O'Neill Dam is an earthfill dam on San Luis Creek, west of

Los Banos, California Los Banos ( ), alternatively Los Baños ( ), is a city in Merced County, California, Merced County, California, United States. It is located in the San Joaquin Valley in Central California, near the junction of California State Route 152, Stat ...

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, on the eastern slopes of the

Pacific Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States; ; ) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Althoug ...

Merced County Merced County ( ) is a county located in the northern San Joaquin Valley section of the Central Valley, in the U.S. state of California. As of the 2020 census, the population was 281,202. The county seat is Merced. The county is named after ...

. Forming the

O'Neill Forebay O'Neill Forebay is a Forebay (reservoir), forebay to the San Luis Reservoir created by the construction of O'Neill Dam across San Luis Creek (California), San Luis Creek approximately west of Los Banos, California, United States, on the eastern s ...

, a forebay to the

San Luis Reservoir The San Luis Reservoir is an artificial lake on San Luis Creek (California), San Luis Creek in the eastern slopes of the Diablo Range of Merced County, California, approximately west of Los Banos, California, Los Banos on California State Rou ...

, it is roughly downstream from the

San Luis Dam San Luis Dam, also known as B.F. Sisk Dam, is a major earth-filled dam in Merced County, California, which forms San Luis Reservoir, The dam and reservoir are located in the Diablo Range to the east of Pacheco Pass and about west of Los Banos. ...

Background

Built from 1963 to 1967, the dam is an earthfill and rockfill construction stretching over across the valley of San Luis Creek. At high, with a maximum reservoir depth of , the crest of the dam is long, at an elevation of . A morning-glory type spillway lies at the

left bank In geography, a bank is the land alongside a body of water. Different structures are referred to as ''banks'' in different fields of geography. In limnology (the study of inland waters), a stream bank or river bank is the terrain alongsid ...

of the reservoir, with a capacity of per second and a circumference of .

O'Neill Forebay reservoir

The O'Neill Forebay reservoir is fed by releases from the San Luis Dam as well as from the

Delta–Mendota Canal The Delta–Mendota Canal is a aqueduct (water supply), aqueduct in central California, United States. The canal was designed and completed in 1951 by the U.S. Bureau of Reclamation as part of the Central Valley Project. It carries freshwater ...

. Water from the Delta–Mendota Canal is lifted a vertical distance of into a channel running into the forebay. The peak inflow to the forebay is per second, from both the San Luis Dam and the Delta–Mendota Canal. Drainage area of the reservoir downstream of the San Luis Dam is only .

O'Neill Pumping-Generating Plant

The O'Neill Pumping-Generating Plant produces . Irregular water releases from the San Luis Dam and William R. Gianelli Powerplant are collected in the reservoir of the O'Neill Dam, which has a capacity of .

Notes

References

External links