If the boards, acting jointly, shall establish such district, the auditors of the several counties shall immediately thereafter, acting jointly, cause notice to be given of the time and place of the meeting of the boards for letting contracts for the construction of the improvement. The notices, bids, bonds, and all other proceedings in relation to letting contracts shall be the same as provided where the district is wholly within one county, but duplicates of contractors' bonds shall be filed with the auditor of each county.
Iowa Code § 468.289
89 Acts, ch 126, §2