OXFORD – The Thompson Lake Environmental Association has launched a fundraising drive to keep its modified pontoon boat on the lake and cleaning up milfoil.

The group wants to raise $215,000 over six years from the four towns that surround Thompson Lake, their residents, and through grants. The money will pay to keep the Hippobottomus afloat. The boat has been operated for six summers on Thompson Lake to eradicate tons of milfoil.

“We put a mailing out Monday to 1,100 people,” said fundraising committee chairman Barry Jorve in a telephone interview from Florida over the weekend. Jorve hopes at least 100 people give $1,000 for three years to raise $30,000 of the $80,000 goal from residents.

The association also seeks $90,000 in grants and $30,000 from the four towns around the lake, Oxford, Poland, Otisfield and Casco.

Another $15,000 will come from association’s assets, Jorve said.

“It’s going to be tough,” Jorve said of raising the money, particularly from the towns. That will require town meeting approval.

Jorve added that the milfoil, an invasive aquatic plant that can destroy a lake, doesn’t stop growing.

Grant writing will begin on March 1 followed by attempts to convince town meeting voters of the merits of the program, he said.

Thompson Lake is one of about 21 lakes in Maine with an infestation of variable leaf milfoil, according to the association. Auburn Lake is another, as is Poland’s Middle Range Pond, according to the state’s Bureau of Land and Water Quality. Poland has successfully controlled it by removing it by hand.

Jorve said it costs $35,000 a year to operate the boat. Of that $30,000 pays the salaries of three scuba divers who are in the water for 10 weeks, five days a week for eight hours a day. They are paid $25, an hour he said.

Last summer the divers operated the Hippobottomus, harvesting 22 tons of plants, largely from the Greeley Brook area. The method involves funneling the weeds via a vacuum system into a sluice way onto the deck of the boat. The milfoil becomes rich compost for farmers.

The divers were trained by the Department of Environmental Protection.

Previous efforts to eradicate milfoil by putting down benthic barriers was considered too slow and labor-intensive for Thompson Lake, according to the association.

“We think we will have the problem 95 or 98 percent under control in six years. It’s a pretty impressive operation,” Jorve said.

Jorve said that property values can be tied to the health of a lake. Limerick recently lowered assessments on Arrowhead Lake shorefront property by 10 to 15 percent because of milfoil infestation, according to Scott Bernardy, chairman of the association environmental committee.

Contributions can be made by check to the Milfoil Fund, Thompson Lake Environmental Association, P.O. Box 25, Oxford, ME 04270. Jorve can be contacted at 207-627-7481.