At a public hearing at the Jefferson Village School May 27, the Maine Dept. of Environmental Protection said they plan to use herbicide to control hydrilla in Damariscotta Lake.
Hydrilla is an invasive plant species that can over-populate a lake and drive out native plant species and hurt fish populations.
A Damariscotta Lake Watershed Association-trained volunteer found hydrilla in the lake last fall. This is only the second instance of hydrilla found in Maine.
So far, it has only been found in and around Cranberry Cove, .3-acre lagoon near an area of the lake known as the Narrows.
The plant is fairly dense in the cove, and only a handful of plants have been found in the surrounding areas, said John McPhedran with the DEP Invasive Species Program. However, because of the tenacity of the plant, even this relatively small outbreak must be treated with extreme caution, McPhedran said.
“It’s unlikely that hydrilla will ever be entirely eradicated from Damariscotta Lake, but you do what you can,” McPhedran said.
Last fall, DEP removed 28 large trash bags full of hydrilla from the cove and used nets to seal off the cove from the rest of the lake, to help prevent pieces of the plant from drifting out and starting new colonies.
This winter, they used crushed stone to fully seal off the cove.
Now, DEP has recommended the use of the herbicide flouridone in Cranberry Cove. The cove is sealed off from the rest of the lake, so the herbicide can be used in the cove with limited risk of exposing the lake at large.
Many native plant species will be killed by the herbicide, “but they come back,” McPhedran said. Fish will not be affected by the herbicide in the amounts that it will be used.
Following the 60 to 90 day herbicide treatment, which will begin in mid to late June, the DEP plans to use benthic barriers to smother the plant. Benthic barriers are sheeting that is placed over the floor of the lake to prevent sunlight from reaching the plants.
“The herbicide is buying time this season for benthic barriers as a longer-term solution,” said Paul Gregory, also with the DEP Invasive Species Program.
The plants found outside the cove will be dealt with on an individual basis, McPhedran said.
Whenever the DEP authorizes the use of herbicide, the public has a 30-day period to file appeals with the DEP to voice any concerns or opposition to its use. That 30-day period ends June 10.
At the meeting at JVS, Robert French of Raymond warned that in Massachusetts, appeals from environmental groups stopped the state from acting until it was too late.
When invasive plants were found in Massachusetts’s lakes 15 years ago, the appeals tied up the application of herbicide for 13 years, French said. “Now there’s nothing they can do.”
“The first year is the most important,” said Al Railsback, the Executive Director of the Damariscotta Lake Watershed Assn., “If you don’t get on this stuff early, you can’t take care of it at all.”
When it takes hold in a lake, it forms an “impenetrable green mass,” Railsback said.
The state of Florida spends $20 million each year mowing the hydrilla in their waterways just to make them navigable, said Gregory.
California has paved over some small ponds in last ditch attempts to stop the plant from spreading, Gregory said.
Hydrilla is hard to combat because even a small fragment can grow into a new plant. The DEP plans to seal off the cove entirely next year and continue the efforts to remove the infestation.
Although the plant hasn’t been found anywhere else in the lake at this point, it’s important to make sure, Railsback said. So the DLWA will work to scan the rest of the shoreline.
The DLWA is seeking any volunteers willing to search the lake or perform boat inspections for plants on engines and trailers, said Julia Davis, stewardship coordinator for the DLWA.
Hydrilla can grow in water up to 40 feet deep, but the search will be limited to the shore where it will be easier to find.
“If it’s not in three to four feet, you can assume it’s not in 30 to 40 feet,” Railsback said. “At least that’s the thinking.”
Along with preserving the integrity of Damariscotta Lake, it’s important to remove hydrilla to prevent it from spreading to the other lakes on boats, Railsback said.
“Hopefully the Pemaquid people are paying attention,” Railsback said. “Because even if you’re not on a lake, the lakes are tied to the tax bases in these towns.”
The most important thing that people can do to protect lakes, and the only sure-fire solution for stopping the spread of invasive aquatic plants, is to inspect their equipment, McPhedran said.
“It’s amazing how difficult it is to get people to bend over and look at their propeller and the license plate on their trailer,” Gregory said.
