| Big Cliff Dam | |
| Location Map: | Oregon |
| Coordinates: | 44.751°N -122.2831°W |
| Country: | United States |
| Location: | Linn County–Marion County, Oregon |
| Purpose: | Power |
| Status: | O |
| Construction Began: | 1949 |
| Owner: | U.S. Army Corps of Engineers |
| Dam Type: | Concrete gravity |
| Dam Crosses: | North Santiam River |
| Dam Length: | 280feet |
| Dam Height: | 191feet |
| Dam Elevation Crest: | 1212feet |
| Res Name: | Big Cliff Lake |
| Res Capacity Total: | 6450acre.ft |
| Res Surface: | 128acres[1] |
| Res Max Length: | 2.8miles |
| Plant Commission: | 1953 |
| Plant Turbines: | 1 x 18 MW Kaplan-type[2] |
| Plant Capacity: | 18 MW |
Big Cliff Dam is a concrete gravity dam on the North Santiam River in the western part of the U.S. state of Oregon.[3] The dam spans the Linn County–Marion County border in the Oregon Cascades.
The dam's primary functions are flood control, power generation, irrigation, fish habitat, water quality improvement, and recreation. It is one of 13 dams created by the U.S. Army Corps of Engineers under the Willamette Valley Project which was authorized by the Flood Control Act of 1938.[4]
It was constructed between March 1949 and May 1953[5] at the same time as Detroit Dam. Big Cliff is 2.7miles river distance below Detroit Dam at river mile 47 of the North Santiam River.
Big Cliff smooths river flow resulting from power generation fluctuations of Detroit Dam, a practice known as river re-regulation. Big Cliff Reservoir, primarily known as Big Cliff Lake, has daily depth variations of up to 24feet.[3]
Big Cliff can generate up to 18 megawatts of power.[3]
The dams' operators try to keep the water temperature in the 50°F59°F range for ideal fish habitat by mixing water from the top of Detroit Lake with water from the bottom.[6]