The three reservoirs on the Savannah River operated by the U.S. Army Corps of Engineers have entered the first drought trigger level.
The Corp’s Savannah office made the announcement Monday.
On Saturday, the lake level at Thurmond Lake dipped below 326 feet above mean sea level.
With extremely low rainfall amounts and most of North Georgia now in an extreme drought status, the Corps has gone to the Drought Trigger Level 1 Status much earlier than normal..
Under the existing drought plan, the Corps limits outflow from Thurmond Dam to 4,200 cubic feet per second (cfs), averaged over the week.
Drought Trigger Level 1 is defined as below 656 ft-msl for Hartwell and 326 ft-msl for Thurmond.
The pool elevation on July 25 was 325.79 ft-msl at Thurmond Lake, prompting the Drought Trigger Level 1 status, according to Corps spokesman Billy Birdwell.
“That automatically sets off the trigger for the entire basin. When either Hartwell or Thurmond drop below their trigger level 1 level then it throws the entire basin into drought condition one, and they stay that way until both Hartwell and Thurmond come two feet above the trigger level.” Birdwell said.
Birdwell said reducing outflow conserves more water in the reservoirs but decreases the amount of hydropower generated through the dams.
“We have been using the pump back capabilities at Russell Dam for several weeks almost to the maximum and that way we generate power during the heat of the day when the demand is highest. and then at night when demand is low we purchase electricity off the commercial grid to pump the water back out of Thurmond lake back into Russell to be used again the next day.” said Birdwell.
Additionally, the 28-day average flow of the Broad River which flows into Thurmond Lake is 11 percent of normal.
On Monday, water managers began to reduce to 4,200 cfs averaged over 24 hours today.
Birdwell said they expect the Broad River to drop below 10 percent of normal flow later this week.
“The Broad River is a large river that flows into Thurmond lake and it is uncontrolled. There are no dams or anything on it so we watch the flow on that. That flow would equal the natural flow of the basin and if it goes below 10% which we anticipate it will in the next two days then that triggers a different call so that we reduce our outflows from Thurmond Dam just a little bit further down to 4,000 cubic feet per second.” said Birdwell.
And the low lake levels now mean increased hazards for people boating or swimming in any of the three reservoir lakes.
Birdwell advises everyone using the lakes to be careful.
“We urge people, boaters and skiers particularly to be careful when the reservoir is going to drought conditions because the rocks and stumps that were left over from when the reservoirs were created are much closer to the surface now then they were before. So we want people to be extremely careful and always, always, always wear that life jacket when they’re in, on or near the water.” said Birdwell.
Birdwell said swimmers should not venture outside designated swimming areas, Dock owners may need to move their docks to remain in adequately deep water.