Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for Astragalus magdalenae, 41258-41284 [07-3674]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 144 (Friday, July 27, 2007)]
[Proposed Rules]
[Pages 41258-41284]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-3674]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU98


Endangered and Threatened Wildlife and Plants; Revised Critical 
Habitat for Astragalus magdalenae var. peirsonii

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; notice of availability of the draft economic 
analysis; notice of public hearings.

-----------------------------------------------------------------------

SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
revise currently designated critical habitat for Astragalus magdalenae 
var. peirsonii (Peirson's milk-vetch) pursuant to the Endangered 
Species Act of 1973, as amended (Act). In total, approximately 16,108 
acres (ac) (6,519 hectares (ha)) in Imperial County, California, fall 
within the boundaries of the proposed revised critical habitat 
designation. Lands being proposed as critical habitat are under Federal 
(15,857 ac (6,418 ha)), private (240 ac (97 ha)), and State (11 ac (4 
ha)) ownership.
    Section 4 of the Act requires us to consider the economic and other 
relevant impacts of specifying any area as critical habitat. We have 
conducted an analysis of the economic impacts of designating the 
aforementioned areas as critical habitat for Astragalus magdalenae var. 
peirsonii, and are announcing the availability of the draft economic 
analysis for public review. We hereby solicit data and comments from 
the public on all aspects of this revised proposal, including data on 
the economic and other impacts of the designation.
    We are also announcing that public hearings will be held on both 
the proposed critical habitat rule and the draft economic analysis.

DATES: We will accept comments from all interested parties until 
September 25, 2007. The public hearings will take place on August 23, 
2007, from 1 p.m. to 3 p.m. and from 6 p.m. to 8 p.m. at the Carlsbad 
Fish and Wildlife Office in Carlsbad, California (see ADDRESSESS).

ADDRESSES: Public Hearings. The public hearings will be held at the 
Carlsbad Fish and Wildlife Office, 6010 Hidden Valley Road, Carlsbad, 
California, 92011.
    Comments. If you wish to comment on the proposed rule and/or the 
draft economic analysis, you may submit your comments and materials, 
identified by RIN 1018-AU98, by any of the following methods:
    (1) You may send comments by electronic mail (e-mail) to 
fw8cfwocomments@fws.gov. Include ``RIN 1018-AU98'' in the subject line.
    (2) You may fax your comments to Jim Bartel, Field Supervisor, 
Carlsbad Fish and Wildlife Office at 760-431-5901.
    (3) You may mail or hand-deliver your written comments and 
information to Jim Bartel, Field Supervisor, Carlsbad Fish and Wildlife 
Office at the address above.
    (4) You may submit your comments at the Federal eRulemaking Portal, 
https://www.regulations.gov. Follow the instructions for submitting 
comments.
    Comments and materials received, as well as supporting 
documentation used in the preparation of this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the Carlsbad Fish and Wildlife Office at the above address 
(telephone 760-431-9440). Copies of the draft economic analysis are 
available for downloading from the Internet at https://www.fws.gov/
carlsbad/ or by contacting the Carlsbad Fish and Wildlife Office 
directly at the above phone number or address.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad 
Fish and Wildlife Office, at the address listed under ADDRESSES 
(telephone 760-431-9440; facsimile 760-431-5901). Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339, 24 hours a day, 7 
days a week.

SUPPLEMENTARY INFORMATION:

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 critical habitat rule and its associated draft 
economic analysis are hereby solicited. On the basis of public comment, 
during the development of the final rule we may find that areas 
proposed are not essential or are appropriate for exclusion under 
section 4(b)(2) in which case they would be removed from the final 
critical habitat designation.
    Comments particularly are sought concerning:
    (1) The reasons any habitat should or should not be determined to 
be critical habitat as provided by section 4 of the Act, including 
whether the benefit of designation will outweigh any threats to the 
taxon caused by designation.
    (2) Specific information on the amount and distribution of 
Astragalus magdalenae var. peirsonii habitat, and what areas that were 
occupied at the time of listing that contain features essential for the 
conservation of the taxon should be included in the designation and 
why, and what areas that were not occupied at the time of listing are 
essential to the conservation of the taxon and why.
    (3) Additional information on the specific physical and biological 
features (primary constituent elements) that are essential to the 
conservation of Astragalus magdalenae var. peirsonii (see ``Primary 
Constituent Elements'' section of this proposed rule for more details).
    (4) Land use designations and current or planned activities in the 
subject areas

[[Page 41259]]

and their possible impacts on proposed critical habitat.
    (5) Information on how many of the State and local environmental 
protection measures referenced in the draft economic analysis were 
adopted largely as a result of the listing of Astragalus magdalenae 
var. peirsonii, and how many were either already in place or enacted 
for other reasons.
    (6) Whether the draft economic analysis identifies all State and 
local costs attributable to the revised proposed critical habitat 
designation, and information on any costs that have been inadvertently 
overlooked.
    (7) Whether the draft economic analysis makes appropriate 
assumptions regarding current practices and likely regulatory changes 
imposed as a result of the designation of critical habitat.
    (8) Whether the draft economic analysis correctly assesses the 
effect on regional costs associated with land use controls that derive 
from the designation of critical habitat.
    (9) Whether the economic analysis indicated potentially 
disproportionate impacts to any areas included in the proposed 
designation. Based on this information, we may consider excluding 
portions of these areas from the final designation per our discretion 
under section 4(b)(2) of the Act.
    (10) Whether the economic analysis appropriately identifies all 
costs that could result from the designation, in particular, any 
impacts on small entities or families; and whether it is appropriate 
that the analysis does not include the cost of project modifications 
that are the result of informal consultation only.
    (11) Whether the economic analysis appropriately identifies the 
benefits that could result from the designation.
    (12) Whether there is information about areas that could be used as 
substitutes for the economic activities planned in critical habitat 
areas that would offset the costs and allow for the conservation of 
critical habitat areas.
    (13) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    If you wish to comment on the proposed rule and/or the draft 
economic analysis, you may submit your comments and materials by any 
one of several methods (see ADDRESSES section). Please submit e-mail 
comments to fw8cfwocomments@fws.gov. Please include ``Attn: RIN 1018-
AU98'' in your e-mail subject line and your name and return address in 
the body of your message. If you do not receive a confirmation from the 
system that we have received your message, contact us directly by 
calling our Carlsbad Fish and Wildlife Office at phone number 760-431-
9440. Please note that comments must be received by the date specified 
in DATES in order to be considered.
    Before including your address, phone number, e-mail address, or 
other personal identifying information in your comment, you should be 
aware that your entire comment--including your personal identifying 
information--may be made publicly available at any time. While you can 
ask us in your comment to withhold your personal identifying 
information from public review, we cannot guarantee that we will be 
able to do so.

