State officials are asked to better regulate sewer treatment plants after “sewage fungus” appears in Middle Tennessee waterway

In November 2022, Harpeth Conservancy in partnership with the Southern Environmental Law Center, filed an official complaint to the Tennessee Department of Environment and Conservation (TDEC) alerting state officials to a bacterial bloom near a sewer treatment plant (STP) outfall (an outfall is the place where a drain or sewer empties into the sea, a river, or a lake, see Picture below). The complaint urges the department to impose stricter limits in the sewer plant’s discharge permit and halt additional sewer connections until the problem is corrected.

Sewer Treatment Plant outfall

The letter comes after the discovery of a massive and persistent bloom of what is suspected to be Sphaerotilus natans on Trace Creek, directly downstream from the White Bluff Wastewater Treatment Plant’s outfall in Dickson County. S. natans is a species of bacteria that thrives in waterways that contain improperly treated sewage. Its presence in Trace Creek is evidence that the White Bluff facility, which is operated by the Water Authority of Dickson County, is not fully treating the sewage before discharging it into the waterway.

“Trace Creek flows into the heart of the Narrows of the Harpeth River, which is one of the most popular and beloved rivers for paddling, tubing, and fishing in middle Tennessee,” Dorie Bolze, President and CEO of the Harpeth Conservancy, said. “All of Tennessee’s creeks, no matter how small, are supposed to be clean and safe to use.”

The extensive bacterial bloom on Trace Creek is indicative of larger development problems across Tennessee. As the state’s population grows and more rural areas rapidly develop, smaller sewage treatment plants are quickly becoming overwhelmed. In many cases, those overwhelmed facilities end up discharging undertreated sewage into creeks and streams. As these situations occur, we heavily rely on our community partners and members of the public to help us identify water quality issues that are negatively impacting our rivers and streams – learn what to look for and how to report water quality issues.

These increasingly common issues will worsen the already widespread water quality problems across the state. Recent state data shows that an estimated 59% of surveyed Tennessee waterways are considered ‘impaired,’ meaning they are too polluted to support their basic functions. Nitrogen and phosphorous pollution – which can result from improperly treated sewage discharges – are some of the most common causes of stream impairment statewide.

“Tennessee’s rivers, streams, and creeks are some of the state’s most important natural resources,” George Nolan, Senior Attorney for the Southern Environmental Law Center, said. “Simply put, Tennessee regulators should not allow wastewater treatment plant operators to recklessly dump improperly treated sewage into our waterways. They must require the Water Authority of Dickson County to do better.”

In the complaint, SELC and the Harpeth Conservancy tell TDEC that it must modify the Water Authority of Dickson County’s permit for the White Bluff plant to include specific numeric limits for nitrogen and phosphorous pollution in order to stop harmful discharges into Trace Creek. The letter also asks that the Department impose a moratorium on connecting new dischargers to the plant until the current violations are rectified and more protective permit limits are in place. Additionally, TDEC must update other permits for similar sewage treatment facilities to ensure the health of our shared waterways.