Dissolved-Solids Concentrations and Loads in Return Flows to the Colorado River from Agricultural Land in Southern California

摘要

The dissolved-solids concentration in Colorado River water increases from less than 50 mg/l (milligrams per liter) at the river's origin to about 700 mg/l at the California border and to about 900 mg/l at the United States-Mexico boundary. Much of the latter increase is due to depletion by agricultural use and irrigation return water with salts leached from soils under cultivation. Forty sites in three agricultural areas--Fort Mojave, Bard Valley, and Palo Verde Valley--were sampled to describe the dissolved-solids concentrations in return flows. Emphasis was on Palo Verde Valley. Selected drains in Palo Verde Valley were sampled several times to determine dissolved-solids loads from subareas within the valley. Loads determined in this study were compared with those of an earlier study. The differences are thought to be due to generally lower water discharge observed in drains during this study.