The witness

I was doing some senior portraits in a park near downtown yesterday, and as I was about to pose my client on a bridge, I noticed a snake in the shallow creek far below us. I quickly snapped off a few frames as it slithered around in the water. The snake actually looked up at me and opened its mouth as I took its picture. It looked like it might have been hissing at me! Any herpetologists out there? What kind of snake is this? Also, in processing the pictures I noticed that it had several large black nodes on its head, around its eyes. You can just barely see them in this picture. I don't think they were a natural part of the snake. Possibly it has snake ticks (yes that's a thing, I gamely googled snake diseases for this blog post and came up with some rather unsavory stuff -- I won't be doing that again, no thank you!), or maybe it has a fungus. Anyway, it was a brief moment of excitement for me and my client, then we got back to portrait-taking. My job is always interesting!