The Sanitation Districts are a partnership of "special districts" formed under California law. Special districts are governed by a board of directors made up of elected officials from the local government agencies served by the district. The board of directors for a county sanitation district is made up of elected officials from each city within the sanitation district and the Chairperson of the Board of Supervisors representing unincorporated areas. In cases where a county sanitation district is entirely within one city or is entirely unincorporated territory, either all members of the city council or the Board of Supervisors are the board of directors. The boundaries of county sanitation districts are often established by drainage areas and may not follow political boundaries.