In northwestern La., giant lake bed smolders

In northwestern La., giant lake bed smolders

30 October 2010

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USA —  A blaze touched off by a trash fire has been smoldering for two months — with occasional flareups — in the bed of a twisting, narrow lake drawn down as part of northwestern Louisiana’s fight against an invasive water fern.

It started during the Labor Day weekend and spread for miles along the edge of long, narrow Lake Bistineau. But it also burrowed under the lake bed, erupting in new spots days or weeks after crews put out what they could see.

“There’s still hot spots where it’s burning the ground at the middle,” Deputy Chief Ryan Foster of the South Bossier Fire District said Thursday. And rains have been few and light.

The only way to put out the fire for good is to refill the lake, said Sandy Davis, head of the Caddo-Bossier Parish Office of Emergency Preparedness. But he said that would take a lot of rain — even in Oklahoma, Arkansas and Texas.

Ron Stone, who lives on the lake, said he learned about the fire when a neighbor called him.

“He said, ‘You might want to get your dogs in. The lake is on fire.’ I ran out there and sure enough, it was burning. Really coming on strong,” Stone said.

Lake Bistineau is about 14 miles long. It usually covers 17,500 acres, but Davis said about half the bed was exposed when drought followed a planned release of lake water. Grasses grew high — Stone estimates 5 feet to 6 feet tall — on a lake bed rich with eons of silt and plant debris. Then drought turned the grass to a brown straw mat.

Fire raced across it.

Stone said he and his neighbor jumped onto their tractors and dug firebreaks 10 feet to 12 feet wide.

“We widened them further, because the fire jumped that,” he said.

It burned the aboveground knees and the wide, shallow roots of healthy baldcypress trees. They toppled, spreading the fire another way. In other trees, some green but hollow and others dead, it rose into torches 20, 30, 40 feet high.

“There wasn’t enough water in the world to put it out,” Stone said. “Control it, is the main thing.”

Four parishes border the lake. Crews from Bossier, Webster, Bienville and Red River parishes and state forestry crews dug firebreaks and poured water to keep the fire inside the dry lake.

The lake bed is made up of layered silt and vegetation, built up over thousands of years, Davis said.

“You can walk across it and drive a four-wheeler across it and think it’s solid dirt. But when it gets to burning, it may be burning two feet deep,” Davis said. “You’ll have a 10-foot circle that’s burning on the surface, and 200 yards away, from under the lakebed, comes up another spot.”

Foster said the hot spots now are near the water rather than the edge, with firelines along the shoreline and on both sides of the fire. But no one can go out there because some trees have burned roots that make them unstable.

Conditions for the fire were created by the fight against a rootless fern imported from South America to decorate aquariums and outdoor ponds. A half-dozen or more varieties of salvinia have spread across the South from Virginia to California. Infestations often start from aquarium water dumped into a storm drain, but they can spread from one waterway to an unconnected one hundreds of miles away by a few leaves carried on a boat.

Giant salvinia covered nearly half of Lake Bistineau last year. It creates mats extending anywhere from several inches to several feet under water. Tiny hairs covering each leaf make them resistant to herbicides.

The Department of Wildlife and Fisheries has tried to control it by “pulsing” the water level — opening Lake Bistineau’s spillway and letting out water to strand and dry out the floating plant. This hasn’t worked because the mats get caught on some of the hundreds of thousands of cypress trees dotting the lake, said LDWF biologist Mark McElroy, who is in charge of the campaign against salvinia there.

The department wants to get rid of some of the trees that are dead or hollow, McElroy said, so officials exposed 4,000 to 5,000 acres of the lake bed to map that area and better decide which trees to fell.

They began letting out water Sept. 16, 2009, but heavy rains filled the lake faster than water flowed out. Finally, in May, it reached the desired 7-foot level.

“A winter of all winters” killed most of the salvinia, which now covers about 500 acres rather than 7,000. “Now we’re trying to bring the lake up and we’ve got a drought,” McElroy said.

About 1,200 acres of the lake bed burned in three fires, he said Friday, with 1,000 of that in a single blaze.

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