The Tennessee Valley Authority and the US Army Corps of Engineers created impoundments on the Tennessee and Cumberland rivers, beginning in 1971. Many of the Cumberlandian combshell's historic populations were lost when this occurred. Combshells are not known to survive in waters that have been altered by dams. This is because the dams permanently change the free-flowing aquatic habitat that the combshell and their fish host species require. Other populations were lost due to water pollution and siltation. The combshell is particularly vulnerable to pollution from coal mining and poor land-use practices. Also, as urbanization increases, the chances of pollution from nonpoint sources has increased drastically. Combshell populations are currently at extreme risk for extinction by naturally occurring events. The Fish and Wildlife Service (FWS) have defined naturally occurring events as things such as toxic chemical spills.
