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Excerpts on Ground Waters and Site Cleanup <br /> from the <br /> Water Quality Control Plan (Basin Plan) for the <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> Sacramento River Basin and San Joaquin River Basin <br /> Third Edition — 1994 <br /> CHAPTER I. INTRODUCTION <br /> BASIN DESCRIPTION <br /> Ground water is defined as subsurface water that occurs beneath the ground surface in fully <br /> saturated zones within soils and other geologic formations. Where ground water occurs in a <br /> saturated geologic unit that contains sufficient permeability and thickness to yield significant <br /> quantities of water to wells or springs, it can be defined as an aquifer(USGS, Water Supply Paper <br /> 1988, 1972). A ground water basin is defined as a hydrogeologic unit containing one large aquifer <br /> or several connected and interrelated aquifers (Todd, Groundwater Hydrology, 1980). <br /> Major ground water basins underlie both valley floors, and there are scattered smaller basins in the <br /> foothill areas and mountain valleys. In many parts of the Region, usable ground waters occur <br /> outside of these currently identified basins. There are water-bearing geologic units within ground <br /> water basins in the Region that do not meet the definition of an aquifer. Therefore, for basin <br /> planning and regulatory purposes, the term "ground water" includes all subsurface waters that <br /> occur in fully saturated zones and fractures within soils and other geologic formations, whether or <br /> not these waters meet the definition of an aquifer or occur within identified ground water basins. <br /> Sacramento River Basin <br /> DWR Bulletin 118-80 identifies 63 ground water basins in the Sacramento watershed area. The <br /> Sacramento Valley floor is divided into 2 ground water basins. Other basins are in the foothills or <br /> mountain valleys. There are areas other than those identified in the DWR Bulletin with ground <br /> waters that have beneficial uses. <br /> San Joaquin River Basin <br /> DWR Bulletin 118-80 identifies 39 ground water basins in the San Joaquin watershed area. The <br /> San Joaquin Valley floor is divided into 15 separate ground water basins, largely based on political <br /> considerations. Other basins are in the foothills or mountain valleys. There are areas other than <br /> those identified in the DWR Bulletin with ground waters that have beneficial uses. <br /> 1' <br />