Background

    This proposed rule addresses revised critical habitat for 
Astragalus magdalenae var. peirsonii. For additional information on the 
taxonomy, biology, and ecology of this taxon, refer to the final rule 
listing the taxon as threatened, published in the Federal Register on 
October 6, 1998 (63 FR 53596), or the proposed and final rules 
designating critical habitat for this taxon published in the Federal 
Register on August 5, 2003 (68 FR 46143), and on August 4, 2004 (69 FR 
47330), respectively. It is our intention to discuss only those topics 
directly relevant to the revised designation of critical habitat in 
this proposed rule.
    Astragalus magdalenae var. peirsonii is an erect to spreading, 
herbaceous member of the Fabaceae (legume family) (Barneby 1959, p. 
879; 1964, p. 862) that occurs on bowls, swales, and slopes of intact, 
active windblown sand dunes of the Algodones Dunes of Imperial County, 
California and the northeastern Estado de Baja California and Gran 
Desierto of northwestern Sonora, Mexico (Felger 2000, p. 300; 
Spellenberg 1993, p. 598; Willoughby 2005a, p. 2). Please refer to the 
``Primary Constituent Elements'' section below for additional 
discussion on habitat requirements of this taxon. Plants may reach 8 to 
27 inches (in) (20 to 70 centimeters (cm)) in height and develop tap 
roots (Barneby 1964, pp. 863-864) that penetrate deeply to the moister 
sand and that anchor plants in the shifting sand dunes. The root crown 
is often exposed by wind action moving the sand away from the base of 
the plants. Seeds are enclosed in fruits or pods and are either 
dispersed locally by falling out of partly opened fruits on the parent 
plant, ``salt-shaker'' style, or are dispersed further if blown across 
the sand after falling from the parent plant. Thus seeds can be 
transported from one favorable site to another, or remain near the 
parent plant, depending on winds (Phillips et al. 2001, p. 11).
    Seeds require no pre-treatment to induce germination, but 
germination success has been shown to improve dramatically when the 
outer seed coat is scarified (e.g., scratched, chipped) (Porter et al. 
2005, p. 29). Germination appears to be more successful in the cooler 
months of the year when temperatures are less than 86 [deg]F (30 
[deg]C) (Romspert and Burk 1979, pp. 45-46). Therefore, based on our 
current understanding of the taxon's life history, sufficient rain in 
conjunction with cool temperatures and wetter-than-average fall weather 
appears to trigger germination events.
    Depending upon conditions, Astragalus magdalenae var. peirsonii is 
capable of flowering before it is one year old (Barneby 1964, p. 862; 
Romspert and Burk 1979, p. 16; Phillips et. al 2001, p. 10; Phillips 
and Kennedy 2005, p. 22). Porter et al. (2005, pp. 31-32) hypothesized 
that if rains occur early in the growing season, then flowering can 
begin in as little as 3 months after germination. If, on the other 
hand, rains (and germination) do not occur until late February, then 
flowering is delayed until the next rainy season. In dry years, 
individuals die and are not replaced by new seedlings.
    This variability in annual abundance of above-ground plants has 
caused this taxon to be considered variously as an annual (completing 
its life cycle in a year or growing season) or a perennial (living for 
more than 2 years) (Munz 1932, p. 7; Munz 1974, p. 432; Barneby 1959, 
p. 879; Barneby 1964, p. 862; Spellenberg 1993, p. 598; Willoughby 
2001, p. 21). Recent evidence has confirmed that this species is a 
short-lived perennial (Phillips et al. 2001, p. 10; Porter et al. 2005, 
pp. 31, 34). This taxon likely depends on the production of seeds in 
wetter years and the persistence of the seed bank from previous years 
to survive until appropriate conditions for germination occur again. 
Porter et al. (2005, p. 29) identified the primary dormancy mechanism 
in Astragalus magdalenae var. peirsonii as the impermeability of the 
seed coat to water and demonstrated little loss of viability in seeds 
stored for 5 years. This dormancy mechanism is consistent with species 
having a seed bank (Given 1994, p. 67). Dispersed seeds in a given year 
that do not germinate during the subsequent growing season become part 
of the soil seed bank (Given 1994, p. 67).

[[Page 41260]]

Species Distribution and Abundance

    In the United States, Astragalus magdalenae var. peirsonii is 
restricted to about 53,000 acres (ac) (21,500 hectares (ha)) in a 
narrow band running 40 miles (mi) (64 kilometers (km)) northwest to 
southeast along the western portion of the Algodones Dunes of eastern 
Imperial County, California, which is the largest sand dune field in 
North America. Astragalus magdalenae var. peirsonii has also been 
documented from the Gran Desierto of Sonora, Mexico (Felger 2000, p. 
300) from an area south and southeast of the Sierra Pinacate lava 
field, but the Service has no additional information on the size of the 
population or extent of area occupied (63 FR 53599). The taxon was 
noted from the Borrego Valley, California, by Barneby (1959, p. 879) 
but no verified, reproducing population exists (Porter et al. 2005, pp. 
9-10). Other observations from Yuma, Arizona, and San Felipe, Baja 
California, Mexico, were based on misidentified specimens (see Porter 
et al. 2005, pp. 9-10, and Phillips et al. 2001, p. 7, for detailed 
accounts).
    The Algodones Dunes are one of the largest sand dune fields in 
North America, extending about 40 mi (64 km), trending from northwest 
to southeast (Norris and Norris 1961, p. 608). Please refer to the 2003 
proposed critical habitat rule for a more detailed discussion on the 
geomorphology of the Algodones Dunes (68 FR 46143). These dunes are 
often referred to as the Imperial Sand Dunes, a designation derived 
from their inclusion in the Imperial Sand Dunes Recreation Area (ISDRA) 
established by the Bureau of Land Management (BLM). The majority of the 
Algodones Dunes is managed by BLM within 8 management areas, of which 7 
are occupied by Astragalus magdalenae var. peirsonii (Mammoth Wash, 
North Algodones Wilderness, Glamis, Gecko, Adaptive Management Area 
(AMA), Ogilby, and Buttercup). The State of California and private 
individuals own some small inholdings in the Mammoth Wash management 
area.
    The ISDRA is the most popular off-highway vehicle (OHV) area in the 
southwest United States, with a specified major focus to ensure that 
OHV recreation opportunities are continuously available while 
responding to increased need for protection of plant and animal species 
in the dunes (Willoughby 2003, pp. 1-3). As a result of a settlement 
agreement reached in 2000, the BLM agreed to establish 5 interim 
closure areas within the Algodones Dunes, temporarily closing these 
areas to OHV recreation (see Index Map in ``Rule Promulgation'' 
section). As a result of a June 3, 2005, lawsuit, these temporary 
closures are still in place (see ``Previous Federal Actions'' section 
below for more information about the 2005 lawsuit).
    The Algodones Dunes are in one of the driest and hottest regions in 
the United States. The rainfall is often described as scattered or 
patchy with amounts differing from place to place and from year to 
year, with areas to the northwest being generally dryer than those to 
the southeast (Willoughby 2001, p. 20). Romspert and Burk (1979, p. 11) 
reported average yearly rainfall during the period 1941-1970 was 2.6 in 
(66 millimeters (mm)). Average yearly rainfall between 1997 and 2002 at 
seven weather stations in the vicinity of the dunes ranged from a low 
of 0.1 in (3.3 mm) during the 2001-2002 growing season to a high of 6.1 
in (155 mm) in the 1997-1998 growing season (Willoughby 2004, p.13). 
Average yearly rainfall between 2002 and 2006 at two weather stations 
on the dunes ranged from a low of 0.2 in (5.3 mm) during the 2005-2006 
growing season to a high of 4.8 in (122 mm) during the 2004-2005 
growing season (Willoughby 2006, p.18).
    The distribution and abundance of Astragalus magdalenae var. 
peirsonii has been recorded during several ongoing survey efforts. As 
discussed in the 2004 final critical habitat rule (69 FR 47330), the 
1977 dunes-wide survey for A. m. var. peirsonii and four other rare 
psammophytic (sand-loving) scrub species (WESTEC 1977) was considered 
the most extensive survey of the Algodones Dunes conducted at that 
time. The BLM conducted rare plant surveys for 5 consecutive years from 
1998 through 2002, generally repeating the methodology used by WESTEC 
in its 1977 survey (Willoughby 2001, p. iii). Raw data from the 2001 
and 2002 surveys were provided by the BLM to the Service for use in the 
development of the 2004 final critical habitat rule. However, a written 
report of the 2001 and 2002 surveys (Willoughby 2004) was completed in 
October 2004, after the publication of the August 4, 2004, final 
critical habitat rule. As also discussed in the 2004 final critical 
habitat rule, Phillips and Kennedy (2002, 2003) conducted surveys for 
A. m. var. peirsonii from 2001 through 2003. Since publication of the 
2004 final critical habitat rule, both the BLM (Willoughby 2005a, 
2005b, 2006) and Phillips and Kennedy (2004, 2005, 2006) continued to 
conduct annual surveys for this species through 2006. Table 1 below 
summarizes all of the various survey efforts, including the number of 
sampling points or transects and the effective area surveyed by each 
effort as well as the estimated population by the survey methodology 
and the actual number of plants counted.

