Lake Minnewaska in the Catskills Mountains in New York State is infested with leeches!
How leeches got into Lake Minnewaska is a big mystery—especially since none of the other lakes nearby have leeches. What scientists do know is that over the past few years, the lake has gone from having a lot of acid in it; this made it inhospitable not only for leeches, but for fish, too. To having very little acid; now there are two kinds of fish living in the lake, plus lots of leeches. Recently, the lake was treated with a pesticide called copper sulfate. But it didn't kill the leeches. Swim here at your own risk!