Excessive coverage of aquatic vegetation has reduced aesthetic quality and recreational value in Felsenthal Reservoir, Arkansas. A large portion of the 6,000-ha impoundment of the Ouachita River, located within the Felsenthal National Wildlife Refuge, is covered by dense aquatic vegetation. Grass carp are commonly used to control aquatic vegetation in closed systems, but results of stocking grass carp for vegetation control in open systems is less certain. Radio transmitters were implanted in 48 adult triploid grass carp. Grass carp were released in the reservoir during fall 2006. Radio-tagged grass carp were relocated approximately semi-monthly during a 12-mo period. Of the 48 fish that were stocked, 39 (82%) were consistently located in Felsenthal Reservoir. Three fish (6%) were never relocated, one fish (2%) moved upstream of Felsenthal Reservoir then returned, and five fish (10%) were located upstream of Felsenthal Reservoir in both the Ouachita and Saline Rivers. Average (SD) home range was 576 (638) ha. Maximum movement from release site averaged 5.7 and 51.4 km for grass carp that remained in and left Felsenthal Reservoir, respectively. The greatest amount of movement occurred during the fall season, with an average daily movement of 238 m/d. Grass carp stocked into Felsenthal Reservoir were not likely to emigrate, and if they did, they were more likely to move upstream than downstream.