ELLSWORTH — Last week’s confirmation of the discovery of aggressive Eurasian water milfoil (Myriophyllum spiactum) on a boat entering a lake in the town of Norway (along with the “alarming” discovery by Maine Department of Environmental Protection staff of a non-native mussel) has put invasive species-watchers in the state on high alert.
But Roberta Hill isn’t daunted by the fight against the slimy, feathery plants threatening Maine’s freshwater shores.
“I feel really hopeful that we will hold the line in Maine,” said Hill, who directs the Invasive Species Program at the nonprofit Lake Stewards of Maine (LSM). (A piece of the Eurasian species was found on a trailer entering Toddy Pond last year, Hill said.)
Many residents and visitors splashing on the waters of Maine’s sparkling lakes and ponds this summer may be familiar with variable leaf milfoil (Myriophyllum heterophyllum). The slender, perennial plant bears a resemblance to some of Maine’s six native leafy milfoil species, producing spiky red flowers and growing in dense mats close to shorelines.
But where native milfoils have adapted to their watery environs and live in relative peace with their ecological neighbors, variable leaf and Eurasian milfoils are aggressive invaders. With few natural predators, they grow quickly and largely unimpeded, snarling swimmers and boat propellers, depleting oxygen for fish and providing a perfect breeding ground for mosquitoes.
But thanks in part to Hill and the 4,500 volunteers of the Invasive Plant Patrol, many Maine boaters and beachgoers have been spared wading through the clinging weed. Less than 1 percent of Maine’s monitored lakes are affected, Hill said. Hancock County in particular has been successful in its efforts.
“Of all the counties of Maine, Hancock County has been at this from the very earliest moment,” said Hill, adding that “no known invasive aquatic plants” have been found on the region’s monitored lakes.
“We’ve taken a really aggressive approach. We have really strong laws to help make sure our lakes are kept free of invasives.”
The state has heavily promoted its “Clean, Drain and Dry” message to boaters nationwide, and it has also relied on thousands of volunteers from programs such as LSM (formerly the Maine Volunteer Lake Monitoring Program).
Many of these volunteers are shorefront property owners or boaters, Hill said. They are often retired, heading out in pairs in canoes or kayaks to hunt for invasive species along their adopted section of shoreline.
“We call it ‘recreation with a purpose,’” Hill said. “You’re out on the water, you get to pick your day. The beauty of teams is many eyes make light work, and the job isn’t onerous for anybody.”
LSM trains even the botanically averse to recognize species that threaten Maine waters, many of which have innocent and whimsical common names, such as curly-leaf pondweed (Potamogeton crispus) and European frogbit (Hydrocharis morsus-ranae).
If an infestation is discovered, eradication efforts begin immediately. Notoriously difficult to kill, milfoil can be combated with herbicides, pulling the weeds by hand, or with benthic barriers, heavy tarps that kill weeds by blocking out sunlight (as well as killing everything else beneath them).
Although the state has largely been spared the kind of milfoil infestations that have decimated other New England shorelines, Mainers are not out of the woods, Hill said.
“We can’t let our guard down.”
Potential invasive plant patrollers interested in training are welcome at trainings set for Thursday, July 12, 1 to 7 p.m. at the Sullivan town office. Another is planned for Friday, July 13, 9 a.m. to noon at the public boat landing at Flanders Pond in Sullivan.
Participants are requested to register in advance, which can be done on the organization’s website at www.lakestewardsofmaine.org or by calling 783-7733.