In June 2017 the Pennsylvania Department of Health (PDOH) was notified of acute gastrointestinal illness among attendees of a festival held at Venue A. Additional cases were identified from two additional Venue A festivals held in May 31-June 18. Social media pages for Venue A and affected events were used to solicit illness reports. Stool and vomitus specimens wee collected and tested for enteric pathogens. An environmental assessment was conducted on July 18-19 at Venue A and well, creek and ground water was tested for fecal microbes. PDOH received 179 self reports of illness associated with 3 festivals during June. Norovirus was detected in 7/8 clinical samples. Creek and well water samples also contained norovirus and other fecal microbes. A septic leach field was identified as the likely source of well contamination.