 Table 1.--Comparison of Survey Data Collected for Astragalus magdalenae var. peirsonii in the Algodones Dunes;
                                     Data Taken From 13 Unpublished Reports
----------------------------------------------------------------------------------------------------------------
                                                   Number of       Estimated        Number
             Year                  Surveyor     plants counted    population        samples      Effective area
----------------------------------------------------------------------------------------------------------------
1977.........................  WESTEC.........             N/A             N/A             542  53,000 ac
1998.........................  BLM \1\........           5,064             N/A             542  53,000 ac
1999.........................  BLM \1\........             942             N/A             542  53,000 ac
2000.........................  BLM \1\........              86             N/A             542  53,000 ac
2001.........................  BLM \1\........           5,930             N/A             542  53,000 ac
2002.........................  BLM \1\........           2,297             N/A             542  53,000 ac
2001.........................  Phillips \2\...      \3\ 71,926             N/A             127  ~35,000 ac
2001.........................  Phillips \2\...          30,771             N/A              25  138 ac
2003.........................  Phillips \2\...          33,202             N/A              25  138 ac
2005.........................  Phillips \2\...          77,922     \4\ 173,328              25  138 ac
2006.........................  Phillips \2\...           1,233       \4\ 2,035              25  138 ac
2004.........................  BLM \1\........          25,798         286,374          37,169  53,000 ac
2005.........................  BLM \1\........         739,805       1,831,076         123,488  53,000 ac

[[Page 41261]]

 
2006.........................  BLM \1\........             N/A          83,451             775  53,000 ac
----------------------------------------------------------------------------------------------------------------
(1) BLM reports cited as Willoughby; (2) Phillips reports cited as Phillips et al. or Phillips and Kennedy; (3)
  reconnaissance of unspecified area; (4) estimated population for 60 specific sample sites.

