- The refuge is bounded on the north by the Arkansas state line, on the east by the Ouachita River and on the west and south by private land.
The topography is flat in the Ouachita River flood plain, with rolling hills present along most of the western boundary. Elevations range from 52 feet MSL at the river's edge to almost 85 feet MSL in the northwest portion of the refuge. Approximately three-fouths of the area is inundated annually by backwater flooding from December to June.
Upper Ouachita NWR is located on the Arkansas state line in Union and Morehouse Parishes in north-central Louisiana.