Local non-profits stepped up the fight this year against variable milfoil, an invasive aquatic plant that poses a threat to lakes throughout Maine, by employing new methods to kill off infestations of the plant. As their efforts wind down this fall and coming winter, the organizations look ahead to new strategies such as “suction harvesting” to combat milfoil.

This past August, the Little Sebago Lake Association began removing milfoil from coves in Windham and Gray by sucking the plant out the water with their own self-designed “suction harvester.”

“This by far is the best method we’ve come across,” said Scott Lowell, president of the lake association. “It’s not the fastest, but it’s the most efficient.”

Like hand removal, “suction harvesting” requires underwater divers to loosen the plants so they can be sucked up a hose, like a vacuum cleaner, and onto the pontoon boat where a sophisticated “sluice” filters the milfoil into bags for disposal.

The “suction harvester,” a pontoon boat outfitted by the lakes association, has already turned out to be a “great success,” said Scott, having helped to remove more than 100 fifty-pound bags of milfoil from the lake in the short time it has been in operation.

And this success has recently drawn the attention of a Bridgton conservation group. Last Sunday, Sept. 25, Peter Lowell, director of Lakes Environmental Association, visited Little Sebago Lake to study the “suction” operations in hopes of building their own “suction harvester” to combat milfoil infestations in the Songo River.

“It’s pretty cool,” Peter Lowell said of the Little Sebago suction harvester. “There are some aspects of the design that need to be tweaked, but I think it works nicely.”

This year, as part of their Songo Project 2005, the Lakes Environmental Association, with the help of a Libra Grant, placed “bottom barriers,” or tarps, to cover and suffocate milfoil infestations on the Songo River.

“It’s very dense where it exists,” Lowell said. “It seems to be either dense or non-existent. One side you’ll have a big infestation and other side there will be nothing.”

One of the biggest fears, Lowell said, is that boaters passing through the Songo Locks will get the plant caught on their anchors and carry it into the lakes.

Two weeks ago, scientist Ken Wagner of ENSR International toured the Songo River and recommended that Lakes Environmental try lowering the water level this winter to kill the milfoil.

While milfoil on the lower Songo does not pose much of a threat to deep Sebago Lake, the upper infestation does pose a serious threat to shallow parts of Brandy Pond and Long Lake, said Wagner.

Lakes in other states have been ruined by the non-native plant, Wagner said, because it spreads aggressively and can choke off native plant and fish populations.

“If we knew then what we know now (about milfoil), we would have nuked the stuff when it started,” Wagner said.

Last year, Lakes Environmental hand-removed a small patch of milfoil discovered by the Naples Causeway and said they have found no plants there since.

A recent “sweep” of the river revealed a few plants close to the mouth of Brandy Pond, Peter Lowell said, which were removed by divers.

Lowell said there is a good chance that if the river level can be lowered a few more feet this winter, exposure to cold temperatures might kill off much of the infestation.

“If you can get the river bottom exposed to the elements, you get a pretty complete die-off of the root system and the plant,” Peter said.

Regardless of whether or not this technique works, Lakes Environmental plans to work with the Little Sebago Lake Assocation to build their own suction harvester for the Songo Project.

As for the lake association, Scott Lowell said they plan to “fine tune” the suction appartus over the winter and possibly have another professional survey done of the lake to assess the milfoil extent.