The Louisville District website ( is moving to the Great Lakes and Ohio River Division website ( This website is scheduled to be decommissioned on July 15, 2024. Please update all saved links to

Cecil M. Harden Lake replaces hydraulic power unit

U.S. Army Corps of Engineers, Louisville District
Published Aug. 2, 2021

The hydraulic power unit which provides pressure to open the Mansfield Dam main gates at Cecil M. Harden Lake in Rockville, Indiana was replaced April 2021. The requirement to replace the unit was identified on July 21, 2015 during a record lake pool level of 690.1 feet above mean sea level (msl). The operation of only one of three service gates was possible until water levels dropped near 685 msl when there was sufficient hydraulic power to operate all three gates. When water levels exceed 690 msl, the dam’s spillway provides a safe path for the excess flows.

"Replacement of this system has been a cooperative effort between engineering, operations and project staff,” said Joe Staigl, operations manager for the Middle Wabash area. “This cooperative effort has resulted in increased performance in the system and confidence knowing the project will operate properly under high water conditions.”

The original hydraulic system, which was put into operation in July 1960, produced enough pressure to open the 4 foot by 8.5-foot main gates when lake pool levels reached 685 msl. Lake water levels are kept at 662 msl during the summer and released at an average of 22 cubic feet per second to reduce downstream flooding and provide a reservoir area for recreation. During the winter, the water is drawn down to 640 msl to allow for storage of snowmelt and spring rains to reduce downstream flooding on Big Raccoon Creek.

The replacement hydraulic system was redesigned and approved July 14, 2017 to ensure full operation of all three main gates when the lake experiences flood level pools of 690 msl. The upgraded system includes higher horsepower motors, larger hydraulic pumps, counterbalance valves, pressure relief valves, and a new electrical service. This new system will allow the dam at Cecil M. Harden Lake to operate at any pool level, which is critical to maintaining dam safety and reducing flood damages downstream.