Iowa Code § 400.1: Appointment of commission.

1. In cities having a population of eight thousand or over and having a paid fire department or a paid police department, the mayor, one year after a regular city election, with the approval of the council, shall appoint three civil service commissioners. The city shall publish notice of the names of persons selected for appointment pursuant to section 362.3. Commissioners shall hold office, one until the first Monday in April of the second year, one until the first Monday in April of the third year, and one until the first Monday in April of the fourth year after such appointment, whose successors shall be appointed for a term of four years. In cities having a population of more than fifty thousand, the city council shall establish, by ordinance, the number of civil service commissioners at not less than five but not more than seven.

2. For the purpose of determining the population of a city under this chapter, the federal census conducted in 1980 shall be used.