July 3 – 9, 2020Vol. 22, No. 4

7 Lakes Alliance: Mobilizing Against Milfoil

Diver Matt Kelly of the 7 Lakes Milfoil Crew.

Left unchecked, aggressive non-native variable leaf milfoil grows rampantly, forming large mats on the surface, recreational boating, fishing and swimming, and even reducing property values. This year, with ice-out about a month earlier than usual and abundant sunshine, invasive plants have gotten a head-start.

With favorable conditions, invasive plants started reaching the surface of the water a month early, while native plants did not appear to grow as quickly in response to early ice out. Invasive plants started growing bracts — reproductive in mid-June which is much earlier than normal (usually mid- July). Native milfoils with emergent reproductive structures have not started growing emergent spikes yet.

The invasive milfoil's rapid growth in May did not escape notice, but there was no time to waste. 7 Lakes Alliance's Milfoil Project Manager Sharon Mann noted "I knew it was critical to mobilize the team right away, to be sure that the infestation's growth did not get ahead of us." The crew was in the water about one month earlier than usual in response to the aggressive plant growth.

This year, the team is targeting "stubborn" areas, where the milfoil repeatedly returns, covering them with benthic barriers that lay on the bottom and starve the plants of sunlight. This year, burlap barriers will be used in many areas instead of plastic. These are biodegradable, work well in flowing waters, and minimize the amount of fragments. The goal is to defeat the reoccurring patches and reduce the infestation to a more manageable level. Wooden stakes in Great Meadow Stream are part of the burlap benthic barrier treatment; they will be removed when the burlap has become sufficiently waterlogged so that it will not be moved by the water flow.

Finally, the Maine Department of Inland Fisheries and Wildlife and the Department of Environmental Protection approved a Surface Use Restriction for Great Meadows Stream in Great Pond. This restriction means that in a small, clearly-marked portion of North Bay in Great Pond, only non-motorized boats are permitted. This both minimizes the potential spread of plant fragments and helps keep our dive-team safe.

On July 17 from 6 p.m. — 7 p.m., join 7 Lakes Alliance's webinar to hear the milfoil crew's stories from the field and the latest invasive milfoil updates. In the meantime, 7 Lakes needs volunteers to do "fragment patrol" in North Bay and Great Meadow Stream. No experience is required, just a paddle craft and a passion for helping the watershed. Contact Sharon Mann at 495-6039 for details. Odds are that she and the team will be underwater, but she'll get right back to you!