Don't know anything about bad water quality at the lake, but I do know there are 3 signs at different locations around the lake warning about the alligator (that's one alligator). The first is to the left of the little box that holds the payment envelopes when you first drive in; the second is on the bulletin board by the "vault" where you deposit your $5 and envelope (at the start of the paved trail down to the lake); the third is on the bulletin board to the right of the wooden steps that go from the parking lot to the lake.
I fish the lake once a week this time of year, and have asked both the camp hosts (Paul and Raymond) about the alligator signs and they say an alligator approx 2 feet long was sighted earlier this year. It hasn't been seen lately. If it's a joke they are in on it, because the signs have been up for at least a month.