WERNER, SANFORD L., Consulting Geohydrologist-Engineer Geologist-Water Quality Specialist, Canoga Park, CA

ABSTRACT: Historic "Native" Water Well Data: A Valuable Source of Background Geohydrologic and Water Quality Data

The application of historic water well data in any environmental study is a must to establish background or "native" ground water conditions, such as depth to and quality of shallow groundwater. By 1900, thousands of water wells had been dug or drilled in southern California to depths of up to 300 ft or more. The present condition of most of these wells is unknown.

Historic "native" water well data is defined as that geohydrologic and water quality data reported between 1900 and 1950 in the southern California area. Generally, this data is not readily accessible nor found in the microfiche files of public agencies. Historic data includes well description, location, and depth;

water levels; lithology and ground water quality; etc. The Los Angeles-Orange County coastal plain is a part of southern California's vast groundwater system of major underlying aquifers, and an important source of water well production. Locally, it has been significantly contaminated from intense industrial development, especially the unconfined sediments and shallow groundwater of the Semiperched Aquifer which lie above the Bellflower Aquiclude.

With historic water well data, the "reciprocal" of the Law of Uniformitarianism ("the present is the key to the past") has great application. That is, the past is the key to the present.

AAPG Search and Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach, California, May 5-7, 1993.