The Galesville Reservoir is located on the upper portion of Cow Creek, a tributary of the South Umpqua River. It was built in 1986 and is the largest dam in the Umpqua Basin. The dam is 167 feet tall from the streambed to the spillway and 950 feet long. It drains an area of 74 square miles.
The storage capacity of the dam is 42,225 acre feet and its primary purposes are to regulate water flow for downstream irrigation, industrial use, and municipal use, regulate and release stream flow for fish and other aquatic life and provide flood control. It is also used to generate hydroelectric power and recreational activities.
Galesville Dam prevents all anadromous salmonids from migrating into the Upper Cow Creek Watershed. The portion of the Cow Creek stream above the reservoir provides habitat for cutthroat trout and other native fish such as sculpin and dace. The reservoir itself provides fishing opportunities for large and smallmouth bass, yellow perch, bluegill and brown bullhead. These fish are considered to have reproducing populations within the reservoir. The Oregon Department of Fish and Wildlife also stock the reservoir regularly with trout and coho smolt. The reservoir provides a large variety of recreational fishing opportunities and does have a campground and boat ramp for additional recreation.