Iowa Code § 468.168
The board of any county into which a levee or drainage improvement extends shall cause a competent engineer to inspect such levee or drainage improvement as often as it deems necessary for the proper maintenance and efficient service thereof. The engineer shall make report to the board of the condition of the improvement, together with such recommendations as the engineer deems necessary. For any claim for services and expenses of inspection, the engineer shall file with the auditor an itemized and verified account of such service and expense to be allowed by the board in such amount as it shall find due and paid out of the drainage funds of the district. If the district extends into two or more counties, such action shall be had jointly by the several boards, and the expenses equitably apportioned among the lands in the different counties.
Iowa Code § 468.168
89 Acts, ch 126, §2