Descriptions and chemical analyses for selected wells in the Tehama-Colusa Canal Service Area, Sacramento Valley, California

The Tehama-Colusa Canal Service Area is in the northwestern part of the Sacramento Valley, in parts of Yolo, Colusa, Glenn, and Tehama Counties. The area includes 450 square miles (1,160 square kilometres). The boundaries are: West, the eastern slopes of the Coast Ranges; north, Elder Creek; northeast, the Sacramento River and the Glenn-Colusa Canal; east and southeast, the Colusa Basin Drainage Canal; and south, Oat Creek.

Between April and July 1974, 393 wells were selectively canvassed and between August and October 1974, water samples were collected for chemical analysis from 222 wells of the 393 wells canvassed. Field determinations of alkalinity, conductance, pH, and temperature were made on the site at the time of sampling. The samples were then field prepared for shipment and analysis for individual constituents at the Geological Survey Central Laboratory, Salt Lake City, Utah. Descriptive data for water wells are listed in table 1, chemical data in tables 2 and 3, and the location of these wells is shown on maps 1-28.