    Since different methodologies and survey effort were used by the 
BLM as compared to Phillips and Kennedy, it is difficult to compare the 
annual estimates of dunes-wide species abundance reported from the two 
different survey efforts. Early surveys conducted by WESTEC in 1977 
(WESTEC 1977) and by BLM from 1998 through 2002 (Willoughby 2001, 2004) 
incorporated a methodology [whereby plants encountered along driving 
transects were qualitatively indexed to an abundance value] and 
represented in quadrants measuring 0.45 mi on each side. Analysis of 
these coarse, dune-wide surveys could only provide relative comparisons 
of mean abundance values between years. In 2004, the BLM embarked on a 
new sampling methodology that sampled a larger portion of the dunes in 
greater detail (Willoughby 2005a, pp. 1-5). Unlike previous surveys, 
the recent BLM surveys were scientifically and statistically designed 
to estimate the standing Astragalus magdalenae var. peirsonii 
population (Willoughby 2005a, 2005b, 2006). Data were compiled in 
adjacent 25 x 25-meter (m) cells along 4-5 km transects covering the 
full length of the dunes, and all micro-habitats were sampled along 
each transect (Willoughby 2005b, pp. 1-3). Within these 25 x 25-m 
cells, surveyors noted: The total number of plants; age class of 
plants; number of seedlings; number of flowering versus non-flowering 
plants; number of plants exhibiting damage from OHVs; and the number of 
plants showing damage from other sources (Willoughby 2005b, p. 3). The 
recent BLM surveys also increased the number of sample transects to 135 
in 2004, and to 510 for the spring 2005 surveys; the increased transect 
numbers and more detailed survey methodology increased their overall 
sample count to 37,169 and 123,488, respectively (Willoughby 2005b). In 
2006, the BLM used a randomized sample of 2005 known occupied cells 
during the very dry winter and spring of 2006 to yield a population 
estimate for the 2005-2006 survey year (Willoughby 2006, p. 6). Both 
the WESTEC and BLM surveys covered an effective area of about 53,000 ac 
(21,200 ha) and encompassed all management areas containing Astragalus 
magdalenae var. peirsonii (Willoughby 2005a, p. 2).
    By comparison, Phillips et al. (2001, p. 6) counted individual 
Astragalus magdalenae var. peirsonii from 127 specific locations 
covering an unspecified area of about 35,000 ac (14,165 ha) (Phillips 
and Kennedy 2002, Appendix A). Phillips and Kennedy (2002, 2003, 2004, 
2005, 2006) then established 25 monitoring sites from these 127 
locations for their multi-year survey effort, which had an effective 
area of about 138 ac (56 ha).
    The disparity between these three survey methods and the data 
collected makes it difficult to assess status and trends of the 
Astragalus magdalenae var. peirsonii population. However, we consider 
the surveys conducted by BLM to be the most extensive and precise 
effort to determine overall population abundance and distribution for 
this species, because this effort covered an effective area of about 
53,000 ac (21,200 ha) and encompassed all management areas containing 
Astragalus magdalenae var. peirsonii. Also, the amount of data gathered 
in 2005 was the result of an exceptionally good rainfall year and 
extraordinary monitoring effort. We agree with the BLM that the 2005 
survey effort represents the best estimate to date of distribution and 
abundance of the species on the Algodones Dunes (Willoughby 2006, p. 
v). The 2005-2006 survey year was an exceptionally dry year, with no A. 
m. var. peirsonii germination reported (Willoughby 2006, p. vi).
    While direct comparison of annual estimates of Astragalus 
magdalenae var. peirsonii abundance reported by BLM and Phillips and 
Kennedy is difficult due to differences in survey methodologies and 
effort used by the surveyors, some comparisons can be made which 
illustrate the wide variation in numbers of standing individuals found 
in any given year and in any given area of the dunes depending on 
abundance and distribution of rainfall. If we compare BLM data from 
1998 with BLM 2000 data and compare Phillips and Kennedy's 2001 data 
with their 2003 data, we see the annual variation in species abundance 
at occupied sites. Along the same series of west to east transects, BLM 
counted a total of 5,064 plants in 1998, a heavy rainfall year, and 86 
plants in 2000, a low rainfall year (Willoughby 2004, p. 36). The 
record of steep decline of the cohort counted by Phillips et al. in 
2001 was tracked by Phillips and Kennedy (2002, p. 18), who reported 
that only 26 percent of the plants seen in spring of 2001 were present 
in late 2001. Phillips and Kennedy (2003, p. 12) also reported that 
only 0.26 percent of the plants counted in spring 2001 survived to 
spring 2003.
    This wide variation in numbers of standing individuals is also 
evident when comparing results of the BLM's dunes-wide surveys 
conducted in 2004, 2005, and 2006. In 2004, estimated dunes-wide 
abundance was 286,374 plants (5.5 plants/ac (13.5/ha)) (Willoughby 
2005a, p. 37). In 2005, estimated dunes-wide abundance was 1,831,076 
plants (39.8 plants/ac (86/ha)) (Willoughby 2005b, pp. 9-11). In 2006, 
estimated dunes-wide abundance was 83,451 plants (1.6 plants/ac (3.9/
ha)) (Willoughby 2006, p. vi). Differences in densities (plants per 
acre) are likely due to differences in rainfall between years. An above 
average amount of rainfall was recorded during the 2004-2005 growing 
season, resulting in the greatest abundance of plants to date, while 
the 2005-2006 growing season was considered an exceptionally dry year, 
resulting in zero reported germination. Density in 2004 may have also 
been decreased due to higher average monthly maximum temperatures 
recorded during the survey period, potentially impacting germination 
(Willoughby 2005a, p. 12).
    In any given year, Astragalus magdalenae var. peirsonii may be 
present as standing plants, as a ``soil seed bank'' in the sand dunes, 
or as plants persisting as perennial root crowns in the sand dunes. 
During any given year, the suitable habitat for A. m. var. peirsonii 
may be occupied by various combinations of these three life history 
phases. The dynamics of dune morphology, local rainfall patterns and 
amounts, and the spatial distribution of the soil seed bank contribute 
to the

[[Page 41262]]

patchy or mosaic nature of the distribution of standing plants of A. m. 
var. peirsonii. As discussed above, local rainfall patterns and amounts 
are likely to cause shifts in the proportions of these three life 
history phases.
    This species was federally listed as threatened due to threats of 
increasing habitat loss from OHV use and associated recreational 
development, destruction of plants, and lack of protection afforded the 
plant under State law (63 FR 53596). Impacts to individual plants and 
their habitat associated with OHV activities and recreation development 
continue to be the primary threat to this species in the United States. 
Please refer to the final listing rule (63 FR 53596) for a detailed 
discussion of the threats to the species and to the ``Special 
Management Considerations or Protection'' section of this proposed rule 
for a more detailed discussion on threats to this species' habitat.

Previous Federal Actions

    For more information on previous Federal actions related to the 
designation of critical habitat for Astragalus magdalenae var. 
peirsonii, refer to the final listing rule published in the Federal 
Register on October 6, 1998 (63 FR 53596), and the proposed designation 
of critical habitat for this species published in the Federal Register 
on August 5, 2003 (68 FR 46143). On August 4, 2004 (69 FR 47330), we 
designated approximately 21,836 acres (ac) (8,848 hectares (ha)) of 
land in Imperial County, California, as critical habitat for this 
species.
    On June 3, 2005, the Center for Biological Diversity, Sierra Club, 
Public Employees for Environmental Responsibility, and Desert Survivors 
filed suit against the BLM and the Service alleging, among other 
violations related to the protection of Astragalus magdalenae var. 
peirsonii and desert tortoise (Gopherus agassizii), that the Service 
did not properly consider and weigh the benefits and costs associated 
with designating critical habitat for A. m. var. peirsonii. In a 
September 25, 2006, order and injunction regarding final relief, the 
court ordered the Service to submit a new final critical habitat rule 
to the Federal Register for publication no later than February 1, 2008. 
In addition, the Court ordered that the August 4, 2004 final critical 
habitat designation remain in full force and effect pending completion 
of the new final rule, and that the August 5, 2003 proposed designation 
of critical habitat be reinstated and remain effective pending 
completion of the new final rule or the issuance of a new proposed 
critical habitat rule for A. m. peirsonii. Therefore, under the Court's 
order, this proposed rule replaces the August 5, 2003 proposed critical 
habitat designation, and the August 5, 2003 proposed rule is no longer 
in effect. All areas currently designated under the August 4, 2004 
final rule remain designated pending completion of the new final 
critical habitat rule.
    On November 30, 2005, we published a notice of 90-day finding on a 
petition to delist this species and an initiation of a status review in 
the Federal Register (70 FR 71795). Please see the notice of 90-day 
finding for a discussion of the previous Federal actions related to the 
delisting petition history of this species. We are currently completing 
a status review of Astragalus magdalenae var. peirsonii and will 
publish our 12-month finding on the delisting petition in the Federal 
Register later this year.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as--(i) The 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. Conservation, as defined under section 3 of the Act means 
to use and the use of all methods and procedures that are necessary to 
bring any endangered species or threatened species to the point at 
which the measures provided under the Act are no longer necessary.
    Critical habitat receives protection under section 7(a)(2) of the 
Act through the prohibition against destruction or adverse modification 
of critical habitat with regard to actions carried out, funded, or 
authorized by a Federal agency. Section 7(a)(2) of the Act requires 
consultation on Federal actions that are likely to result in the 
destruction or adverse modification of critical habitat. The 
designation of critical habitat does not affect land ownership or 
establish a refuge, wilderness, reserve, preserve, or other 
conservation area. Such designation does not allow government or public 
access to private lands. Section 7(a)(2) of the Act is a purely 
protective measure and does not require implementation of restoration, 
recovery, or enhancement measures.
    To be included in a critical habitat designation, the habitat 
within the area occupied by the species at the time of listing must 
first have features that are essential to the conservation of the 
species. Critical habitat designations identify, to the extent known 
using the best scientific data available, habitat areas that provide 
essential life cycle needs of the species (areas on which are found the 
primary constituent elements, as defined at 50 CFR 424.12(b)).
    Occupied habitat that contains the features essential to the 
conservation of the species meets the definition of critical habitat 
only if the essential features thereon may require special management 
considerations or protection. Thus, we do not include areas where 
existing management is sufficient to conserve the species. (As 
discussed below, such areas may also be excluded from critical habitat 
under section 4(b)(2) of the Act.)
    Unoccupied areas can be designated as critical habitat. However, 
when the best available scientific data do not demonstrate that the 
conservation needs of the species require additional areas, we will not 
designate critical habitat in areas outside the geographical area 
occupied by the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, the Service's 
Policy on Information Standards Under the Endangered Species Act, 
published in the Federal Register on July 1, 1994 (59 FR 34271); 
Section 515 of the Treasury and General Government Appropriations Act 
for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658); and the associated 
Information Quality Guidelines issued by the Service provide criteria, 
establish procedures, and provide guidance to ensure that decisions 
made by the Service represent the best scientific data available. They 
require Service biologists, to the extent consistent with the Act and 
with the use of the best scientific data available, to use primary and 
original sources of information as the basis for recommendations to 
designate critical habitat. When determining which areas are critical 
habitat, a primary source of information is generally the listing 
package for the species. Additional information sources may include the 
recovery plan for the species, articles in peer-reviewed journals, 
conservation plans developed by States and counties, scientific status 
surveys and studies, biological assessments, or other unpublished 
materials and expert opinion or personal knowledge. All information is 
used in accordance with the provisions of Section 515 of the

