Weird water weed could move into lakes
Written by Detroit Free Press   
Sunday, 25 February 2007 03:46

Using the language of cancer, studded with words like "early detection" and "aggressive growth," environmental officials in Michigan are gearing up to battle hydrilla, a dreaded water weed that could show up soon in state lakes.

Michigan already is home to more than 140 invasive species, but this one is especially fearsome.

"Hydrilla is our No. 1 concern this year," said Roger Eberhardt of the Department of Environmental Quality's Great Lakes Office.

Hydrilla hasn't reached the state border yet, but last fall it was found just 55 miles south, in an Indiana lake -- the first time it has been found in the Midwest.

The name itself sounds sinister and dangerous, like a lurking water monster. Experts say the description fits.


• Hydrilla is an aggressive, fast-growing weed that needs little light to grow, can reproduce in four ways (including from tubers that can lie dormant up to four years on lake beds), and it spreads like a blanket on lakes, choking out fish and plant life below.

• It tangles boat motors and clogs water intake pipes.

• It can't be hurt by deep freeze winters.

• It can raise water temperatures and create stagnant water that breeds mosquitoes.

• It grows best in shallow areas with soft bottoms, but has been found at depths of up to 45 feet and can grow in free-floating bunches near the surface.

About the only good thing anyone can say about hydrilla is that ducks and geese find it scrumptious.

State officials fear that hydrilla infestation of the Great Lakes or some of the state's 11,000 inland lakes is inevitable. The weed often spreads as a hitchhiker on boats or trailers that were in an infected lake.

"Obviously, it's going to be here soon," said Howard Wandell, who works on lake and stream issues at the Department of Fisheries and Wildlife at Michigan State University. "It's not if, but when."

Catching it early

Wandell said that the weed already might be growing in a Michigan lake.

Boaters and anglers need to be the "extra eyes and ears" to let researchers know if they find it, said Carol Swinehart, communications manager for the Michigan Sea Grant program, which does research on invasive species.

In April, Wandell will train some lake association members on how to spot hydrilla.

"Early detection is crucial," Eberhardt said. Still, using weed killer to control hydrilla is expensive and the state doesn't have the money, he said. "It's a critical issue."

Eberhardt said the worst scenario is hydrilla in the Great Lakes with shallow connecting waters like Lake St. Clair especially vulnerable.

"That would be very difficult to stop," he said.

Indiana officials were surprised to find hydrilla in 734-acre Lake Manitou in Rochester. The lake has an average depth of about 14 feet.

"It took a large leap to get here," said Doug Keller, aquatic invasive species coordinator for Indiana's Department of Natural Resources. Pennsylvania and Tennessee are the next nearest states with hydrilla, he said.

Keller said the hydrilla, which looks similar to a native weed named elodea, had been growing for two or three years when it was discovered and likely hitchhiked to Indiana on a boat that had been infected elsewhere. It already has formed a dense mat in some areas of the lake.

In effect, the lake has been quarantined. Popular bass fishing tournaments have ended. Only boats that were already on the lake can use it.

Keller said it will cost about $2 million over four years to treat the lake with herbicides. And there's no guarantee they'll work.

"It's worse than Eurasian milfoil," another recent invader, he said.

Weed problems aren't new to Michigan lakes. In 2002, officials treated Houghton Lake, near Roscommon, the state's largest inland lake, after Eurasian milfoil had all but claimed the lake. Most residents and anglers were happy with the outcome.

As in public health, education and boat hygiene -- the careful cleaning of boats, trailers and fishing equipment -- are crucial in fighting hydrilla and other water pests like zebra mussels, experts say.

Hydrilla first invaded the United States in the 1950s, when an aquarium plant buyer dumped some into a Florida canal. According to the Washington state Department of Ecology Web site, it is native to Africa, Australia and parts of Asia. Despite spending $150 million to control it since 1982, hydrilla is found in 40% of Florida's waters.

California eradicated it from its largest lake, Clear Lake, but it took nearly 10 years.

Michigan intends to act quickly, if it can find the money, to keep hydrilla from spreading, Wandell said.

"If it ends up being as problematic as we think it will be, we might have to close lakes and a lot of money will have to be spent," he said.

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