Flowing into the heart of the Mojave Desert, the Mojave River exists mostly underground. Surface channels are usually dry absent occasional groundwater surfacing and flooding from extreme weather events like El Niño.
Prado Dam – built in 1941 in response to the Santa Ana River’s flood-prone past – separates the river into its upper and lower watersheds. After the devastation of the deadly Los Angeles Flood of 1938 that impacted much of Southern California, it became evident that flood protection was woefully inadequate, prompting the U.S. Army Corps of Engineers to construct Prado Dam.
The Colorado River Aqueduct, a 242-mile-long channel completed in 1941 by the Metropolitan Water District of Southern California, carries water from the Colorado River to to urban Southern California. The aqueduct is one of three conveyance systems of imported water to Southern California, the other two being the California Aqueduct and the Los Angeles Aqueduct.
With a holding capacity of more than 260 billion gallons, Diamond Valley Lake is Southern California’s largest reservoir. It sits about 90 miles southeast of Los Angeles and just west of Hemet in Riverside County where it was built in 2000. The offstream reservoir was created by three large dams that connect the surrounding hills, costing around $1.9 billion and doubling the region’s water storage capacity.
As one of the most productive agricultural regions in the world, the Imperial Valley receives its water from the Colorado River via the All-American Canal. Rainfall is scarce in the desert region at less than three inches per year and groundwater is of little value.
This issue looks at the dilemma of the shrinking Salton Sea. The shallow, briny inland lake at the southeastern edge of California is slowly evaporating and becoming more saline – threatening the habitat for fish and birds and worsening air quality as dust from the dry lakebed is whipped by the constant winds.