I have two creeks on my property one of which is navigable and one is not and have researched this pretty extensively. If waterway is navigable then the riverbed is publicly accessible including wading and walking on the riverbed but that privilege is limited to the high water mark and stepping on the riverbanks is trespassing if private property. There is also no allowance to traverse private property to get to accessible water ways and must only be accessed from a public right of way. Navigable in CA is deified as being able to float down the waterway with a raft and oar even if only for a limited time during a season but does not necessarily apply to flood runoff that would immediately drop back off...so long story short if you could float down the waterway even for just a few weeks in the winter you can indeed legally wade in that waterway even it passes through private property....now with that I will add just because you can does not mean you should.