The activities or functions of the county shall, with the exceptions herein provided, be distributed among the following departments:
The board may establish any additional departments it deems necessary and appropriate.
In addition, any activity which is unassigned by this form of county organization and government shall, upon recommendation of the county manager, be assigned by the board to the appropriate department. The board may further, upon recommendations of the county manager, reassign, transfer or combine any county functions, activities or departments.
Va. Code § 15.2-616