California Law relating to the public's right to use rivers for recreational use
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SEC. 4.  No individual, partnership, or corporation, claiming or possessing the frontage or tidal lands of a harbor, bay, inlet, estuary, or other navigable water in this State, shall be permitted to exclude the right of way to such water whenever it is required for any public purpose, nor to destroy or obstruct the free navigation of such water; and the Legislature shall enact such laws as will give the most liberal construction to this provision, so that access to the navigable waters of this State shall be always attainable for the people thereof.

CA Codes (hnc:130-135)
131.  Every person who unlawfully obstructs the navigation of any navigable waters, is guilty of a misdemeanor.

 CA Codes (gov:66478.1-66478.14)
66478.2.  The Legislature finds and declares that the public natural resources of this state are limited in quantity and that the population of this state has grown at a rapid rate and will continue to do so, thus increasing the need for utilization of public natural resources.  The increase in population has also increased demand for private property adjacent to public natural resources through real estate subdivision developments which resulted in diminishing public access to public natural resources.

66478.3.  The Legislature further finds and declares that it is essential to the health and well-being of all citizens of this state that public access to public natural resources be increased.  It is the intent of the Legislature to increase public access to public natural resources.

 CA Codes (gov:25660-25662)
SECTION 25660-25662

25660.  On the application of any person interested, the board of supervisors may by ordinance declare all or any portion of any slough, river, or stream to be a public highway for the purpose of fishing therein, if it:
   (a) Does not lie within or run through cultivated land lying within the county.
   (b) Is stocked or supplied in whole or in part with fish by the state or counties.
   (c) Has not been declared by law to be navigable and in fact is not navigable for commercial purposes.
   From the time the ordinance becomes effective, the slough, river, or stream is a public highway for such purpose, subject only to the reservations contained in this article.

25661.   If any owner of land adjacent to or across which the slough, river, or stream declared to be a highway for fishing flows does not consent to its use for such purpose with the right to pass along the banks for the purpose of fishing and on application refuses to grant the right of passage to the county by suitable instrument in writing, the board may contract for and purchase any such rights.

25662.  If the right of passage cannot be purchased at a satisfactory price, the board may authorize condemnation proceedings to be commenced to procure the right.