An independent investigation is underway into one of the largest fish kills ever recorded on the Chattahoochee River.
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…