the species during the 1996 
comment period

[[Page 53633]]

(Pavlik, in litt. 1996) treat the taxon as distinct at the varietal 
level.
    Issue 1: Five commenters raised issues specifically relating to 
Astragalus lentiginosus var. sesquimetralis. The comment concerning a 
delayed determination of the proposed listing of this taxon was 
addressed in the above paragraph regarding A. lentiginosus var. micans. 
This commenter also expressed concern that competition from wild 
licorice (Glycyrrhiza lepidota) was an additional potential threat to 
the Death Valley population.
    Service Response: The Service is not aware of any information 
suggesting that wild licorice poses a threat to A. lentiginosus var. 
sesquimetralis.
    Issue 2: One comment expressed concern about livestock and burro 
trespass and the feasibility of burro-proof fencing at the Death Valley 
site.
    Service Response: Livestock and burro trespass is addressed in 
factors A, B, and C of the ``Summary of Factors Affecting the Species'' 
section of this notice.
    Issue 3: One comment challenged the appropriateness of listing 
plant varieties under the Act.
    Service Response: Section 3(16) of the Act states that ``(t)he term 
``species'' includes any subspecies of fish or wildlife or plants * * * 
which interbreeds when mature.'' The Service discussed in a Federal 
Register notice published on April 16, 1978 (43 FR 17912) the common 
use of the terms ``species'' and ``varieties'' by botanists and 
concluded that plants named as ``varieties'' are essentially subspecies 
and, therefore, ``species'' as defined in the Act.
    Issue 4: One commenter stated that Astragalus lentiginosus var. 
sesquimetralis is a poisonous, narcotic plant that, as such, should not 
be protected by the Federal government. This commenter also expressed 
concern over Federal protection of a species that the State of Nevada 
referred to as ``locoweed'' and had gone so far as to ban its commerce 
under a Nevada Revised Statute (NRS).
    Service Response: In response to the latter concern, no Astragalus 
fit the characteristics of noxious species as classified by the State 
of Nevada, and therefore, none are listed as noxious weeds under the 
NRS (NRS 555) (John O'Brien, Nevada Division of Agriculture, in litt. 
1996). Because many plants are commonly called ``locoweeds,'' plant 
identities are often confused when common names are used in literature, 
and the commenter may have confused Astragalus with other locoweeds. 
Astragalus lentiginosus var. sesquimetralis does contain compounds that 
may cause toxic and/or narcotic reactions when eaten by animals, as do 
most Astragalus species and many other species of plants, including 
some that are common in human diets (e.g., the potato Solanum 
tuberosum) (Kingsbury 1964). That characteristic alone does not affect 
a listing decision under the Act.
    Issue 5: A ``joking reference'' to vandalizing A. lentiginosus var. 
sesquimetralis on the private property where it exists was made at a 
local public meeting in Nye County, NV (Pahrump Valley Times, October 
4, 1996).
    Service Response: Because this comment was not made by the private 
property owner, nor was there any evidence that this threat was 
supported by the property owner, vandalism is not currently considered 
by the Service to be a threat to A. lentiginosus var. sesquimetralis, 
particularly since this species is being withdrawn from consideration 
for listing.

Summary of Factors Affecting the Species

    The Act and implementing regulations found a 50 CFR 424.17(3) 
provide the basis for determining a species to be endangered or 
threatened and for withdrawing a proposed rule when it has not been 
found to be supported by available information. The five factors 
described in section 4(a)(1) of the Act, as they apply to the 
withdrawal of the proposed listing of Astragalus lentiginosus Dougl. 
var. micans Barneby (shining milk-vetch) and Astragalus lentiginosus 
Dougl. var. sesquimetralis (Rydb.) Barneby (Sodaville milk-vetch), are 
as follows:

