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Maine to Use Herbicide in Damariscotta Lake

May 21, 2010 - JEFFERSON -- The group assigned to caring for Damariscotta Lake is throwing its support behind a state plan to use herbicides to remove an invasive plant.

Alan Railsback, executive director of the Damariscotta Lake Watershed Association, said chemicals offer the only chance to prevent hydrilla from spreading through the entire lake.

Hydrilla, considered the most aggressive of all invasive aquatic plants, was discovered last August in a small lagoon and abutting cove.

"Studies have shown that if you don't get it immediately, eventually it's going to beat you," Railsback said. "So far, it looks like it's limited to that area. We're optimistic, if we really jump on it this year, we can arrest its spread."

The Maine Department of Environmental Protection has scheduled a public meeting for 7 p.m. Thursday at Jefferson Village School to talk about efforts to control hydrilla. The DEP also will lay out its case for using the herbicide fluridone, said Paul Gregory of the DEP.

A 2004 Environmental Protection Agency study determined there is a "reasonable certainty" that exposure to fluridone at concentration levels needed to treat hydrilla does not harm humans.

The fluridone application is specifically targeted to the plants.

"It's a limited application in a very small area," Railsback said. "Sometimes the cure is worse than the disease, but in this case I think it's the thing to do."

A trained volunteer spotted hydrilla in Damariscotta Lake last year while surveying the shoreline near his camp on the western side of the lake. The DEP closed off the densely-infested lagoon from the rest of the lake within a week and hand-weeded much of the vegetation, Gregory said. That harvest filled two large pickup trucks.

The herbicide, which is absorbed into the plants as they grow, will likely be added at the end of June. There may be a booster treatment later in the year.

"We definitely want to watch the plant growth," Gregory said. "Right now we're not seeing any plants. The plants have to emerge and foliate, then it will be ideal for applying herbicide."

Lake bottom barriers, similar to weed control fabric used by gardeners, will be placed on the lake bottom to prevent remaining seeds from sprouting.

"The barriers are the long-term control," Gregory said. "This is part of a comprehensive approach to controlling hydrilla in the lake and preventing it from spreading elsewhere."

The DEP already has approval to use the herbicide, but the permit requires the department to hold a meeting on the plan.

"We think its an ideal opportunity to explain what the hydrilla problem is," Gregory said. "It's not a hearing. It's a public information meeting. Essentially it is our intention to use herbicide in this situation."

The DEP has used herbicides on three other Maine lakes, including a gravel pit in Scarborough treated for Eurasian milfoil and a 46-acre pond in Limerick, which was infested with hydrilla.

The most recent application was last September when the DEP treated Eurasian milfoil on Salmon Lake in Belgrade. It is too soon to know for certain the effectiveness of that application, but early signs are encouraging, Gregory said.

The idea of using herbicide in Salmon Lake, as in Damariscotta Lake, is to make it possible to manage the infestations through harvesting and barriers.

"Our objective is to knock back the biomass," Gregory said.

Railsback said it will probably take years to completely control the growth.

In the meantime, his association is training volunteers to conduct shore surveys and courtesy boat inspections.

"This year we have to worry about boats coming out as well as going in," Railsback said. "The (inspections) should be a little more robust than it has been in the past."

by Craig Crosby, May 21, 2010, Kennebec Journal

Lakes: Salmon (Ellis) Pond
Regions: Belgrade


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