Authorities say recent rains have sent bacteria levels soaring in the Chattahoochee River.
Sally Bethea of the Chattahoochee Riverkeeper Organization advises people not to touch the water. She said that E. coli is a major concern.
The river had 76 colonies of bacteria per 100 milliliters of water before the rains came Thursday night. As of early Tuesday morning, that number has shot up to 1,145 just north of Atlanta.
The U.S. Environmental Protection Agency says any mark above 235 is unhealthy.
Experts say the bacteria level increases when rain saturates the ground, rolls off the surface and ends up in the river. They say dry weather and sunshine should cause the levels to return to normal.