CASCO, Maine — Sebago Lake, which provides drinking water to Maine’s largest city as well as recreation to boaters and swimmers, is on the front lines of the state’s war against an aquatic invader.
One type of milfoil already has a foothold and it’s feared a more aggressive variety, Eurasian milfoil, could take root.
Environmental officials have plenty of cause for worry because fast-growing milfoil can easily overwhelm lakes and ponds. Some fear the unsightly plants can reduce shorefront property values and hurt Maine’s $8 billion tourism industry.
Maine, Wyoming and Montana are the only places in the continental United States that have avoided infestation of the dreaded Eurasian milfoil so far.
But with credible evidence of variable milfoil in 10 bodies of water in central and southern Maine and a boat on Crystal Lake found with Eurasian milfoil fragments hanging from its exhaust cover, the threat of infestation is all too real.
“We have every reason to expect it is coming,” said Martha Kirkpatrick, commissioner of the Maine Department of Environmental Protection.
Variable milfoil and Eurasian milfoil take root on the lake’s floor and grow upward, forming mats on the surface that can be dense enough for birds to walk on water.
Prevention appears to be the best defense since both varieties can be resistant to efforts to control them.
Toward that end, the state has launched a public information campaign: Toll collectors warn motorists entering the state with boats. Warning signs are posted at border crossings. TV ads remind boaters to be vigilant.
Gov. Angus King signed a law requiring stickers on all motor boats using inland waters. The fees — $10 for Maine boats and $20 for out-of-state registrations — will help pay for the fight against invasive plants. The sticker program begins Jan. 1.
This summer, the Portland Water District, several state agencies and the Volunteer Lakes Monitoring Program tackled variable milfoil with PVC-coated screens.
The so-called benthic barriers, which block sunlight to variable milfoil, were to be installed around the state park boat launch to create a 100-foot milfoil-free passageway to the main channel. But a diver discovered that the infestation was more extensive that first thought, and now other options are being considered, said Roberta Hill, education coordinator for the water district.
Some options include creating a longer weed-free channel with benthic barriers, employing an inspector to check for plant fragments left on boats and equipment, and moving the boat launch if the area is too infested to manage.
The worst-case scenario Hill hopes to avoid is mechanical harvesting, a labor intensive and costly solution used in some states with the worst infestations. Barges outfitted with a cutter similar to those used to harvest hay may clear areas for boating and swimming, but ultimately can make the infestation worse by spreading plant fragments, Hill said.
New Hampshire abandoned mechanical harvesting in the 1970s.
“During the ’60s we used harvesting but found it was like getting a haircut: it would come back up again,” said Jody Connor, a biologist with the New Hampshire Department of Environmental Services.
Much of New Hampshire’s funds now goes to chemical herbicides, a method shunned on Sebago because it is the source of drinking water for 170,000 people, or about 15 percent of the Vermont population.
In Wisconsin, the Lake Pewaukee Sanitary District, west of Milwaukee, gave up on chemical treatments because they killed native species along with milfoil. Instead, the district regularly harvests milfoil on about 300 of the lake’s nearly 2,500 acres during the summer months.
“We’re harvesting every day, 40 hours a week at a minimum,” said Charlie Shong, the district’s superintendent. Last year, the district harvested about 102 dump truck loads of milfoil, Shong said.
Other techniques used to manage milfoil include introducing fish or aquatic insects that can curb the plant’s growth.
Weevils, aquatic insects whose larvae eat the leaf tissue and burrow into stems, are used in Michigan, Vermont, Wisconsin, Illinois and New York. Minnesota has had some success but the insects are sometimes devoured by fish before they can do their job, state biologist Wendy Crowell said.
The prospect of such serious infestations in Maine feeds the fear in officials and sports fishermen alike.
David Garcia, owner of Naples Bait and Tackle, has fished through thick milfoil in New York’s Catskills. He had to create openings in the milfoil with a long-handled rake to get his line into the water.
“It would be like trying to get a comb through your hair if you had bubble gum in it,” he said.
The Eurasian milfoil was found in July when a boat with plant fragments was launched into Crystal Lake in Gray. It will be a year or two before biologists can determine whether the plant has established itself.
On the Net:
Maine Volunteer Lake Monitoring Program: http://www.mainevolunteerlakemonitors.org
Maine Department Environmental Protection’s invasive plants: http://www.state.me.us/dep/blwq/topic/invasive.htm
End Adv for Sunday, Oct. 14, and thereafter