The website Dalton posted is pretty good. I also found it after reading that article. I couldn't help but check some of the beaches I used to swim back in Cleveland. The ones close to the city also went from red to orange to green after rain like the rivers here. I've always followed the "don't go in after it rains" rule. I personally wouldn't sweat falling in for a moment. Earlier in the year I stepped into a big hole at 4MR and flooded my waders and had to swim back to shallow water. My head didn't go under water but I got dang close. Pretty nasty. but I didn't have any adverse effects. Don't get me wrong, I'm not making that a regular thing.
I see people wading and letting their dogs swim in Rock Creek all the time. That I wouldn't do, although I will admit I've traipsed through ankle-high water in my wading boots to get better angles.
Now, if someone gets a brain-eating amoeba around here, I'm probably going to rethink things.