The August 2023 weed survey found 125 acres of Eurasian watermilfoil in several locations in Lake Mitchell.

These were in different sections than were treated in June. A treatment on August 23 addressed these infested areas.  

Map of Lake Mitchell Treatment Area

Lake Mitchell Bio Volume 2017

Chelated copper versus copper sulfate

For years, every June an airplane would appear flying low over Lakes Mitchell and Cadillac dropping tons of blue copper sulfate crystals into the lake. The chemical would sink down, and kill the snails that carried the organism that would later cause swimmer's itch. The copper sulfate did kill the snails, but it also began to accumulate on the lake bottom as a heavy metal precipitate. Once a buildup occurs, the lake bottom may become sterile which will kill off invertebrates such as insect larvae, crayfish and beneficial bacteria. The practice of using copper sulfate was stopped in the 1990s, however, it has been speculated that the use of copper sulfate may have caused the decline of May fly hatch and diminished the population of crayfish in the lakes.

The heavy buildup of algae in the Camp Torenta Canal and in some areas of the coves has become a concern. To deal with this problem chelated copper will be used this year. With chelated copper algaecides, the copper is released into the water at a slower rate and does not accumulate in the lake sediments. Herbicide manufacturers developed chelated algaecides for long term control and to lessen the potential bio accumulation of available copper.