John Deming packaging weeds

John Deming packages a weed sample that was sent to Grand Valley State University. DNA testing confirmed the presence of Eurasian water milfoil and its hybrid in Clark Lake

As previously reported on this website, DNA testing has confirmed the presence of Eurasian water milfoil and its hybrid in Clark Lake. Since then, a committee formed to discuss the problem. More recently, the Clark Lake Spirit Foundation, publisher of this website, funded a survey of the lake to determine the quantity and location of hybrid Eurasian water milfoil (HEWM), and also to outline options and recommendations for its control or eradication.

There is an active movement at Clark Lake to thwart the invasion of this weed. Among those involved is John Deming, who comments: “At other lakes, infestations like this simply take over. Swimming, boating, fishing and general lake use is greatly curtailed. One lake reported that ducks, instead of swimming over the weeds, actually walked on top of it.”

The survey of the lake was performed by Professional Lake Management in September. A key takeaway from their report is the sheer amount of HEWM already in the lake. The invasive weed is present in over 20-acres of our lake. While you can see the weeds topping the water in areas like the County Park, much more of it is evident in deeper waters along drop offs.

Illustration: Purdue University Extension

Illustration: Purdue University Extension

That leads to another problem. The plants grow to the surface in deeper areas where boats travel. In those areas, props lop off the tops. John Deming goes on to say “What’s more unnerving, is ability of this invader to spread. One cutting the size of a pine needle can create 250-million new plants in just one season.”

The Professional Lake Management (PLM) is clear about the threat. “Eurasian water milfoil is extremely invasive and can inhabit a variety of sediment types and water depths.” The report notes that the weed “forms a canopy above native plants, choking out the competition. [It] also has the ability to overwinter underneath the ice… This gives the plant a head start in growing during the spring and chokes out native plants very quickly. [HEWM] should be controlled as soon as it is found within a lake to prevent further infestation…”

The PLM report presents solutions, most of which have been explored in previous articles on this website. For a compendium of these stories, please click here.

HEWM location mapThe lake was inspected and the report produced by Steve Hanson who has a M.S. degree as a fisheries biologist. In his study of Clark Lake, he carefully noted the various kinds of native aquatic vegetation as well as documenting the HEWM. Please click here for an expanded view of the map and additional detail showing locations and density.

The experience of other lakes offers a lesson. The HEWM is a fast growing invader and it is better controlled early rather than letting it spread widely. It’s interesting how many times one hears from outsiders about the beauty of Clark Lake and how the lake hosts many activities on its waters. Who would want this to change! This website will continue to offer information and progress on steps being taken. If you would like to be involved, please contact John Deming at 529-9117 or