In late September 2009 , the worst flooding ever occurred on the creek , after days of heavy rain . New records were set , and many roads were left underwater by it , including Interstate 20 , which was closed west of I-285 for nearly three days . The USGS stated that it was greater than a 500-year flood ( it does not try to make any greater estimates ) . The National Weather Service said the chances of having more than of rain in a 24-hour period were less than 0.01 % per year , making it a 10,000-year event
worst flooding ever
2009 Southeastern United States floods
Sweetwater Creek (Chattahoochee River tributary)