Seven major stream systems originate in the mountains of San Diego County and drain to the Pacific Ocean. Runoff from these seven watersheds supplies 24 reservoirs that have a combined capacity of about 740,000 acre-feet.

The last major increase in regional water storage capacity was in 2014 when then San Vicente Dam Raise was completed, adding 157,000 acre-feet of capacity. While the region’s reservoirs were built mainly as water supply projects, many of them also provide other benefits such as recreation and flood reduction.

Since the major statewide drought of 1976-1977, annual surface water use from local reservoirs has ranged from 4,100 acre-feet in fiscal year 2015 to 140,300 acre-feet in fiscal year 1984. Over the past two decades, annual local surface water use has averaged approximately 60,000 acre-feet, or about 10 percent of the region’s average total annual water use.

Map of San Diego County Reservoirs

Local Rainfall and Reservoirs Fact Sheet

Metropolitan Water District of Southern California Reservoirs

Date generated: 10/01/2020

Note: Each reservoir’s change in storage level is a function of its unique operational characteristics, which may include movement of imported and local water supplies in and out of the reservoir as well as surface water capture from local rainfall.