Elias Fereres is former Irrigation and Surface Water Specialist, Cooperative Extension, University of California, Davis; Donald A. Martinich is Staff Research Associate, Department of Land, Air, and Water Resources, U.C., Davis; Thomas M. Aldrich is Farm Advisor, Cooperative Extension, Colusa County; Juan Castel is Visiting Scientist, U.C., Davis; Eduardo Holzapfel is Graduate Student, Land, Air, Water Resources, U.C., Davis; Herbert Schulbach is Area Soils and Water Specialist, Cooperative Extension, Colusa County. This research was supported by a grant from the Office of Water Conservation of the California Department of Water Resources.