This is and excerpt from a report prepared in 2002 but I think no laws have changed.
http://healthyshorelines.com/media/T...d_the_Lake.pdf
The report is more about lake shores but does mention....
"Although the banks and shores of most rivers, streams and lakes are public land, and users can walk on bed and shore below the “high water mark” or “bank” without trespassing on adjacent land, users must ensure however, that they have legal access to these water bodies first. If public access across adjacent land (public land under disposition or private) is in question, the user should contact the land owner or lessee for permission to access the water body."