Iowa Code § 311.10: Estimate and apportionment — presumption.

Said estimated cost shall carry the presumption, in the absence of a contrary showing, that the same correctly represents the probable cost of said project as nearly as can be determined in advance of the actual doing and completion of the work. Said apportionment shall carry the presumption, in the absence of a contrary showing, that the same is fair, just, equitable, and in proportion to the benefits and not in excess thereof.