All contracts made for engineering work and the work of constructing improvements of an intercounty district shall be made by written contract executed by the contractor and such person as may be authorized by the boards of the several counties and by joint resolution and shall specify the work to be done, the amount of compensation therefor and the times and manner of payment, all as provided in relation to districts wholly within one county.
Iowa Code § 468.290
89 Acts, ch 126, §2