Perch Lake Study

      Perch lake is a small, shallow, spring fed lake located in Hillsdale county, Michigan.  Because it is shallow, Perch Lake is an ideal habitat for rooted aquatic plants. Unfortunately, these macrophytes can become dense, thereby decreasing the suitability of the lake for recreational use.  The primary macrophyte infesting Perch Lake was Eurasian Milfoil, (Myriophyllum spicatum).

Eurasian Milfoil

     The Perch Lake/Crystal Lake Property Owners Association asked the U. S. Army Corps of Engineers to help control the excessive growth of Eurasian Milfoil with the herbicide fluridone.  The Army Corps treated the entire lake with fluridone during the fall of 2000. Pondweeds were treated with diquat and endothol in summer of 2001.  Purple loosestrife and lily pads were treated with glyphosate in summer of 2001. Pondweeds were treated again with diquat/endothol in the summer of 2002. Eurasian Milfoil patches were treated with 2,4-D in summer 2002.

     The purpose of our study was:

  • Establish initial conditions including water quality, composition and abundance of zooplankton and benthic invertebrates in Perch Lake prior to treatment with aquatic herbicides.
  • Identify any changes to water quality or invertebrate composition and abundance during and following treatment with herbicides.

      Recommendations:

  • Continue monitoring phosphorus, ammonium, and chlorophyll a concentrations.  A large change in one or more of these parameters will signal that the Perch Lake ecosystem is changing in an important way.

  • Avoid removing too many rooted plants from Perch Lake.  Without rooted plants, the lake water may become clouded with algae.

  • Focus management practices on removing exotic nuisance plants such as Eurasion milfoil and curly-leaf pondweed.  Exotic plants tend to overgrow and shade out beneficial native plants.  Management practices that involve the removal of dead plant tissue from the lake will reduce the possibility of wintertime oxygen depletion.

 

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