If any unauthorized person shall willfully do or cause to be done any act by which any work, materials or property, including manhole covers, now or hereafter erected or used within the city or elsewhere by such city, or any person acting under their authority, for the purpose of procuring or keeping a supply of water shall in any manner be injured or removed, or shall erect or place any nuisance on the banks of any river, lake or stream from which the water supply of such city shall be drawn, such person on conviction thereof, shall be deemed guilty of a misdemeanor.