SECTION 4.3 Biological Resources 4.3 BIOLOGICAL RESOURCES This section of the PEIR analyzes the potential environmental effects on biological resources from implementation of the proposed Specific Plan. No comment letters addressing biological resources were received in response to the Notice of Preparation (NOP) circulated for the proposed project. Data for this section were taken from a search of biological resources databases; a review of pertinent literature, photographs, and aerial imagery; and site visits to selected portions of the Specific Plan area. No site-specific biological surveys, vegetation mapping, special-status species protocol-level surveys, or wetland delineation surveys were conducted. Full reference-list entries for all cited materials are provided in Section 4.3.5 (References). The following provides a summarized list of the primary resources consulted for the preparation of this section: ■ Databases Calflora Plant Observation Library (Calflora 2011a) California Department of Fish and Game (CDFG) Natural Diversity Database (CDFG 2011a) California Native Plant Society (CNPS) Inventory of Rare and Endangered Plants (CNPS 2011) Consortium of California Herbaria (Consortium 2011) U.S. Department of Agriculture (USDA) Web Soil Survey (USDA 2011) U.S. Fish and Wildlife Service (USFWS) Critical Habitat Portal (USFWS 2011a) USFWS National Wetlands Inventory Wetlands Mapper (USFWS 2011c) ■ Literature Review CDFG State- and Federally Listed Endangered, Threatened, and Rare Plants of California (CDFG 2011b) CDFG Special Vascular Plants, Bryophytes, and Lichens List (CDFG 2011c) CDFG Special-Status Animals List (CDFG 2011d) 4.3.1 Environmental Setting Regional Context The Specific Plan area is located within the northeastern portion of the City of Laguna Niguel in southern Orange County. The general area also encompasses the cities of Aliso Viejo, Dana Point, Laguna Beach, Laguna Hills, Mission Viejo, and San Juan Capistrano, as well as unincorporated areas of Orange County. Located approximately 5 miles inland and northeast of the Pacific Ocean, the bioregion that defines the area is influenced by a coastal Mediterranean climate. The area‘s climate, coupled with coastal geological formations and land features, give rise to an array of habitat types and vegetation communities that are typical to coastal southern California. Grasslands, coastal sage scrub, chaparral, riparian woodlands and forests, and riverine and palustrine habitats contribute to the overall biological value and aesthetic appeal of the general area. Although past agricultural practices and urbanization have resulted in the conversion of land and development within much of the general area, there remains few larger blocks and linkages of undeveloped land that provide important habitat for plant and wildlife species that reside and migrate to and from the area. Laguna Niguel Gateway Specific Plan PEIR 4.3-1 CHAPTER 4 Environmental Analysis Topography and Soils Topographic features not only provide for scenic viewsheds in a community, but also support the collection and delivery of important water resources, dictate the distribution of valuable habitat types, and aid in the facilitation of wildlife movement to and from important habitat areas. In general, the Specific Plan area is situated within a relatively narrow north-south trending corridor for the Oso Creek watershed. No major ridgeline features or mountain peaks characterize the Specific Plan area. The highest elevations occur within the western portions of the Specific Plan area at approximately 520 feet above mean sea level (amsl). The lowest elevations occur within the southern portions of the Specific Plan area at approximately 220 feet amsl. Two major water features occur within the Specific Plan area: Oso Creek and the Galivan Basin. Within the Specific Plan area, Oso Creek and the Galivan Basin are owned and maintained by the Orange County Flood Control District (OCFCD). The Galivan Basin is a man-made flood control feature located in the northern portions of the Specific Plan area that serves as an overflow and retarding basin for Oso Creek. A small, unnamed drainage feature runs through the Galivan Basin before discharging into Oso Creek. The Galivan Basin is actively maintained by OCFCD and therefore routinely disturbed and cleared of vegetation. An approximately 2.0-mile (11,000-linear-foot) reach of Oso Creek traverses the Specific Plan area, the entirety of which has been channelized and diverted from its natural course. Within the Specific Plan area, nearly all of Oso Creek is contained within a concrete channel, and depending upon flows and seasonal conditions, little or no vegetation occurs. Oso Creek is a blue-line stream and tributary water to Trabuco Creek, which