Built in the saddle of two mountains, Diamond Valley Lake—Southern California’s newest and largest reservoir—is a vital link in the regional system that’s brought water to Southern California for the past 60 years. The lake nearly doubled the area’s surface water storage capacity and provided additional water supplies for drought, peak summer and emergency needs.
Water began pouring into the reservoir in November 1999 and the lake was filled by early 2002. Diamond Valley Lake holds 800,000 acre-feet, or 260 billion gallons of water. By comparison, Lake Havasu, on the Colorado River, holds just 648,000 acre-feet or 201 billion gallons.
