Heavy rains and polluted runoff after months of drought turned parts of the Chattahoochee River near Atlanta into a public health risk, with U.S. Geological Survey monitoring showing E. coli levels far above safe thresholds.
Floodwater didn’t just blanket Atlanta roads—it carried contaminants toward the Chattahoochee River. By the weekend, officials had discovered thousands of dead fish stretching as far as 20 miles south of the city. Now, new U.S. Geological Survey monitoring is pointing to a second. more immediate danger for people who might otherwise head to the river for Memorial Day weekend tubing and boating.
Three testing locations along the Chattahoochee River north of Atlanta—monitored within the Chattahoochee River National Recreation Area—show E. coli levels that spiked to unsafe ranges after days of rain and substantial flooding in the city. Memorial Day weekend typically kicks off “shoot the Hooch” season. when Georgians grab their tubes. canoes. and kayaks and use the river for summer recreation. The U.S. Geological Survey says visitors should stay out of the water until further notice.
The rain that triggered the problem began about a week earlier. with some parts of Atlanta seeing as much as 7 inches of precipitation over the course of a week beginning on May 20. The storm brought road flooding and runoff that flowed into Peachtree Creek. From there, the creek feeds the Chattahoochee River, which runs through the northwestern quadrant of Atlanta.
U.S. Geological Survey tests define “healthy” E. coli as a value lower than 235, based on E. coli colony counts per 100 mL of water. As of May 21—shortly after the most significant day of rain in Atlanta—results at three sites were well above that threshold. The Medlock Bridge testing location, in Johns Creek, recorded an E. coli level of 490. The Powers Ferry testing location, in Sandy Springs, came back at 560. And at the Paces Ferry testing location, in Vinings, the river registered an E. coli level of 1100—nearly five times the safe limit.
The Chattahoochee River National Recreation Area draws nearly 3 million visitors each year, and the agency estimates that 30% of those visitors spend time in the water. In a period that usually marks peak public use, the agency is warning that current conditions are unsafe for people or pets.
E. coli can be harmless—or dangerous—depending on the strain. Mayo Clinic guidance notes that many E. coli strains are harmless, but others can make humans and animals extremely sick. Infections often cause symptoms associated with food poisoning. and people can catch illness from tainted water. tainted food. or through personal contact. If contaminated water is ingested—such as when swimming leads to swallowing small amounts—high levels of specific E. coli can cause diarrhea and other gastrointestinal symptoms. For some people the symptoms may be significant but not life threatening; for others—such as elderly people. children. or those with pre-existing conditions—the infection can become more serious. with kidney failure reported in some cases.
Dead fish were a warning sign, but the die-off likely wasn’t the result of E. coli alone. The Chattahoochee Riverkeeper described the fish kill and river conditions as “unprecedented” in a May 23 statement. saying three environmental factors came together to create “the perfect storm” for die-off conditions.
First, months of drought in Georgia left the river flowing at a very low level. That level is determined by the U.S. Army Corps of Engineers, which can adjust flow through dams. While reservoirs such as Lake Lanier—north of Atlanta—can be used to release water to increase river flow. reservoir levels north of the city were also low due to lack of rain. With water moving slowly, fish can be exposed to pollutants or other harmful materials for longer periods.
Second, stormwater entering Peachtree Creek from the city carried high levels of pollutants. Chattahoochee Riverkeeper said that after stormwater hit pavement on a warm day. the stormwater’s temperatures would have been higher than the creek’s typical temperature. The group also said that. due to a lack of rain. the stormwater flows transported a high load of additional pollutants and nutrient pollution into Peachtree Creek and then into the Chattahoochee River.
Third, a likely sewer system overflow followed the rapid rainfall. Chattahoochee Riverkeeper said Atlanta’s combined sewer system and the West Area Tunnel overflowed into Peachtree Creek, leading to emergency discharges of untreated water and polluted stormwater directly into the river.
The sequence is difficult to ignore: low river flow created a slower-moving environment. stormwater brought heavier-than-usual pollutant loads. and an overflow likely released untreated material during the same period. With that combination, the fish kill and the later E. coli readings appear to point to the same underlying disruption—contaminants moving from urban runoff and wastewater systems into a river people visit every summer.
For now, officials are urging restraint. Visitors to the Chattahoochee River National Recreation Area should stay out of the water until further notice as monitoring continues and officials assess whether E. coli levels drop after the flooding subsides.
Chattahoochee River E. coli Atlanta floods Peachtree Creek USGS fish die-off Johns Creek Sandy Springs Vinings public health