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.
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.
Jennifer Flowers, executive director of the Lake Lanier Association, said areas near the tributaries of Lake Lanier, including the Chestatee and Chattahoochee rivers, have seen extra debris and trash along the shoreline.
“As much rain as we received, it’s going to be bringing in tons of natural debris as well as trash. You can see it on top of the lake, working its way down the lake,” she said. “Eventually, that woody debris will settle out and go to the bottom of the lake and not be too big of an issue.”
Flowers said people should be extra careful when going out on the lake after heavy rains.
“There’s going to be a lot of logs and other debris right below the surface of the lake that a lot of times you can’t see,” she said. “... It’s really easy for boats to run over them and not see them first, so people need to be extremely careful and cautious. I would also suggest, don’t get in the water for at least probably 72 hours it clears up a little bit on that turbidity we’re seeing.”
The effects of the weekend rain were made worse by the rain the area had already seen in the days before, Caldwell 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.