A well water sample taken from a bible summer camp in northeast Albany County, Wyoming, was collected after health officials heard about an outbreak of gastronenteritis that occurred among campers. Laboratory studies identified Campylobacter jejuni and noroviruses (genogroup I and II) as the causes of the outbreak. Epidemiologic and environmental health studies identified the camp’s contaminated well water system as the likely source of the infections. The camp was ordered closed until improvements were made in the camp’s septic system.