Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Acanthomintha ilicifolia, 11946-11988 [07-1100]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 49 (Wednesday, March 14, 2007)]
[Proposed Rules]
[Pages 11946-11988]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-1100]



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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for Acanthomintha ilicifolia (San Diego thornmint); Proposed 
Rule

Federal Register / Vol. 72, No. 49 / Wednesday, March 14, 2007 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU86


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Acanthomintha ilicifolia (San Diego thornmint)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
designate critical habitat for Acanthomintha ilicifolia (San Diego 
thornmint) under the Endangered Species Act of 1973, as amended (Act). 
We have determined that a total of approximately 1,936 acres (ac) (783 
hectares (ha)) in San Diego County, California, meets the definition of 
critical habitat. We are proposing to exclude 1,302 ac (527 ha) from 
the critical habitat designation. If these proposed exclusions are 
adopted, this would result in a designation of critical habitat of 
approximately 634 ac (257 ha) of land under Federal (553 ac (224 ha)), 
and State and local (81 ac (33 ha)), ownership in San Diego County, 
California.

DATES: We will accept comments from all interested parties until May 
14, 2007. We must receive requests for public hearings, in writing, at 
the address shown in the ADDRESSES section by April 30, 2007.

ADDRESSES: If you wish to comment on the proposed rule, you may submit 
your comments and materials identified by RIN 1018-AU86, by any of the 
following methods:
    (1) You may send comments by electronic mail (e-mail) to 
fw8cfwocomments@fws.gov. Include ``RIN 1018-AU86'' 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, 6010 Hidden Valley Road, Carlsbad, CA 92011.
    (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).

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad 
Fish and Wildlife Office at the address or telephone number listed 
under ADDRESSES. Persons who use a telecommunications device for the 
deaf (TDD) may call the Federal Information Relay Service (FIRS) at 
800-877-8339.

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 rule are hereby solicited. 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 
species due to designation;
    (2) Specific information on the amount and distribution of 
Acanthomintha ilicifolia habitat and what areas should be included in 
the designation that were occupied at the time of listing that contain 
the features essential for the conservation of the species, and why and 
what areas that were not occupied at the time of listing are essential 
to the conservation of the species;
    (3) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat;
    (4) Our proposed exclusion of 1,302 acres (ac) (527 hectares (ha)) 
of non-Federal lands already conserved or targeted for conservation 
within subarea plans under the San Diego Multiple Species Conservation 
Program (MSCP) and the San Diego Multiple Habitat Conservation Program 
(MHCP) from the final designation of critical habitat for Acanthomintha 
ilicifolia under section 4(b)(2) of the Act. We are specifically 
seeking public comment on our proposed exclusion of lands covered under 
the City of Encinitas subarea plan of the MHCP (see Exclusions Under 
Section 4(b)(2) of the Act for details of these HCPs). It is our 
understanding that little progress has been made by the City of 
Encinitas to finalize their subarea plan since the 2001 release of the 
draft plan. Based on information received during the public comment 
period, the Secretary may determine that sufficient progress has not 
been made and that lands within the City of Encinitas' subarea plan 
should not be excluded from the final designation. Specifically, useful 
information would include: Whether essential lands within Encinitas are 
being managed, or are proposed to be managed, to conserve A. 
ilicifolia, and; the outlook for completion of the draft subarea plan. 
Please provide information concerning whether the benefits of exclusion 
of any of these specific areas outweigh the benefits of their inclusion 
in designated critical habitat. If the Secretary determines the 
benefits of including these lands outweigh the benefits of excluding 
them, they will not be excluded from final critical habitat;
    (5) Any foreseeable economic, national security, or other potential 
impacts resulting from the proposed designation and, in particular, any 
impacts on small entities; and
    (6) 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, you may submit your comments and materials 
concerning this proposal by any one of several methods (see ADDRESSES). 
Please submit e-mail comments to fw8cfwocomments@fws.gov. Please also 
include ``Attn: RIN 1018-AU86'' 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.
    Our practice is to make comments, including names and home 
addresses of respondents, available for public review during regular 
business hours. Individual respondents may request that we withhold 
their names and home addresses, etc., but if you wish us to consider 
withholding this information, you must state this prominently at the 
beginning of your comments. In addition, you must present rationale for 
withholding this information. This rationale must demonstrate that 
disclosure would constitute a clearly unwarranted invasion of privacy. 
Unsupported assertions will not meet this burden. In the absence of 
exceptional, documentable circumstances, this information will be

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released. We will always make submissions from organizations or 
businesses, and from individuals identifying themselves as 
representatives of or officials of organizations or businesses, 
available for public inspection in their entirety.

Role of Critical Habitat in Actual Practice of Administering and 
Implementing the Act

    Attention to and protection of habitat is paramount to successful 
conservation actions. The role that designation of critical habitat 
plays in protecting habitat of listed species, however, is often 
misunderstood. As discussed in more detail below in the discussion of 
exclusions under section 4(b)(2) of the Act, there are significant 
limitations on the regulatory effect of designation under section 
7(a)(2) of the Act. In brief, (1) designation provides additional 
protection to habitat only where there is a Federal nexus; (2) the 
protection is relevant only when, in the absence of designation, 
destruction or adverse modification of the critical habitat would in 
fact take place (in other words, other statutory or regulatory 
protections, policies, or other factors relevant to agency decision-
making would not prevent the destruction or adverse modification); and 
(3) designation of critical habitat triggers the prohibition of 
destruction or adverse modification of that habitat, but it does not 
require specific actions to restore or improve habitat.
    Currently, only 483 species, or 37 percent of the 1,311 listed 
species in the United States under the jurisdiction of the Service have 
designated critical habitat. We address the habitat needs of listed 
species through conservation mechanisms such as listing, section 7 
consultations, the section 4 recovery planning process, the section 9 
protective prohibitions of unauthorized take, section 6 funding to the 
States, the section 10 incidental take permit process and cooperative, 
nonregulatory efforts with private landowners. The Service believes 
that it is these measures that may make the difference between 
extinction and survival for many species.
    In considering exclusions of areas proposed for designation, we 
evaluate the benefits of designation in light of Gifford Pinchot Task 
Force v. U.S. Fish and Wildlife Service, 378 F.3d 1059 (9th Cir. 2004) 
(hereinafter Gifford Pinchot). In that case, the Ninth Circuit 
invalidated the Service's regulation defining ``destruction or adverse 
modification of critical habitat.'' In response, on December 9, 2004, 
the Director issued guidance to be considered in making section 7 
adverse modification determinations. This proposed critical habitat 
designation does not use the invalidated regulation in our 
consideration of the benefits of including areas in the proposed 
designation. The Service will carefully manage future consultations 
that analyze impacts to designated critical habitat, particularly those 
that appear to be resulting in an adverse modification determination. 
Such consultations will be reviewed by the Regional Office prior to 
finalizing to ensure that an adequate analysis has been conducted that 
is informed by the Director's guidance.
    On the other hand, to the extent that designation of critical 
habitat provides protection, that protection can come at significant 
social and economic cost. In addition, the mere administrative process 
of designation of critical habitat is expensive, time-consuming, and 
controversial. The current statutory framework of critical habitat, 
combined with past judicial interpretations of the statute, make 
critical habitat the subject of excessive litigation. As a result, 
critical habitat designations are driven by litigation and courts 
rather than biology, and made at a time and under a timeframe that 
limits our ability to obtain and evaluate the scientific and other 
information required to make the designation most meaningful.
    In light of these circumstances, the Service believes that 
additional agency discretion would allow our focus to return to those 
actions that provide the greatest benefit to the species most in need 
of protection.

