Snakes on Bonnet Carre Spilway Trail

I have been to this trail a couple times, but first time in August. I had never seen snakes until today, two actually. First one crossed the trail ahead of me about 10 feet away, went into the water. Second did not move until I got about three feet from it, scared the bejesus out of me. I think both were the same kind, 2-3 feet long and all black. So, questions:

1. What kind are they?

2. Are they poisonous?

3. Is this snake high season at the spillway?


This is what I think both looked like, but I am probably wrong. It says it's a crayfish snake.




Thanks in advance