The executive and administrative powers, authorities, and duties in cities adopting the commission plan of government shall be distributed into and among departments as follows:
In cities of the metropolitan class, (1) finance, (2) fire, (3) human resources, (4) human rights and relations, (5) law, (6) parks, recreation, and public property, (7) planning, (8) police, and (9) public works;
In cities of the primary class, (1) department of public affairs, (2) department of accounts and finances, (3) department of public safety, (4) department of streets and public improvements, and (5) department of parks and public property; and
In cities containing two thousand or more and not more than forty thousand inhabitants as determined by the most recent federal decennial census or the most recent revised certified count by the United States Bureau of the Census, (1) department of public affairs and public safety, (2) department of accounts and finances, (3) department of streets, public improvements, and public property, (4) department of public works, and (5) department of parks and recreation.
The city council shall provide, as nearly as possible, the powers and duties to be exercised and performed by, and assign them to, the appropriate departments. The city council may prescribe the powers and duties of all officers and employees of the city and may assign particular officers, or employees, to more than one of the departments, may require any officer or employee to perform duties in two or more of the departments, and may make such other rules and regulations as may be necessary or proper for the efficient and economical management of the business affairs of the city.