A vacancy in an elective City office during a term of office shall be filled, at the Council’s option, by one of the two following procedures:
(Code of Iowa, Sec. 372.13[2])
1. Appointment. By appointment following public notice by the remaining members of the Council within forty (40) days after the vacancy occurs, except that if the remaining members do not constitute a quorum of the full membership, or if a petition is filed requesting an election, the Council shall call a special election as provided by law.
(Code of Iowa, Sec. 372.13[2a])
2. Election. By a special election held to fill the office for the remaining balance of the unexpired term as provided by law.
(Code of Iowa, Sec. 372.13[2b])