Each Saturday morning, by kayak or on foot, with volunteers or on his own, Sean Connaughty picks up trash in Lake Hiawatha. Some 6,500 pounds of it from the south Minneapolis lake over the last five years. Bottles and plastic barrettes. Styrofoam and syringes.

Connaughty, 53, sorts it, bags it and records its origins. Then, sometimes, he uses it to make art.

In the sculpture garden outside the Minneapolis College of Art and Design stand four billboards that, at first, look like advertisements. But Connaughty is drawing a different kind of attention to mega corporations he’s found to be the biggest sources of trash in the lake, recreating their logos with litter.

The iconic curves of McDonald’s golden arches are, for example, bundles of straws.

“If we are going to change this situation — not just for Hiawatha but the larger situation — everyone has to own their part, their responsibility,” he said. “That includes the corporations.”

Connaughty, an artist and University of Minnesota professor, is drawing on his personal activism on behalf of Hiawatha, the 55-acre lake a few blocks south of his house.

He’s an optimist at heart, he said. If people change their behavior, companies change their practices and the city puts a system into place, he said, maybe, just maybe, “the lake will be swimmable again.”