The reservoir is formed by El Capitan Dam on the San Diego River and has a capacity of 112,800 acre⋅ft (139.1 million m3).

In order to make way for the construction of the dam, the native Kumeyaay people were forcibly relocated to the Capitan Grande Reservation.

According to the City of San Diego's General Plan Seismic Element, Division of Safety of Dams engineers "restricted the maximum water surface of El Capitan Dam to an elevation 30 feet lower than spillway, although permitting the temporary storage of storm inflows above the specified level for short periods."

This requirement was added after the 1971 San Fernando earthquake, where "a loss of about 30 feet of dam height resulted" at the Lower Van Norman Dam due to "liquefaction of the hydraulic fill on the upstream side of the embankment".

Fishing is allowed all year, but the recreation is closed on Wednesdays, Thursdays, and the first Friday of each month.