In June 2015, the Cumberland River Compact removed a dam on Sevenmile Creek behind the Edmondson Pike Branch Library. Sevenmile Creek’s water quality has been negatively impacted by habitat alteration, excess sediment, nutrients, and pathogens, and also by low dissolved oxygen. The dam was contributing to almost all these issues, and after removal, many in-stream conditions improved quickly and dramatically. After removal, the roughly 600 feet of stagnant backwater trapped by the dam was released and the stream has returned to a free-flowing waterway once again.

The unused and unmaintained dam was roughly 25’ wide and 4’ tall, and it created a stagnant backwater roughly 600 feet long. Endangered Nashville Crayfish are found in the watershed, so prior to removal, crayfish sweeps were conducted. Nashville Crayfish and other priority species were relocated prior to deconstruction, and removal work was scheduled for June in order to avoid the reproductive season of this at-risk species. 

Removal of the dam enabled backwaters to flow freely again. Improved connectivity has allowed for easier species migration and increased genetic diversity within the creek (eliminating the “aquarium” effect produced between multiple dams on a single waterway).  What was once a stagnant backwater with a sediment-filled bottom is now a mix of diversified habitat including riffles (fast and turbulent shallow water), runs (fast and smooth deep water), and pools. Flowing water prevents nutrients from pooling and causing harmful algal blooms, and it prevents sediment from building up and burying bottom-dwelling microorganisms beneath the muck behind the dam. Many aquatic species are sensitive to temperature increases, and the water that flows through Sevenmile Creek today stays cooler than the slow-moving water that previously heated up behind the dam under the sun. 

Soon after removal, vegetation began to grow, stabilizing formerly submerged banks, improving wildlife habitat, and providing shade and water temperature benefits. Three years of subsequent monitoring showed continued stability and improved habitat.

This work was done in partnership with the Nashville Public Library, Dan and Margaret Maddox Charitable Fund, The Nature Conservancy of TN, KCI Technologies, Metro Parks Nashville, and the Tennessee Wildlife Resources Agency.