It’s Hand-to-Hand Combat In Fight Against Milfoil

Freedom — September 9, 2004 — Maine divers may replace herbicides as the best tool to root out milfoil, the fast-growing underwater plant that threatens Ossipee Lake.

At a meeting this weekend, a group from Maine which uses divers for hand harvesting will offer a proposal to the Town of Freedom and Freedom Conservation Commission to curb the spread of milfoil. Their particular focus is Danforth Pond, where the feathery, shallow-water plant has taken hold. Commercial diver Cliff Cabral of Brownfield explained his approach of managing the spread of milfoil.

“We pull it out by the root,” he said.

A year later, sites in Maine that were treated by hand pulling have remained milfoil free, he said.

“In Sebago Lake, the area that we hand-pulled, we probably spent about three days there for two divers, about 30 hours of dive time under water, and we covered quite a bit of area around a boat ramp, and it was successful,” Cabral said.

Karen Hahnel, invasive aquatic species program environmental specialist, Maine Department of Environmental Protection, confirmed that hand pulling can work under the right conditions.

“I’d say it is successful. It depends on the site, the location, the types of sediments that are there,” she said.

Hahnel confirmed she went back this year and found no significant re-growth at the Sebago Lake site. Her agency contracted Cabral two years in a row to hand pull milfoil. Ossipee Lake has become a sanctuary for non-native strains of the plant, which can imperil lakefront property values and hobble tourism economies by smothering shores and shallows of lakes.

“Between last year and this year, the milfoil went crazy up there,” said David Smith, executive director of Ossipee Lake Alliance, speaking of the Danforth milfoil.

U.S. Senator Judd Gregg announced that New Hampshire will receive $1.09 million in federal funds to battle milfoil, which has infested almost 60 of the state’s 900-plus lakes and ponds since its arrival 40 years ago. But this money is earmarked for research, so the lake alliance and Freedom town officials hope that divers can gain an immediate foothold against the infestation on Ossipee Lake.

The largest and densest infestation to date on Ossipee Lake is at Phillips Brook, Smith said. Water testers detected the outbreak in August 2003, and the milfoil, which grows an inch a day, soon spread to adjacent Leavitt Bay.

“I’d never seen anything quite as bad,” Smith said.

In June, the state treated this part of the lake with herbicides, but already milfoil is resisting these treatments and bounding back, Smith said. Smith toured Danforth Pond this summer by pontoon boat and found similar encroachment by the plant.

Conway Lake and Silver Lake both appear to remain free of milfoil infestations, but all it takes for a new outbreak is one fragment of the plant finding its way into the water, typically via a boat propeller.

“It does quickly take over lake habitat,” said Amy Smagula, a freshwater biologist and New Hampshire’s exotic species program coordinator. “It wouldn’t take much,” she said. “Anywhere where the sunlight can hit the bottom is fair game for milfoil growth. It’s a big threat.”

“One little piece will start it in any lake,” agreed Jody Connor, limnology (fresh water studies) center director for New Hampshire.

Ossipee Lake and Silver Lake both use the Weed Watchers program, where volunteers trained to identify exotic plants notify the department of sightings, Connor noted.

“The quicker that we can get there and try to control it, the better our chances are of controlling it,” he said.

Smith said prevention also is the emphasis of the Lake Host program, active at Conway Lake, Ossipee Lake and Silver Lake. Volunteers are trained to acquaint boaters with problems of milfoil and other invaders and prevent introductions. “So far this year, we’ve had 10 saves, and one of the saves was actually at Silver Lake in Madison where somebody stopped milfoil from going into the lake,” Smith said.

The drawback of Lake Host is that only a few of the dozens of boat ramps can be patrolled. Smith said the Ossipee Lake Alliance hopes to bring on board all owners of boat ramps and develop a comprehensive screening plan.

“What we are doing this fall is joining forces with the three communities on the lake, Freedom, Ossipee and Effingham, and we’re going to put together a task force that will identify all of the boat access points on the lake, and secondly, reach out to all of the owners of those access points,” he said.

“As far as we know, no other lake has done anything like this on this scale,” he added.

New Hampshire Lakes Association president Nancy Christie applauded these efforts and praised Sen. Gregg for securing the $1.09 million research grant. “That’s the long-term answer. We’ve got to find out if there is a natural predator. We really need to know more about its ecology,” she said.

Divers, however, represent the front line of attack.

“If it’s a small infestation or it’s caught early on, the state’s first approach is to send divers down. Another approach is to put down a bottom barrier,” a mat to smother the plant, Christie explained.

The New Hampshire Department of Environmental Services provided a $14,800 grant to Ossipee Lake Alliance for a comprehensive monitoring program to limit movement of milfoil in and out of the lake.

Each spring, the state awards about $60,000 to $80,000 for control efforts such as hand-pulling and herbicide use. Proposals are due later this fall, earlier for herbicide users because the New Hampshire Department of Agriculture must review herbicide-related proposals.

While the battle with milfoil is waged, other invasive plants loom on the horizon. Hydrilla, a submersed, freshwater perennial herb, can thrive in depths exceeding 20 feet and grow more rapidly than milfoil. Both plants root in the lake bottom and sprout upward, forming mats of dense growth on the surface.

If milfoil is a persistent threat, hydrilla — already established in Maine — is the ogre over the hill.

Hahnel with the Maine Department of Environmental Protection said hydrilla has been found in Pickeral Pond, a small pond located near Limerick, Maine. Maine typically does not use herbicides against invasive plants, but in the case of hydrilla, the state is making an exception.

Christie of the New Hampshire Lakes Association said, “If the hydrilla gets in here, it’s curtains.”

It’s Hand-to-Hand Combat In Fight Against Milfoil