Entergy to draw down lakes ahead of Barry
Entergy Arkansas said Thursday that it will slightly lower lakes Hamilton and Catherine beginning Sunday morning in anticipation of potentially heavy rainfall from Tropical Storm Barry.
Normal summertime target levels are 399.7 feet above mean sea level on Lake Hamilton and 304.25 feet msl on Lake Catherine, “so we are essentially lowering Lake Hamilton 3.6 inches and Lake Catherine just under 8 inches,” Kimberly Bogart, Entergy Arkansas’ lakes and property coordinator, said Thursday.
Lake Hamilton will be lowered to a level of 399.4 feet msl and Lake Catherine to a level of 303.6 feet msl. An email newsletter sent out Thursday by the utility said the drawdowns will begin at 12:01 a.m. Sunday and will take around eight to 10 hours to complete.
The newsletter said Entergy has also decided to cancel the recreational floating release scheduled for Sunday below Remmel Dam. “We will close the gate at 10 p.m. on Saturday and reopen upon safe river conditions,” it said.
Bogart noted that, even with the drawdown, both lakes will remain in their normal summertime “operating bands” of 398.9 to 399.9 feet msl on Lake Hamilton and 303 to 305 feet msl on Lake Catherine.
While the lakes are considered
to have constant levels, Bogart said there is normally a 1-foot fluctuation on Lake Hamilton and a 2-foot fluctuation on Lake Catherine. These are what Entergy calls their “bands” or “operating bands” — the levels at which the lakes operate, she said.
“Individuals on the lakes and dock owners should in general not notice a significant change as the lakes can and will fluctuate within their bands throughout the summer,” Bogart said.
Unlike Lake Ouachita, which is formed by Blakely Mountain Dam and managed by the U.S. Army Corps of Engineers, Entergy cannot hold back additional water with Remmel Dam, which forms Lake Catherine above the Ouachita River, and Carpenter Dam, which forms Lake Hamilton above Lake Catherine.
“But, the drawdowns allow us to create a small time buffer to absorb some of the anticipated rainfall as we work to pass the inflow we receive during a heavy rain event through the dams via generation and gate openings,” Bogart said.
“It allows us time to gradually increase downstream flows from the dam while maintaining the lakes within their respective bands. During an event, we will monitor steam levels in our watershed and lake levels to balance water inflow with outflow. When it is predicted that all significant rainfall has left our watershed area we will generally return the lakes back to their normal summertime pool levels unless we expect additional rainfall in the near future. In that case, we might return them to the drawdown levels to prep for the additional rain,” she said.
Bogart said Entergy anticipates the rain to begin in this area Sunday morning. The amount of rainfall will “greatly be influenced by the track of the storm. While every storm contains rain, the majority will fall on the eastern side of it,” she said.
As of noon Thursday, the National Weather Service was predicting that, over the next five days, the area will receive between 2 and 5 inches of rain — “again, we are expecting that to fall not over the next five days but between Sunday and Tuesday. If the track of the storm was to go further to the west we could be looking in excess of that,” she said.
The recreational floating releases from Remmel are normally around 3,600 to 4,000 cubic feet per second of water between noon and 5 p.m. every Saturday and Sunday from Memorial Day to Labor Day. If possible, such as in wet years like this one, Entergy will release for longer hours, for example, a 10 a.m. start or additional days throughout the week whenever water is available to do so, Bogart said.
That flow rate normally provides a three- to four-hour float from just below Remmel Dam to the Whitewater Park in Malvern.
“Due to the predicted rainfall we are expecting a need to increase flows beyond recreational levels on Sunday so we are not going to be able to open the vehicular gate to the put-in location below Remmel Dam that day,” she said.
“But, those that want to try the float out can do so on Saturday prior to the rain or after the rain has passed through our area and we are able to return to normal flow rates to maintain the lake levels.”