Castro Gate BRA text - CAL

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August 11, 2010
Peter Gonzalez
SC PLANNERS
P.O. Box 3302
South Pasadena, CA 91031
Re:
BIOLOGICAL RESOURCES ASSESSMENT FOR THE PROPOSED CASTRO
MOTORWAY GATE, SANTA MONICA MOUNTAINS, LOS ANGELES COUNTY,
CALIFORNIA
Dear Mr. Gonzalez:
PCR Services Corporation (PCR) biologists Maile Tanaka and Joanna Nigro conducted a
biological resources assessment for the proposed Castro Motorway Gate installation project (“study
area”) located in the Santa Monica Mountains, Los Angeles County, California (Figure 1, Regional
Map, attached). The study area is located within the southeastern portion of APN 4464-022-010,
and encompasses approximately 133 linear feet perpendicular to Castro Motorway (including an
approximately 33-foot gate as well as 50-feet of fencing to the north and 50-feet of fencing to the
south of the gate), plus a 10-foot zone of potential disturbance (10 feet on either side of the gate and
fence) for an approximate study area of 0.06 acre.
The study area can be found on the U.S. Geological Survey (USGS) 7.5-minute Point Dume
topographic quadrangle, Section 17, T. 1 S., R. 18 W., as shown in Figure 2, Vicinity Map, attached.
Topography throughout the study area consists of steeply sloping hills with an elevation ranging
from approximately 2,570 feet above mean sea level (MSL) to the south to 2,650 feet above MSL to
the north.
EXISTING CONDITIONS
The study area consists of Castro Motorway, which is a disturbed, unimproved road, with a
chaparral community to the north of the road and a coast live oak woodland community to the south
of the road. In addition, two coast live oak trees were mapped within the vicinity of the proposed
gate. Plant communities and coast live oak tree locations are shown in Figure 3, Plant Communities
Map, attached, and descriptions of each community are provided below. Representative site
photographs are shown in Figure 4, Site Photographs, attached.
The chaparral community within the study area is dominated by scrub oak (Quercus
berberidifolia) with a subdominance of toyon (Heteromeles arbutifolia) and ceonothus (Ceanothus
crassifolius). Other associated species include manzanita (Arctostaphylos sp.), orange-bush
monkeyflower (Mimulus aurantiacus), poison oak (Toxicodendron diversilobum), deerweed (Lotus
scoparius), heart-leaved penstemon (Keckiella cordifolia), California aster (Corethrogyne
filaginifolia), lupine (Lupinus sp.), wild cucumber (Marah macrocarpus), foxtail chess (Bromus
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PETER GONZALEZ
SC PLANNERS
August 11, 2010 - Page 2
madritensis), and ripgut brome (Bromus diandrus). Approximately 0.02 acre of chaparral occurs
within the study area, north of Castro Motorway.
Coast live oak woodland within the study area is dominated by coast live oak (Quercus
agrifolia) and scrub oak. Other associated species include toyon, orange-bush monkeyflower, heartleaved penstemon, California aster, California polypody (Polypodium californicum), Indian pink
(Silene laciniata), golden yarrow (Eriophyllum confertiflorum), foxtail chess, and ripgut brome.
Approximately 0.03 acre of coast live oak woodland occurs within the study area, south of Castro
Motorway.
Disturbed areas within the study area consist of the unimproved road, Castro Motorway.
Approximately 0.01 acre of disturbed, unimproved road occur within the study area.
Wildlife species observed during the site visit included western fence lizard (Sceloporus
occidentalis), turkey vulture (Cathartes aura), western scrub-jay (Aphelocoma californica), western
bluebird (Sialia mexicana), and wrentit (Chamaea fasciata).
BIOLOGICAL CONSTRAINTS ANALYSIS AND RECOMMENDATIONS
Installation of the Castro Motorway Gate will impact 133 linear feet where the gate and
fence will be installed, as well as minor impacts associated with maintenance of the gate and fence.
Additionally, minor temporary impacts to vegetation may occur due to activities associated with the
installation of the gate and fence; however, vegetation is expected to recover once the gate and fence
are in place. Therefore, impacts to plant communities are not significant.
