Whenever one or more persons shall have a subsisting right to water range livestock at a particular place and in sufficient numbers to utilize substantially all that portion of the public range readily available to livestock watering at that place, no appropriation of water from either the same or a different source shall subsequently be made by another for the purpose of watering range livestock in such numbers and in such proximity to the watering place first mentioned as to enable the proposed appropriator to deprive the owner or owners of the existing water right of the grazing use of such portion of the public range, or substantially to interfere with or impair the value of such grazing use and of such water right.