Hydrilla Fight Goes on at Lake *** Five-Year Project Aims at Making Area Navigable

By RICHARD BURGESS

HENDERSON – St. Martin Parish officials hope a five-year regimen of lowering Lake Henderson will rein in an invasive weed that has taken over the popular waterway.

Hydrilla, a foreign plant that appeared in the Atchafalaya Basin lake in the 1990s, sometimes becomes so thick that it chokes out aquatic life and makes boating nearly impossible.

Henderson Mayor Sherbin Collette, a commercial fisherman, estimates that the invasive weed now covers about 80 percent of the 5,000-acre lake.

“Now is the growing time,” he said. “It’s actually closing in some of the canals.”

Locals have wrangled with hydrilla for years at Lake Henderson, which has one of the worst infestations in Louisiana.

The state has spent about $1 million on herbicide, and the lake was practically drained six years ago in an effort to kill the weed – a near catastrophe for the boat landings, bait shops and swamp tour businesses in the area.

The weed has been dealt a few blows over the years, but it keeps coming back as strong as before.

The five-year plan was hatched last year.

It calls for lowering the lake 2 feet to 3 feet below normal levels, then applying herbicide.

The hope is that the sun will dry out the plants that are exposed when the lake is lowered and the herbicide can be targeted in the water that remains.

St. Martin Parish President Guy Cormier said the plan is a compromise to try to control the weed while keeping water levels high enough for boat traffic.

Boat landings, bait shops and tour boat operators that depend on the lake might suffer a bit, but Cormier said he sees no option.

“You do nothing, and hydrilla takes over the lake,” he said. ” We will remove water off the flats, which you can’t get to anyway because of the hydrilla.”

The first lowering under the plan last year resulted in no great reduction of hydrilla, but Cormier said no one expected to see positive effects until at least the third year.

“The first year after a drawdown, the hydrilla does come back strong,” said Charles Dugas, who oversees aquatic plant control for the state Department of Wildlife and Fisheries.

Dugas said an initial drying out of hydrilla can trigger dormant tubers to emerge with vigor, but continued exposure combined with herbicide spraying should be effective in controlling the weed.

He cautions that Lake Henderson will be fighting hydrilla off and on for years to come because the plant has firmly settled in.

“We can never completely eradicate it,” Collette said. ” We just want to get it at the point where we can live with it.”

No one is certain how hydrilla found its way into Lake Henderson, but the plant is believed to have begun spreading after its importation into the United States for use as an ornamental plant in ponds and aquariums.

Dugas said that Wildlife and Fisheries and the state Department of Natural Resources have about $200,000 to $250,000 for herbicide application at Lake Henderson this year.

Parish government must receive approval from the U.S. Army Corps of Engineers to lower the lake.

Public comment on the permit ends next month.

Written comments on the permit application must reference St. Martin Parish government as the permit applicant and include the permit application number, MVN-2006-2221-WII.

Mail comments to:

Attention: Regulatory Branch, Department of the Army, New Orleans District Corps of Engineers, P.O. Box 60267, New Orleans, LA 70160- 0267.

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