The Miami Conservancy District is starting a $1.14 million project to strengthen the Germantown Dam flood safety infrastructure. The project will rehabilitate the dam's auxiliary spillway, an important safety feature designed to safely carry floodwaters during the most extreme storm events.
The work went out to bid in April. See Dam Spillway to Receive $1.9 Million in Repairs
Google Maps shows the spillway north of the dam, reconnecting to Twin Creek on Old Mill Road.
The recent rains have shown the importance of the Germantown Dam in preventing catastrophic flooding. Last week’s rain marked the 25th flood storage event of 2026 among the Miami Conservancy District’s five flood protection dams.
Miami Conservancy District’s five dry dams — Englewood, Germantown, Huffman, Lockington and Taylorsville — work together as one regional flood protection system. During high-water events, the dams temporarily store runoff upstream and release it gradually as river conditions allow, reducing downstream flood risk across multiple communities.
"Maintaining this infrastructure is one of the most important things we do to keep our flood protection system reliable," said Don O’Connor, chief engineer of the Miami Conservancy District. "While most people will never see the auxiliary spillway in action, it is a critical safety feature that helps ensure the dam performs as designed during the largest floods."
Germantown Dam is one of five dry dams operated by the Miami Conservancy District as part of a regional flood protection system built after the Great Flood of 1913. The spillway project is part of a series of upgrades to ensure the flood protection systems remains strong and effective for the region. Together, the system protects more than one million residents, thousands of homes and businesses, major transportation corridors, and billions of dollars in public and private infrastructure throughout Southwest Ohio.
What Is an Auxiliary Spillway?
An auxiliary spillway serves as a dam's emergency overflow channel.
During exceptionally large storms, when floodwaters rise above normal operating levels, the spillway provides a safe path for excess water to pass through the dam without causing damage to the structure. Although it has never been used, it is one of the dam's most important safety features and must remain in excellent condition to function properly during an extreme flood.
Why the Work Is Needed
The Germantown Dam auxiliary spillway has been in service for more than 100 years. Over time, repeated freeze-thaw cycles have caused significant deterioration to the concrete lining, structural weirs, and surrounding slopes.
Routine inspections and engineering evaluations conducted by Miami Conservancy District staff, together with the Ohio Department of Natural Resources Dam Safety Program, identified the need for rehabilitation. The project is being completed to meet current dam safety requirements and ensure the spillway continues to perform reliably for decades to come.
Without these repairs, continued deterioration could allow erosion of the spillway's side slopes and underlying bedrock during an extreme flood event.
Project Improvements
Construction will include:
Replacing deteriorated concrete that protects the spillway
Extending concrete protection along the spillway slopes
Installing a drainage system beneath the spillway floor to improve long-term performance
Replacing aging concrete weirs that help safely direct water through the spillway
These improvements will strengthen the spillway, improve its durability, and extend the service life of this critical piece of infrastructure.
Construction Schedule
Construction is scheduled to begin August 17 and conclude by October 31.
Following a competitive bidding process, Miami Conservancy District selected Brumbaugh Construction to complete the work.
Construction activities will occur within the dam property. While the public may notice construction equipment in the area, there are no significant impacts to the operation of the flood protection system expected during construction.
Trail Impacts
A large portion of Germantown MetroPark, leased to and managed by Five Rivers MetroParks, is located on land owned by the Miami Conservancy District. The park's extensive trail network runs through the flood protection infrastructure, and public recreation is made possible because of the flood storage basin created by the dam.
From August 17 through October 31, visitors should expect intermittent closures or detours on sections of the Pink and Brown Trails near the Spillway Trailhead while crews complete repair work on the auxiliary spillway. All closures and detours will be marked with on-site signage.
Investing in the Future
The Miami Conservancy District regularly inspects, maintains, and rehabilitates its flood protection infrastructure to ensure it continues to meet modern engineering and safety standards.
"These dams were built to protect future generations, and that requires ongoing investment," said O’Connor. "Projects like this ensure the flood protection system remains ready when our communities need it most."
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