Idaho Code § 42-301

If the holder of a permit to appropriate the public waters shall fail to comply with the requirements of his permit as to the commencing of work or the filing of bond thereunder, or the completion of one-fifth (1/5) of the construction work within one-half (½) the time allowed for the entire completion of such construction work, or shall fail to complete the entire construction work within the time specified in his permit, said permit may be cancelled and voided by the department of water resources as hereinafter provided at the instance of any person or persons holding any permit for the diversion of water from the same stream, such permit postdating the permit which is sought to be cancelled.