Hills, Iowa is a small town of approximately 700 residents located roughly 10 miles south of Iowa City, Iowa. During an EPA investigation of a former USDA Grain Storage site, perchlorate was detected in a background groundwater sample. Subsequent investigations revealed a sizeable plume of perchlorate in groundwater in excess of the 15 ppb action level with no obvious source (annual town fireworks displays are suspected but not confirmed). Because Hills did not have a public water system at the time and all residences and businesses sources their water from private, and usually shallow, wells, affected residents were immediately supplied with bottled water to sever the exposure pathway while investigations were performed. Following this, private wells were tested regularly and any home affected by the contamination was provided with a reverse osmosis filter system until a permanent solution was put in place. In September 2015, the city of Hills officially opened its Public Water Treatment Plant, which had been designed to treat the water for the perchlorate and provide safe, clean drinking water to the community.