Iowa Code § 50.45: Canvass public — result determined.

All canvasses of tally lists shall be public, and the persons having the greatest number of votes shall be declared elected. When a public measure has been submitted to the electors, the proposition shall be declared to have been adopted if the vote cast in favor of the question is greater than fifty percent of the total vote cast in favor and against the question, unless laws pertaining specifically to the public measure election establish a higher percentage of a favorable vote. All ballots cast and not counted as a vote in favor or against the proposition shall not be used in computing the total vote cast in favor and against the proposition.