[[Page 41263]]

Treasury and General Government Appropriations Act for Fiscal Year 2001 
(Pub. L. 106-554; H.R. 5658) and the associated Information Quality 
Guidelines issued by the Service.
    Habitat is often dynamic, and species may move from one area to 
another over time. Furthermore, we recognize that designation of 
critical habitat may not include all of the habitat areas that may 
eventually be determined to be necessary for the recovery of the 
species. For these reasons, critical habitat designations do not signal 
that habitat outside the designation is unimportant or may not be 
required for recovery.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the Act and to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available information 
at the time of the action. Federally funded or permitted projects 
affecting listed species outside their designated critical habitat 
areas may still result in jeopardy findings in some cases. Similarly, 
critical habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans, or 
other species conservation planning efforts if new information 
available to these planning efforts calls for a different outcome.

Methods

    As required by section 4(b)(2) of the Act and regulations at 50 CFR 
424.12, we used the best scientific and commercial information 
available in determining areas that contain the features essential to 
the conservation of Astragalus magdalenae var. peirsonii, areas that 
are essential to the conservation of A. m. var. peirsonii, or both. 
This included data from unpublished research and survey reports, such 
as WESTEC (1977); Porter et al. (2005); BLM surveys conducted from 1998 
to 2006 (Willoughby 2001, 2004, 2005a, 2005b, 2006); peer-reviewed 
journal articles; site visits; and discussions with species experts. We 
are not including in this proposed critical habitat rule any areas 
outside the geographical area presently occupied by the species.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas within the geographical area 
occupied by the species at the time of listing to propose as critical 
habitat, we consider those physical and biological features (primary 
constituent elements) that are essential to the conservation of the 
species, and that may require special management considerations or 
protection. These include, but are not limited to: (1) Space for 
individual and population growth and for normal behavior; (2) food, 
water, air, light, minerals, or other nutritional or physiological 
requirements; (3) cover or shelter; (4) sites for breeding, 
reproduction, and rearing (or development) of offspring; and (5) 
habitats that are protected from disturbance or are representative of 
the historic, geographical, and ecological distributions of a species.
    The specific primary constituent elements (PCEs) required for 
Astragalus magdalenae var. peirsonii are derived from the biological 
needs of A. m. var. peirsonii as described in the ``Background'' 
section of this proposed rule, and also in the final listing rule (63 
FR 53596) and in the ``Background'' section of the 2003 proposed 
critical habitat rule (68 FR 46143).

Space for Individual and Population Growth, Including Sites for 
Germination, Reproduction, Seed Dispersal, Seed Bank, and Pollination

    Astragalus magdalenae var. peirsonii is found on active sand dunes 
between active faces (so-called slip faces) of the dunes, in bowls, or 
on semi-stabilized shallow slopes, facing the slip-faces of active 
dunes (Porter et al. 2005, p. 14). Active sand dunes provide the space 
needed for individual and population growth, including sites for 
germination, reproduction, seed dispersal, seed bank, and pollination 
of A. m. var. peirsonii. Active sand dunes are characterized by bowls 
(hollows among the dunes), swales (low area), and slip faces (areas so 
steep that the loose sand naturally cascades downward) that run 
transverse to the primary ridge line. A. m. var. peirsonii generally 
occurs on west-facing slopes where there is relative substrate 
stability from the floor of the dune basin to beyond the ridge; the 
greatest concentrations are generally above the middle of the slope 
(WESTEC 1977, p. 75; Porter et al. 2001, pp. 12-13).
    Sand movement, dune-building, and dune migration are likely 
determined by the wind regime (Norris and Norris 1961, p. 609). Winds 
from the northwest are prevalent in the winter, while in the summer the 
winds are from the southeast (Romspert and Burk 1979, p. 11). Muhs et 
al. (1995, pp. 43-44) found, during a study of the sand source for the 
Algodones Dunes, that dominant sand-moving winds are as follows: 
Prevailing from the northwest all year at Indio, California; from the 
west or southwest all year at El Centro, California; and from the 
northwest in winter and from the southeast in summer at Yuma, Arizona. 
These winds are responsible for the local dispersal of seeds that 
either fall out of partly opened fruits or pods on the parent plant or 
that are released from fruits blown across the sand after falling from 
the parent plant (Phillips et al. 2001, p. 11).
    Seed germination patterns likely reflect the horizontal and 
vertical distribution of the seed bank in the shifting sand dunes 
(seeds will not effectively germinate if buried more than 3 in (8 cm) 
below the surface of the dune (Bowers 1996, p. 69)). As an adaptation 
to shifting sands and low soil moisture, this species has developed 
extremely long tap roots (Barneby 1964, p. 862) that penetrate deeply 
to the moister sand and that anchor the plants in the shifting dunes. 
According to Porter et al. (2005, p. 28), seedlings may have roots 
descending only 4 in (10 cm), whereas older plants (e.g., 4 years or 
older) are likely to have roots ``many meters deep.'' Seeds buried in 
the sand function as the seed bank and allow for growth when suitable 
conditions, such as adequate rainfall, scarification, and suitable sand 
depths, are met.
    Wind-driven sand appears to provide the primary mechanism for seed 
scarification (e.g., scratching or chipping of outer cover). While 
seeds require no pre-germination treatment to induce germination, 
scarification appears to significantly increase germination success. 
Porter et al. (2005, p. 29) conducted germination trials of Astragalus 
magdalenae var. peirsonii seeds collected from Algodones Dunes and 
found that, averaging over all germination trials, scarified seeds had 
99.1 percent germination whereas unscarified seeds displayed 5.3 
percent germination. In germination trials conducted by Romspert and 
Burk (1979, pp. 45-46), 92 percent or more seeds germinated within 29 
days at temperatures of 77 [deg]F (25 [deg]C) or less, and no seeds 
germinated at temperatures of 86 [deg]F (30 [deg]C) or higher. This 
observation indicates that seeds on the dunes likely germinate in the 
cooler months of the year. Porter et al. (2005, p. 29) identified the 
primary dormancy mechanism in A. m. var. peirsonii as the 
impermeability of the seed coat to water and demonstrated little loss 
of viability in seeds stored for 5 years.
    Seedlings may be generally present in suitable habitat throughout 
the dunes,