The California Natural Diversity Database (CNDDB) was run for the Point Dume quadrangle
and five surrounding quadrangles (Newbury Park, Thousand Oaks, Calabasas, Triunfo Pass, and
Malibu Beach). Federal and State-listed species which were reported to occur within the vicinity of
the study area include: Braunton’s milk-vetch (Astragalus brauntonii) (Federal Endangered), San
Fernando Valley spineflower (Chorizanthe parryi var. fernandina) (Federal Candidate, State
Endangered), Santa Susana tarplant (Deinandra minthornii) (State Rare), Agoura Hills dudleya
(Dudleya cymosa ssp. agourensis) (Federal Threatened), marcescent dudleya (Dudleya cymosa ssp.
marcescens) (Federal Threatened, State Rare), Santa Monica dudleya (Dudleya cymosa ssp.
ovatifolia) (Federal Threatened), Conejo dudleya (Dudleya parva) (Federal Threatened), Verity’s
dudleya (Dudleya verityi) (Federal Threatened), Conejo buckwheat (Eriogonum crocatum) (State
Rare), California Orcutt grass (Orcuttia californica) (Federal Endangered, State Endangered),
Lyon’s pentachaeta (Pentachaeta lyonii) (Federal Endangered, State Endangered), arroyo toad
(Anaxyrus californicus) (Federal Endangered), tidewater goby (Eucyclogobius newberryi) (Federal
Endangered), southern steelhead (Oncorhynchus mykiss irideus) (Federal Endangered), coastal
California gnatcatcher (Polioptila californica californica) (Federal Threatened), California redlegged frog (Rana draytonii) (Federal Threatened), bank swallow (Riparia riparia) (State
Threatened), and least Bell’s vireo (Vireo bellii pusillus) (Federal Endangered, State Endangered).
Of these, the following species are not expected to occur due to lack of suitable macrohabitat (that
PETER GONZALEZ
SC PLANNERS
August 11, 2010 - Page 3
is, natural communities in which these species occur, such as vernal pools, salt marshes, riparian
habitats with surface water, etc.): San Fernando Valley spineflower, Conejo dudleya, California
Orcutt grass, arroyo toad, tidewater goby, southern steelhead, coastal California gnatcatcher,
California red-legged frog, bank swallow, and least Bell’s vireo. In addition, Braunton’s milk-vetch,
Santa Susana tarplant, Agoura Hills dudleya, marcescent dudleya, Santa Monica dudleya, Verity’s
dudleya, Conejo buckwheat, and Lyon’s pentachaeta are not expected to occur due to lack of
suitable microhabitat for the species (that is, open disturbed areas, sandstone rock outcrops, etc.),
and/or because the study area is outside of the known elevation range for the species. For all other
plant species considered sensitive by the California Native Plant Society (CNPS) (i.e., CNPS-listed
species) and wildlife species considered sensitive by the California Department of Fish and Game
(CDFG) (Species of Special Concern), due to the minimal impacts associated with the installation of
the gate and fence, implementation is not expected to significantly impact regional populations of
these species and impacts are considered less than significant.
Oak trees are regulated under the County of Los Angeles Oak Tree Ordinance [(Ord. 880157 § 2, 1988: Ord. 82-0168 § 2 (part), 1982) as outlined in Chapter 22.56.2050 et seq. of the Los
Angeles County Code]. The Ordinance regulates all tree species of the oak genus that measure 25
inches or more in circumference (eight inches in diameter) for trees with a single trunk and 38
inches of combined circumference (12 inches in diameter) for any two trunks of trees with multiple
stems, as measured at breast height, or 4.5 feet above natural grade (diameter at breast height, or
“DBH”). The Ordinance also covers the “protected zone” of the oak trees, which extends to five
feet outside of the dripline of the oak tree, or 15 feet from the trunk(s) of a tree, whichever distance
is greater. Additionally, the Ordinance regulates all tree species of the oak genus (Quercus) that fall
within 200-feet of project construction. As such, any impacts to regulated oaks without
incorporation of appropriate mitigation measures would be considered significant. No impacts to
regulated coast live oak trees are anticipated. Should any impacts to coast live oak trees be
determined to be necessary, the appropriate permits for oak tree removal and/or encroachment will
be obtained.
Additionally, to ensure no impacts to migratory nesting songbird and raptor species occur,
vegetation removal activities associated with installation of the gate should be scheduled outside the
nesting season (nesting season is typically February 15 to August 31) to avoid potential impacts to
nesting songbirds and raptors. If vegetation removal must occur during the nesting season, all
suitable habitat should be thoroughly surveyed for the presence of nesting songbirds and raptors by a
qualified biologist before commencement of any clearing. If any active nests are detected, a buffer
of at least 300 feet (500 feet for raptors) should be delineated, flagged, and avoided until the nesting
cycle is complete as determined by the biological monitor to minimize impacts.
PETER GONZALEZ
SC PLANNERS
August 11, 2010 - Page 4
CONCLUSION
With implementation of avoidance or monitoring measures to ensure no impacts to migratory
nesting songbird and raptor species occur, the installation of the Castro Motorway Gate will not
significantly impact biological resources.
If you have any questions regarding the findings please contact Steve Nelson
([email protected]) or Maile Tanaka ([email protected]) at (949) 753-7001.
Sincerely,
PCR SERVICES CORPORATION
Steve Nelson
Senior Vice President/
Director of Biological Services
Maile Tanaka
Biologist
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