ABSTRACT-Setting priorities to schedule and implement wellhead protection programs for municipal and community drinking water supplies is presented in the framework of a general risk assessment approach. This includes a hazard identification procedure representing the likelihood of contaminants being released to the surface environment, a hydrogeologic vulnerability assessment representing the risk of contaminants entering the groundwater supply, and an impact assessment, strongly linked to the population at risk. A methodology was developed to aggregate information on a county basis for Minnesota. The resulting composite risk index map shows a number of counties in the central part of the state roughly following a line from the Twin Cities Metropolitan area along two major transportation axes to the St. Cloud and Fargo-Moorhead area, and toward the south to the Rochester-Austin area to which a high priority for phasing-in of the program is recommended. These counties emerge in addition to those in the southeastern karst area of Minnesota that traditionally have been identified as vulnerable areas
