Be it further enacted, That within the framework established by this Act, the administrative organization of the city shall be organized into departments of general government, finance, and such other departments necessary to provide health, welfare, police, recreation, fire, public works, utilities, and other municipal services as shall be provided in a plan of administrative organization approved by the city council and adopted by ordinance. The council may by ordinance amend the plan of administrative organization. Such departments as are in effect on the effective dates of this Act shall continue in effect until changed by ordinance.