Procedural and Resource Difficulties in Designating Critical Habitat

    We have been inundated with lawsuits for our failure to designate 
critical habitat, and we face a growing number of lawsuits challenging 
critical habitat determinations once they are made. These lawsuits have 
subjected the Service to an ever-increasing series of court orders and 
court-approved settlement agreements, compliance with which now 
consumes nearly the entire listing program budget. This leaves the 
Service with little ability to prioritize its activities to direct 
scarce listing resources to the listing program actions with the most 
biologically urgent species conservation needs.
    The consequence of the critical habitat litigation activity is that 
limited listing funds are used to defend active lawsuits, to respond to 
Notices of Intent to sue relative to critical habitat, and to comply 
with the growing number of adverse court orders. As a result, listing 
petition responses, the Service's own proposals to list critically 
imperiled species, and final listing determinations on existing 
proposals are all significantly delayed.
    The accelerated schedules of court-ordered designations have left 
the Service with limited ability to provide for public participation or 
to ensure a defect-free rulemaking process before making decisions on 
listing and critical habitat proposals, due to the risks associated 
with noncompliance with judicially imposed deadlines. This in turn 
fosters a second round of litigation in which those who fear adverse 
impacts from critical habitat designations challenge those 
designations. The cycle of litigation appears endless, and is very 
expensive, thus diverting resources from conservation actions that may 
provide relatively more benefit to imperiled species.
    The costs resulting from the designation include legal costs, the 
cost of preparation and publication of the designation, the analysis of 
the economic effects and the cost of requesting and responding to 
public comment, and in some cases the costs of compliance with the 
National Environmental Policy Act (NEPA) (42 U.S.C. 4321 et seq.). 
These costs, which are not required for many other conservation 
actions, directly reduce the funds available for direct and tangible 
conservation actions.

Background

    It is our intent to discuss only those topics directly relevant to 
the designation of critical habitat in this proposed rule. For more 
information on the biology and ecology of Acanthomintha ilicifolia, 
please refer to the final rule listing the species as threatened 
published in the Federal Register on October 13, 1998 (63 FR 54938). 
This species has been listed by the State of California as endangered 
since 1982.

Species Description and Life History

    Acanthomintha ilicifolia (San Diego thornmint) is an annual member 
of the mint family in the genus Acanthomintha. This plant ranges in 
height from 2 to 6 inches (in) (5 to 15 centimeters (cm)) and has 
white, two-lipped, tubular flowers with rose-colored markings on the 
lower lip (Jokerst 1993, p. 713). Members of this genus have paired 
leaves and several sharp spiny bracts (modified leaves) below whorled 
flowers. Acanthomintha ilicifolia can be distinguished from other 
members of the genus by its flower, which has hairless anthers and 
style.

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Distribution, Ecology, and Habitat

    Acanthomintha ilicifolia usually occurs on heavy clay soils in open 
areas surrounded by shrubby vegetation. These openings are generally 
found within coastal sage scrub, chaparral and native grassland of 
coastal San Diego County and south to San Telmo in northern Baja 
California, Mexico (Beauchamp 1986, p. 175; Reiser 2001, pp. 3-5). 
Acanthomintha ilicifolia is frequently associated with gabbro soils, 
which are derived from igneous rock, and gray calcareous clays derived 
from soft calcareous sandstone (Oberbauer and Vanderwier 1991, pp. 208-
209). This species is endemic to San Diego County, California, and 
northwestern Baja California, Mexico, and grows on open clay lenses 
described as friable, meaning that these soils have a loose, crumbly 
texture.
    In the final listing rule for Acanthomintha ilicifolia (63 FR 
54938, October 13, 1998), 32 of 52 historic populations were presumed 
to be extant (still in existence). In the listing rule we estimated 
that the total number of individual plants in all remaining populations 
was approximately 150,000 to 170,000 (63 FR 54938). Throughout this 
proposed rule, occurrences of A. ilicifolia are referred to by their 
element occurrence (EO) number. This is a code that is assigned to each 
specific location of rare species that is cataloged in the California 
Natural Diversity Database (CNDDB). Element occurrences do not 
necessarily represent populations, but are used to represent areas 
where a species is found. Element occurrences that are close together 
may be part of the same population. Therefore, the number of element 
occurrences does not represent the number of populations that exist for 
this species. For the purpose of this proposed critical habitat 
designation, we are assuming that element occurrences within one mile 
(1.6 kilometers (km)) of each other and on habitat that is not 
fragmented by roads or structures are part of the same population.
    Through surveys associated with the development of Habitat 
Conservation Plans (HCPs) and additional surveys on public and private 
lands since the time of listing, additional populations of A. 
ilicifolia have been discovered. We currently have data for a total of 
88 element occurrences (or 64 populations) of which 54 element 
occurrences (or 34 populations) are extant or presumed extant and 34 
element occurrences (or 30 populations) are considered to be extirpated 
(no longer in existence) or possibly extirpated. Specifically, we 
consider 68 element occurrences to have been known at the time of 
listing in 1998 (52 historic populations) and an additional 20 element 
occurrences to have been discovered since the time of listing (12 new 
populations). Detailed information about the new element occurrences is 
available upon request from the Carlsbad Fish and Wildlife Office (see 
ADDRESSES).

