MONMOUTH — On a recent weekday morning, Cliff Cabral was several feet below the surface of Annabessacook Lake, wearing scuba gear and guiding yellowish-green plants into a hose that sucked them out of the depths.

Those plants, variable leaf water milfoil, are an invasive plant species that was first detected in Annabessacook Lake three years ago, and Cabral was vanquishing them with great efficiency.

“I have to say, it’s my favorite patch of the season,” he said, after coming to the surface for a break. “It was all milfoil, no other plants. … We might kill 5,000 gallons this week.”

Cabral owns a business, New England Milfoil, that was recently contracted to remove the nonnative species from Annabessacook Lake. Once he guided the plants into the hose, they were pumped into a storage area on the side of his boat. Two other employees were on the boat, guiding the milfoil fronds into large plastic bins.

From time to time, Ryan Burton, a technician with the Cobbossee Watershed District, used his own boat to ferry the fronds to dry land so they could eventually be incinerated.

The fact that they removed so much milfoil last week was, from a lake protection perspective, both promising and ominous: promising because all those invasive plants were no longer in the lake, but ominous because the invasion is more serious than lake watchers first realized and could take a couple more years to eradicate.

More serious than first thought

Since the milfoil infestation was discovered on Annabessacook Lake in 2014, this was the first year that state officials haven’t removed the plant themselves and have instead delegated the work to local groups.

When the infestation was discovered, the three employees of the state’s invasive aquatic plants team initially viewed it as a rapid response that they could perform themselves, said John McPhedran, the team’s leader.

But this year, the state provided about $38,000 in grant funds to Friends of the Cobbossee Watershed for milfoil removal and boat inspections in Annabessacook Lake and other infested waters, Whitmore said.

State officials made that decision because the infestation was more serious than originally thought and they trusted local water groups with the task.

“We responded rapidly because we thought the infestation was incipient and thought we could eradicate or knock it back to a level that required minimal annual effort,” McPhedran said. “But after two seasons removing, we realized it was better established or more extensive than we previous thought. The plants were more established. That’s why we had to switch to the management mode. We don’t have the resources to do annual management on all the infestations around the state.”

Variable leaf water milfoil can spread when just a small fragment reaches a new area. Once it starts growing, it can crowd out other plants species, reduce water quality and impair recreational activities like boating and swimming, according to the Maine Department of Environmental Protection.

Also, some studies have suggested a relationship between milfoil infestation and reduced lakeside property values, McPhedran said.

Variable leaf water milfoil is found around New England and has been reported in 19 water systems in Maine, according to state data.

Besides Annabessacook Lake — which straddles 1,420 acres in Winthrop and Monmouth — milfoil has become even more established in nearby Cobbossee Stream and Pleasant Pond.

With assistance from the state, several area groups have been trying to remove the current infestations, as well as monitor for new ones, prevent milfoil from spreading to other waters and train volunteers who can help. Those groups include the Cobbossee Watershed District, Friends of the Cobbossee Watershed and the Annabessacook Lake Improvement Association.

Local response

In Cobbossee Stream and Pleasant Pond, Friends of the Cobbossee Watershed uses its own boat to remove milfoil every summer. Known as a DASH boat, for “diver-assisted suction hose,” it pumps the invasive plants out of the water much like the vessel New England Milfoil was using on Annabessacook Lake last week.

But local groups view the Annabessacook Lake infestation as a “high priority” because it’s relatively new and they think they’ll be able to clear it in the next couple years, Whitmore said. They also want to prevent milfoil from spreading downstream to Cobbossee Lake and have planted yellow buoys that mark infested areas.

Friends of the Cobbossee Watershed paid about $5,000 to New England Milfoil for its work on Annabessacook Lake last week, Whitmore said.

Its divers focused their removal efforts on the area around the Waugan Road boat launch, hugging the north side of the channel that leads out to the lake. In that channel, the milfoil grew alongside green wild grasses, purple pickerel weeds and bulbous yellow cow lilies.

The workers hoped to remove between 3,000 and 5,000 gallons of milfoil, which would be taken away in large bins to an incinerating operation in West Gardiner.

“The tricky thing about Annabessacook is that this invasive plant is located in the channel area where boats are motoring out to get to the lake,” Whitmore said. “They’re chopping it up, so each fragment could make a whole new plant and become more widespread. … It’s going to take a couple years, but we’re going to keep hitting it hard like this.”

Though the infestations are unfortunate, Whitmore said, one silver lining of the local and statewide efforts has been increased awareness about the need to prevent the spread of invasive species, by carefully removing vegetation from boats and fishing gear and avoiding areas that have been infested.

In 2017, the state provided about $450,000 in grant funds to groups across the state doing similar work, McPhedran said. The state’s invasive aquatic plants program, including those grants, is funded with proceeds from boat registration fees.

While some infestations have come on rapidly and refused to go away, the state has also seen some success stories, McPhedran said. In Belgrade, for example, a different type of milfoil, Eurasian water milfoil, took root in Salmon Lake a number of years ago. But by 2012, there were no more signs of it.

“We responded rapidly, and we have not seen Eurasion water milfoil return after our response,” McPhedran said. “The effectiveness and success of programs varies depending on the infestation and the water quality.”

Charles Eichacker — 621-5642

[email protected]

Twitter: @ceichacker