Last month was the wettest December on record for the Thurmond sub-basin, or the streams and tributaries that flow into the reservoir, said Army Corps of Engineers spokeswoman Tracy Robillard.
The lake had risen to 333.3 feet above sea level on Tuesday, about 7.3 feet above the normal water level for this time of year. The full summer pool is 330 feet. On Dec. 22 and 23, 3.2 inches of rain were measured in the sub-basin. Another 2.3 inches fell Saturday and Sunday, creating a total 8.5 inches for the month.
“December has been a really wet month for Thurmond,” Robillard said. “A lot of it fell in these single rain events.”
Water run-off continued to fill the lake early this week. Thurmond, in addition to upstream lakes Hartwell and Russell, were in flood storage capacity, enabling large volumes of water to be retained and released safely into the lower Savannah River.
“Our plan is to increase outflows at Thurmond Dam so we can pass some of that excess water,” Robillard said, adding that the water will pass through the dam’s turbines to generate hydropower.
Releases were increased to 20,000 cubic feet per second on Tuesday, and on Wednesday, were scheduled to increase another 5,000 cubic feet per second for the remainder of the week. Park rangers and volunteers were continually assessing flooding at recreation areas and flagging off areas. Robillard said impacts downstream will be negligible.
After Thurmond Lake approaches normal pool levels, the Corps plans to increase water releases at Hartwell and Russell dams.