In a county which has adopted a county manager form of government, the county manager shall distribute the administrative activities among the following departments:
1. Department of finance.
2. Department of public works.
3. Department of public welfare. The board of county commissioners may establish additional departments. Upon recommendation of the county manager, any activity which is unassigned by this chapter shall be assigned by the board to an appropriate department and any activity so assigned may be reassigned to another department.