Foster Dam is located at river mile 38.5 on the South Santiam River, at the confluence of the South Santiam and Middle Santiam rivers, four miles northeast of Sweet Home, Ore.
Foster Dam is a rock-fill structure with a concrete gated spillway, and was completed with Green Peter Dam in1968 at a cost of $82.3 million.
Foster Dam is used to regulate power-generating water releases from Green Peter Dam and regulate flows from the south Santiam River. Foster Dam has two generators capable of producing 10 megawatts each. Foster Dam works in coordination with Green Peter Dam for flood risk management, hydropower, water quality improvement, irrigation, fish and wildlife habitat, and recreation.