Estimated permeabilities for soils in the Sacramento Valley, California

Analysis of engineering and hydrologic data from 15 previous soil studies, analysis of particle-size distribution, and analysis of descriptions of soil profiles show that 50 percent of the Sacramento Valley area has soils having permeabilities characterized by infiltration rates of less than 2 feet per day (0.6 meter per day). Consolidated barriers that could impede vertical flow were found in 30 percent of the area.