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Salvinia still a problem

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Courtesy photos The port of Lake Bistineau launch shows that the giant salvinia on the water is still a problem.

Lake Bistineau trying to solve aquatic weed issue

Amanda Crane

acrane@bossierpress.com

 

A familiar green site still plagues the water at Lake Bistineau.

The giant salvinia level has reached an astounding 1,550 acres of the lake, located near Minden and extending southward to Bossier Parish near Elm Grove.

The Louisiana Department of Wildlife and Fisheries has scheduled a controlled drawdown next month that will shrink the 17,000 acre lake down to about 8,000 acres with hopes of ridding the waters of the invasive aquatic fern that is prohibiting residents from using its waters for recreational purposes and choking the economy surrounding the lake’s tourism.

Evan Thames, District Fisheries Biologist Manager, said the amount of salvinia is higher this year already due to the mild 2012 winter.

“Cold weather kills it,” Thames said. “It’s growing so fast that we’re utilizing different ways to keep up with it.”

Giant salvinia, an aggressive species native of South America, is a small free-floating fern that grows in clusters and develops into dense, floating mats or colonies. Because of its rapid growth abilities, giant salvinia has become one of the most problematic aquatic plants in southern states.

According to the U.S. National Park Service website, giant salvinia can deplete oxygen in the water if it covers the surface, cutting off light to other aquatic plants and reducing the oxygen content for fish and other aquatic organisms.

The invasive aquatic fern was discovered on Lake Bistineau in February of 2006. Along with the drawdown, Thames said LDWF continues to spray the plant with herbicide and will begin adding weevils, a small, black insect that feed on the growing tips of the salvinia (suppressing further growth) to the fight.

The water control structure on Lake Bistineau is scheduled to open on July 15, 2013. However,the LDWF says an immediate opening would be necessary if salvinia coverage reaches 2,500 acres prior to that date. The LDWF has set a dewatering rate of four to six inches of water per day, which will take Lake Bistineau to the maximum drawdown level of seven feet below normal pool stage.

Following an initial drying period of 60 days, the control gates will be operated for minor water fluctuation to strand additional salvinia plants. LDWF says the control gates will close no later than November 30, 2013 to allow the lake to refill.

“The drawdown works,” Thames added. “When the water dries up, the plant dries out and dies.”

Boaters will still have access to the lake from the Port of Bistineau Launch (East side Webster Parish); Bossier Public Launch (West side of the lake); Grice’s (Southeast side of lake at the dam); and Bayou Dorcheat Public Launch (North side of lake on main bayou Dorcheat in Webster parish- HWY 164). The LDWF advises that boaters should be cautious during the low water period as boat lanes will not provide normal clearance of underwater obstructions.

For more information on the scheduled drawdown, contact Evan Thames with the Department of Wildlife and Fisheries at (318) 371-5216.