Lake Manitou has a new and worrisome problem: Hydrilla verticillata.
The Indiana Department of Natural Resources has issued an alert about the invasive water plant, which has the potential of choking out other aquatic plants.
Lake Manitou is the only lake in the Midwest where hydrilla is known to exist, said Doug Keller, the state's aquatic invasive species coordinator. He's alarmed and working quickly to develop a plan to stop the invasion of the rapidly-spreading weed, he said.
"We're actually rushing to develop some management plans to address the plant," Keller said. "It is kind of troubling that we found it this late in the season because we are wondering how long it's been out there."
Hydrilla, classified as a federal noxious aquatic weed, is most commonly found in southern states.
Keller said it was tentatively identified here two weeks ago during a routine plant survey by DNR biologists.
"They found this plant that looked a little bit different," he said "Luckily, it caught their eye."
Samples were sent to the University of Florida and Mississippi State University for positive identification, which was provided a couple days ago.
The weed has been located "mainly along the north shore, kind of beginning around the city boat ramp, then wrapping around the north shore to the east," he said. It's also spread from the boat ramp to the south and around Coney Island, east of The Dam Landing.
"That's not to say that's the only places it's found," Keller cautioned. "We're not sure how extensive it is in other parts of the lake."
Lake Manitou boaters are asked to avoid weedy areas because fragments of hydrilla and another common invasive species in the lake, Eurasian watermilfoil, can float to another part of the lake and take root.
To prevent spread of the weed to other bodies of water, boaters also should watch for hitchhiking plants and dispose of them in the trash before leaving the launch area after a day on the lake, officials say.
Keller said DNR biologists will be out in the lake soon to find the extent of the hydrilla's range.
The state is looking at a variety of funding sources to pay for ridding the lake of hydrilla. "We're certainly not anywhere close to announcing any plans yet," he said.
The weed likely was carried into Lake Manitou one of two ways.
"It could have gotten here from boats being trailered from other infested areas in other states," Keller said.
The other possible method of invasion was through water garden or pond plants being chucked into the lake when someone was doing yard work, he said. "When we talked with the university people, they asked if water lilies were planted in Manitou recently. One supplier had hydrilla tubers contaminating those pots."
Orv Huffman, Lake Manitou Association's lake manager, learned Friday about the hydrilla invasion. He called the association's environmental consulting firm, J.F. New, and the DNR.
The DNR is posting signs at both boat ramps, he said, and providing flyers for the windshields of vehicles at the ramps to inform people about the danger of spreading the weed.
It also will provide Huffman with a hydrilla brochure, which he will e-mail to everyone on the association's electronic mailing list.
An invasive weed is troubling, Huffman said. The association, with grants from the DNR, has worked for two years to rid the lake of Eurasian watermilfoil, another invasive plant and has reduced the population by 80 percent.
According to the University of Florida, Hydrilla verticillata, could easily be called the perfect aquatic plant because of how easily, and extensively, it adapts to the aquatic habitat. Such characteristics allow hydrilla to be an aggressive and competitive colonizer of aquatic habitats.
Hydrilla grows submersed in water and generally is rooted to the bottom, although sometimes fragments will break loose and survive in a free-floating state. Erect stems can be quite long when the plant grows in deep water. Branching is usually sparse until the plant grows to near the water surface, where it becomes profuse.
"Where the plant occurs, it causes substantial economic hardships, interferes with various water uses, displaces native aquatic plant communities, and adversely impacts freshwater habitats," the University of Florida says.
