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After weekend rains and runoff this is what's in Lake Lanier
lanier sediment
Debris floats in Lake Lanier near Thompson Bridge following the remnants of Hurricane Delta dumping at least 3-4 inches of rain overnight Oct. 10-11, 2020. Photo courtesy Dale Caldwell with Chattahoochee Riverkeeper.

Heavy rains the weekend of Oct. 10-11 have filled Lake Lanier with sediment, runoff and debris, which can make boating conditions dangerous and have adverse environmental effects, according to Chattahoochee Riverkeeper. 

According to the National Weather Service, Gainesville got about 4.78 inches of rain late Saturday and early Sunday as the remnants of Hurricane Delta moved over the region. The lake stood at 1,074.01 as of 1:15 p.m. Oct. 12, according to the U.S. Geological Survey.

Dale Caldwell, headwaters director for Chattahoochee Riverkeeper, said the weekend storms brought more debris to the Thompson Bridge area than he has ever seen with previous severe weather. The area near Thompson Bridge on Ga. 60 is the meeting point of Wahoo Creek and Little River, so that spot is often severely impacted by heavy rains. 

“With that type of intensity and volume (of rain), you also see severe erosion, so a lot of sediment and just pollutants you would see in most events as far as trash, anything on the landscape as far as bacteria or oils,” Caldwell said.  

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Caldwell said the debris in the lake could be a hazard for boaters or someone on a personal watercraft and people should be cautious on the water. The effects of the weekend rain were made worse by the rain the area had already seen in the days before, he said.  

“Our soils act as a sponge, and that sponge was already saturated before the event,” he said. “There’s nowhere for that water to go, except run off into the creeks and rivers, and Lake Lanier afterward.” 

Runoff also builds up when there is less open soil to absorb the rains, Caldwell said.  

“You don’t need record rain events to see record flooding these days because of development pressure,” he said. “The more impervious surface we have on the landscape, as far as asphalt, concrete, buildings, that are built on top of our soils, which is our sponge, you’re going to see more record flooding events.” 

The rains also overwhelmed Gainesville Water Resources infrastructure. An estimate of more than 2 million gallons of raw sewage overflowed into Flat Creek after a pump failure at the Flat Creek Water Reclamation Facility during the weekend’s heavy rains, according to the city department. 

Several roads also remained closed following washouts caused by the rain.

lanier runoff
Lake Lanier's level is high near Thompson Bridge following the remnants of Hurricane Delta dumping at least 3-4 inches of rain overnight Oct. 10-11, 2020, and runoff bringing sediment and debris into the lake. Photo courtesy Dale Caldwell with Chattahoochee Riverkeeper.