Idaho Code § 42-101
Water being essential to the industrial prosperity of the state, and all agricultural development throughout the greater portion of the state depending upon its just apportionment to, and economical use by, those making a beneficial application of the same, its control shall be in the state, which, in providing for its use, shall equally guard all the various interests involved. All the waters of the state, when flowing in their natural channels, including the waters of all natural springs and lakes within the boundaries of the state are declared to be the property of the state, whose duty it shall be to supervise their appropriation and allotment to those diverting the same therefrom for any beneficial purpose, and the right to the use of any of the waters of the state for useful or beneficial purposes is recognized and confirmed; and the right to the use of any of the public waters which have heretofore been or may hereafter be allotted or beneficially applied, shall not be considered as being a property right in itself, but such right shall become the complement of, or one of the appurtenances of, the land or other thing to which, through necessity, said water is being applied; and the right to continue the use of any such water shall never be denied or prevented from any other cause than the failure on the part of the user thereof to pay the ordinary charges or assessments which may be made to cover the expenses for the delivery of such water.
Idaho Code § 42-101