ONALASKA — Water lettuce doesn’t exactly sound like a menace, but it was enough of a threat to Lake Onalaska that several dozen volunteers mobilized Sunday to remove the plants by hand.
And, thanks to the emergency effort and work that has continued through the week, the threat from the aggressive invasive species was drastically reduced.
“I think Lake Onalaska just dodged a very big bullet,” said Fritz Funk, who helped organize Sunday’s collection effort. “This story may have a happy ending, and that is extremely unusual for invasive species.”
Shawn Giblin, a water quality specialist for the Wisconsin Department of Natural Resources, said he found some remnants of the infestation during an inspection of Lake Onalaska on Tuesday, including some plants at the south end of the lake. But he was very impressed with the mobilization and cleanup effort Sunday.
“That was incredible to see that many people come out to protect the lake,” Giblin said. “I think it’s pretty well cleaned up there now. … The big wild card in this is if it overwinters.”
Water lettuce is a native of South America and has been popular for use in aquariums and decorative backyard ponds. It is, however, illegal in Wisconsin and Minnesota, according to Kendra Niemec, deputy district manager for the La Crosse District of the Upper Mississippi River National Wildlife and Fish Refuge.
Niemec described water lettuce as pale green rosettes, pretty easy to spot on the lake. “It’s pretty distinct from the other things we have out there,” she said.
Someone reported finding the plant on the north end of the lake Wednesday, and by Friday night Funk was putting the word out, trying to recruit volunteers to harvest the free-floating lettuce plants on Sunday. The infestation seemed to be confined to 3.5-mile stretch of shoreline, mostly between the barrier islands and the north shore of the lake. The biggest concentration north of the Fred Funk Boat Landing between “the tubes” and the landing.
On Sunday, Funk and Niemec were hoping to collect all the water lettuce plants on the eastern portion of the infestation, where strong winds expected Monday could have driven them into the open waters of Lake Onalaska. From there they could have spread into other bodies of water, including the Black and Mississippi rivers.
In addition to property owners who got out and collected water lettuce in front of their homes, Sunday morning saw more than two dozen volunteers show up at the boat landing, many bringing their own watercraft, including everything from kayaks and canoes to pontoons. Many of the volunteers worked until 3 p.m.
By the time they were done, an apparently complete cleanup of the infestation had been accomplished all along the north shore, or at least as complete as possible.
“I would say it’s probably impossible to get every last scrap,” Niemec said. “I was really impressed that people were so diligent. … Without them we wouldn’t have been able to get what we got.”
Water lettuce infestations have been a real problem in the southern region of the country, said Niemec, who formerly lived in Florida, where it got bad enough to clog canals and impede navigation.
The winter weather this far north will kill most of the plants, but Niemec said some plants from a water lettuce infestation in Buffalo County in 2011 survived the winter. They’ve since been eradicated.
The source of the water lettuce is believed to be a backyard pond near “the tubes.” An investigation is underway, and the person responsible could face charges.
Funk urged people to be on the lookout for water lettuce that might have escaped the dragnet or that might have come from other sources.
Tim Miller, district manager for the La Crosse District of the Upper Mississippi River National Wildlife and Fish Refuge, said close monitoring of the lake will be required to make sure water lettuce doesn’t take hold.
“If there’s a leaf that has a little bit of the vegetative root on it, they can spread from that,” Miller said. “I think our effort Sunday really helped. The other part that’ll help is a good freeze.”
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