An optional unified form of county government shall have all functions, except when otherwise allocated by this act, performed by 1 or more departments of the county or by the remaining boards, commissions, or authorities. Each department shall be headed by a director. Subject to the authority of the county manager or elected county executive the following departments and their respective directors may be established and designated to be responsible for performance of the functions enumerated:

    (a) The department of administrative services shall perform general administrative and service functions for the county government; carry on public relations and information activities and deal with citizen complaints; plan for, assign, manage, and maintain all county building space; and manage a central motor pool.

    (b) The department of finance shall supervise the execution of the annual county budget and maintain expenditure control; perform all central accounting functions; collect moneys owing the county not particularly within the jurisdiction of the county treasurer; purchase supplies and equipment required by county departments; and perform all investment, borrowing, and debt management functions except as done by the county treasurer.

    (c) The department of planning and development shall prepare comprehensive plans for the overall development of the county; coordinate the preparation of county capital improvement programs; supervise economic development functions; and represent the county in joint planning activities with other jurisdictions.

    (d) The department of medical examiners shall coordinate and supervise medical investigative activities.

    (e) The department of corporation counsel if adopted shall perform as provided by law all civil law functions and provide property acquisition services for the county as provided by law.

    (f) The department of parks and recreation shall develop, maintain, and operate all county park and recreation facilities and supervise all recreation programs except where the same is under a board of county road commissioners, or a parks and recreation commission.

    (g) The department of personnel and employee relations shall perform all personnel and labor relations functions for the county.

    (h) The department of health and environmental protection shall perform all public health services for the county and carry on environmental upgrading programs.

    (i) The department of libraries shall operate a general library program for the county if no library board or commission exists and may operate libraries for other governmental and semi-governmental entities.

    (j) The department of public works shall construct, maintain, and operate all county storm and sanitary sewer, sewage disposal, general drainage, and flood control facilities except as the same are performed by the county drain commissioner; may perform general engineering, construction, and maintenance functions for all county departments and, upon approval of the board, for other governmental and semigovernmental entities; may operate the county airport except where the airport is operated by a board of county road commissioners; may construct, maintain, and operate county solid waste systems including resource recovery and distribution; and may construct, maintain, and operate water processing and distribution systems.

    (k) The department of institutional and human services shall supervise county human service programs including hospitals and child care institutions.