Are you perhaps thinking of William Colby? He was head of the CIA and later was found drowned/dead after going for a paddle in his canoe.
You are correct. It was William Colby. My feeble mind should have googled it:
http://www.nytimes.com/1996/05/07/us/william-e-colby-76-head-of-cia-in-a-time-of-upheaval.html