The rising Savannah River is being fueled by factors that include additional rains on top of soil already saturated from one of the wettest Junes on record.
The U.S. Geologic Survey, which has a gauge near Augusta, said Monday’s flow was 26,500 cubic feet per second and rising. The median flow for that segment of the river is 6,510 cubic feet per second, with much lower flows observed in recent years.
“What you’re seeing now is not a record by any means, but it is very high in terms of the normal experience,” said research scientist Shawn Rosenquist of the Southeastern Natural Sciences Academy, which monitors river flow and water quality in the Savannah.
Residents may not notice an increase in elevation of the river in the downtown Augusta area because the pool is held steady at about 114 feet above sea level by the New Savannah Bluff Dam near Augusta Regional Airport.
“You will see higher flows that increase velocity, but not necessarily elevation,” he said.
Below New Savannah Bluff, however, the river’s elevation rises and falls as the water spreads across a broad floodplain swamp that extends toward the coast.
On Monday, the elevation below the dam had risen from about 101 feet above sea level on July 1 to more than 113 feet above sea level on Monday – almost at the same level maintained above the dam.
Much of the water that is pushing river levels higher is entering the river below Thurmond Dam.
The Army Corps of Engineers is releasing about 14,000 cubic feet per second from the dam into the river, said corps spokesman Billy Birdwell. That figure is just over half the volume measured at the Butler Creek gauge below Augusta on Monday.
Thurmond Lake, with a normal full pool of 330 feet above sea level, was at 331.94 on Monday, well above its full stage.
The last time the reservoir held that much water was Nov. 15, 2009, when the level was measured at 332.33, Birdwell said.
The current releases are higher than usual, but by no means unprecedented, he said.
In February of 2010, releases from the dam were averaging between 24,000 and 28,000 cubic feet per second, he said.
Heavy storms that moved through the area late Sunday and early Monday dumped varying amounts of precipitation, said Pam Tucker, director of Columbia County’s Emergency and Operations Division.
About 1.9 inches fell overnight at the Evans Government Center, with 2 inches at Little River and just 0.80 inches at the Clarks Hill Water Treatment Plant near Pollard’s Corner, she said.
Since the beginning of the month, however, some totals have been impressive.
“My rainfall readings in Rivershyre (subdivision) since last Sunday total 8.96 inches - an amount that we don’t see in a month or even two months most times, and some areas measured more than that,” she said.