Previous Federal Actions

    Acanthomintha ilicifolia was federally listed as threatened on 
October 13, 1998 (63 FR 54938), and has been listed as endangered by 
the State of California since 1982 (CDFG 2006, p.1). This species 
currently does not have a recovery plan.
    At the time this plant was federally listed, the Service compared 
the benefits of designating critical habitat to the detrimental effects 
(threats) of increased collection and vandalism and the potential for 
private landowner misunderstandings about the effects of critical 
habitat designation on private lands (63 FR 54938, pp. 54951-54953). 
Additionally, we conflated the jeopardy standard with the standard for 
destruction or adverse modification of critical habitat, stating that a 
jeopardy finding would be equivalent to a finding of adverse 
modification of critical habitat thereby resulting in identical section 
7 findings. Based on these factors, the Service found that designation 
of critical habitat for A. ilicifolia was not prudent.
    On August 10, 2004, the Center for Biological Diversity and 
California Native Plant Society challenged our failure to designate 
critical habitat for this species as well as four other plant species 
(Center for Biological Diversity v. Norton, C-04-3240 JL (N. D. Cal.)). 
In settlement of the lawsuit, the Service agreed to withdraw our 
previous not prudent finding and deliver a proposed determination of 
critical habitat, if prudent, to the Federal Register on or before 
February 28, 2007 and a final designation by February 28, 2008.
    We have re-evaluated the prudency of designating critical habitat 
for this species. Despite the potential threats to this species from 
collection and vandalism and the continuing potential for private 
landowner misunderstandings about the effects of critical habitat 
designation on private land, we believe that designation of critical 
habitat will benefit A. ilicifolia. As a result of the Gifford Pinchot 
court ruling in 2004, we now recognize the jeopardy standard and the 
standard for destruction or adverse modification of critical habitat 
are separate and distinct. Additionally, we recognize critical habitat 
designations may provide benefits to the recovery of a species. 
Therefore, we now find designation of critical habitat for A. 
ilicifolia to be prudent because designation of critical habitat has 
the potential to provide greater protections to the species and its 
habitat than the jeopardy standard under section 7(a)(2) of the Act.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as--(i) the 
specific areas within the geographical area occupied by 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 which are necessary to 
bring any endangered species or threatened species to the point at 
which the measures provided pursuant to the Act are no longer 
necessary. Such methods and procedures include, but are not limited to, 
all activities associated with scientific resources management such as 
research, census, law enforcement, habitat acquisition and maintenance, 
propagation, live trapping, and transplantation, and, in the 
extraordinary case where population pressures within a given ecosystem 
cannot be otherwise relieved, may include regulated taking.
    Critical habitat receives protection under section 7 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 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 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 must first have features that 
are essential to the conservation of the species. Critical habitat 
designations identify, to the

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extent known using the best scientific data available, habitat areas 
that provide essential life cycle needs of the species (i.e., areas on 
which are found the primary constituent elements, as defined at 50 CFR 
424.12(b)). Habitat within the geographic area occupied by the species 
at the time of listing may be included in critical habitat only if the 
essential features thereon may require special management 
considerations or protection. Areas outside of the geographic area 
occupied by the species at the time of listing may only be included in 
critical habitat if they are essential for the conservation of the 
species. Accordingly, 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 at the time of 
listing. An area currently occupied by the species but not known to be 
occupied at the time of listing will likely, but not always, be 
essential to the conservation of the species and, therefore, typically 
included in the critical habitat designation.
    The Service's Policy on Information Standards Under the Endangered 
Species Act, published in the Federal Register on July 1, 1994 (59 FR 
34271), and 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 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 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.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. 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, we used the best 
scientific data available in determining areas that contain the 
features that are essential to the conservation of Acanthomintha 
ilicifolia. This includes information from the proposed listing rule 
(60 FR 40549, August 9, 1995); final listing rule (63 FR 54938, October 
13, 1998); data from research and survey observations published in 
peer-reviewed articles; site visits and unpublished survey data; 
regional Geographic Information System (GIS) layers including soil, 
vegetation and species coverages from San Diego County and data 
compiled in the California Natural Diversity Database (CNDDB). More 
specifically, the information sources used for this proposal include: 
(1) CNDDB element occurrence data (2005 and 2006); (2) Bauder and 
McMillan (1994, pp. 1-87); (3) McMillan (2001, pp. 1-91); (4) herbarium 
records from San Diego Natural History Museum, University of California 
at Berkeley and Rancho Santa Ana Botanical Garden; (5) personal 
communications with A. ilicifolia experts (Bauder 2006; Hanson 2006; 
Kelly 2005; McMillan 2006; Sproul 2006; and Vinje 2006); (6) site 
visits by Service biologists to several known element occurrences of A. 
ilicifolia in 2005 and 2006; and (7) information provided by the 
Cleveland National Forest of the U.S. Forest Service (Winter and Young 
2005).

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 to propose as critical 
habitat, we consider those areas occupied by the species at the time of 
listing that contain physical or biological features (primary 
constituent elements (PCEs)) 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, space for individual 
and population growth and for normal behavior; food, water, air, light, 
minerals, or other nutritional or physiological requirements; cover or 
shelter; sites for breeding, reproduction, and rearing of offspring, 
germination, and seed dispersal; and habitats that are protected from 
disturbance or are representative of the historic geographical and 
ecological distributions of a species.
    The specific primary constituent element required for Acanthomintha 
ilicifolia is derived from the biological needs of A. ilicifolia as 
described in the proposed and final listing rules (60 FR 40549; 63 FR 
54938).

