We call plants or animals "invasive" if they are not native to our lakes. But there's more to it than that. These foreign species are often aggressive in consuming resources and spreading rapidly. Currently, invasive plants are the primary concern in the Belgrade watershed, though there are also questions about fish like pike, which were unfamiliar to older generations and have significantly altered lake ecosystems.

One plant, in particular, has taken center stage: variable-leaf milfoil. This aquatic invader has already established itself in Belgrade Stream, Messalonskee Lake, Great Meadow Stream, and now Great Pond. Alarmingly, even a one-inch fragment can root and multiply. Shallow waters and coves are increasingly choked by this fast-spreading plant.

So what can we do to meet this challenge? Above all: prevention. Once an invasive takes hold, containment becomes difficult and costly. We must stop their spread into new waters and prevent their further movement from infected areas.

Variable-leaf milfoil is just one of eleven aquatic plants posing threats. Three others—hydrilla, Eurasian milfoil, and curly-leaf pondweed—have already spread in other parts of Maine. The remainder are thriving in neighboring states, often brought in unknowingly by visitors.

Vigilance is our strongest defense. We must learn to recognize invasive plants and inspect watercraft, trailers, and gear that could harbor fragments. Early detection makes eradication far more feasible than waiting until a plant becomes established.

If invasive plants are found in our lakes, we inherit the duty of inspecting outbound boats as well. Milfoil, for example, can cling to propellers and hulls and spread through even small fragments. This is why thorough Courtesy Boat Inspections at launches like Route 27 are so essential.

In some cases, such as Messalonskee, the invasion has gone too far for full removal. Efforts there have shifted to control and stabilization—strategies that contain the problem rather than eliminate it. Hopefully, new research will produce better tools. Until then, we must all do our part to protect Maine’s lakes.

Remember: Prevention is easier than restoration. Let’s keep our lakes healthy by stopping invasives before they spread.