Santa Susana Mountains Trails Master Plan Phase 2.

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The County of Los Angeles Department of Parks and Recreation (DPR) proposes to adopt a multi-use trails master plan for two unincorporated areas within the Santa Clarita Valley Planning Area and the San Fernando Valley Planning Area. The California Environmental Quality Act (CEQA), as established by statute (Public Resources Code 21000 et seq.), requires that the environmental implications of an action by a local agency be estimated and evaluated before project approval. This Initial Study was prepared by the County of Los Angeles pursuant to CEQA, as amended (Division 13, California Public Resources Code) and the State CEQA Guidelines (Division 6, California Administrative Code). DPR proposes to complete the Santa Susana Mountains Trails Master Plan-Phase II (SSMTMP-PII), ultimately to amend the Parks and Recreation Element of the Los Angeles County General Plan 2035 (County General Plan) to include the SSMTMP-PII, which would guide future trail development and recommend improvements to existing trails. The proposed project would ultimately result in the construction and use of trails in public and private lands, some of which may involve the expenditure of public funds, and thus constitutes a project pursuant to CEQA. These trails would be located in the unincorporated territory of Los Angeles County; therefore, the County is the Lead Agency pursuant to CEQA.

The SSMTMP-PII (proposed project) is located in the unincorporated territory of the northwestern portion of the County of Los Angeles, immediately east of the boundary with the County of Ventura (Figure 1.4-1, Regional Vicinity Map). The proposed project comprises an expansion of a 13-square-mile Phase II study area that was established in the Santa Susana Mountains Final Trails Master Plan (SSMFTMP).1 The earlier study was made up of two areas: Phase I, generally located on the south-facing slopes of the Santa Susana Mountains; and Phase II, generally located on the north-facing slopes of the Santa Susana Mountains (Figure 1.4-2, Local Vicinity Map). The adopted trails master plan provided a detailed trails network for Phase I and identified potential surrounding trail connections for Phase II, but deferred trail planning for Phase II to a later date.

The area addressed as Phase II in the 2015 adopted plan will be evaluated as a portion of Phase II.a for the current investigation. In addition, the project study area was expanded to include approximately 9 square miles between the Phase II area and Henry Mayo Drive (State Route 126), generally known as Stevenson Ranch; as well as approximately 2 square miles, generally known as Woolsey Canyon/Dayton Canyon/Bell Canyon. The southern expansion area will be evaluated as Phase II.b.

The proposed project, including Phase II.a and Phase II.b, represents approximately 24 square miles (approximately 14,408 acres). The project study area appears on the U.S. Geological Survey (USGS) 7.5- minute series Val Verde, Newhall, Simi Valley East (Santa Susana), Oat Mountain, and Calabasas topographic quadrangles (Figure 1.4-3, Topographic Map with USGS 7.5-Minute Quadrangle Index).

Phase II.a: The Phase II.a area is an approximately 22-square-mile area located in the north-facing slopes of the Santa Susana Mountains and the Santa Clarita Valley. Phase II.a is composed of generally mountainous and valley terrain that abuts Henry Mayo Drive (State Route [SR] 126) to the north, the Interstate-5 freeway to the east, Phase I of the SSMFTMP area to the south, and the Newhall Ranch Specific Plan area to the west (see Figure 1.4-2). The Phase II.a area, which is located in the County of Los Angeles Fifth Supervisorial District, includes a portion (Phase II) of the SSMFTMP Area. The community of Stevenson Ranch and Six Flags Magic Mountain are located within the Phase II.a area. The elevation of the Phase II.b area ranges from 946 feet above mean sea level (MSL) within the Santa Clara River near SR-126, to 3,430 feet above MSL in the southwestern corner of the Phase II.a area. Sand Rock Peak (2,511 feet above MSL) is located within the northwestern portion of the Phase II.a area.

Phase II.b: The Phase II.b area is an approximately 2-square-mile area located in the foothills of the Santa Monica Mountains, including Bell Canyon, Dayton Canyon, and Woolsey Canyon, west of San Fernando Valley. The Phase II.b area, which is also located in the County of Los Angeles Fifth Supervisorial District, is composed of generally mountainous and valley terrain that abuts Ventura County to the north and west and the City of Los Angeles to the east and south (see Figure 1.4-2). The elevation of the Phase II.b area ranges from 896 feet above MSL at the northeastern corner of the Phase II.b area near Chatsworth Reservoir, to 1,877 feet above MSL near the northwestern corner of the Phase II.b area. There are no named peaks within the Phase II.b area.

The project study area, located within the Santa Clarita Valley Planning Area and San Fernando Valley Planning Area, is generally bordered to the north and east by the City of Santa Clarita (administered by the City of Santa Clarita General Plan),2 to the south and east by the City of Los Angeles including the Chatsworth-Porter Ranch Community Plan area, and to the west by the Newhall Ranch Specific Plan Area and by Ventura County (administered by the Ventura County General Plan). The Northwest San Fernando Valley Subarea (NWSFV Subarea) of the adopted SSMFTMP area within the City of Los Angeles and Ventura County property divide the project study area. Portions of the project study area are subject to the provisions of Specific Plans and the County of Los Angeles Rural Outdoor Lighting District Ordinance.3,4 Approximately 0.6 square mile (387 acres) within the northern portion of the Phase II.a area is located within the jurisdiction of the Castaic Area Community Standards District. Approximately 10.3 square miles (47 percent) of the Phase II.a area and the entire 2-square-mile Phase II.b area are located within the jurisdiction of the County of Los Angeles Rural Outdoor Lighting District (Figure 1.6-1, County of Los Angeles Rural Outdoor Lighting District and Community Standards District Boundaries). The County land use designations for the project study area are predominantly Rural Land 10 (RL10), Parks and Recreation (OS-PR) (Table 1.6-1, Project Study Area Land Use Designations; and Figure 1.6-2, Los Angeles County Land Use Designations). Trails are compatible with all of the County's land use designations for the project study area.