By Nate Jones

Staff Writer 

Nobody knows how one of the most invasive plants in the state got into the waters of a man-made pond between South Portland’s Highland Avenue and Scarborough’s Pleasant Hill Road. 

“It could have been somebody emptying their fish tank,” Maine Department of Environmental Protection Environmental Specialist Paul Gregory said. “Or maybe a bird dropped it. Ospreys, once they catch a fish, don’t let go until they’re back at the nest. What if a little piece of plant life got caught up in its talons?”

However it got there, Gregory said the Maine DEP has known about the presence of Eurasian water milfoil in the unnamed pond since November 2004. Eurasian water milfoil is the most aggressive of the invasive species. The more commonly found variable milfoil is largely concentrated in the Sebego Lakes region. Gregory said the DEP was contacted by the owner of “The Food Guy” restaurant on Pleasant Hill Road who noticed a thick, vegetative mat spreading over more than half of the pond’s shoreline. It was the first recorded case of the plant in Maine, and it has since shown up in Salmon Lake, part of the Belgrade Lake system, Gregory said. 

For nearly the past five years, Gregory said the DEP has used its own funding to help contain the Eurasian water milfoil so it does not spread to the rest of the state.

Gregory said to transplant even part of the sponge-like mass from the 46-acre pond in Scarborough to another body of water would be “an invitation for disaster.”

“Eurasian milfoil is much more aggressive,” Portland Water District Water Resource Specialist Kirsten Mess said. “Invasive plants are very good at what they do. One inch of a plant is all it takes to establish a colony."

Once established, Eurasian water milfoil naturally grows on the bottom of a lake or pond, then detaches itself as a large mass – described as a thick mat of vegetation – that floats to another location where it may establish another colony, said Gregory. As far as the DEP is concerned, the real trouble with milfoil, especially the Eurasian type, is that it has the potential to affect the growth of other plants and negatively affect water quality of an entire lake system. Without a variety of plants, Gregory said water may not contain the right amount of nutrients or plant species that filter bacteria, resulting in a body of water that could be unsafe as a source of drinking water.

To battle the invasive species, the DEP has partnered with the Portland Water District and environmentalist volunteer groups to contain and reduce the presence of milfoil in Maine’s lakes and ponds, Gregory said. 

Mess said the Portland water district focuses primarily on the Sebago Lake region, where a concentration of variable milfoil is greatest in the state. Together, the different organizations conduct hand-removal operations, sometimes involving scuba divers, and in severe cases Gregory said they introduce an herbicide into the water body to kill the milfoil.

Gregory said introduction of herbicide into the Scarborough pond has helped reduce the plant that once dominated up to two-thirds of its shoreline, to a manageable amount far below the surface. 

“We know it’s here but we’re confident we can maintain it,” Gregory said. “Every milfoil presence is different – as different as Maine lakes and ponds can be. If you have a lake with a lot of activity, it’s much different. We can do all this work to remove the milfoil and one guy can come in with his boat and reintroduce it.”

Mess said it is important not only to remove the existing milfoil, but to raise awareness of how to prevent it from being spread. 

“We always tell people ‘Don’t put aquatic plants where they didn’t come from. Don’t empty your fish tank into a body of water, check your boat and trailer to see if you’re carrying anything,’” she said. 

Mess said it takes a professional to remove milfoil, and anyone who sees it should not pull on the plant, as that could actually help it spread. If you think you see a milfoil plant in the Sebago Lake region call the Portland Water District at 774-5961. Otherwise, contact the Maine DEP at 783-7733.

Staff Writer Nate Jones may be reached at 282-4337 ext. 233.