Cottage Grove Dam and Reservoir is located at river mile 29 of the Coast Fork of the Willamette River, about five miles south of Cottage Grove, Ore.
Cottage Grove Lake is an earthfill dam with concrete spillway and was completed in 1942 at a cost of $3.3 million. Since then, it has helped prevent almost $1.2 billion in potential flood damages and controls runoff drained by the Coast Fork Willamette River, an area of 104 square miles.
The authorized primary project purpose of the Cottage Grove Dam is flood damage reduction, but other approved uses include irrigation, recreation, and improved navigation downstream.
Update: The U.S. Army Corps of Engineers implemented an alcohol ban at Dorena and Cottage Grove lakes.