Gillham Lake is a small reservoir located along the Cossatot River, mostly in Howard County, but also extending westward into Polk County, Arkansas.

The Flood Control Act of 1958 approved the lake for construction.

The lake provides flood control, water supply and wildlife conservation.

Canoeing and fly fishing on the Cossatot River are popular.

Gillham Lake also has the Coon Creek Walking Trail which is located on the entry road to Big Coon Creek Park.