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

    Off highway vehicle use has been the primary threat to Astragalus 
lentiginosus var. micans. Beginning in the 1960s, the Eureka Dunes 
became a popular location to ride OHVs, including dune buggies (Service 
1982). On Easter weekend in 1976, for example, almost 50 vehicles were 
reported at the Eureka Dunes (BLM 1976). The height of vehicle damage 
to the endemic plants of the Eureka Dunes probably occurred by the mid 
to late 1970s (Service 1982). Two other plant taxa endemic to the 
Eureka Valley were listed as endangered in 1978 (43 FR 17910) as a 
result of OHV activity.
    Due, in part, to public concern over the declining condition of the 
dune's endemic flora, BLM officially closed the Eureka Dunes to OHV use 
in 1976. However, it was not until 1980 that BLM rangers and other 
personnel effectively enforced the closure (Service 1982). In the 1980s 
and early 1990s, BLM continued to maintain the closure and installed 
pipe barriers, wooden barriers, and signs around the northwest and 
central parking areas to block vehicle access to the dunes and to 
direct visitor use. During the past decade, the patrols and barriers 
have effectively prevented most vehicle trespass outside the confines 
of the parking area, although occasional trespass has still occurred 
(BLM, in litt. 1992; Glenn Harris, BLM, pers. comm. 1996). During 
transfer of the management of the Eureka Valley to NPS, the wooden 
barriers in the northwest parking area were stolen (G. Harris, pers. 
comm. 1996) and a few individual plants of Astragalus lentiginosus var. 
micans recolonizing the parking area were run over by vehicles (Renee 
Beymer, NPS, in litt. 1996; Diane Steeck, Service, pers. obs. 1996). In 
the fall of 1996, NPS installed temporary t-post barriers in the 
parking area, which they replaced with NPS wilderness markers a few 
months later. The Park is in the process of placing more permanent 
barriers and reducing the size of the parking area to allow the milk-
vetch to recolonize an area at the dune base previously denuded by 
vehicles. The NPS reports that ranger patrols of the area occur at 
about the same level as before the Eureka Valley was transferred to its 
management (NPS, in litt. 1996).
    The Service concludes that the BLM's earlier efforts to reduce 
vehicle trespass at the north end of the Eureka Dunes, combined with 
the current reduction in the size of the northwest parking area to 
allow Astragalus lentiginosus var. micans to continue recolonizing the 
sandy flats, and the continuation of enforcement patrols by NPS have 
reduced vehicle trespass into the population to the extent that vehicle 
trespass does not currently constitute a significant threat to the 
survival of this taxon. The Service is working with NPS to identify and 
implement additional conservation activities to manage visitor numbers 
and use patterns into the future.
    The second location where Astragalus lentiginosus var. micans 
occurs, the Saline Spur Dunes, is also located within wilderness under 
NPS management. This location is fairly isolated, lacks road access, 
and receives little human visitation, consequently the Service believes 
threats to this location are minimal.
    The alkaline spring-associated habitat of Astragalus lentiginosus 
var. sesquimetralis is vulnerable to surface developments, water 
diversions, vehicular traffic, and trampling by

[[Page 53634]]

domestic and wild herbivores. The Cold Spring and Sodaville populations 
of this taxon occur entirely on private land. Any development 
activities that result in surface disturbances or decreased spring 
flows could threaten these populations. While the owner of the 
Sodaville property has expressed future intent to develop a portion of 
the 64 ha (160 ac) surrounding the springs, his intention is not to 
disturb or threaten A. lentiginosus var. sesquimetralis or its habitat 
(Durk Pearson, HRH Resources, pers. comm. 1996). To date, neither 
property owner has filed for any of the State or county permits 
necessary for development of property or the waters thereon. The 
Service has no evidence of activity that would represent a substantial 
threat to A. lentiginosus var. sesquimetralis on private property at 
this time.
    The Big Sand Spring site recently has passed from BLM authority to 
that of NPS by inclusion in Death Valley National Park through the CDPA 
of 1994. While under BLM authority, this site was managed as both an 
Area of Critical Environmental Concern and a Wild Horse and Burro Herd 
Management Area. As such, it was vulnerable to trampling by feral 
burros and livestock due to breaks in exclosure fencing and other means 
of access. As part of NPS's current management activities to mitigate 
or eliminate potential threats to this taxon (NPS, in litt. 1996), new 
fencing has been constructed around Big Sand Spring. The NPS has 
identified and implemented further conservation activities, such as 
monitoring and increased patrol efforts.
    The Service concludes that development does not pose a threat to 
this taxon, and impacts from livestock have currently been reduced to 
the extent that they no longer pose a threat to this taxon.