Space for Individual and Population Growth and Normal Behavior

    Acanthomintha ilicifolia occurs on isolated patches of clay soils 
derived from gabbro and soft calcareous sandstone substrates (Oberbauer 
and Vanderwier 1991, pp. 208-209) (PCE). The soils derived from gabbro 
substrates are red to dark brown clay soils, and those derived from 
soft calcareous sandstone are gray, sometimes loamy, clay soils. These 
patches of clay soils are called ``clay lenses,'' and in San Diego 
County and northern Baja California, Mexico, clay lenses are known to 
support a variety of narrow endemic (restricted to a specific 
geographic area) plants. Clay lenses tend to have an open or 
unpopulated look because many common species cannot tolerate living on 
these clay soils. Clay lenses are typically devoid of woody, perennial 
shrubs (PCE). It is believed shrubs have difficulty surviving on these 
soils because in the rainy winter months these soils become saturated

[[Page 11950]]

with water and the large root systems of shrubs are not able to get 
oxygen (Oberbauer and Vanderwier 1991, pp. 208-209). Also, as the soils 
become saturated they expand and move, and when the soils dry they 
contract and crack, making it difficult for shrubs to become 
established. Likewise, relatively few common annual plant species 
inhabit clay lenses due to the harsh conditions, and those plants that 
are adapted to these conditions, in some cases, have become 
differentiated from their common relatives. Due to the absence of most 
common native vegetation from these clay lenses, the areas where A. 
ilicifolia occurs appear as open areas in a matrix of coastal sage 
scrub or chaparral (PCE).
    Clay lenses are generally inhabited by a specific flora that 
consist of forbs, native grasses, and geophytes (perennial plants 
propagated by buds on underground bulbs, tubers, or corms such as 
lilies, iris, and onions). Native plant species that characterize the 
vegetation found with Acanthomintha ilicifolia on clay lenses include 
Hesperevax sparsiflora var. sparsiflora (erect evax), Harpagonella 
palmeri (Palmer's grappling-hook), Convolvulus simulans (bindweed), 
Apiastrum angustifolium (mock parsley), and Microseris douglasii ssp. 
platycarpha (small flowered microseris) (Bauder et al. 1994, pp. 9-10; 
McMillan 2006, p. 1; Vinje 2006b, pp. 1-2).
    In addition to the characteristics discussed above, the texture and 
structure of the clay lenses are essential for supporting the seedling 
establishment and growth of Acanthomintha ilicifolia. This soil 
provides many small pockets where seeds from A. ilicifolia become 
lodged as they fall from decomposing plants (Bauder and Sakrison 1999, 
p. 28). The seeds then stay in the soils until the temperatures become 
cooler in the winter months and the soil becomes saturated with the 
winter rains (Bauder and Sakrison 1997, p. 28). The seedlings then 
germinate and grow to mature plants. These plants do best when they are 
not crowded or shaded by other plants (Bauder and Sakrison 1999, p. 
12). The loose, crumbly texture of the soil provides the proper 
substrate to hold the seed bank and allow for root growth (PCE).
    Clay lenses generally form on gentle slopes. An analysis of 20 
sites where Acanthomintha ilicifolia was observed found that the slopes 
range from 0 to 25 degrees, with the majority of the sites having 
slopes below 20 degrees (Bauder et al. 1994, pp. 10-11) (PCE). This 
study also found that many thriving, natural populations were on slopes 
that faced southeast, south, southwest, and west, although not all 
sites fit this pattern (Bauder et al. 1994, pp. 10-11). Using GIS, we 
found that the known populations of Acanthomintha ilicifolia range in 
elevation from sea level to 3,000 ft (914 m). Acanthomintha ilicifolia 
occurs on several soil types. These soils are mapped as Las Posas, 
Olivenhain, Redding, Huerhuero, Altamont, Cieneba, and Linne (Bowman 
1973, pp. 22-24, 38-40, 54-55, 61-64, 67-68, and 71-72) and are derived 
from gabbro and soft calcareous sandstone substrates with a loose, 
crumbly structure and deep fissures that provide space for population 
and individual growth and substrate for seedling establishment.

Water and Hydrology

    The loose, crumbly clay soils that support Acanthomintha ilicifolia 
act like a sponge and are saturated by winter rains. The saturation of 
these soils allows for seeds of A. ilicifolia to imbibe with water and 
germinate in the cool winter months (Bauder and Sakrison 1997, p. 32). 
As such, the species requires a natural hydrological regime to 
reproduce. Since we do not have specific information on the 
hydrological regime that this species requires, we did not include 
hydrological regime as a primary constituent element.

Reproduction and Pollination

    The breeding system of Acanthomintha ilicifolia has not been 
studied, but it has been determined that other members of the genus 
Acanthomintha are self-compatible (Steeck 1995, pp. 27-33). A 1996 
study (Bauder and Sakrison 1997, p. 38) found that several insect 
species visited the flowers and moved from plant to plant. These 
insects represented possible pollinators of A. ilicifolia; however, 
none were thought to represent species-specific pollinators (Bauder and 
Sakrison 1997, p. 39). Since we do not have information on any species-
specific pollinators that visit A. ilicifolia, we did not include 
pollinators as a primary constituent element.

Primary Constituent Elements for Acanthomintha ilicifolia

    Pursuant to our regulations, we are required to identify the known 
physical and biological features (PCEs) essential to the conservation 
of Acanthomintha ilicifolia.
    Based on our current knowledge of the life history, biology, and 
ecology of the species and the requirements of the habitat to sustain 
the essential life history functions of the species, we have determined 
that the PCE for Acanthomintha ilicifolia is:
    Clay lenses that provide substrate for seedling establishment and 
space for growth and development of Acanthomintha ilicifolia, that are:
    (a) Within chaparral and coastal sage scrub;
    (b) On gentle slopes ranging from 0 to 25 degrees;
    (c) Derived from gabbro and soft calcareous sandstone substrates 
with a loose, crumbly structure and deep (approximately 2 feet (60 cm)) 
fissures; and
    (d) Characterized by a low density of forbs and geophytes, and a 
low density or absence of shrubs.
    This proposed designation is designed for the conservation of those 
areas containing the PCE necessary to support one or more of the 
species' life history functions. All units and subunits in this 
proposed designation contain the PCE and support multiple life 
processes. This proposed rule would protect the PCE and thus the 
conservation function of the habitat.

