Owning the riverbed doesn't mean much in Washington. As others have noted, you can be deeded the land under a sidewalk, but you have no right to kick pedestrians off of it. And don't confuse the ambiguous federal "navigability" precedent with Washington's very clear Shoreline Management Act. Anything that flow's over 20cfs is governed by the SMA and it guarantees the Ordinary High Water Mark as accessible to anglers. I've dealt with the guy on the Kalama who gets pissed when you stand on "his" island in the river. I'm tempted to remind him that I know where he lives and I firmly believe in human sacrifice.