Section 2 Description of MHCP Study Area 2.0 DESCRIPTION OF MHCP STUDY AREA This section describes the ecological and socioeconomic setting in which the MHCP must accomplish its stated goals. The section briefly summarizes information on the geography, biological resources, land ownership, existing and planned land uses, and historical and forecast human population growth in the study area. These conditions strongly influence opportunities and constraints for implementing a viable subregional preserve system. 2.1 SUBREGIONAL SETTING The MHCP study area encompasses about 175 square miles (111,865 acres) comprising the seven incorporated cities of northwestern San Diego County (Carlsbad, Encinitas, Escondido, Oceanside, San Marcos, Solana Beach, and Vista). Unincorporated portions of the county, including several areas completely surrounded by incorporated cities, are excluded from the study area and will be planned by the County as the North County Subarea of the MSCP. The Pacific Ocean shoreline defines the western border of the study area; Marine Corps Base Camp Pendleton borders the study area on the north; and unincorporated County of San Diego borders most of the study area on the east and south. This area of north coastal San Diego County is known for its natural beauty and mild Mediterranean climate, which make it a popular recreational and tourist destination. The area is largely developed, with approximately 30% consisting of vacant lands that still support natural vegetation communities. Major land uses within the study area include residential, commercial, and industrial development; parks, preserves, and golf courses; and agriculture. Larger areas of undeveloped and naturally vegetated lands adjoin the study area, particularly on unincorporated lands to the east and south, and on Camp Pendleton to the north. Topography in the study area ranges from flat to hilly, with relatively gentle slopes on the coastal terraces and in broad valleys. Steeper hills, ranging up to about 2,100 feet in elevation, are found in the south-central portion of the study area (eastern Carlsbad and southern San Marcos), and in northern portions of San Marcos and Escondido. Steep canyons associated with predominantly east-west drainages cut through some of the hills and mesas. Four coastal lagoons are more or less evenly distributed along the coast, each representing the terminus of one or more local drainages. One major river, the San Luis Rey, crosses the northern portion of the study area through the City of Oceanside. 2.2 SUBAREA PLANNING AREAS In general, the subarea planning areas comprise the incorporated boundaries of the seven MHCP cities (Figure 1-2). However, the participating cities have in many cases removed from their planning areas lands over which they do not have land use authority. In other cases they have included lands outside their current boundaries that they either own or intend to annex in the near future. Lands omitted from jurisdictional subarea planning areas thus include Caltrans rights-of-way, county-owned lands (e.g., Palomar Airport and Guajome Regional Park), and some school district or university lands. Additions to subarea planning areas include water district lands owned by Escondido east of the city’s incorporated boundary, and several parcels within the spheres of influence of San Marcos and Encinitas that these cities intend to annex. As described in Section 5.7, cities can also defer planning on portions of their jurisdiction until later, and then amend their subarea plan to include those areas. Such action generally requires reinvolvement of the wildlife agencies and completion of a National Environmental Policy Act/California Environmental Quality Act (NEPA/CEQA) document for the amendment. The City of San Marcos has chosen to defer conservation planning on some biologically important parcels in the 314552000 2-1 PUBLIC REVIEW DRAFT MHCP VOL. I Section 2 Description of MHCP Study Area central part of the city due to controversy over the disposition of these lands. The so-called “San Marcos Major Amendment Area” includes several parcels that support diverse vernal pool complexes and critical populations of several narrow endemic MHCP species. The city intends to work with the landowners to plan conservation solutions for these parcels at a later date. Due to the significance of these lands to the viability of several MHCP species, ultimate resolution of the San Marcos Major Amendment Area is cited by the MHCP as a coverage condition for these species. 2.3 BIOLOGICAL RESOURCES A comprehensive biological database was developed for the MHCP study area using GIS computer technology. The original database, completed in 1992, has been updated periodically as new information became available. Data layers were created for natural vegetation communities (using a classification system based on Holland 1986), sensitive species locations, vernal pools, topography, soils, animal microhabitats, climate zones, and other pertinent information. 2.3.1 Methods The vegetation community layer was generated using data from a variety of sources, including existing digital (computer) vegetation files and hard copy data from biological documents, EIRs, and other technical reports. Infrared aerial photograph interpretation (at 1:24,000 scale) was used to map areas not previously mapped, and limited field surveys were used for ground truthing. In 1997, the vegetation data layer was systematically updated using 1995 satellite imagery and a change detection algorithm. This method updated the previous database primarily by detecting areas that had been developed (vegetation removed) during intervening years. In addition, new vegetation maps from biological technical reports and EIRs were incorporated, where appropriate, in this systematic update. A sensitive species data layer was created using the California Natural Diversity Database (CNDDB), review of existing environmental documentation for projects in the study area, review of the scientific literature, personal communications from local biologists, and limited field reconnaissance. This layer has also been updated as new information became available (e.g., results of field surveys for environmental documents). Species locations associated with areas cleared of vegetation since 1992 have been coded in the GIS to indicate that the locations are no longer extant. For some species recorded in multiple years at the same locations, the redundant location points are coded in the GIS to avoid artificially inflated population or location estimates. For some birds, testing for duplicate points is based on approximate species-specific territory radii. Thus, for California gnatcatchers, older points within 200 feet of a newly recorded point are coded as duplicates; for least Bell’s vireos (Vireo bellii pusillus) older points within 100 feet of new points are coded as duplicates. The database was used to generate 1:24,000-scale U.S. Geological Survey (USGS) quadrangle maps depicting vegetation communities, topography, sensitive species locations, vernal pools, and other pertinent base map features (e.g., roads, water bodies, and city boundaries). These maps were reviewed in 1992 by local biologists, the MHCP Advisory Committee, the USFWS, the CDFG, environmental groups, and other interested organizations and individuals. During February and March 1997, the updated database was again subject to public review by all interested parties. The revised biological quadrangle maps and regional maps of species distributions were reviewed by over 30individual biologists, city planners, land owners, environmentalists, and other interested parties. Written and mapped information provided by these individuals was reviewed by the USFWS and used to refine and update the MHCP GIS database. PUBLIC REVIEW DRAFT MHCP VOL. I 2-2 314552000 Section 2 Description of MHCP Study Area This Public Review Draft MHCP document is based on database information incorporated up to May 1999. More recent information may be added for the Final Draft. 2.3.2 Vegetation Communities Figure 2-1 depicts the distribution of major vegetation communities remaining in the MHCP study area and vicinity and Table 2-1 quantifies the acreage of these vegetation communities within the study area. This section briefly summarizes the distribution and quality of vegetation communities as they relate to preserve planning within the MHCP study area. Approximately 29,895 acres (26.7%) of natural vegetation remain in the 111,865 -acre study area. The largest blocks of natural vegetation (greater than 1,000 contiguous acres each) occur in northern Escondido (Daley Ranch) and in the hilly areas of southeastern Carlsbad and southwestern San Marcos. Other relatively large blocks of habitat (at least several hundred contiguous acres each) occur along the northern boundary of Oceanside (adjacent to Camp Pendleton), and in scattered areas in eastern and central Carlsbad, northern San Marcos, and southern Escondido. Otherwise, natural habitats in the MHCP area are highly fragmented and occur primarily in small (less than 200 acres), scattered patches surrounded by development or agriculture. The remnant natural vegetation occurs disproportionately on developmentally constrained lands, such as steep slopes and canyons, and lands at the periphery of incorporated cities. Approximately 8,570 acres (7.6% of study area) of Diegan coastal sage scrub remain in the study area. Prior to development, coastal sage scrub probably stretched in a nearly unbroken