[[Page 41264]]

especially during above-normal precipitation years. In intervening dry 
years, plant numbers decrease as individuals die and are not replaced 
by new seedlings. Porter (et al. 2005, p. 35) estimated that a total- 
or near-total failure of seedling recruitment occurs 20 percent of the 
time (1 of every 5 years). This species likely depends on the 
production of seeds in the wetter years and the persistence of the seed 
bank from previous years to survive until appropriate conditions for 
germination occur again.
    Astragalus magdalenae var. peirsonii occurs only in a vegetation 
community referred to as psammophytic (sand-loving) scrub, 
characterized by Croton wigginsii (Dunes croton), Eriogonum deserticola 
(Desert buckwheat), Helianthus niveus ssp. Tephrodes (Algodones Dunes 
sunflower), Palafoxia arida var. gigantean (Giant Spanish-needle), 
Pholisma sonorae, Tiquilia plicata (Plicate coldenia), Petalonyx 
thurberi (Thurber's sandpaper plant), and Panicum urvilleanum (Dunes 
panic grass) (WESTEC 1977, p. 58; Porter et al. 2005, p. 14). However, 
none of these species truly dominates the landscape (Porter et al. 
2005, p. 14).
    In areas where the sand dunes are more stabilized (less sand dune 
building and movement), such as along the margins of the dune fields, 
the open canopy psammophytic scrub community is replaced by the sandier 
phases of the creosote bush scrub community. Astragalus magdalenae var. 
peirsonii is apparently excluded from the relatively more closed 
canopy, creosote bush scrub community. The presence of this associated 
co-adapted psammophytic scrub plant community is important for 
population growth of A. m. var. peirsonii, because it provides habitat 
for insect pollinators required by A. m. var. peirsonii for fruit 
production (Porter et al. 2005, p. 35). The white-faced digger bee 
(Habropoda pallida) has been found to be the most frequent visitor on 
and may be the primary pollinator for this taxon (Porter et al. 2005, 
p. 32).

Intervening Areas for Gene Flow and Connectivity Within the Population

    The active sand dunes are continuous along the northwest-to-
southeast axis. The continuity of the sand dunes provides connectivity 
and facilitates gene flow within the population by allowing the 
movement of pollinators and the wind dispersal of fruit and seeds. 
Therefore, areas of the sand dunes between bowls occupied by Astragalus 
magdalenae var. peirsonii are important for maintaining gene flow 
within the population.

Areas That Provide the Basic Requirements for Growth (Such as Water, 
Light, and Minerals)

    A soil survey for the Imperial Valley area of Imperial County did 
not include the areas east of the Coachella Canal, but did depict a few 
adjacent portions of the Algodones Dunes as Rositas fine sand with 9 to 
30 percent slopes (Zimmerman 1981, p. 32). Rositas fine sand is 
described as deep, somewhat excessively drained, sloping soils formed 
in wind-blown sands of diverse origin. Dean (1978, p. 65) describes the 
sand as quartz with a mean grain size of 0.006 in (0.17 mm). The dunes 
contain 60 to 70 percent quartz and 30 to 40 percent feldspar sand 
(Norris and Norris 1961, p. 610). Porter et al. 2005 (pp. 26-27) 
describes the sand as containing very little organic material (less 
than 1 percent). They also found that following rainfall, the dune 
surface held considerable moisture. Within two to three weeks of a 
rainfall event, moist sand was found 1 in (3 cm) below the dune surface 
and later in the season (e.g., April) moist sand was found 7 in (19 cm) 
below the surface (Porter et al. 2005, pp. 26-27). Therefore, Rositas 
fine sands are required by this species to provide the basic 
requirements for growth.
    Based on the best available information at this time, the primary 
constituent elements required by Astragalus magdalenae var. peirsonii 
are:
    (1) West and/or northwest-facing sides of bowls, swales, and slopes 
consisting of Rositas fine sands within intact, active sand dune 
systems (defined as sand areas that are subject to sand-moving winds) 
in the existing range of the species that provide space needed for 
individual and population growth, including sites for germination, 
reproduction, seed dispersal, seed bank, and pollination;
    (2) The associated co-adapted psammophytic scrub plant community 
characterized by Croton wigginsii, Eriogonum deserticola, Helianthus 
niveus ssp. tephrodes, Palafoxia arida var. gigantean, Pholisma 
sonorae, Tiquilia plicata, Petalonyx thurberi, and Panicum urvilleanum 
that provides habitat for insect pollinators, particularly the white-
faced digger bee (Habropoda pallida), required for reproduction; and
    (3) Areas within intact, active sand dune systems between occupied 
bowls, swales, and slopes that allow for pollinator movement and wind 
dispersal of fruit and seeds.
    This proposed revision to the critical habitat designation is 
designed for the conservation of those areas containing PCEs necessary 
to support the life history functions that were the basis for the 
proposal and the areas containing those PCEs. Because not all life 
history functions require all the PCEs, not all proposed critical 
habitat units will contain all the PCEs.
    Units are designated based on sufficient PCEs being present to 
support at least one of the species' life history functions. Some units 
contain all PCEs and support multiple life processes, while some units 
contain only a portion of the PCEs necessary to support the species' 
particular use of that habitat.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the areas 
determined to be occupied at the time of listing contain primary 
constituent elements that may require special management considerations 
or protection. We have also considered how revising the current 
designation highlights habitat that needs special management 
consideration or protection.
    Astragalus magdalenae var. peirsonii was listed due to destruction 
of plants and modification of habitat associated with OHV activity and 
associated recreational development (63 FR 53596). OHVs can impact 
habitat for A. m. var. peirsonii by:
    (1) Disrupting the natural processes that support dune formation, 
movement, and structure which could disrupt the available habitat 
needed for individual and population growth (PCE 1 and 3);
    (2) Causing the collapse of dune faces and ridges, which could 
result in burial of the seed bank (PCE 1);
    (3) Disturbing surface sand, thereby decreasing soil moisture 
needed for individual and population growth (PCE 1); and
    (4) Degrading the psammophytic scrub plant community that provides 
habitat for pollinators required for reproduction (PCE 2).
    In the 2004 final critical habitat rule, we stated that OHVs may 
also increase sand compaction (69 FR 47330). However, Porter et al. 
(2005, p. 27) measured soil compaction associated with undisturbed 
dunes, OHV-traversed sand dunes, and dunes disturbed by foot traffic, 
and found that soil compaction on the undisturbed dunes was 
significantly higher. They state that winds and rains cause the sand 
grains on the surface of the dune to sort and pack in undisturbed 
areas, thereby potentially reducing evaporative water loss from the 
dunes. They theorize that OHV activity or walking disturbs the surface 
and may result in increased