Criteria Used To Identify Critical Habitat

    As required by section 4(b)(1)(A) of the Act, we use the best 
scientific and commercial data available in determining areas that 
contain the features that are essential to the conservation of 
Acanthomintha ilicifolia. All of the areas proposed for designation are 
currently occupied by the species. Occupied areas were determined from 
survey data and element occurrence data in the CNDDB (CNDDB 2006). For 
the purpose of this proposal, we assumed that each element occurrence 
represents a population of A. ilicifolia, except in cases where there 
are several element occurrences located within 1 mile (1.6 km) of each 
other and the habitat is not fragmented by manmade features. In these 
cases, we considered the group of element occurrences as a single 
population. Examples of this include the Manchester Preserve in 
Encinitas (element occurrence (EO) 28, EO 42, and EO 54), McGinty 
Mountain near Jamul (EO 21, EO 22, and EO 30), and Viejas and Poser 
Mountains near Alpine (EO 12, EO 50, EO 51, EO 62, EO 73, EO 74, and EO 
75).
    We then identified the areas that contain the features that are 
essential to the conservation of A. ilicifolia by identifying areas 
that: (1) Support populations that occur on rare or unique habitat 
within the species' range; (2) support the largest known populations of 
A. ilicifolia; or (3) support stable populations of A. ilicifolia. 
These

[[Page 11951]]

criteria are explained in greater detail below. Areas containing the 
primary constituent elements and that meet at least one of the above 
criteria were considered for critical habitat designation. To evaluate 
locations occupied by this species we used: the California Natural 
Diversity Database (CNDDB 2006); a study by Bauder et al. (1994); 
biological surveys (City of San Diego 2000; City of San Diego 2001; 
City of San Diego 2003; City of San Diego 2004; City of San Diego 2005; 
Conservation Biology Institute 2002, p. A3-1; County of San Diego 2002, 
p. 17; Dudek and Associates, Inc. 2006, Appendix A pp. 3-4; Helix 
Environmental Planning, Inc. 2002, p. 6; and REC Consultants, Inc. 
2004, p. figure 5); and interviews with botanists working on this 
species (Kelley 2005; McMillan 2006).
    The first criterion we used to identify proposed critical habitat 
was areas that support populations that occur on rare or unique habitat 
within the species' range. The majority of areas that currently support 
Acanthomintha ilicifolia are on dark brown to reddish brown clay soils 
that are derived from gabbro substrates. Historically, A. ilicifolia 
also occurred on gray clay soils that are derived from soft calcareous 
sandstone substrates. The only remaining population on this soil type 
is northeast of the intersection of Palomar Airport Road and El Camino 
Real, in the City of Carlsbad. Conserving unique soil types that this 
species occurs on will help to reduce the risk of extinction for this 
species because it may allow for the preservation of a greater amount 
of genetic diversity within the species' gene pool. Therefore, this 
area containing population (EO 70) is proposed for critical habitat 
designation under criterion one.
    The second criterion we used to identify proposed critical habitat 
was areas that support the largest known populations of Acanthomintha 
ilicifolia. The CNDDB includes data for this species that date back to 
1978. Populations of this species range from just a few individual 
plants to several thousand. The majority of the known populations range 
from 50 to 2,000 plants. Yet, there are four populations that stand out 
as the largest, each having greater than 25,000 plants. The four 
largest populations and the estimated population at each location are: 
Sycamore Canyon (EO 32), 31,000 plants; Slaughterhouse Canyon (EO 64), 
60,000 plants; Viejas and Poser Mountains (EO 12, EO 50, EO 51, EO 62, 
EO 73, and EO 74), 29,650 plants; and Hollenbeck Canyon (EO L), 100,000 
plants. These large populations are vital for the conservation of this 
species because they occur within large blocks of open space and are 
less likely to be impacted by edge effects associated with smaller 
populations in highly urbanized areas. Additionally, the conservation 
of these large populations will increase the persistence of the species 
across its range. Therefore, the area containing these populations is 
proposed for critical habitat designation under criterion two. These 
four populations represent approximately 75 percent of the total known 
plants of this species.
    The third criterion we used to identify proposed critical habitat 
was areas that support stable populations of Acanthomintha ilicifolia. 
For the purpose of this proposed critical habitat designation, we 
defined stable populations as those that contained more than 1,000 
plants at least once during the period for which we have survey data. 
We evaluated the population data from the CNDDB and determined that 
populations with more than 1,000 plants at one time had the ability to 
rebound following years with low population numbers. Therefore, we 
considered populations with more than 1,000 plants to have a high 
probability of persisting into the future and thus contribute to the 
conservation of the species. The locations of these populations are 
generally characterized by a series of clay lenses where the plants are 
found in a matrix of intact coastal sage scrub and chaparral. Although 
these areas are not free from exotic plant competitors, these 
populations have persisted over time without being out-competed by the 
exotic plant species present. This may be due in part to the low 
density of exotic plant species at these locations. In addition to all 
of the areas that meet criterion two, five other areas meet criterion 
three: the southeast portion of the City of Carlsbad (EO 47); the 
Manchester Preserve in Encinitas (EO 28, EO 42, and EO 54); Los 
Pe[ntilde]asquitos Canyon (EO 19); Sabre Springs (EO 36); and McGinty 
Mountain in the southern part of San Diego County (EO 21, EO 22, and EO 
30). Each of these areas provides habitat that consistently supports 
large populations of A. ilicifolia. Therefore, the area containing 
these populations is proposed for critical habitat designation under 
criterion three.
    The 10 areas that we identified as meeting the criteria for 
critical habitat contain the features that are essential for the 
conservation of this species. These areas support the only population 
of Acanthomintha ilicifolia on calcareous clay soil and the largest and 
most stable populations. These areas were mapped using data from field 
surveys and element occurrences in the CNDDB (CNDDB 2006), and unit 
boundaries were created using GIS.
    Annual plants experience annual fluctuation in population density 
and spatial distribution. Through the review of existing survey data 
and as a result of field work conducted by Service biologists, it 
appears that this holds true for Acanthomintha ilicifolia, as 
additional individuals are frequently located outside initially mapped 
occurrence areas (Bauder et al. 2004, pp. 14-15; CNDDB 2006, pp. 11, 
28-29, and 70; Service unpublished data 2006). Because soil data are 
not available on a fine enough scale to ensure that proposed critical 
habitat included all occupied habitat, each area mapped for A. 
ilicifolia in the CNDDB was enlarged to include habitat within 500 ft 
(152 m) around the edge of mapped occurrences. Using aerial 
photography, we confirmed that no identifiable portion of an occupied 
clay lens appeared to have been inadvertently omitted and removed 
manmade features such as roads, buildings, parking lots and 
agricultural fields. This boundary was then used as our proposed 
critical habitat boundary.
    When determining proposed critical habitat boundaries within this 
proposed rule, we made every effort to avoid including developed areas 
such as lands covered by buildings, paved areas, and other structures 
that lack the PCE for Acanthomintha ilicifolia. 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 may affect the species or primary constituent 
elements in adjacent critical habitat.
    We are proposing to designate critical habitat on lands that we 
have determined were occupied at the time of listing that contain the 
PCE that supports life history functions essential for the conservation 
of the species and lands that were not known to be occupied at the time 
of listing, but that we have determined are essential to the 
conservation of the species. The lands that were not known to be 
occupied at the time of listing are all currently occupied and contain 
the PCE essential for the conservation of the species. The 10 areas 
defined above, each representing one population, have been

