Not in every state. For instance in CO if someone owns the land on both sides a river then they also own the river bottom, the river itself and access to it. This means you can put in on a public landing but get into a place where you can definitely be tickets for trespassing even if you never get out of a canoe or kayak. I know of several places on the Colorado River that have fences stretched across them for this reason.

This is why TOP tells you to check regs for individual states. What is legal in your area may get you arrested in another.