[[Page 41265]]

evaporative water loss in the dunes (Porter et al. 2005, p. 27).
    Special management considerations or protection may be required to 
minimize impacts to Astragalus magdalenae var. peirsonii habitat 
resulting from OHV recreation. The BLM (2003, Appendix 1 p. 13) listed 
the following possible management options to protect A. m. var. 
peirsonii and its habitat: (1) Use restrictions based on a permit 
system that would allow a specified level of use (high, medium, low, no 
use); (2) temporally based closures or limitations (open during some 
months or years, closed in others); (3) recognition and management of 
certain areas within a management area; and/or (4) increased education 
and outreach to OHV users to avoid certain areas. Special management 
considerations needed may also include additional enforcement to ensure 
visitor compliance with these management options.

Criteria Used To Identify Critical Habitat

    All proposed revised critical habitat units are within areas that 
we have determined were occupied at the time of listing, and that 
contain sufficient primary constituent elements (PCEs) to support life 
history functions essential for the conservation of the species. Lands 
were proposed for designation based on sufficient PCEs being present to 
support the life processes. Some lands contain only a portion of the 
PCEs necessary to support the particular use of that habitat.
    We consider BLM's 2005 (Willoughby 2005b) survey data to be the 
best available information on the distribution and range of Astragalus 
magdalenae var. peirsonii on the Algodones Dunes. As discussed in the 
``Background'' section of this proposed rule, an exceptional amount of 
rainfall was recorded during the 2004-2005 growing season, resulting in 
the highest recorded abundance of the species to date with an estimated 
1,831,076 plants (39.8 plants/ac (86 plants/ha)) in the dunes 
(Willoughby 2005b, pp. 9-11). This rainfall event coincided with the 
start of BLM's revised survey methodology, which consisted of a more 
detailed survey approach, as previously described in the ``Background'' 
section, and covered a larger portion of the dunes (Willoughby 2005a, 
pp. 1-5). The 2005 survey contained 123,488 sample points covering an 
effective area of 53,000 acres. Because these surveys occurred under 
the best possible growth and germination conditions for the plant and 
covered the largest area and greatest number of sample point locations, 
we relied on BLM's raw 2005 survey data as the basis for our criteria 
and GIS model to delineate proposed critical habitat for A. m. var. 
peirsonii.
    As discussed in further detail below, we used the following 
criteria to delineate proposed critical habitat: (1) Areas occupied by 
the species at the time of listing; (2) areas occupied at a density 
greater than 100 plants per ha according to BLM's 2005 survey data 
(Willoughby 2005b); and (3) areas containing the features essential to 
the conservation of the species. As stated in the final listing rule 
(63 FR 53596), the Algodones Dunes was, and continues to be, the only 
area in the United States known to be occupied by Astragalus magdalenae 
var. peirsonii.
    We delineated the revised proposed critical habitat boundaries 
using the following GIS model:
    (1) We selected occupied cells (defined in Willoughby (2005b) as 
25-m\2\ survey areas) with a plant density greater than 100 plants per 
ha (6 plants per cell) as core areas. About half of the plants observed 
in 2005 were in cells with a density more than or equal to 100 plants 
per ha. We used a density of 100 plants per ha since this captured the 
majority of the large clusters of standing plants. We believe these 
higher density core areas contain a larger extent of high quality 
habitat (e.g., suitable dune morphology and soil moisture) and 
therefore the PCEs required by this species. Also, since these core 
areas contain higher numbers of standing plants in proximity to each 
other, we believe that these areas likely support relatively large seed 
banks (a greater number of seeds being contributed by a greater number 
of standing plants). Therefore, based on our assumptions that these 
core areas contain a larger extent of high quality habitat and larger 
seed banks, we considered these areas most likely to contribute to the 
recovery of the species.
    (2) We expanded each core area to 1 ha then merged 1-ha core areas 
within 100-m distances of each other to form aggregated core areas. We 
expanded core areas to one ha to capture the entire population and seed 
bank in a dune bowl, based on our field observations that most occupied 
dune bowls are approximately one ha in size. We aggregated the 1-ha 
core areas within 100 m of each other to maintain space for wind 
dispersal of seeds between occupied dune bowls. This 100-m distance is 
a dunes-wide approximation of the average distance between aggregated 
core areas.
    (3) We then eliminated outlying or remote core areas greater than 
400 meters (4 bowls) from adjacent core areas and core areas less than 
400 m away but with a plant density less than approximately 370 plants 
(= 0.0005 of the total observed population of 739,805) within the 
aggregated core area. This step allowed us to remove core areas with 
low numbers of plants considered not essential to the conservation of 
the species. Since these areas are a greater distance from aggregated 
core areas and/or contain relatively fewer standing plants, we believe 
these areas either contain a smaller extent of high quality habitat 
(e.g., suitable dune morphology and soil moisture) and/or support 
relatively small seed banks. Since we were not able to determine the 
importance of these outlying or remote areas to the long-term 
conservation of the species, we did not include them in the proposed 
designation.
    (4) We then overlaid a 100-m\2\ grid onto the final core areas to 
define the legal boundaries of the proposed critical habitat. We 
removed remaining small polygons less than 400 m from the core habitat 
in which the plant density was low. Since these polygons contained a 
low number of standing plants, we believe these areas contain a smaller 
extent of high quality habitat (e.g., suitable dune morphology and soil 
moisture) and/or support relatively small seed banks. Since we are not 
able to determine the importance of these lower density areas to the 
long-term conservation of the species at this time, we did not include 
them in the proposed designation.
    This methodology captured approximately 92 percent of the 2005 
observed population and includes areas we believe contain high density 
core populations, a large extent of high quality habitat, and a large 
seed bank and therefore important for the recovery of the species.
    Areas meeting the proposed critical habitat boundaries were then 
analyzed to determine if any existing conservation or management plans 
exist that benefit the taxon and its PCEs. As discussed in the 2004 
final critical habitat rule (69 FR 47330), BLM released a proposed 
Recreation Area Management Plan (RAMP) for the ISDRA in 2003 (BLM 
2003). The RAMP includes an intensive monitoring/study plan that the 
BLM has implemented (BLM 2003). As a result of the September 25, 2006, 
order and injunction regarding final relief, referenced in the 
``Background'' section of this proposed rule, the Environmental Impact 
Statement associated with the 2003 RAMP was remanded back to the BLM 
for further consideration.

