BRIDGTON – An invasive milfoil, discovered in the Songo River in 2003, is in the process of being removed by employees of the Lakes Environmental Association, some of whom have helped combat the infestation for the last eight summers.

A majority of the variable leaf milfoil has been successfully weeded out, said Peter Lowell, longtime executive director of Bridgton-based group, on Thursday, Aug. 15, as he and his crew trolled the river in a pontoon boat.

Around 30 percent of the milfoil extracted from the river that runs from Brandy Pond in Naples to Sebago Lake may return the next year and the plant is never fully eradicated, Lowell said. According to Lowell, this is just one reason his group hasn’t stopped combing the infested waters since the discovery 10 years ago.

Variable leaf milfoil is one of two non-native milfoils that threaten Maine’s fresh waters and is the same plant that has taken over the Songo River. Eurasian milfoil also threatens Maine waters. If left to fester, milfoil will eventually choke off the oxygen supply in a water body, harming fish and causing algae blooms.

Lowell and his team of milfoil eradicators have dedicated 32 hours per week since 2007 in an effort to remove milfoil located from Songo Lock to the upper parts of the river, and the shoreline of Brandy Pond, where the plant was discovered in 2004.

“We also regularly check the southern area of Long Lake, though we haven’t found any plants there,” said Adam Perron, LEA’s project coordinator and education director, while on the job last Thursday.

There is still a lot of routine maintenance that must be done in order to prevent the milfoil from spreading too “robustly,” and to identify any new outbreaks, Perron said.

This year, however, Perron said the density of milfoil in the Songo has decreased significantly thanks to the group’s efforts.

Milfoil toil

Lakes Environmental Association members use what is called a diver-assisted, surface-supplied air system – or in their words, an “aquatic vacuum” – to remove the milfoil from below the water’s surface.

Nearly 60, 20-by-30 foot benthic barriers, or tarps, some made of plastic, others made of burlap, were unrolled onto the patches of milfoil on the river’s bottom this summer to “starve it of sunlight,” Perron explained. The barriers prevent the milfoil from continuing to grow or to get transported by boaters from one area to another.

The group originally used only the benthic barriers for milfoil control, but realized that with downed trees, some infested areas were difficult to cover and other areas too steep.

“It’s labor intensive and not selective at all. You end up killing everything under the tarp. The idea of the suction harvester [surface-supplied air system] is that we wanted to leave some native plants behind in places where there was milfoil,” Perron said.

Christian Oren, 22, who has been working for LEA since 2008, said that the suction harvester, while it can be physically exhausting to maneuver, is an effective way to remove milfoil. And, it’s been quite the learning process, he said.

“We have to manually pull out each plant,” Oren said. “[It helps us] make a decision what plants to take. It can be really exact, so we aren’t pulling up any natives [plants] or anything else we don’t want to pull up.”

After being extracted from the bottom of the river, Oren said, the milfoil gets fed into a hose, discharged into a sluiceway and diverted into chutes connected to mesh onion bags. From there, the milfoil gets taken to shore and is eventually composted, he explained.

Songo River is

“representative’

Last summer, Perron said, the group was successful with milfoil removal at the Sebago Lake State Park boat launch and the lower part of the Songo, one of the busiest waterways in Maine.

The reason for such perseverance rides mainly on the fact that LEA “wants [the Songo] to be representative of what recreation in Maine can be,” Perron said.

Though the milfoil’s fine and fragile characteristics make removal difficult since even a small piece can re-root easily, LEA has made tremendous progress on the project and is ahead of schedule, he explained. “The goals we set this year for the project were achieved in July,” he said, and the group has a couple more months to go before the removal season ends.

According to Lowell, the group set a goal last year to eradicate 1,000 yards of milfoil per year, and has far exceeded that projection this summer.

In 2010, inspectors found boats in the Songo Lock carrying milfoil fragments. Aiming to limit the spread of the invasive plant, the LEA requested the state close the lock. The process, however, Lowell said, involved several state agencies, which proved complicated and time-consuming. He also ran into fierce opposition from marina owners and boaters reluctant to close the popular river.

As a result, the lock remained open, and the Maine Department of Environmental Protection decided to increase boat inspections. It also marked the lower Songo with colorful navigational buoys and bright orange signs to urge boaters to avoid passing through milfoil infested areas.

The group is still searching for milfoil in the backwaters of the Songo, including oxbows, Perron said. People who fish in these areas will soon be able to do so without the fear of spreading it to a non-affected area, he said.

Funding for the removal effort, according to Perron, was made possible almost entirely through a single anonymous donation, as well as a grant from Ram Island Conservation Fund through the Maine Community Foundation.

According to Lowell, just this summer, LEA will spend nearly $60,000 on materials and labor. Labor makes up two-thirds of the cost.

“We consider this work, and the work we do in our schools, a service to the community,” Perron said.

“That’s where public education is important,” he continued. “To make sure people are aware of milfoil, that they understand the risk of boating in an infested body [of water] and to teach them how to mitigate that risk.”

Adam Perron, above, project coordinator for Lakes Environmental Association, explains the group’s eight-year effort to remove invasive milfoil from the Songo River. Employees of the Lakes Environmental Association in Bridgton, at right, gear up to dive in Songo River last week to continue their efforts to remove an invasive variable leaf milfoil that was discovered in the river in 2003.Employees of the Lakes Environmental Association in Bridgton gear up to dive in Songo River last week to continue their efforts to remove an invasive variable leaf milfoil that was discovered in the river in 2003.Lakes Environmental Association employee Tyler Oren, who has been helping with milfoil removal since 2009, shows a fragment of the plant.Invasive variable leaf milfoil plants are visible from the surface of the upper Songo River.