Iowa Code § 468.148: Injuring or diverting — damages.

Any person who shall willfully break down or through or injure any levee or bank of a settling basin, or who shall dam up, divert, obstruct, or willfully injure any ditch, drain, or other drainage improvement authorized by law shall be liable to the person or persons owning or possessing the lands for which such improvements were constructed in double the amount of damages sustained by such owner or person in possession; and in case of a subsequent offense by the same person, the person shall be liable in treble the amount of such damages.