[[Page 11952]]

categorized into four units. Due to large amounts of area that did not 
contain the PCE in each of the four units, the units were further 
broken down into 17 subunits so that the essential habitat could be 
accurately mapped and not include areas that do not have the PCE. These 
units/subunits are described in the Unit Descriptions section.
    Section 10(a)(1)(B) of the Act authorizes us to issue permits for 
the take of listed animal species incidental to otherwise lawful 
activities. An incidental take permit application must be supported by 
a habitat conservation plan (HCP) that identifies conservation measures 
that the permittee agrees to implement for the species to minimize and 
mitigate the impacts of the requested incidental take. We often exclude 
non-Federal public lands and private lands that are covered by an 
existing operative HCP and executed implementation agreement (IA) under 
section 10(a)(1)(B) of the Act from designated critical habitat because 
the benefits of exclusion outweigh the benefits of inclusion as 
discussed in section 4(b)(2) of the Act. While section 10(a)(1)(B) of 
the Act does not cover take of listed plant species, HCPs often cover 
both listed animal and plant species. Acanthomintha ilicifolia is a 
covered species in approved subarea plans under two major HCPs, the San 
Diego Multiple Species Conservation Program (MSCP) and the San Diego 
Habitat Conservation Program (MHCP). We are proposing to exclude areas 
from the final designation of critical habitat where this species is 
covered by one of these HCPs. See the Exclusions under Section 4(b)(2) 
of the Act for a detailed discussion of these exclusions. We identify 
the areas proposed for exclusion in the discussion of individual 
critical habitat units below.

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.
    As stated in the final listing rule, threats to Acanthomintha 
ilicifolia include trampling and grazing, the presence of exotic plant 
species, off-road vehicles (ORVs), mining, and urbanization (63 FR 
54938). Through our review of the existing data on A. ilicifolia, the 
threats listed in the final listing rule continue to impact this 
species and could impact the PCE as well. Building on the information 
contained in the final listing rule, data on the effects of competition 
from exotic plant species have been studied in greater detail (Bauder 
and Sakrison 1999, pp. 6-19, 28-44) and attempts have been made to 
manage this threat (Kelly 2002, pp. 1-3).
    Urban development near Acanthomintha ilicifolia populations may 
alter the habitat characteristics required by the species. The 
destruction of habitat can change the slope and aspect of the site, 
making it uninhabitable for A. ilicifolia (PCE). The close proximity of 
development to populations of A. ilicifolia may affect other aspects of 
the site. For example, increased water runoff from developments may 
erode the clay lens and change the topography of the site (Bauder et 
al. 1994, p. 23) (PCE).
    The introduction of exotic plant species such as Centaurea 
melitensis can drastically change the species present in, and eliminate 
the open character of, the clay lens habitat (PCE). Centaurea 
melitensis has been shown, in field and greenhouse experiments, to 
negatively effect the biomass (growth) and seed production 
(reproduction) of Acanthomintha ilicifolia (Bauder and Sakrison 1999, 
p. 16). Populations of A. ilicifolia that are close to urbanized areas 
or in areas that have been heavily grazed generally have a high density 
of exotic plant species. In disturbed soils, C. melitensis is a common 
weed. When this and other exotic plant species become established they 
can out-compete A. ilicifolia for light, water, nutrients, and space. 
A. ilicifolia often grows larger and at a higher density when 
competition with exotic weeds is reduced (Bauder and Sakrison 1999, pp. 
12-16; Vinje 2007, p. 10).
    The final listing rule (63 FR 54938) discusses the impacts of ORV 
activity and trampling. In recent years the impacts associated with the 
use of mountain bikes has been observed to cause similar impacts (Vinje 
2006a, p. 1). Trampling, ORV activity, and mountain bike use outside of 
designated, maintained trails can compact the loose, crumbly soils 
(PCE). The repeated travel over a trail or track degrades the habitat 
of Acanthomintha ilicifolia in two ways: (1) by displacing soil; and 
(2) by compacting soil and reducing the amount of water that can 
percolate, thus reducing the plant's ability to establish roots.
    Mining has been documented as a threat at two sites known to 
support Acanthomintha ilicifolia (63 FR 54938; Bauder et al. 1994, p. 
17). Mining can alter many aspects of A. ilicifolia habitat. Heavy 
machinery can compact or remove clay lenses (PCE) or alter the slope of 
an area (PCE). The grading of large areas adjacent to A. ilicifolia 
habitat can make those areas vulnerable to invasion by exotic plant 
species and lead to the subsequent crowding and shading of A. 
ilicifolia habitat (PCE). All of these impacts may in turn lead to the 
disruption of the growth and reproduction of A. ilicifolia .

Proposed Critical Habitat Designation

    We are proposing a total of 1,936 ac (783 ha) in four units as 
critical habitat for Acanthomintha ilicifolia . These four units are 
further subdivided into 17 subunits. The critical habitat areas 
described below constitute our best assessment at this time of areas 
known to be occupied at the time of listing that contain the primary 
constituent elements that may require special management considerations 
or protection, and those additional areas that were not known to be 
occupied at the time of listing (subunits 3E and 4D), but are essential 
to the conservation of Acanthomintha ilicifolia . The four units 
proposed for designation as critical habitat are: (1) Unit 1: Northern 
San Diego County; (2) Unit 2: Central San Diego County; (3) Unit 3: 
Viejas Mountain and Poser Mountain, San Diego County; and (4) Unit 4: 
Southern San Diego County. We are proposing to exclude 1,302 ac (527 
ha) under section 4(b)(2) of the Act from the final designation of 
critical habitat. Table 1 identifies the occupancy status for each 
subunit. Table 2 identifies the acreage and ownership of the areas 
being proposed as critical habitat and the areas proposed for exclusion 
from the final designation under section 4(b)(2) of the Act (see 
Relationship of Critical Habitat to Habitat Conservation Plan Lands--
Exclusions Under Section 4(b)(2) of the Act below for a detailed 
discussion).

