The epic flood of September 2009 deluged the city of Atlanta’s R.M. Clayton sewage treatment plant on the Chattahoochee with up to 15 feet of water.

In a pile of old papers, I found my father’s rain charts from the 1960s and ‘70s: meticulously-recorded measurements from the rain gauge in our backyard. The numbers tell the weather story of those decades; it was very wet in Atlanta (70-plus inches in one year) and throughout the Southeast.

But the rains of my childhood were steady, soaking events that rarely resulted in topped riverbanks or massive damage. There were not the deluges, with extensive flooding, that we’re now experiencing thanks to a changing climate and watersheds hardened with roads, rooftops and parking lots.

Kent Frantz also remembers those rainy years and the water that was “always around him,” growing up in Louisville, Kentucky. These early experiences led him to the Navy where he trained in aerography (the production of weather charts) and then to a 40-year career with the National Weather Service (NWS) as a senior hydrologist.

 Atlanta’s Epic Storm

I recently visited Kent at the NWS Forecast Office in Peachtree City to talk about El Nino (expected to continue bringing abnormally heavy rains this winter) and to learn about the flood inundation maps that his team developed with the Corps of Engineers and U.S. Geological Survey.

After Hurricane Floyd’s devastation of the East Coast in 1999, the NWS created the Advanced Hydrologic Prediction Service to help emergency managers plan for weather-induced disasters with new mapping tools to predict the location and extent of flooding events.

Ten years after Floyd, the Atlanta region experienced a catastrophic flood in September of 2009, the result of multiple days of prolonged (El Nino-induced) rainfall that fell faster than local watersheds could handle. Property damage exceeded $300 million, 20,000 homes and buildings were harmed and 10 people lost their lives.

At the city’s largest sewage plant – built in a vulnerable, low-lying area along the Chattahoochee in the 1930s – the earthen berm between the river and the facility was topped when the river crested at more than 28 feet. For weeks, the R.M. Clayton plant was submerged under up to 15 feet of water and raw sewage poured into Atlanta’s drinking water source.

Sewage Plant Could Flood Again

In the years following the 2009 flood, the city repaired and upgraded the Clayton plant. Kent and his colleagues completed flood inundation maps to predict future impacts in four developed watersheds in the Atlanta region.

But the berm – the barrier to keep the river out of the plant – was not raised as recommended by federal emergency managers, even after they offered to pay 75 percent of the $772,000 total project cost, according to local news reports. The city’s share would be less than $200,000 to safeguard the sewage plant and the Chattahoochee River.

Last fall, WSB-TV’s Katie Walls asked a city representative, on camera, why action had not been taken to fix the serious problem. The response: “That is a question that we’ve got to leave to the legal experts.” (The city is engaged in litigation with its insurance company over the settlement for the disaster that occurred six years ago).

The weather of the 1960s is not likely to return any time soon, if ever again. Heavier downpours and flooding, already observed, will become increasingly common, according to weather and climate experts.

We can use state-of-the art forecasting tools to prepare for the future by raising berms and keeping development out of low-lying areas. Or we can let lawyers handle the weather and manage our risks.

I know which solution I prefer.

         To view the Flood Inundation Maps, see weather.gov/atlanta and click on Rivers/Lakes (National Weather Service) or ga.water.usgs.gov/fim/ (USGS).

Sally Bethea

Sally Bethea is the retired executive director of Chattahoochee Riverkeeper and an environmental and sustainability advocate. Her award-winning Above the Waterline column appears monthly in Atlanta Intown.