COBB COUNTY, Ga. — An independent investigation is underway into one of the largest fish kills ever recorded on the Chattahoochee River.
[DOWNLOAD: Free WSB-TV News app for alerts as news breaks]
The incident happened in late May, when thousands of dead fish washed up along riverbanks coated with black sludge. Now, officials are focusing on sewage tunnels that may have been overwhelmed after heavy rainfall followed an extended drought.
While much of the sludge has since disappeared, environmental advocates and city officials are working to determine exactly what went wrong.
“The Chattahoochee River is the smallest river that provides a water supply to a major metropolitan city in the entire country,” said Jason Ulseth, executive director of Chattahoochee Riverkeeper.
Ulseth said he has never witnessed anything comparable during his years on the river.
“I’ve been on this river my entire life. I’ve never seen anything like this,” he said.
According to Ulseth, heavy rain caused the sewage system to overflow, sending sludge and debris into the river. Combined with high temperatures and low water levels, oxygen levels in the water dropped dramatically, suffocating fish.
RELATED STORIES:
- Thousands of fish found dead in the Chattahoochee River after flash flooding
- ‘The perfect storm:’ Riverkeeper says drought, stormwater, sewage caused Chattahoochee fish kill
- Chattahoochee River E. coli levels spike more than 17 times the healthy limit
- City opening independent investigation after thousands of dead fish found in Chattahoochee River
“It was a perfect storm that resulted in this fish kill,” Ulseth said.
In response, Atlanta’s Department of Watershed Management has hired an independent engineering firm to evaluate system operations, with a particular focus on the tunnels that handle sewage flows.
“We are looking at every aspect of our operations,” said Greg Eyerly with the Department of Watershed Management. “What engineering measures we have may have failed or may not have worked.”
Ulseth said the investigation must determine why the system was unable to handle the flow, especially given the Chattahoochee’s role as a drinking water source for millions of people.
“We have to invest a lot of money, a little time and a lot of science into this system to prevent it from overflowing in the future,” he said.
There is some encouraging news.
Ulseth says that in recent weeks, sonar shows some fish are returning, and that conditions in the river are starting to be livable again.
[SIGN UP: WSB-TV Daily Headlines Newsletter]
©2026 Cox Media Group