B. Over Utilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    There are no known commercial values or purposes for these species.

C. Disease or Predation

    Disease is not known to be a factor for these taxa. As discussed 
under Factor A of the ``Summary of Factors Affecting the Species'' 
section of this notice, Astragalus lentiginosus var. sesquimetralis may 
be subject to grazing by livestock and burros in the Big Sand Spring 
location, but trampling is more likely, due to toxicity of the plants 
(BLM, in litt. 1992). New fencing at the site has been constructed to 
prevent access by livestock and burros (C. Mullen, pers. obs. 1997).

D. The Inadequacy of Existing Regulatory Mechanisms

    The Endangered Species Act should provide protection to Astragalus 
lentiginosus var. micans at the Eureka Dunes and Saline Spur Dunes by 
virtue of the co-existence of this taxon with two other listed plant 
taxa, Oenothera californica ssp. eurekensis and Swallenia alexandre. 
Although they prefer somewhat different sand depths and stability, the 
majority of the mapped distribution of A. lentiginosus var. micans 
coincides with that of the Oenothera at the Eureka Dunes and with both 
taxa over much of the Saline Spur Dunes (BLM 1976, Bagley 1986). In 
1982 the Service funded preparation of a Recovery Plan for the Eureka 
Valley Dunes. The two major tasks identified in the plan involved, (1) 
removing human threats to the Eureka Dunes and auxiliary dunes where 
these species occur, and (2) determining population and habitat 
conditions needed to ensure their survival, and then managing for those 
conditions. These tasks have been partially completed and have 
benefitted A. lentiginosus var. micans as well as the two listed taxa 
(Harris 1994 as cited in Noell 1994). The co-occurrence of A. 
lentiginosus var. micans with these listed plants should offer it 
substantial protection from visitor use and vehicle trespass, providing 
NPS enforces compliance and manages visitor use to adequately protect, 
and promote the recovery of, the listed taxa.
    Long-term management actions to mitigate or eliminate potential 
threats to areas in the eastern Mojave Desert, including Park sites 
that support Astragalus lentiginosus var. micans and A. lentiginosus 
var. sesquimetralis are currently being formulated by NPS for inclusion 
in the NEMO Plan (NPS, in litt. 1996), a joint effort of NPS, BLM, and 
the Service. This plan is still being formulated, however, and does not 
currently provide any additional protection to these species. NPS is 
developing a monitoring program for both A. lentiginosus var. micans 
and A. lentiginosus var. sesquimetralis at the sites within Death 
Valley National Park where they occur.
    Astragalus lentiginosus var. sesquimetralis is on the State of 
Nevada's list of critically endangered species in accordance with 
Nevada Revised Statute 527.270. Under the terms of State law, this 
statute provides that ``no member of its kind may be removed or 
destroyed at any time by any means except under special permit issued 
by the State Forester Firewarden'' (NRS 527.270). Private property 
development affecting the plant directly, or indirectly through habitat 
modification, would require a permit from the Nevada Division of 
Forestry prior to removal or destruction. The Sodaville site is also 
the location of a population of Railroad Valley Springfish, a federally 
listed threatened fish that is protected under the Act. Existing 
regulatory mechanisms, given the current status of the species, are 
adequate.

