Diamond Valley Lake

Diamond Valley Lake is a man-made off-stream reservoir located near Hemet, California, United States. It is one of the largest reservoirs in Southern California and also one of the newest. With a capacity of 800,000 acre-feet, the lake nearly doubled the area's surface water storage capacity and provides additional water supplies for drought, peak summer, and emergency needs.The Metropolitan Water District of Southern California began the $1.9 billion construction project in 1995. Filling of the lake, by way of the Colorado River Aqueduct, began in 1999 and was completed in 2003. The lake is currently served by the Inland Feeder.

The lake features three earth fill dams, two located on either side of the valley and one on the north rim. Construction of the dams utilized nearby materials, and was one of the largest earthworks projects in the United States.