http://www.nationalrivers.org/river-fact-or-fiction.html
TL;DR
A river navigable in fact (via canoe) is navigable in law.
Navigable water are held in trust by states, not ownership. States cannot sell the river segments, just the right to possess it and manage it.
Water is defined by high water mark. So if you own a land by the river, your land starts at seasonal high water mark (excluding flood).
