Northwestern Wisconsin has the highest concentration of plastic pollution

BAYFIELD, Wis. (AP) - A recent study of 35 national parks found the waters off an island in northwestern Wisconsin had the highest concentration of plastic pollution.

The National Park Service, South Carolina's Clemson University and the National Oceanic and Atmospheric Administration Marine Debris Program began working on the study in 2015.

Wisconsin Public Radio reports that samples collected from the Apostle Islands National Lakeshore had an average of 170 to 225 pieces of microplastic per kilogram of sand.