Branch-Hillsdale-St.Joseph Community Health Agency (CHA) reported an outbreak of cryptosporidiosis in 28 people who participated in a private pool party. Investigators said the problem resulted from improper operation of a system that uses salt to create chlorine to disinfect the pool. CHA authorities said the owner was not running the system enough for the heavy load of people at the 3-day party so the residual chlorine was not there.