[[Page 11953]]



               Table 1.--Occupancy of Proposed Critical Habitat units for Acanthomintha ilicifolia
----------------------------------------------------------------------------------------------------------------
                                      Known to be occupied
       Critical habitat unit             to the time of      Occupied currently?          Acres (hectares)
                                            listing?
----------------------------------------------------------------------------------------------------------------
Unit 1: Northern San Diego County
  1A. Palomar Airport (EO 70)......  Yes..................  Yes..................  88 ac (36 ha)
  1B. Southeast Carlsbad (EO 47)...  Yes..................  Yes..................  73 ac (29 ha)
  1C. Manchester (EO 28, EO 42 and   Yes..................  Yes..................  92 ac (37 ha)
   EO 54).
Unit 2: Central San Diego County
  2A. Los Penasquitos Canyon (EO     Yes..................  Yes..................  63 ac (25 ha)
   19).
  2B. Sabre Springs (EO 36)........  Yes..................  Yes..................  52 ac (22 ha)
  2C. Sycamore Canyon (EO 32)......  Yes..................  Yes..................  306 ac (124 ha)
  2D. Slaughterhouse Canyon (EO 64)  Yes..................  Yes..................  77 ac (31 ha)
Unit 3: Viejas Mountain and Poser
  Mountain 3A. Viejas Mountain (EO   Yes..................  Yes..................  33 ac (13 ha)
   73).
  3B. Viejas Mountain (EO 50)......  Yes..................  Yes..................  208 ac (84 ha)
  3C. Viejas Mountain (EO 51)......  Yes..................  Yes..................  318 ac (128 ha)
  3D. Viejas Mountain (EO 62)......  Yes..................  Yes..................  82 ac (33 ha)
  3E. Poser Mountain (EO 74).......  No...................  Yes..................  34 ac (14 ha)
  3F. Poser Mountain (EO 12).......  Yes..................  Yes..................  163 ac (66 ha)
Unit 4: Southern San Diego County
  4A. McGinty Mountain (EO 21).....  Yes..................  Yes..................  18 ac (7 ha)
  4B. McGinty Mountain (EO 22).....  Yes..................  Yes..................  220 ac (89 ha)
  4C. McGinty Mountain (EO 30).....  Yes..................  Yes..................  27 ac (11 ha)
  4D. Hollenbeck Canyon (EO L).....  No...................  Yes..................  84 ac (34 ha)
                                                                                  ------------------------------
    Total*.........................  .....................  .....................  1,936 ac (783 ha)
----------------------------------------------------------------------------------------------------------------
* Some columns may not sum exactly due to rounding of values.


Table 2.--Proposed Critical Habitat for Acanthomintha Ilicifolia and the Areas Being Proposed for Exclusion From
    the Final Critical Habitat Designation Under Section 4(b)(2) of the Act (acres (ac), hectares (ha), CNDDB
                                            Element Occurrences (EO))
----------------------------------------------------------------------------------------------------------------
                                                    Area that meets                       Area being considered
     Critical habitat unit        Land ownership   the definition of  Area proposed as  for exclusion from final
                                                    critical habitat  critical habitat      critical habitat*
----------------------------------------------------------------------------------------------------------------
Unit 1: Northern San Diego
 County
  1A. Palomar Airport (EO 70).  Private..........  7 ac (3 ha)......  7 ac (3 ha).....  7 ac (3 ha)
                                State/Local......  81 ac (33 ha)....  81 ac (33 ha)...  0 ac (0 ha)
  1B. Southeast Carlsbad (EO    Private..........  73 ac (29 ha)....  73 ac (29 ha)...  73 ac (29 ha)
   47).
  1C. Manchester (EO 28, EO 42  Private..........  92 ac (37 ha)....  92 ac (37 ha)...  92 ac (37 ha)
   and EO 54).
Unit 2: Central San Diego
 County
  2A. Los Penasquitos Canyon    State/Local......  63 ac (25 ha)....  63 ac (25 ha)...  63 ac (25 ha)
   (EO 19).
  2B. Sabre Springs (EO 36)...  Private..........  1 ac (1 ha)......  1 ac (1 ha).....  1 ac (1 ha)
                                State/Local......  51 ac (21 ha)....  51 ac (21 ha)...  51 ac (21 ha)
  2C. Sycamore Canyon (EO 32).  Private..........  30 ac (12 ha)....  30 ac (12 ha)...  30 ac (12 ha)
                                State/Local......  276 ac (112 ha)..  276 ac (112 ha).  276 ac (112 ha)
  2D. Slaughterhouse Canyon     Private..........  77 ac (31 ha)....  77 ac (31 ha)...  77 ac (31 ha)
   (EO 64).
Unit 3: Viejas Mountain and
 Poser Mountain
  3A. Viejas Mountain (EO 73).  Private..........  33 ac (13 ha)....  33 ac (13 ha)...  33 ac (13 ha)
  3B. Viejas Mountain (EO 50).  Private..........  156 ac (63 ha)...  156 ac (63 ha)..  156 ac (63 ha)
                                Federal..........  52 ac (21 ha)....  52 ac (21 ha)...  0 ac (0 ha)
  3C. Viejas Mountain (EO 51).  Private..........  38 ac (15 ha)....  38 ac (15 ha)...  38 ac (15 ha)
                                Federal..........  280 ac (113 ha)..  280 ac (113 ha).  0 ac (0 ha)
  3D. Viejas Mountain (EO 62).  Private..........  50 ac (20 ha)....  50 ac (20 ha)...  50 ac (20 ha)
                                Federal..........  32 ac (13 ha)....  32 ac (13 ha)...  0 ac (0 ha)
  3E. Poser Mountain (EO 74)..  Federal..........  34 ac (14 ha)....  34 ac (14 ha)...  0 ac (0 ha)
  3F. Poser Mountain (EO 12)..  Private..........  7 ac (3 ha)......  7 ac (3 ha).....  7 ac (3 ha)
                                Federal..........  156 ac (63 ha)...  156 ac (63 ha)..  0 ac (0 ha)
Unit 4: Southern San Diego
 County
  4A. McGinty Mountain (EO 21)  Private..........  18 ac (7 ha).....  18 ac (7 ha)....  18 ac (7 ha)
  4B. McGinty Mountain (EO 22)  Private..........  210 ac (85 ha)...  210 ac (85 ha)..  210 ac (85 ha)
                                State/Local......  10 ac (4 ha).....  10 ac (4 ha)....  10 ac (4 ha)
  4C. McGinty Mountain (EO 30)  Private..........  27 ac (11 ha)....  27 ac (11 ha)...  27 ac (11 ha)
  4D. Hollenbeck Canyon (EO L)  Private..........  23 ac (9 ha).....  23 ac (9 ha)....  23 ac (9 ha)
                                State/Local......  61 ac (25 ha)....  61 ac (25 ha)...  61 ac (25 ha)
                               ---------------------------------------------------------------------------------

