The U.S. Army Corps of Engineers broke ground July 21 on the second phase of a safety modification project at Rough River Dam in Kentucky, launching a six- to eight-year, effort to fix a foundation problem the agency has been monitoring for years.

The $891 million project follows a dam safety evaluation that found the dam's foundation posed an unacceptable risk, the Army said in a news release. Initial risk reduction work was completed in 2017 during the first phase, but ongoing monitoring showed the foundation deterioration has continued. 

Phase 2 of the project includes construction of new outlet works on the dam's left abutment, with a new control tower and stilling basin connected by a tunnel, plus a full-depth cutoff wall across the dam's crest that will range from 75 to 180 feet deep, the Army said. Once the new outlet works is operational, the dam’s crew will abandon the existing tower. 

Highway 79, which now runs over the dam, will be detoured during construction. It will be moved back once the work is done.

The Corps awarded the Phase 2 construction contract to Thalle-Bauer LLC, based in Hillsborough, North Carolina, in December 2025.

“The work planned in Phase 2 will help to lower the dam’s risk and will ensure that it can continue to provide flood risk reduction benefits and serve the local community for years to come,” Louisville District Commander Col. L. Reyn Mann, said in the release. “We saw its value firsthand in the historic floods in spring 2025, and over the last year alone the dam has prevented more than $70 million in flood damages.”

Rough River, a tributary of the Green River in west-central Kentucky “is more than a lake,” Brig. Gen. Daniel Herlihy, commander of the U.S. Army Corps of Engineers Great Lakes and Ohio River Division, said. “It’s a lifeline for this region, where families make memories, businesses thrive, and communities benefit from the protection this dam provides.”

“I’m confident we have the right team, the right expertise, and the right partnerships to deliver this important project safely and successfully,” Herlihy said. “This project is about ensuring Rough River Dam continues to safeguard the people and communities who depend on it for generations to come.”

The 5,100-acre Rough River Lake draws 1.6 million to 2 million visitors annually for boating, fishing and camping. The dam is located near Falls of Rough, Kentucky, and spans Breckinridge, Hardin and Grayson counties.