Union Valley Reservoir is a

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

in eastern

El Dorado County, California El Dorado County (; ''El Dorado'', Spanish for "The Golden ne), officially the County of El Dorado, is a county located in the U.S. state of California. As of the 2020 census, the population was 191,185. The county seat is Placerville. Th ...

, about northeast of Placerville. The lake is in

Eldorado National Forest Eldorado National Forest is a U.S. National Forest located in the central Sierra Nevada mountain range, in eastern California. Geography Most of the forest (72.8%) lies in El Dorado County. In descending order of land area the others countie ...

in the

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

at an elevation of . It was formed in by the high earth and rockfill Union Valley Dam on Silver Creek, which is a tributary of the

American River The American River is a List of rivers of California, river in California that runs from the Sierra Nevada (U.S.), Sierra Nevada mountain range to its confluence with the Sacramento River in downtown Sacramento. Via the Sacramento River, it ...

. The reservoir is part of the Upper American River Project of the

Sacramento Municipal Utility District The Sacramento Municipal Utility District (SMUD) is a community-owned electric utility serving Sacramento County and parts of Placer County. It is one of the ten largest publicly owned utilities in the United States, generating the bulk of its po ...

, a public electric utility, which operates the dam and many other dams in the area. Recreation such as

boating Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether powerboats, sailboats, or man-powered vessels (such as rowing and paddle boats), focused on the travel itself, as well as sports activities, suc ...

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

and

camping Camping is a form of outdoor recreation or outdoor education involving overnight stays with a basic temporary shelter such as a tent. Camping can also include a recreational vehicle, sheltered cabins, a permanent tent, a shelter such as a Bivy bag ...

is available there. It stores snow melt runoff during the spring and releases it during the summer when electrical demand is greatest to a chain of

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

power plants downstream. Union Valley Powerhouse at the base of the dam has a capacity of 46.7 MW and is operated as a

peaking power plant Peaking power plants, also known as peaker plants, and occasionally just "peakers", are power plants that generally run only when there is a high demand, known as peak demand, for electricity. Because they supply power only occasionally, the powe ...

, supplying electricity during times of the greatest demand. Consumptive rights to the water itself are held by the City of

Sacramento, California Sacramento ( or ; ; ) is the List of capitals in the United States, capital city of the U.S. state of California and the county seat, seat of Sacramento County, California, Sacramento County. Located at the confluence of the Sacramento Rive ...

. The reservoir is fed by Big Silver Creek, Jones Fork Silver Creek, Tells Creek, Wench Creek and the outflows of Robbs Peak and Jones Fork powerhouses. Jones Fork Powerhouse is not on Jones Fork Silver Creek but instead conveys water from Ice House Reservoir. Robbs Peak Powerhouse gets its water from the Middle Fork American River headwaters, by way of Loon Lake Reservoir, and small reservoirs on Gerle Creek and South Fork Rubicon River. Downstream from Union Valley Dam, Silver Creek waters are largely diverted through two additional powerhouses below small reservoirs before joining the South Fork American River a few miles north of

Pollock Pines, California Pollock Pines is a census-designated place (CDP) in El Dorado County, California, United States. It is part of the Sacramento– Arden-Arcade– Roseville Metropolitan Statistical Area. Pollock Pines lies at an elevation of in the Sierra ...

. Silver Creek was an intermittent creek before the development of Union Valley Reservoir and the diversions from the Middle Fork American River.

References

Sacramento Municipal Utility District
{{authority control Reservoirs in El Dorado County, California Lakes of the Sierra Nevada (United States) Sacramento Municipal Utility District American River (California) Eldorado National Forest Reservoirs in Northern California

See also

References