Question:
While fishing on Hot Creek (Mono County), I came to a fenced-off section of the creek, posted with no trespassing signs. I have always been under the impression that once you legally access (don't cross private property) a river, you may continue fishing the length of it. Am I wrong?

Answer:
According to California law, most water in above-ground, free-flowing waterways is state water and not considered private property. The land underneath the water, however, may or may not be held by the state. On small or ephemeral streams, for example, the land in the bed of the stream could be privately owned.

If you have legally gained access to the state's water, such as at a boat ramp or on your own property, or another person has granted you permission, you can most likely continue up or down the waterway in a boat without trespassing. But anytime you touch the bed or bank of the stream that is not owned by you, you may be trespassing.

If there is a fence across the stream, which is common on smaller streams in areas where livestock are common, you cannot assume that it is legal to cross over it even if you can do so without touching the bank or bed of the stream. You should not attempt to do so until you have either gained the permission of the person who owns the property or received a determination that the land underneath the stream is owned by the state.