Overview
Nimbus Dam, 7 miles downstream of Folsom Dam on the American River, regulates releases made through Folsom Dam. Nimbus Dam forms Lake Natoma, with a surface area of 540 acres and a capacity of 8,760 acre-feet. Nimbus Dam is a concrete gravity dam 1,093 feet long and 87 feet high. Eighteen radial gates, each 40-feet by 24-feet, control the flows.
A loud horn and flashing siren, along with posted signage, notifies the public to stay clear when releases will soon be increasing.
Nimbus Powerplant is located on the right abutment of the dam, on the river’s north side. Its two generators have a capacity of 7,763 kilowatts each. Water is supplied to the two 9,400 horsepower turbines that drive the generators through six 46.5-foot-long penstocks. Nimbus Dam and Powerplant began operating in 1955.
General
| Project | CVP-Folsom |
| Longitude | -121.2233 |
| Watercourse | American River |
| Reservoir | Lake Natoma |
| Original Construction | 1952-1955 |
| Latitude | 38.6367 |
| National ID Number | CA10174 |
| Base Width | 135 ft |
Dimensions
| Structural Height | 87 ft |
| Crest Length | 1093 ft |
| Crest Width | 28 ft |
| Volume of Dam Construction Materials | 121000 cu yd |
| Crest Elevation | 132.0 ft |
| Hydraulic Height (Normal Operating Depth at Dam) | 46 ft |
Hydraulics & Hydrology
| Spillway Capacity at Elevation | 300000 cfs at 126.5 |
| Drainage Area | 1898 sq mi |
| Total Water Storage at Elevation | 8760 acre-ft at 125 |
| Net Generation | 67,752,000 kWh |
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