WATER RESOURCES OF LOWER COLORADO RIVER-SALTON SEA AREA added recharge is balanced largely by discharge from the system through an extensive drainage network, and therefore it does not appreciably affect the aquifers several hundred feet or more below the land surface. In 1942 the All-American Canal became the sole means for diverting Colorado River water to the Imperial Valley; in 1948 the Coachella Canal, which supplies water to the lower part of Coachella Valley, was completed. Leakage from these canals is a major source of recharge to the groundwater system. Leakage during 1950-67 totaled about 4.5 million acre-feet from the All-American Canal and 2.7 million acre-feet from the Coachella Canal. Along the All-American Canal the water-level rise generally was more than 40 feet between 1939 and 1960; along the Coachella Canal it was about 40 feet near the head of the canal and gradually increased northward to more than 70 feet. Recharge to the groundwater reservoir by underflow from tributary areas is small compared with recharge from the imported Colorado River water. Groundwater underflow from tributary areas in the San Felipe Creek drainage basin in western Imperial Valley is about 10,000 acre-feet per year. Total recharge to the groundwater system from precipitation within the valley is estimated to be somewhat less than 10,000 acre-feet per year. Ground water generally moves toward the axis of the valley and thence northwestward toward the Salton Sea. The principal area of discharge is the central, cultivated part of the valley. Ground water also is discharged to the lower reaches of the Alamo and New Rivers and through numerous small springs and seeps. Some of the springs probably are associated with discharge of ground water along the San Andreas fault system, and many are associated with leakage from the Coachella Canal. Wells discharge only a small part of the groundwater supply, because most of the hundreds of used wells furnish only small stock or domestic supplies. Many of the wells are in a 6-to 10-mile-wide flowing-well area between the Alamo River and the East Highline Canal that extends about 30 miles northward from near the international boundary. A few wells yield hot water used to heat homes, but most are utilized only for domestic and stock purposes. The average rate of discharge is about 10 gallons per minute, and the total average annual discharge is only a few thousand acre-feet. Most of the few wells that are used for irrigation are in the lower Borrego Valley, where alfalfa is the principal crop. A few hundred acre-feet of ground water is pumped for industrial, private, and public supplies in the western part of the valley near Ocotillo and Coyote Wells. The chemical quality of the ground water in the Imperial Valley differs greatly. Total dissolved solids range from a few hundred to more than 10,000 mg/1 (milligrams per liter). Generally, ground water that is derived locally from precipitation and that |has not yet reached the more saline deposits of the central part of the valley conta...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.