The county board establishes policy by approving ordinances. Ordinances are local laws prescribing rules of conduct and are enforced by county officials. Ordinances become a permanent part of the governmental code and may be amended from time to time. Once policy has been approved by the county board of supervisors through plans, budgets, ordinances, and resolutions, it is the responsibility of county staff to implement the decisions of the board.
Wisconsin Counties Association

Current Polk County Code of Ordinances 
Code of Ordinance - MuniCode Comprehensive Ordinance Library

The legacy, historic versions of the County Ordinances can be found here.