Uhh, at least two of the feet were traced back to a kid who committed suicide in 2004 by jumping of an upstream bridge. There was a big article in the National Post just today. It seems likely these are all results of people jumping to their deaths.

http://news.nationalpost.com/2011/09/02/search-in-a-‘floating-feet’-case-leads-to-troubled-young-man-from-surrey-b-c/