SALVINIA: The Battle Continues

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While this looks like a golf course with a boat sitting in the middle of it, it’s not. This is Black Lake as seen from the Hwy 9 bridge Thursday, April 6. La. Dept. of Wildlife and Fisheries contractor crews were spraying vegetation control, part of over 7,000 acres treated since this photo was taken.

By Juanice Gray

Salvinia on area lakes. Is it a problem that will ever go away?

La. Dept. of Wildlife and Fisheries are taking drastic measures to hold back the spread of the detrimental salvinia. In April, spraying began along areas of Black and Clear Lakes. To date, more than 7,000 acres total were sprayed said LDWF biologist Villis Dowden. “In areas of high density, like the Hwy 9 bridge area, we went over those again,” he said. “It is finally beginning to thin out.”

In addition to spraying, a drawdown has the lake at approximately 4 feet below pool stage. “We are taking it down as far as Red River will let us,” said LDWF Biologist Director Ricky Moses. “The river levels cause back pressure and will keep it up.”

This angle shows the salvinia at the boat launch by the Hwy 9 bridge. In the foreground the plants are turning brown and the drawdown is evident by the water level. In the background bollards are being used to contain the salvinia and clear the channel.

The drawdown gives biologists the opportunity to visually access the salvinia. “We are watching to see when it is not free floating. When it turns brown and sinks is when it is classified as dead and gone,” Dowden said.

There are some areas where salvinia eating weevils were placed and they are monitoring those sites as well. “The real test is seeing if they survive the winter and create larvae in the spring. The larvae actually drill the holes in the salvinia making the plant less buoyant,” Dowden said. “It (salvinia) can’t survive or thrive when it can’t go through the photosynthesis process.”

Many areas that were treated are beginning to thin out and turn brown. That is a good sign according to both biologists.

At a recent Northwest La. Game and Fish Preserve Commission meeting, Dowden said the LDWF is also not ruling out aerial spraying. Moses said the issue with that is not spraying cypress trees. “We need 300-400 acres of space without trees to make it cost effective for the helicopter to spray. It doesn’t have to be all together, it can be 100 acres here and 100 acres there. We can jump around a little bit,” Moses said. The costs to hire the helicopter for the day, plus herbicide must be offset by the area sprayed.

Follow up contractor spraying from boats is also on the table.

The lakes will be drawn down until Dec. 1. During this time LDWF reminds boaters and fishermen and women to use caution. “There are a lot of stumps and other debris that can do damage once you are out of the boat lanes,” Dowden said. “The lake is open and accessible, but use caution.” Launches at Westwind, Chandlers and Black Lake Lodge are open. Dowden said fishing is good on the lake right now and reminds everyone the bag limits are still in effect.

“We’ve treated the lake more this year than we ever have,” Dowden said.

Hopefully their efforts will lead to less salvinia in the Sportsman’s Paradise.

This photo shows approximately the same view from the Hwy 9 bridge Aug. 10. Considerable progress has been made. Black Lake is drawn down to 4 feet below pool stage to further assist the efforts to get the salvinia under control.
Photos by Juanice Gray
The yellow things are bollards. They float and contain the salvinia to a certain area.