Nacimiento Dam
| Nacimiento Dam | |
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Satellite view
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 Location of Nacimiento Dam in California
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| Country | United States |
| Location | San Luis Obispo County, California |
| Coordinates | 35°45′31″N 120°53′06″W / 35.75861°N 120.88500°WCoordinates: 35°45′31″N 120°53′06″W / 35.75861°N 120.88500°W |
| Purpose | Irrigation, flood control |
| Construction began | 1955 |
| Opening date | 1957 |
| Owner(s) | Monterey County Water Resources Agency |
| Dam and spillways | |
| Type of dam | Earthfill |
| Impounds | Nacimiento River |
| Height (foundation) | 210 ft (64 m) |
| Length | 1,630 ft (500 m) |
| Elevation at crest | 825 ft (251 m) |
| Reservoir | |
| Creates | Lake Nacimiento |
| Total capacity | 377,900 acre·ft (466,100,000 m3) |
| Catchment area | 324 sq mi (840 km2) |
| Surface area | 5,400 acres (2,200 ha) |
| Power station | |
| Installed capacity | 4000 KW |
| Annual generation | 12,352,000 KWh (2010) |
Nacimiento Dam is a dam on the Nacimiento River about 10 miles (16 km) northwest of Paso Robles, California in the United States. The primary purpose of the dam is to provide groundwater recharge for agriculture in Monterey County and northern San Luis Obispo County supported by the Salinas Valley aquifer, as well as flood control, domestic water supply, and hydropower. It forms Lake Nacimiento, popular for boating, fishing and camping, and known locally as the "Dragon Lake" due to its shape.
Although located in San Luis Obispo County, the Nacimiento Dam and nearby San Antonio Dam, which forms Lake San Antonio, are both owned and operated by the Monterey County Water Resources Agency. It was completed in 1957.
Prior to the construction of Nacimiento Dam, the lower Nacimiento River (and the Salinas River) only flowed during the wet season between December and May. Without enough time to be absorbed into the Salinas Valley aquifer, much of the stormwater flowed directly into the Pacific Ocean. As the Salinas Valley developed as a major agricultural region dependent on groundwater, the Monterey County Flood Control and Water Conservation District (now Monterey County Water Resources Agency, MCWRA) proposed a reservoir on the Nacimiento River to capture winter floods, and release it at a low enough rate throughout the year to maximize groundwater recharge. Because the Nacimiento River is the biggest tributary of the Salinas River, the dam would capture up to half the annual peak flows in the entire Salinas River Basin.
Under the county plan, water would only be stored when the flow rate at the confluence of the Nacimiento and Salinas Rivers exceeded 300 cubic feet per second (8.5 m3/s), which was estimated as the highest volume the riverbed can naturally absorb. When natural runoff exceeded this amount, no water would be released. The California Department of Fish and Game (DFG) opposed the project due to the detrimental impacts this would have on winter run steelhead trout. The DFG sought a minimum flow of 50 cubic feet per second (1.4 m3/s) in the Nacimiento River, which the county believed would place too great a demand on the new reservoir. Ultimately, the county won and was granted the water rights for the reservoir in 1955 without any provisions for fishery flows.
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Wikipedia