Detroit Dam, Hydroelectric power station in Marion County, United States

Detroit Dam is a gravity dam on the North Santiam River, located on the border of Marion and Linn counties in Oregon. The structure holds back the river to form a large reservoir and channels water through turbines to produce electricity for the region.

The U.S. Army Corps of Engineers began work on the dam after World War II delayed earlier plans, completing it in 1953. The project was designed both to generate electricity and to control seasonal flooding along the North Santiam River.

Detroit Lake, the reservoir formed by the dam, draws anglers, boaters, and campers throughout the year. The lake has become a natural gathering point for outdoor recreation in the Willamette Valley.

The dam stands about 5 mi (8 km) west of the city of Detroit, reached by road along the North Santiam River; the crest and spillway are seen from the road and from pull-offs on either side. The reservoir level is kept lower than full pool, so shoreline and boat ramps shift with the water line.

In 2021 the U.S. Army Corps of Engineers judged the dam at risk of failure in a large Cascadia subduction zone earthquake, which could send a potentially catastrophic flood toward Salem, Oregon's capital downstream. The reservoir was lowered by five feet to reduce stress on the concrete.