[[Page 11954]]

 
    Total **..................  .................  1,936 ac (783 ha)  1,936 ac (783     1,302 ac (527 ha)
                                                                       ha).
----------------------------------------------------------------------------------------------------------------
* Lands proposed for exclusion from final critical habitat under section 4(b)(2) of the Act due to the
  conservation provided for Acanthomintha ilicifolia from the City of Carlsbad and City of Encinitas subarea
  plans of the San Diego MHCP and the City of San Diego and County of San Diego subarea plans of the San Diego
  MSCP.
** Some columns may not sum exactly due to rounding of values.

    Below, we present brief descriptions of all units and subunits, and 
reasons why they meet the definition of critical habitat for 
Acanthomintha ilicifolia. The PCE in each subunit of critical habitat 
is threatened by the presence of exotic plants and recreational 
activities (e.g., trampling, erosion and soil compaction caused by 
hiking, off-road vehicle activity, and mountain biking); therefore, 
special management considerations or protections of the PCE is required 
to address these threats.

Unit Descriptions

Unit 1: Northern San Diego County

    Unit 1 consists of 253 ac (102 ha) in northern San Diego County 
divided into three subunits. This critical habitat unit includes 
habitat for Acanthomintha ilicifolia in the cities of Carlsbad and 
Encinitas under private, State, and local ownership (Table 1). The 
majority of habitat for A. ilicifolia in northern San Diego County is 
located in proximity to residential and commercial development; 
however, the habitat being proposed as critical habitat is mostly on 
land that has been set aside for the conservation of this and other 
species. This unit contains five element occurrences, all of which were 
known at the time of listing. The majority of the element occurrences 
in this unit are covered by the San Diego Multiple Habitat Conservation 
Program (MHCP). As part of the MHCP, each city will complete a subarea 
plan. At this time, the City of Carlsbad has completed its subarea plan 
under the San Diego MHCP and the City of Encinitas is nearing the 
completion of its subarea plan. We are proposing to exclude 172 ac (70 
ha) in the City of Carlsbad (portions of Subunit 1A and all of Subunit 
1B) and the City of Encinitas (Subunit 1C) from the final designation 
of critical habitat based on protections afforded to A. ilicifolia 
under the Carlsbad and Encinitas subarea plans of the MHCP (see 
Relationship of Critical Habitat to Habitat Conservation Plan Lands--
Exclusions Under Section 4(b)(2) of the Act below for more 
information). The remaining 81 ac (33 ha) in Subunit 1A is owned by the 
County of San Diego and is not part the San Diego MHCP.
Subunit 1A, Palomar Airport (EO 70)
    Subunit 1A consists of 88 ac (36 ha) and was known to be occupied 
at the time of listing. This subunit contains several habitat patches 
known to support Acanthomintha ilicifolia and contains the feature 
(PCE) considered to be essential to the conservation of the species. 
The subunit meets our selection criteria because it supports a 
population on a unique soil type (criterion 1). This is the only area 
where A. ilicifolia is still known to occupy calcareous clay soils. The 
PCE in this subunit may require special management considerations or 
protection to control exotic plant species and reduce impacts 
associated with recreational activities. This subunit is within the 
designated preserve area for the Carlsbad subarea plan (referred to as 
the Carlsbad Habitat Management Plan (HMP)) of the San Diego MHCP; 
however, most of this subunit is owned by the County of San Diego and 
not a part of the Carlsbad HMP. The portion covered by the Carlsbad HMP 
will be managed for the conservation of this species. Therefore, we are 
proposing to exclude the 7 ac (3 ha) of this subunit that are covered 
by the Carlsbad HMP from the final designation of critical habitat 
(Table 1) (see Relationship of Critical Habitat to Habitat Conservation 
Plan Lands--Exclusions Under Section 4(b)(2) of the Act below for more 
information). The remaining 81 ac (33 ha) of land owned by the County 
of San Diego is proposed for inclusion in the designation of critical 
habitat.
Subunit 1B, Southeast Carlsbad (EO 47)
    Subunit 1B consists of 73 ac (29 ha), was known to be occupied at 
the time of listing, and contains the feature (PCE) considered to be 
essential to the conservation of the species. The subunit meets our 
selection criteria because it supports a stable population (criterion 
3). This population was estimated to have 400 plants in 1989, 2,000 
plants in 1994, and 500 plants in 2006. The PCE in this subunit may 
require special management considerations or protection to control 
exotic plant species and reduce impacts associated with recreational 
activities. The majority of the lands within this subunit are within an 
area designated as a hardline conservation area (an area that has 
already been or is slated to be preserved) and the entire subunit is 
covered by the Carlsbad HMP of the San Diego MHCP which will provide 
substantial protection and management of the PCE essential to the 
conservation of Acanthomintha ilicifolia. Therefore, we are proposing 
to exclude this subunit from the final designation of critical habitat 
(Table 1) (see Relationship of Critical Habitat to Habitat Conservation 
Plan Lands--Exclusions Under Section 4(b)(2) of the Act below for more 
information).
Subunit 1C, Manchester (EO 42, EO 28, and EO 54)
    Subunit 1C consists of 92 ac (37 ha), was known to be occupied at 
the time of listing, and contains the feature (PCE) considered to be 
essential to the con