ATLANTA — Scientists knew the recent flooding that enveloped parts of Georgia were rare but a new analysis is showing just how unusual the heavy rains were.

The U.S. Geological Survey released its analysis of the September floods on Wednesday.

They gathered data in part by reviewing high-water-mark surveys and indirect peak discharge computations throughout the flood-affected region.

USGS National Flood Program Coordinator Robert Holmes said the annual chance of flooding in some of the affected areas was so minuscule that the geological survey couldn't accurately calculate the probability.

He said the Atlanta flooding is near the top of the worst floods in the United States during the past 100 years and it's a testament to officials and emergency workers that more lives weren't lost.