Here in Upstate NY the house I lived in prior (built in the mid 30's) the original property line went to the middle of the river. Then the road became paved and the town exercised eminent domain and took enough for the road and it was extended and connected to another road further upstream. This was before me. Then the same eminent domain was used in the 70's and the property on the backside of the road out to the river was purchased by the state at what they determined to be a fair price.
I believe there is some clause for "navigability" of a piece of water. We have local farmers who run fences across small streams and creeks and pretty effectively control who has access. Water rights and uses are pretty regulated. For instance: you can't dam certain size streams or creeks that inconvienence or endanger folks downstream.
Like a lot of things. You'll never know 'till you ask or try.