If any person shall willfully obstruct any stream or waters improved under the provisions of this act or any part thereof, or shall willfully destroy or injure any buildings, piers, dams, fixtures, banks, or other constructions in use upon the same, belonging to said company, such person or persons so offending, shall, for every offense, be deemed guilty of a misdemeanor, and shall be punished by a fine not exceeding 500 dollars, or by imprisonment in the county jail not more than 1 year, in the discretion of the court.