Hydrology and Water Quality
Section 2.5 Hydrology and Water Quality This section describes the hydrology and water quality conditions in the County and the regulatory framework applicable to hydrology and water quality. It also assesses the potential impacts on hydrology and surface and groundwater quality that could result from project implementation, and presents mitigation measures that would reduce potentially significant impacts. Water resources can be classified into two categories: (1) surface water, which collects in streams, rivers, lakes, and reservoirs; and (2) groundwater, which resides in subsurface aquifers. This section deals with surface water. Groundwater resources are discussed in Section 2.8, Water Supply and Groundwater. Topics related to floods, levees, or dams, and seiche, tsunami, or mudflow are discussed in Chapter 3, Environmental Effects Found Not to be Significant. 2.5.1 Existing Conditions 2.5.1.1 Surface Water Hydrology Surface water bodies in the County (e.g., estuaries, lagoons, bays, lakes, reservoirs, rivers, and creeks) capture the flow of the region’s water runoff, often combining natural runoff with imported water. Many of these water bodies support natural habitat and recreational areas, and serve as storage reservoirs for the County’s water supply. The San Diego region is divided into two hydrologic basins (the South Coast Basin and the Colorado River Basin) by the northwest-trending Peninsular Range. The County is divided into two hydrologic regions: (1) the San Diego Hydrologic Region, which drains in a westerly direction toward the Pacific Ocean and encompasses most of the County, parts of southwestern Riverside County, and southwestern Orange County; and (2) the Colorado Hydrologic Region, which drains in an easterly direction toward the desert and Colorado River basin.
[Show full text]