Idaho Code § 42-207
Whenever the holder of a permit to appropriate water for power purposes within the state of Idaho, desires to sell, assign, transfer or mortgage such permit so held by him, he shall file with the director of the department of water resources a copy of the deed, bill of sale, assignment, mortgage or other document of transfer, together with such proof as the director of the department of water resources may require that the new owner, holder or assignee of such permit, or the mortgagee, or one or more of the trustees under any mortgage trust indenture, possesses the qualifications set forth in section 42-206, [Idaho Code,] and that such transfer is made in good faith, and not for purposes of speculation or delay; and the sale, transfer, assignment or mortgaging of any such permit except as herein provided shall be void, it being the express intention of the legislature to prohibit the transfer of permits to appropriate water for power purposes by mortgaging the same or otherwise, except in accordance with the provisions of this act.
Idaho Code § 42-207