Geohydrology of the Escondido hydrologic subarea, San Diego County, California
The San Diego region of California is undergoing rapid growth with a corresponding increase in the demand for water. To update the basin plan developed in 1975 by the California Regional Water Quality Control Board, San Diego Region, water-level and water quality data for the 44-sq mi Escondido hydrologic subarea were collected and analyzed. Water-level measurements indicate that groundwater in most of the subarea was within 20 ft of land surface. Groundwater generally moves from the weathered crystalline rocks on hillsides into the alluvium. Groundwater moves from north to south in Reidy Canyon and from east to west in the alluvium along Escondido Creek. Water from all 20 wells sampled in 1987 had dissolved-solids concentrations greater than the U.S. Environmental Protection Agency recommended limit of 500 mg/L; concentrations ranged from 720 to 4,500 mg/L. Nitrate (as nitrogen) concentrations ranged from 1.1 to 86 mg/L. Water from 14 of the 20 wells had nitrate (as nitrogen) concentrations greater than the U.S. Environmental Agency recommended limit of 10 mg/L. (USGS)