unprecedented fish – After Atlanta saw an intense burst of rain on May 20, officials and environmental advocates say polluted stormwater and a likely sewer overflow swept into the Chattahoochee River. With the river running low after months of drought, the conditions helped trigge
Flash flooding in Atlanta happened fast—so fast that by the next day, dead fish were showing up across the river.
On May 20. severe weather hit the Atlanta metro area and dumped an estimated 3 inches of rain in under an hour within the I-285 area. according to Chattahoochee Riverkeeper. The surge did not stay in place. Polluted runoff—stormwater from the city—moved into Peachtree Creek over the next 24 hours and eventually poured into the Chattahoochee River south of the city.
A day later, officials found dead fish everywhere.
Chattahoochee Riverkeeper called the situation “unprecedented.” In a May 23 statement, the group said the die-off was tied to heavy rains and the runoff that followed, coming at a time when Georgia had been in serious drought for months.
Inside the “perfect storm” behind the die-off
Three environmental factors lined up in the days after May 20, Chattahoochee Riverkeeper said—each one making the next worse.
First, drought left the Chattahoochee flowing low. The river’s flow is determined by the U.S. Army Corps of Engineers, which can adjust water releases through a series of dams. Water can be released from major reservoirs such as Lake Lanier, north of Atlanta, to increase flow when needed. But reservoirs north of the city are also low because of the lack of rain statewide. With the river moving slowly, fish faced exposure to pollutants—or other harmful conditions—for longer periods.
Second, the stormwater reaching Peachtree Creek carried high pollutant levels. The group said that once stormwater hit pavement on a warm day. its temperature would have been higher than the creek’s typical temperature. With drought limiting rainfall. the flows also carried heavy loads of additional pollutants and nutrient pollution into Peachtree Creek and onward into the Chattahoochee River.
Third, the rapid rainfall made a sewer system overflow likely. Chattahoochee Riverkeeper said the City of Atlanta’s combined sewer system and the West Area Tunnel overflowed into Peachtree Creek. That emergency discharge meant untreated water and polluted stormwater went directly into the river.
Taken together, the organization said those were the right conditions to trigger a massive fish die-off—something it said had not been seen in the river in recent memory.
The downstream impact is real—and long
Jason Ulseth, the executive director of Chattahoochee Riverkeeper, told CBS News that the die-off extends 20 miles down the river. He said it is something he has never seen before in his two decades with the organization.
“ We ‘ve had a lot of time for a lot of materials to accumulate on the roadways. on the parking lots. in the dog parks. So. you know. when you get a heavy flush of rain like that. it washes in a lot of contaminants that go into the system. ” Ulseth said. “That has problems (down) the food chain, other animals that eat the fish, depend on the fish for their well-being. And, you know, there’s a lot of fishermen in this stretch and people are upset. I’m very upset because I’m a fisherman and going down the river and seeing these trophy fish that are just dead because of something that. you know. we’ve been trying to control for so long.”.
Ulseth also said the storm that settled over Atlanta last Wednesday used to be a 1-in-150-years event, but that in the past decade there have been multiple storms like that.
For Atlanta, the flooding wasn’t only an environmental crisis
The same storm system that helped drive the river’s contamination also pushed the city’s infrastructure into dangerous territory.
An area of the Atlanta Connector was shut down last week when rainwater reached multiple feet deep and cars could not pass through. Multiple vehicles became submerged, and in at least one case, a driver had to be rescued from the roof of her car.
Elsewhere, water turned roads into lakes. Waymo autonomous vehicles shut down service as the cars drove into high water. A power outage at a nearby water treatment plant also left a large section of central Atlanta under a boil water advisory at the end of last week.
Residents have described these failures as something that has gone on for decades. Now, with the city preparing for another week of rainy conditions and possible flooding, the National Weather Service warned it could happen again.
One more storm can turn “washed-in” pollution into a visible disaster—dead fish included—especially when drought has left the river slow and vulnerable.
Atlanta flash flooding Chattahoochee Riverkeeper fish die-off stormwater runoff Peachtree Creek combined sewer overflow West Area Tunnel drought Lake Lanier boil water advisory Atlanta Connector shutdown Waymo vehicles