Iowa Code § 75.1: Bonds — election — vote required.

1. When a proposition to authorize an issuance of bonds by a county, township, school corporation, city, or by any local board or commission, is submitted to the electors, such proposition shall not be deemed carried or adopted, anything in the statutes to the contrary notwithstanding, unless the vote in favor of such authorization is equal to at least sixty percent of the total vote cast for and against said proposition at said election. All elections on such proposition shall be held on the date specified in section 39.2, subsection 4, paragraph “d”.

2. Ballots cast but not counted as a vote for or against the proposition shall not be used in computing the total vote cast for and against said proposition.