Critter in lake

There is a underwater trench leading from under the tree at the edge of the lake out about 3 feet. I have seen the critter swim out like a flash but today I finally got a good look at it. It was underwater, about a foot or so, black, and I think it had webbed feet. It was fast, swam out toward the deeper water, and I didn't see it after that. It just seems to vanish.



Otter?