The lower Mountain Fork below the dam is one of the most productive trout streams in the south-central United States, even though Oklahoma is not a state most anglers associate with trout. The Oklahoma Department of Wildlife stocks it heavily with rainbows, with brown trout reproducing naturally on the spring-fed sections. A trout licence is required in addition to a regular fishing licence.
The river is also popular for floating. The Re-Reg Dam section just below the main spillway runs cold and shaded, while the lower river warms up enough for tubing in summer. Outfitters at the park rent canoes, kayaks, and tubes by the day.