For the last five years the Lake Leelanau Lake Association (LLLA) and the Grand Traverse Band (GTB) of Ottawa and Chippewa Indians have worked to eradicate Eurasian Water Milfoil (EWM) within Lake Leelanau. While not all milfoils are invasive, EWM is.
EWM is a grave threat to Lake Leelanau because of its hardiness. Without intervention, EWM forms thick, dense mats underwater that outcompete native aquatic vegetation. Local fishing, boating, and water quality are significantly negatively impacted. And while LLLA has done well containing this destructive invasive, it becomes harder to control when EWM finds its way into streams and rivers.
The Leelanau Conservancy’s 548-acre Cedar River Preserve is one of the wildest places left in Leelanau and an ecological gem filled with rare plant and animal life unique to the state.
But it is at risk because of its proximity to Lake Leelanau and a nearby boat launch. New reports show a small EWM infestation far upstream from the mouth of the Cedar River, likely carried from the lake by watercraft. This infestation should be a warning against the dangers of destroying fish habitat and other aquatic life through dredging or other means. Bare river bottom combined with increased powerboat traffic could provide the conditions for the rapid spread of EWM. When EWM invades a river ecosystem, the delicate balance of the aquatic environment is thrown into chaos. The dense mats impede water flow, alter sedimentation patterns, and hinder the movement of native fish. This has a ripple effect on the entire food web, limiting resources for fish and other wildlife.
EWM works by strangling out native plants. It can eventually close a river mouth and block out sunlight, which native aquatic plants depend on for photosynthesis. The river’s water temperature is affected, impacting oxygen availability. Sunlight also keeps water clean through photodegradation of organic matter and contaminants. EWM directly contributes to species loss and reduced water quality.
So what can be done? LLLA and the GTB have committed to controlling EWM without using herbicide. The partners use burlap blankets to cover infestations by blocking out sunlight. The burlap’s biodegradable material allows for native plants to grow through it, reclaiming the area. However, EWM must be completely smothered. If the smallest plant fragment is left behind, EWM can regrow. Plus, the river’s flow makes EWM a moving target.
You can help stop EWM from entering the Cedar River. Always check your propeller and anchor for signs of EWM, and clean your fishing equipment. To prevent new introductions, LLLA and GTB will install four boat cleaning stations on South Lake Leelanau at the DNR Narrows, Bingham, West boat launches, and on North Lake Leelanau at Suelzer Park. Boaters are encouraged to utilize these stations before and after launching in Lake Leelanau. Launching with a clean boat is Michigan law.
A little done today to prevent invasive spread adds up to a lot tomorrow in keeping Leelanau’s waters healthy and vibrant.
Tom Nelson, Leelanau Conservancy Annalise Povolo, Lake Leelanau Lake Association
