The microplastic footprint of a marina with an open-bottom polystyrene dock extends about 80 m perpendicular to the shore. Sediment samples contain microplastics that have settled and will persist for a long time. In the past, all 3 marinas had docks with fully exposed polystyrene foam. A few years ago, Kosh Lake Marina upgraded their docks, so their docks no longer shed microplastics, though concentrations remain high. As well, the new owners of Blue Mountain Lodge are replacing their docks.

The pollution footprint of a private open-bottom polystyrene dock extends about 20 m perpendicular to the shore. Last summer, we did not have time to collect additional samples, so this estimate is based on 3 samples. We also did not collect samples to determine the width of the footprint along the shore.