I've seen a lot of video of kids playing in flood water the past couple of days. Each time, I've yelled at my TV, computer or smartphone, "Watch out for snakes!!" They abound in south Louisiana, and many of them are poisonous. Snakes like the water just as much as humans do. The bite of a water moccasin, cottonmouth, or other venomous reptile can be life threatening for an adult, even more so for children.
They're no more interested in your company than you are in theirs, but rising flood waters will cause them to explore places they otherwise wouldn't. If you surprise a snake, you may be in for an unpleasant, potentially deadly surprise.