El Capitan Reservoir is a reservoir in central San Diego County, California

San Diego County, California

San Diego County is a large county located in the southwestern corner of the US state of California. Hence, San Diego County is also located in the southwestern corner of the 48 contiguous United States. Its county seat and largest city is San Diego. Its population was about 2,813,835 in the 2000...

 about 30 miles (50 km) northeast of the city of San Diego

San Diego, California

San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...

 and two miles north of the town of Alpine

Alpine, California

Alpine is a census-designated place in San Diego County, California. Alpine had a population of 14,236 at the 2010 census, up from 13,143 at the 2000 census.Alpine is the residence of former United States Representative Duncan Hunter...

. The reservoir is formed by El Capitan Dam

El Capitan Dam

El Capitan Dam is an embankment dam on the San Diego River in southern California. Completed in 1934, the dam forms El Capitan Reservoir and serves mainly to supply water to the city of San Diego as well as providing flood control. It is the largest storage facility in San Diego's water supply...

 on the San Diego River

San Diego River

The San Diego River is a river in San Diego County, California. It originates in the Cuyamaca Mountains northwest of the town of Julian, then flows to the southwest until it reaches the El Capitan Reservoir, the largest reservoir in the river's watershed at . Below El Capitan Dam, the river runs...

 and has a capacity of 112800 acre.ft. The 237-foot (72 m) dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

 is composed of hydraulic fill

Hydraulic fill

A hydraulic fill is an embankment or other fill in which the materials are deposited in place by a flowing stream of water, with the deposition being selective...

 and was completed in 1934. The dam is owned by the city of San Diego and its primary purpose is to supply drinking water

Drinking water

Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...

. It is the largest of the city's reservoirs.

The amount of runoff that enters the reservoir varies considerably. During a 25-year period, it ranged from 1,000 to 70000 acre.ft per year (39 to 2,700 L/s). The water in the reservoir usually consists of runoff from above the dam, but in years of drought

Drought

A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...

, water is sometimes transferred to it from San Vicente Reservoir

San Vicente Reservoir

San Vicente Reservoir is a reservoir created by the San Vicente Dam in the Cleveland National Forest of San Diego County, California, approximately 7 km north of Lakeside off of California State Route 67 in the Laguna Mountains.-Description:...

, which is the terminus of the First San Diego Aqueduct

San Diego Aqueduct

The San Diego Project, more popularly referenced as the San Diego Aqueduct, is a system of four aqueducts in the U.S. state of California, supplying about 90 percent of the water supply for the city of San Diego. The system comprises the First and Second San Diego Aqueducts, carrying water from the...

.

There is limited recreation available at the reservoir. Boating

Boating

Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels , focused on the travel itself, as well as sports activities, such as fishing or water skiing...

 and water skiing

Water skiing

thumb|right|A slalom skier making a turn on a slalom waterski.Waterskiing is a sport where an individual is pulled behind a boat or a cable ski installation on a body of water, skimming the surface.-History:...

 are available from May through October. Personal water craft

Personal water craft

A personal water craft , also called water scooter, is a recreational watercraft that the rider rides or stands on, rather than inside of, as in a boat....

 are limited to a designated zone, except when towing someone. Also, the long and narrow north arm of the lake is only open to watercraft on Sundays. Fishing

Fishing

Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

 is allowed all year. There is no camping at the lake. The nearest camping site is about 10 miles (16 km) away at Lake Jennings

Lake Jennings

- Camping :The campground at Lake Jennings Park has a variety of campsites available, including hookups and primitive tent sites....

.