On a calm morning in late summer 2019, Jim Bailey was kayaking on Lake Superior near Thunder Bay, Ontario, when he found himself paddling through thick green scum, the likes of which he’d never seen in those waters. Puzzled, he headed into the open bay where he could see green patches stretching out about 3 kilometers.
Great Lakes Now
https://www.greatlakesnow.org/2021/08/lake-superior-summer-algae-bloom/