The Colorado River Basin Region is located in the most arid area of California. Despite the relatively dry climate, the Region contains some substantial surface water bodies, including the Colorado River and the Salton Sea. Many of the alluvial valleys in the Region are underlain by ground water aquifers that in many cases are the sole source of water for local areas.
The most Regionally important ground water basin underlies the Coachella Valley.
Some of the primary challenges facing the Region include pollution from Mexico, increasing salinity, selenium, and eutrophication in the Salton Sea, silt, nutrient, and pesticide pollution of the agricultural drains in Imperial Valley and the New and Alamo Rivers, and underground leaking tanks.