Rain has slowed the fall rate of the drawdown of Lake Bistineau, but officials say the drawdown has done its job by killing thousands of acres of giant salvinia.
Biologist Supervisor of Inland Fisheries Jeff Sibley, District 1 of the Louisiana Department of Wildlife and Fisheries, said although the fall rate has slowed, the drawdown, along with continuous herbicide spraying, has knocked the invasive aquatic weed back to 793 acres as of July 14.
“With the kind of rain we’re getting right now, it’s not enough to fill it back up, but the plants will start growing again,” he said. “This is prime growing season for salvinia. Our control efforts are much more effective, because instead of fighting it over 17,000 acres, we’ve got it contained in the 9,000 to 10,000 acres that remain.”
The lake’s fall rate has been much slower this year compared to a typical drawdown this time of year, he said. The lake is now 6
and a half feet below pool stage, and the lake needs to drop about 1 and a half feet more.
“A lot of the places the salvinia is now will dry up once we get that extra foot,” he said.
Lake Bistineau, at full pool stage is about 17,000 acres. When the gates at the dam were opened, salvinia covered about 3,742 acres, he said.
The gates were opened a few months earlier than normal due to the large amount of salvinia covering the lake at that time. Sibley said the gates will close on Nov. 30.
October and November are usually when the rainy season begins again, and in late November, Louisiana usually sees its first cold snap, he said.
To date, LDWF has contracted herbicide spraying in conjunction with weevils that survived the last two milder winters. Lake residents were recently given an opportunity to introduce those weevils into the lake at their homes and camps. They are still studying the effects of the weevils at this time.