Brook trout like cool water.
Trees that overhang their rivers and streams provide shade and cool the water. Without them, the water can get warm enough to harm or even kill the fish.
So "river maintenance" for groups like Gitche Gumee Trout Unlimited is more than just cleaning up litter; it means replanting native trees on riverbanks where they might have been cut back decades ago.
The Sucker River Cleanup event page has more information about tonight's get-together.