Clark Lake continues to guard against invasive species.  Lakes that didn’t (or don’t) deal with Hybrid Eurasian Water Milfoil (HEWM) and Starry Stonewort face the consequences.  Recreational, fishing, and habitat are threatened.  Some lakes waited too late, and that affected property values.

By 2014 at Clark Lake, something akin to an underwater jungle lurked below and was increasingly surfacing.  Those who had to pause their raft ride to clear their prop may remember the experience.  That exotic growth likely began earlier than 2014, but had become painfully noticeable by then.   A group of Clark Lake residents came to the defense.  With overwhelming support form the Clark Lake community, a special assessment district (SAD) was formed, and PLM was contracted for treatments.

The photo was taken as the weed control project began.

In their first survey, PLM found that “Eurasian water milfoil was in approximately 32% of the 63 sites surveyed. In addition, genetic testing of the milfoil plants by Grand Valley State University found that many of the samples collected were of a hybrid milfoil, a cross between native milfoil and the exotic Eurasian watermilfoil. Hybrid milfoils tend to be more difficult to control and grow back rapidly following control efforts. Management efforts to date have focused on controlling this hybrid milfoil in Clark Lake.”

Where does that leave the lake today?  On June 21st, PLM treated 4.6 acres of Clark Lake for HEWM.  “During the September survey, only two of the sixty-five survey sites contained Eurasian watermilfoil.  Both sites are in the northeast corner of the lake, adjacent to the County Park. Although the plants were clearly impacted by treatment, it appears as though some of the plants may survive.”  Clark Lake’s situation has improved significantly.

Another threat is Starry Stonewort.  This plant masquerades as Chara. PLM says “Chara is a highly desired species because it is typically low growing, keeps the water clear and can slow down the invasion of exotic weed species. Starry stonewort also forms dense mats, but unlike Chara, it can grow from 5 to 7 feet tall. Starry stonewort can be very detrimental to a lake’s ecosystem and has the ability to kill off native plants and have a negative impact on a lake’s fisheries.”  The good news?  No Starry Stonewort was found in the September survey.  Previously Starry showed up near the County Park and Eagle Point.  You might say Clark Lake nipped it in the bud.

The control program targets only invasive species.  In some cases, non-invasive, native weeds can be bothersome.  Residents may take it upon themselves to eliminate them.  PLM makes the following comments about non-invasive weeds. “Aquatic plant management should preserve species diversity and cover of native plants sufficient to provide habitat for fish and other aquatic organisms. Native plants should be managed to encourage the growth of plants that support the Clark Lake fishery (by creating structure and habitat) provided that they do not excessively interfere with recreational uses of the lake (e.g., swimming and fishing) in high-use areas. Where they must be managed, management techniques that reduce the stature of native plants without killing them (e.g., harvesting, contact herbicides) should be used whenever possible. Specific areas should be set aside where native plants will not be managed, to provide habitat for fish and other aquatic organisms.”

This chart shows what’s growing in Clark Lake.

The fall survey also monitors water quality.  Here’s what PLM says about Clark Lake:

• Minimum dissolved oxygen is adequate for good fish production.
• pH is within acceptable limits.
• Phosphorus and Nitrogen are within acceptable limits.
• No remedial action recommended at this time.

The cost to lakefront property owners is about $59 per year, and is included in the tax bill.  The program is under the auspices of Columbia Township, and the tax money collected can only be used to control Clark Lake’s invasive weeds.