Just below the water’s surface on Contoocook Lake wafts a piece of pond weed, tall and thin, with bushy leaves.
It is not supposed to be there.
Mike Golibersuch, president of the Contoocook Lake Area Preservation Association, or CLAPA, was making a round on his boat last summer, near the head of where the Contoocook River enters Contoocook Lake, an area he calls “milfoil heaven.” It’s an ironic name for one of the areas of the lake that was most plagued by the invasive variable milfoil that has been a major issue for not only Contoocook, but other New Hampshire lakes, ponds and rivers for decades.
“It’s a very aggressive plant and it will dominate all other plant life, and mess up the ecology of your lake,” said Golibersuch. “And it’s also just a nuisance. Nobody wants to swim in an area with milfoil. Boats are going to get clogged up in it, fishing is difficult. It interferes with the recreation use of the lake, and because it’s so dominant, if you don’t treat it, it will basically take over the whole lake.”
CLAPA was formed in 1969 to fight the milfoil that had been discovered in the lake, and that’s still one of its duties today. On a yearly basis, the association hires divers to yank out the milfoil by hand, but every few years, they take a more aggressive approach with chemical treatment.
Indeed, in June of last year, that was what Golibersuch was doing out on the lake — monitoring the chemical treatment of milfoil with an herbicide, Presellacor EC, a chemical that kills invasive milfoil without harming the native plants in the water.
Rocco Notaro, an aquatic specialist with Solitude Lake Management, treated about 30 acres of the 350-acre lake that had been identified as infested with milfoil. He used a boom off the back of his boat to deposit the chemical in the water subsurface, where the milfoil absorbed it. He said the treatment can see a significant reduction of the plant — between three-quarters to full reduction in treated areas — which will last for three to five years. The last time Contoocook chemically treated the lake using the same herbicide was about seven years ago, said Golibersuch.
The cost for about 30 acres of treatment is $27,000, half of which is paid for through CLAPA dues and fundraising, and the other half through a New Hampshire Department of Environmental Services grant, which helps combat invasives.
“It’s a never-ending fight,” said Golibersuch. “Dealing with the problem, for us, goes back over 50 years.”
Treating water with herbicide does come with temporary water use restrictions, though those range from hours to days after the treatment. Swimming is not recommended within six hours following treatment, within 200 feet of the treated areas. The water should not be used for residential or non-agricultural irrigation, such as landscape plants or gardens, golf courses, or irrigation around business or industrial properties for seven days, for any intakes within 200 feet of the treatment area, and all wells within 50 feet of the shoreline within 200 feet of treatment areas.
For Michael Romanow, the president of the Lake Monomonac Property Owners Association, it’s a fight he also knows well. He said the Rindge side of the lake is about four years out from its last treatment with Presellacor EC.
“That’s been wonderful for us,” said Romanow, who added that the treatment eliminated large swaths of milfoil, about 30 acres worth, although patches remain that they treat annually with divers removing plants, and continued surveillance to see where the plants crop back up.
“We’ve been very pleased with those results,” said Romanow. He said the treatments have been “a success story that requires maintenance,” because once milfoil is in a lake, it is not ever going to be eliminated.
A persistent problem
Amy Smagula, the chief aquatic biologist in the Watershed Management Bureau of the New Hampshire Department of Environmental Services, said when it comes to invasive plants, unfortunately, full eradication is elusive.
“At this point in time, 100% eradication isn’t really possible,” said Smagula, speaking of variable milfoil. “Our mantra is early detection, rapid response.” That’s because milfoil is a plant that can regrow from small pieces. If a piece breaks off or is chopped up by a boat propeller, it can float to another part of the lake, take root, and grow a whole new patch. And it’s a fast-growing plant.
“The problem with invasives is that they’re not well-behaved,” said Smagula. “Milfoil can grow an inch a day in the summer, and it grows between 10 and 15 feet tall, creating a canopy over other natives. It looks like a cornfield. It can affect oxygen levels and predator-prey interactions. Nothing is going to eat it or otherwise control it.”
Invasion of milfoil is a real economic threat to lakefront property owners, as well as to the recreational landscape that attracts visitors each year.
A 2003 University of New Hampshire study showed that variable milfoil infestations could affect lakefront property values by as much as 20% to 40% compared to similar properties on lakes without infestations. A Washington study on properties on lakes impacted by invasive Eurasian milfoil showed a 19% decline in mean property values, or about $94,385 lower prices in comparable homes between properties on shorefronts without milfoil and those with a known infestation.
A prevalent problem
Smagula said variable milfoil is the top invasive concern for New Hampshire lakes.
Out of New Hampshire’s more than 1,000 lakes, about 8% have some sort of invasive species, Smagula said. Of those impacted by an invasive species, about 90% are dealing with variable milfoil — meaning about 11 river systems and 88 lakes and ponds have identified a variable milfoil infestation.
“It’s the leading invasive in the state,” she said.
Variable milfoil has been around in New Hampshire since the 1960s, and Smagula said it’s unknown for sure how it got into state waters. The two main ways that invasive plants and animals enter new waterways are by being attached to boats or by people dumping their aquariums into lakes or ponds.
Smagula said that New Hampshire has native species of milfoil, and the variable milfoil that has become such a problem is actually native to the Midwestern United States. In fact, in Ohio, it is considered a threatened plant. But New Hampshire’s acidic waters cause it to thrive and outgrow its native competitors.
Keeping milfoil out of NH waters
Pool Pond in Rindge doesn’t have any variable milfoil in its waters.
David DelGuidice, president of the Pool Pond Protection Association, said they want to keep it that way — and they’re active in their efforts.
Pool Pond has adopted a Lake Host program, a statewide effort to prevent not only milfoil, but also other invasive plants and animals, from transferring from lake to lake. This is done by posting a Lake Host at the boat launch, to offer, voluntarily, to inspect boats going into or coming out of the water, to check for invasive plant life, snails, or mollusks that may have gotten attached to the hull or caught in a propeller.
Pool Pond has a paid Lake Host position, with the host paid for about six hours a week, on Friday night and Saturday morning, peak hours for boating, to offer boat inspections. The positions are paid in part by a grant from New Hampshire Lakes, matched by the Pool Pond Association with other volunteer hours, either by other hours of Lake Hosts, or training of their volunteers.
“If someone comes from Contoocook, Pearly or Monomonac, it could spread here really fast,” said DelGuidice, speaking of variable milfoil. “I’m actually surprised that we don’t have it yet.”
In part, DelGuidice said, it’s as much about spreading awareness as it is about catching the plant before it enters the water. Especially, he said, since it’s often the same people returning to the lake week-to-week and year-to-year.
Since 2002, Lake Hosts have inspected nearly 1.5 million boats and prevented more than 1,500 invasive species from entering or leaving lakes in the state, according to New Hampshire Lakes.
Romanow said Monomonac also relies on a Lake Host program to help educate boaters, and keep the lake’s milfoil from being transported to other waterways, with a host on call on Friday, Saturday and Sunday.
Boaters can help prevent the spread of invasive plants by taking a few steps before entering or after leaving the water: inspect all equipment, remove aquatic plants and organisms, drain and flush live wells and bait buckets, and check the hitch, trailer tongue, rollers, wet well, cavitation plate and propeller.
It is illegal to transport and introduce exotic aquatic plants into New Hampshire water bodies.
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