Abstract: A barge system for hydraulic spreading of aquatic capping material is provided. The barge system includes a barge, a piping system, a spreader, a system for moving the barge and a controller. The barge has a deck extending between a front end and a rear end and two opposing sides. The piping system is mounted on the deck and used for the transmission of capping material slurry that includes a capping material. The piping system has a first end and a second end. A source of capping material slurry is connected to the first end and fed through the piping system to the spreader. The spreader has an inlet end in communication with the second end of the piping system and a discharge end. The spreader evenly distributes the capping material slurry from the end of the barge. The controller positions the barge based on the flow rate and density of the slurry. The barge system is used to deposit a predetermined thickness of the capping material on the bottom of the body of water.