Entergy returns to 3-foot drawdowns
The annual wintertime drawdown of lakes Hamilton and Catherine will be 3 feet this season, beginning Nov. 1, according to Entergy Arkansas Inc.
Entergy and the Arkansas Game and Fish Commission recently completed their annual vegetation survey of the lakes, according to a post the utility made on its Facebook page earlier this week.
The survey monitors vegetation growth and helps determines the depth of the winter drawdown for both lakes Hamilton and Catherine.
The depth of the drawdown varies each winter, in part, to curb the growth of nuisance vegetation. A vegetation management plan developed in conjunction with the Arkansas Game and Fish Commission usually calls for alternating 3-foot and 5-foot drawdowns.
Due to the above-normal temperatures of the last couple winters, “we deviated and did back-to-back 5-foot drawdowns. This year, there has been no noticeable increase in undesired aquatic vegetation, so we are returning to the 3-foot drawdown,” the post said.
The drawdown was 3 feet in 2014-15 and 5 feet in 2015-16. Entergy said in August 2016 that even though its annual vegetation inspection with the AGFC showed less vegetation present on the lakes, a 5-foot drawdown was warranted on Hamilton and Catherine for the winter of
2016-2017, given the previous season’s mild winter and wintertime projects planned for the lakes.
This winter’s drawdown will begin on Nov. 1 at a rate of around
6 inches per day. On Nov. 6, the target elevation for Lake Hamilton will be 396.7 feet above mean sea level, with a daily fluctuation range between 397.20 feet msl and 396.20 feet msl.
Lake Catherine’s target will be 301 feet msl, with a daily fluctuation range between 300 and 302 feet msl.
Varying the depth of the drawdowns keeps certain plant species from getting accustomed to a constant lake level.
Other factors include water clarity, since reduced visibility can decrease the amount of sunlight that can reach the bottom of the lake’s shallow areas, and the severity of the winter, Entergy says.