E. Other Natural or Manmade Factors Affecting Their Continued Existence

    A potential threat to Astragalus lentiginosus var. micans at the 
Eureka Dunes is the occurrence and spread of Russian thistle. Although 
Russian thistle was documented on the dunes in the 1970s and 1980s, it 
appears to have increased from the mid to late 1980s around the base of 
the main Eureka Dune, particularly along the dune's east side (Bagley, 
pers. comm. 1996). While there is substantial concern about the 
occurrence of Russian thistle around the dunes (Mary DeDecker, CNPS, in 
litt. 1996; Mark Bagley, CNPS, pers. comm. 1996, Mary Ann Henry, CNPS, 
in litt. 1996), its effect on A. lentiginosus var. micans is unknown. 
Pavlik (in litt. 1996) did not find that cover by Russian thistle 
affected reproduction or survivorship of A. lentiginosus var. micans 
when he conducted research on the dunes, although cover of thistle may 
have increased since that time (Bagley, pers. comm. 1996). However, the 
active growing season of A. lentiginosus var. micans and Russian 
thistle do not coincide. Astragalus lentiginosus var. micans exhibits 
most of its growth in the early spring, with flowering from March to 
June (Pavlik 1979), while the period of greatest growth for Russian 
thistle is late spring and summer, with flowering from August to 
October (The Nature Conservancy 1986; BLM, in litt. 1992; B. Pavlik, in 
litt. 1996). This reduces the likelihood of direct competition for 
water between these taxa (BLM, in litt. 1992; B. Pavlik, in litt. 
1996). Although Russian thistle may not exhibit a direct, measurable, 
effect on A. lentiginosus var. micans, it may affect it indirectly, 
through its influence on other biota or on abiotic factors of the dune 
community (B. Pavlik, in litt. 1996). Nonetheless, based on the 
evidence available at this time, the Service concludes that Russian 
thistle does not substantially affect the long-term existence of this 
taxon in the Eureka Valley.
    The possibility of destruction of plants, especially seedlings, of 
Astragalus lentiginosus var. micans

[[Page 53635]]

from trampling by dune visitors is also a concern (R. Beymer, pers. 
comm. 1996; B. Pavlik, in litt. 1996). The road leading out of the 
north end of Death Valley National Park, past the Eureka Dunes access 
road, has been improved in the last 2 years, and additional portions of 
it have been paved (R. Beymer, pers. comm. 1996). Although NPS has 
neither publicized nor planned any improvements in facilities at the 
Eureka Dunes, the area is likely to attract more visitors due to its 
recent inclusion within a National Park. The Service acknowledges the 
potential for trampling by visitors to affect A. lentiginosus var. 
micans, but concludes that evidence is insufficient to conclude that 
the Park cannot adequately manage visitor use to effectively protect 
this taxon and promote the recovery of the co-occurring listed taxa on 
the dunes.
    The naturally limited global distribution and abundance of 
Astragalus lentiginosus var. micans and A. lentiginosus var. 
sesquimetralis increase their vulnerability to extirpation or 
extinction by unforeseen catastrophic events, either natural (e.g., 
prolonged drought combined with disease outbreak) or human-caused. Pro-
active recovery efforts to lessen the threat of such random events 
typically involves the establishment of additional populations. 
However, the Service has no evidence to suggest that these taxa have 
ever been found beyond the areas they currently occupy. Therefore, 
their conservation would not include increasing the number or 
distribution of populations beyond the dunes which they currently 
inhabit. Because of the low probability of an unforeseen catastrophic 
event(s), either natural (e.g., prolonged drought combined with disease 
outbreak) or human-caused, taking place and affecting entire 
populations or colonies of these taxa, the significance of threat from 
such an event is insufficient to warrant listing at this time.
    The Service has carefully assessed the best scientific and 
commercial information available in the development of this withdrawal 
notice. After review and consideration of all information available 
regarding the past, present, and future threats, and past and current 
conservation efforts by BLM and NPS, the Service has determined that 
insufficient evidence of threat exists at this time to warrant listing 
of Astragalus lentiginosus var. micans and Astragalus lentiginosus var. 
sesquimetralis as threatened under the Act. The Service will continue 
to monitor data involving population status, visitor use, vehicle 
trespass, the presence of nonnative species (including livestock and 
feral burros) or other activities or habitat changes affecting these 
two taxa.

References Cited

    A complete list of all references cited herein is available upon 
request from the Ventura Field Office (see ADDRESSES section).
    Authors: The primary authors of this withdrawal notice are Diane 
Steeck, Ventura Field Office and Christine Mullen, Nevada State Office 
(see ADDRESSES section).

Authority

    The authority for this action is section 4(b)(6)(B)(ii) of the 
Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.)

List of Subjects in 50 CFR Part 17

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

    Dated: September 29, 1998.
Jamie Rappaport Clark,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 98-26735 Filed 10-5-98; 8:45 am]
BILLING CODE 4310-55-P