A team of scientists, educators, and teenagers discovered the objects, some of which may have been delivered by a fireball that streaked across the sky in 2017.
Road salt is primarily to blame for the shift, though the water remains within safe levels for now.
Nearby vegetation affects the color of organic matter, a new study finds.
Teens helped by scientists and educators seek meteorites that plunged into Lake Michigan early this year. Weather radar guided the search for the projectiles.