At all times this act shall be construed in a liberal manner for the purpose of preserving to the State of Illinois and the people of the State, fully and unimpaired, the rights which the State of Illinois and the people of the State of Illinois may have in any of the public waters of the State of Illinois, and to give them in connection therewith, the fullest possible enjoyment thereof, and to prevent to the fullest extent, the slightest improper encroachment or invasion upon the rights of the State of Illinois, or any of its citizens with reference thereto.