[[Page 41266]]

    When determining proposed critical habitat boundaries within this 
proposed rule, we made every effort to avoid including developed areas 
such as buildings, paved areas, and other structures that lack PCEs for 
Astragalus magdalenae var. peirsonii. The scale of the maps prepared 
under the parameters for publication within the Code of Federal 
Regulations may not reflect the exclusion of such developed areas. Any 
such structures and the land under them inadvertently left inside 
critical habitat boundaries shown on the maps of this proposed rule 
have been excluded by text in the proposed rule and are not proposed 
for designation as critical habitat. Therefore, Federal actions limited 
to these areas would not trigger section 7 consultation, unless they 
affect the species or primary constituent elements in adjacent critical 
habitat.

Summary of Changes From Previously Designated Critical Habitat

    The areas identified in this proposed rule constitute a proposed 
revision of the areas we proposed to designate as critical habitat for 
Astragalus magdalenae var. peirsonii on August 5, 2003 (68 FR 46143), 
and designated on August 4, 2004 (69 FR 47330). The main differences 
include the following:
    1. This proposed revision includes 16,108 ac (6,519 ha) of land in 
Imperial County, California, a reduction of 36,672 acre (14,840 ha) 
from the 2003 proposed rule (68 FR 46143) and 5,728 ac (2,329 ha) from 
the 2004 final critical habitat rule (69 FR 47330). The differences in 
data and selection criteria between the currently designated critical 
habitat and this proposed revision are described further below.
    2. The reduction in total acreage from the 2003 proposed critical 
habitat designation is primarily the result of a revised methodology to 
delineate critical habitat. The model used to delineate critical 
habitat boundaries in the 2003 proposed rule was based primarily on 
species survey data collected by the BLM from 1998 through 2002 along 
transects throughout the areas of the Algodones Dunes occupied by 
Astragalus magdalenae var. peirsonii. Each transect was composed of a 
series of grid squares measuring approximately 0.45 mi\2\. In order to 
create the model, we used the coarse scale BLM survey data to 
extrapolate the values for four variables: (1) The presence or absence 
of standing plants of A. m. var. peirsonii; (2) the abundance of A. m. 
var. peirsonii; (3) the frequency of occurrence of A. m. var. peirsonii 
over the survey years; and (4) the number of associated rare 
psammophytic plant taxa present. These variables were scored, then 
standardized, and finally compiled. Because of the dynamic nature of 
the distribution of this plant, the cyclic nature of suitable climatic 
regimes, and the presence of a seed bank for A. m. var. peirsonii, grid 
squares where this plant was not found were included in critical 
habitat if they were contiguous with occupied grid squares (68 FR 
46143). The data used to create the 2003 model was considered the best 
available at that time and allowed us to identify areas known to be 
occupied by A. m. var. peirsonii as well as areas likely to be occupied 
based on the presence of suitable habitat (e.g. presence of associated 
psammophytic plant taxa).
    As discussed in the ``Background'' and ``Criteria Used to Identify 
Critical Habitat'' sections of this proposed rule, the model used to 
delineate revised critical habitat boundaries in this revised proposed 
rule is based on survey data collected by BLM in 2005 (Willoughby 
2005b). A higher than average rainfall occurred during the 2004-2005 
growing season, resulting in the highest Astragalus magdalenae var. 
peirsonii densities to date. Based on these survey data, our revised 
model uses occupancy and density to outline areas known to be occupied 
by the species. The model used to delineate the revised proposed 
critical habitat is based on data collected along a larger number of 
transects (510 versus 34) during a year of the highest recorded A. m. 
var. peirsonii abundance. Therefore, the data are more robust, relying 
primarily on occupancy documented over a larger area of the dunes and 
at a finer spatial resolution (25 m\2\ grid cells) during optimal 
environmental conditions instead of on the presence of suitable habitat 
(e.g., the presence of associated rare psammophytic plant taxa) as did 
the 2003 model.
    In summary, we consider the model used to delineate revised 
critical habitat boundaries in this proposed rule to more accurately 
depict the areas known to be occupied by the species than the model 
used to delineate the 2003 proposed critical habitat boundaries. We 
believe that the 2003 designation was more inclusive due to limited 
data and the rough spatial scale of the data, and the 2005 data now 
provide more specific and reliable information regarding abundance and 
distribution, allowing us to more precisely identify habitat essential 
to the conservation of the species associated with core population 
areas. Based on the new model, we determined that 36,535 ac (14,785 ha) 
previously proposed as critical habitat in 2003 are not essential to 
the conservation of the taxon, and therefore did not include these 
areas in the revised proposed critical habitat designation.
    3. Of the 16,108 ac (6,519 ha) included in this proposed revision 
to critical habitat, 14 ac (6 ha) in Subunit 3B, 331 ac (134 ha) in 
Subunit 3C, and 75 ac (30 ha) in Unit 4 were not included in the 2003 
proposed critical habitat rule. Also, 9,573 ac (3,874 ha) in Subunits 
2A, 2B, 3A, 3B, 3C and all of Unit 4 (218 ac (88 ha)) were not included 
in the 2004 final rule (see Table 2 below). These 9,573 ac (3,874 ha) 
were excluded in the 2004 final rule under section 4(b)(2) of the Act 
as the Secretary determined that the economic benefits of excluding 
these lands outweighed the conservation benefits of including these 
lands in the designation due to the large potential economic and human 
costs of the designation (69 FR 47330). These lands are again under 
consideration for critical habitat in this proposed revision to 
critical habitat.
    All lands proposed for critical habitat have been re-evaluated in a 
revised economic analysis, consistent with the lawsuit discussed in the 
``Previous Federal Actions'' section of this proposed rule. The new 
draft economic analysis is available for public review and comment 
concurrently with this rule (see ``Economic Analysis'' section below). 
Based on public comment and information in the economic analysis, 
habitat being proposed as critical habitat herein may be excluded from 
final critical habitat by the Secretary under the provisions of section 
4(b)(2) of the Act and in our implementing regulations at 50 CFR 
424.19. Table 2 below outlines the changes in Unit/Subunit number and 
area between the 2003 proposed critical habitat rule, the 2004 final 
critical habitat rule, and the 2007 revised proposed critical habitat 
rule for Astragalus magdalenae var. peirsonii.

[[Page 41267]]



 Table 2.--Changes in Unit/Subunit Numbering and Area (