I saw a movie a few years back that sounds ALOT like your first one. I can't remember the name of it, but the man who crashes into the lake and comes out crazy was actor Richard Kiel. He's the guy that played JAWS in a couple of bond flicks. Hope this helps some.
I think you just found the mystery movie - lake, robot dog, and all! "The Humanoid" (1979):
http://www.imdb.com/title/tt0080058/