Idaho Code § 50-333
Cities are authorized to prevent the flooding of the city or to secure its drainage, to assess the cost thereof to the property benefited, and for such purpose may make any improvement or perform any labor on any stream or waterway, either within or without the city limits, when necessary to protect the safety of life and property of the city. Any city shall have power to cause any parcel of land within its limits on which water may at any time become stagnant to be filled or drained in such manner as may be directed by a resolution of the council, and such owner or his agent shall, after service of a copy of such resolution, comply with the directions of such resolution within the time therein specified; and in case of failure or refusal to do so, it may be done by said city and the amount of money so expended shall be assessed against such property and the amount thereof collected as special assessments under section 50-1008.
Idaho Code § 50-333