I believe there are warning buoys for the dam at Leavittsburg/Canoe City. Can't recall is there is for the Newton Falls dam. Don't know about the dams in Warren. Perhaps someone else from the club will chime in here.
Go look at the river/dam from shore so you will have an idea of when you are coming up on it if you are not with someone who does.
Check out
this recent thread on this forum