What Supervisors Do

Here is a link to the Jefferson County Board of Supervisors main page. It describes all about who the current supervisors are and what they do.
The Board of Supervisors is the executive and administrative branch of county government. The supervisors make policy for the county, administer the various county programs, have final authority over the county budget, and represent the county at the state level.

The three Jefferson County Supervisors are elected to four-year terms by both rural and city voters. They share an office on the first floor of the Jefferson County Courthouse.

County governments are the quiet, consistent providers of essential services. Structurally, the county governments continue to serve as the regional government for Iowa. They also perform many state administrative functions such as the issuance of licenses and permits.

Also, they provide public services of a purely local nature such as roads and bridges, property ordinances, provision of health and indigent care, and maintenance of the county jail. Counties also cooperate among themselves to provide enhanced services to their citizens.

http://www.jeffersoncountyiowa.com/supervisors.htm