Progress Around Minnesota. Minnesota Statewide Mussel Survey. Taking inventory of these natural assets to sustain freshwater mussels in Minnesota for future generations. The DNR has prepared this advice for avoiding or treating swimmer's itch. Duckweed can be removed by skimming or applying a DNR-approved herbicide.
Filamentous algae is composed of long, green threads often matted together, resembling green cotton.
Filamentous algae can be controlled with copper sulfate or other copper-based algicides. If it looks like green cornmeal, it is probably watermeal. If it cannot be swept aside with your hand and it is stringy, hairlike, or slimy or colors the water green or brown, it is likely algae. For these reasons, it is important to ensure that the device is used appropriately. A permit valid for three years may be obtained if the device is operated in an area of submerged vegetation that is no larger than 2,500 square feet, and extends no more than 50 feet along the shore or one-half the property owner's frontage, whichever is less.