COBB COUNTY, Ga. — The Chattahoochee Riverkeeper says drought, polluted runoff and sewage overflows contributed to a massive fish kill along at least 20 miles of the river last week.
“All of these combined factors just made for the perfect storm and caused the massive fish kill on the Chattahoochee,” Jason Ulseth, the executive director of the Chattahoochee Riverkeeper, told Channel 2’s Bryan Mims.
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He said thousands of dead fish washed up along the riverbanks after a storm Wednesday afternoon that dumped up to three inches of rain on downtown Atlanta.
Warm and polluted stormwater, along with treated and untreated sewage, gushed into the Peachtree Creek, then into the river, which has been unusually low because of the drought.
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“The volume of the stormwater and the sewage was significantly more than the volume of the water in the river,” he said.
Ulseth said it wasn’t the toxicity of the stormwater and stormwater, but the high temperature of the deluge that killed the fish. Warm water contains lower oxygen levels, causing fish to suffocate. Wastewater from treatment plants also typically have low levels of oxygen.
Ulseth also found black muck along the banks of the Chattahoochee for several miles downstream of Peachtree Creek. He said that likely came from Atlanta’s eight-and-a-half mile West Area Tunnel, which stores raw sewage and stormwater runoff to be treated later. It’s designed to keep older sewer lines from becoming overwhelmed in heavy rain.
“The problem Wednesday was that the tunnel completely filled and then overflowed directly into Peachtree Creek and the Chattahoochee River,” Ulseth told Channel 2 Action News.
The Georgia Environmental Protection Division and Atlanta’s Department of Watershed Management, along with the Chattahoochee Riverkeeper, are investigating the exact causes of the fish kill and plan a meeting Thursday.
Ulseth said despite the fish kill, the river is mostly free of pathogens with low levels of e-coli.
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