Attack Of The Killer Weeds

carousel, Elise Manbert, who has continued to work at a UCLA campus coffee shop five months after graduation. CBS

Kenneth Hausmann reached elbow-deep into the mucky water behind his Lake Austin home, closed his fist and wrenched out a stringy, dripping mass of green and brown weeds.

Hydrilla. It's steadily encroaching on Lake Austin, annoying property owners, boaters and swimmers.

"It grows so thick you would swear you could walk across it," Hausmann said. "Plus, it stinks in the summertime when it gets real hot. It's just rotting vegetation."

Only three years after hydrilla was first spotted in a stretch of the Colorado River lined with expensive riverfront homes, the fast-growing weed covers one-fourth of Lake Austin, by some estimates, and is prompting a battle over what to do about it.

The most controversial step comes in February, when officials plan to dump 1,600 sterile Asian grass carp into the lake. They could eventually put 6,000 carp in the lake, an idea that has enraged bass fishermen.

Hydrilla grows in huge clumps along the shore, and a mat of green algae spreads along the top when it breaches the surface.

It's ugly and smelly, and residents of Lake Austin want it gone. The weed clogs boat engines and creates congestion on the waterways. Swimmers warn that it could be dangerous.

Hausmann's wife, Debbie, said the weed scratches her children when they swim, and she fears for their safety ever since a man drowned in the lake in 2001 - his family said he got caught in the hydrilla.

Bass fisherman, however, say hydrilla is a boon for anglers and improves water quality by filtering river sediment. They warn that measures to kill the weed could do more harm than good.

Hydrilla gets its name from Greek mythology. The Hydra was a nine-headed serpent slain by Hercules. When any one of its heads was cut off, it was replaced by two others.

In 1999, hydrilla covered 23 acres of Lake Austin, a 1,600-acre body of water between the Mansfield and Tom Miller dams and the source of Austin's drinking water. A private study recently estimated the hydrilla's current reach at more than 400 acres.

The plant was partly blamed for July flooding along the river because it slowed the water flow after heavy rains.

Officials grew alarmed when hydrilla clogged a filtered cooling system for the hydroelectric generators at Tom Miller Dam. It cost about $300,000 to stop the generators and clean the filtering system.

State and local officials developed plans to beat back the weed.

In October, the Texas Parks and Wildlife Department introduced Hydrilla Leaf Mining Flies, tiny gnat-like bugs that kill the upper 12 inches or so of the weed. The Lower Colorado River Authority this month lowered the lake by 12 feet to expose the plant to kill off leaves and stems.

Officials also plan to use federally approved herbicide and hydrilla-mowing boats. Because hydrilla can grow from cut strands, boaters who throw the plant back into the water can be fined up to $2,000.

But the carp dumping plan has run up against stiff opposition.

Mike Hastings, an Austin-area fishing guide and director of the Pro Team Tournament Trail circuit, said the carp grow into 70-pound eating machines that won't stop with hydrilla.

"Fishermen will support the idea of managing the hydrilla," Hastings said. "We're strongly opposed to eradication of vegetation of the lake."

Hydrilla is good for anglers because it makes a "fantastic fish habitat" with good cover, Hastings said, and a steady food supply of insects and small fish.

He worries the carp will migrate elsewhere and attack vegetation downstream.

"Carp are simply not a management tool," Hastings said. "You can't control them, they're very long-lived, and you can't control what plant species they eat. It's just like a cow grazing in a field."

State officials at first rejected using carp. Bill Provine, chief of research and management with inland fisheries for the Texas Parks and Wildlife Department, called the fish a "fairly radical" solution.

But, Provine said, anglers must understand dangers posed to swimmers and property owners by hydrilla.

"We've gotten to the point where the problem is a little bigger than how it's going to affect fishing," he said. "Fishing is not going to be held in the same light as health and property."

Carp were used to battle hydrilla from Lake Conroe in 1981, a plan that resulted in major problems. More than 200,000 fish were dumped in and ate every plant in sight until there was nothing left. Carp were dumped, along with a powerful herbicide, into Lake McQueeny in 1996, but that success was the result of a more controlled release.

State officials hope the carp will be just enough to control the Lake Austin hydrilla without wiping it out. That way, they would keep munching on hydrilla instead of feasting on other plants, Provine said.

Officials were also cheered by the results of a controlled release of 24 fish. Most stayed in the area, even after the July floods, despite fear that some would be washed downstream.

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