Cow is right on with that link
basically according to the supreme court:
Any river has to be deemed navigable if...

1 it can was or could have been be used as a highway to transport people or goods.
2. is useable by customary modes of transportation on the water
there might be one other thing but these two are the main things..
The corps of engineers has NO jurisdiction over whats nagagable or not, neither does the coast guard Though they use the term to define certain water types neither deffinition can be used to determine " navagability for title purpose" and therefore public ownership of the streambed.
it's my opinion that many streams are improperly classified as non navagable.. like certain parts of the Kalama.
According to my interpretation of federal law if you can get a driftboat down a river in it's natural state then the state must find it legally navagable and therefore own theriver bed. Also though these are state lands they are "held in trust" specifically for the use of the public and it is against federal law to restrict such access..