Invasive weed threatening Milton Three Ponds

European naiad (Courtesy Maine.gov)

AUGUSTA, Maine - Marine biologists from Maine and New Hampshire have now learned that the invasive weed European naiad is present in Milton Three Ponds.

"We're finding well-established populations in Northeast Pond and in the narrow thoroughfare leading to Milton Pond with the thickest growth in northern portions of Northeast Pond," says biologist John McPhedran of the Maine DEP. "It is our immediate objective to monitor the extent of this infestation throughout the entire impoundment so that we can consider response options with New Hampshire for 2016."

The infestation was first discovered in early September by an area volunteer citizen scientist. Subsequent monitoring has been provided by trained volunteers coordinated by the York County Soil and Water Conservation District, the local interstate Three Ponds Protective Association, New Hampshire Department of Environmental Services (NH DES) and Maine DEP.

European naiad can overtake native lake habitats by shading and outcompeting ecologically valuable aquatic plants, European naiad grows from an annual seed into 7-foot long plants. A productive, one-acre infestation can generate tens of millions of seeds per season. Dense infestations can alter water chemistry and oxygen levels.

European naiad has been confirmed in one small Maine Pond in Kittery and in a handful of New Hampshire water bodies this growing season.

The invasive plant had been documented previously in two New Hampshire water bodies, but populations declined on their own without management, according to Amy Smagula of the New Hampshire DES. "European naiad has not been a common problem species in this area, though with several new infestations documented in New Hampshire in 2015, that may be about to change. It warrants further investigation."

Maine DEP and NH DES have distributed invasive species warning signs to be posted at boat ramps urging boaters to inspect for and remove plant debris before and after accessing the impoundment. Also notified were boat ramp and other land owners, fishing tournament organizers, and fisheries and warden services from both states.