Upper Duncan Reservoir   Be the first to submit input for Upper Duncan Reservoir. If you have info on Upper Duncan Reservoir, Malheur County, Oregon please submit it here to improve this web site.          These outdoors activities are available near Upper Duncan Reservoir.   Whitewater Near Upper Duncan Reservoir: Owyhee River, MalheurCounty, 15 miles away       Class III-IV(V) - 37 miles long (Three Forks to Rome) Owyhee River, -blank-County, 16 miles away       Class III+(V+) - 65 miles long (Garat Crossing to Three Forks) Owyhee River, MalheurCounty, 20 miles away       Class III-IV - 65 miles long (Rome to Owyhee Reservoir)