I didn't live there, but my grandparents did and my family summered there (on Long Lake) every year from the early 80's thru the last few years. I snorkels and later dove in Lake Michigan and surrounding connected and non-connected lakes. The water definitely got more clear in the 90's and 2000's to my unscientific eye.

It's beautiful country up there. Nothing much compares, to me, to northern lower-peninsula Michigan summers.