occurs further to the south of the Specific Plan area, as depicted on the San Juan Capistrano, California USGS 7.5″ topographic quadrangle map. Trabuco Creek is a tributary water to San Juan Creek, which discharges into the Pacific Ocean approximately 6.0 river miles downstream of the Specific Plan area. The geology and soils associated with topographic features give way to varying habitat types and often provide unique safe havens for plants and animals with specific microhabitat requirements such as clay, shale, granite, and limestone pockets, rock outcrops, and cliff faces. In highly urbanized settings, such as the Specific Plan area, the native soils are often heavily disturbed and altered from their natural state. In most cases, urbanization has resulted in the cutting and filling of native soils for the placement of permanent developments. The underlying soils of the Specific Plan area consist of Capistrano Formation bedrock from late Miocene to early Pliocene age. Quaternary alluvium of Oso Creek and its tributaries overlie the bedrock. The Specific Plan area is mapped as being supported by eighteen separate soil map units. The dominant soil unit is Alo clay, which underlies roughly 50 percent of the Specific Plan area. Other soil units identified include various types of clay, loam, clay loam, sandy loam, loamy sand, cobbly sandy loam, and riverwash. Vegetation The vegetation mapping for this programmatic assessment takes a broad-based approach toward defining habitat types and vegetation communities that occur within the Specific Plan area. Vegetation communities have been defined based on overall dominance of trees, shrubs, and herbaceous plants that occur over relatively large areas, as determined by review of aerial imagery, relevant literature, photographs, and field visits to the Specific Plan area. As environmental conditions change and more 4.3-2 Laguna Niguel Gateway Specific Plan PEIR SECTION 4.3 Biological Resources specific studies are conducted, deviations from the large-scale assessment may occur as specific data is collected, and more fine-scale mapping may reveal a greater diversity of habitat types. A total of five general vegetation communities or habitat types characterize the Specific Plan area. These include urban/developed, grassland, coastal sage scrub, riparian, and unvegetated channel. For general location of these communities within the Specific Plan area, refer to Figure 4.3-1 (Vegetation Communities). The names and definitions of vegetation communities are discussed below and are suggested based on general definitions provided by Holland (1986) and Sawyer and Keeler-Wolf (2009) natural communities classification systems. Urban/Developed Urban/developed includes land that has been permanently altered due to the construction of aboveground developments such as buildings and roads. Urban/developed areas may include stands of nonnative vegetation planted for landscaping improvements, including ornamental tree- and shrub- vegetated slopes and rights-of-way and groundcover-vegetated parks. Nonnative species typical of urban/developed areas may include ornamental tree plantings such as pine (Pinus spp.), gum (Eucalyptus spp.), pepper (Schinus spp.), and palms (Arecaceae family), ornamental shrubs such as wattle (Acacia pycnantha, Acacia spp.), oleander (Nerium oleander), pittosporum (Pittosporum spp.), and tea tree (Leptospermum spp.), and nonnative groundcover species such as freeway ice plant (Carpobrotus edulis), crystalline ice plant (Mesembryanthemum crystallinum), and various turf grasses (Fescuta spp., Cynodon spp., Digitaria spp., Eremochloa spp., Zoysia spp.). Urban/developed land is the predominant land use or vegetation community within the Specific Plan area, generally occurring in the form of industrial and commercial developments, surface streets, arterials, and other infrastructure. Areas characterized by urban/developed land provide very limited biological function and value. Grassland For the purposes of this assessment, grassland can be divided into two general categories: native grassland or nonnative grassland. The predominant native grassland type that is known to occur in the region is valley needlegrass grassland. Valley needlegrass grassland has been defined as supporting a vegetative cover that includes at least 10 percent coverage by native purple needlegrass (Nassella pulchra), with the remaining 90 percent comprised of other native and nonnative grasses and forbs (Sawyer and Keeler-Wolf 2009). Nonnative grassland, or annual grassland, is more prevalent and widespread in the region, and is described as a dense to sparse cover of nonnative annual grasses, often associated with numerous ruderal species and native annual forbs, especially in years with