Dead Water Snakes

While walking along the mounds in the middle of the wet fields, I came across 2 dead snakes. Now I don't know how they were killed or who or what killed them. The first one, as shown below, was lying in the shallow water with its ventral side up.

I then took the snake up with a stick and placed it on the ground to try and identify it. All I can say is that it is a species of watersnake, maybe a keelback.

And after walking several minutes, I encountered another dead snake, this one too, in the water with its ventral side up.

I'm concluding that these snakes died probably due to humans or birds like herons killing and throwing them away. I did spot a live one but it immediately swam into the muddy water before I could grab a shot.