These guidelines deal with health hazards associated with recreational water use, as well as aesthetic and nuisance conditions. Health hazards associated with direct contact with water include infections transmitted by pathogenic microorganisms, as well as injuries and illness due to physical and chemical properties of the water. The guidelines discuss the indicator organisms such as enterococci, Escherichia coli, other fecal coliforms, and coliphages, as well as health risks related to exposure to waterborne pathogenic bacteria, viruses, protozoa, and toxic blue-green algae. Sampling of recreational waters is also addressed. Other sections deal with physical, chemical, and aesthetic characteristics, nuisance organisms, microbiological methods of sampling and analysis, and posting of beaches and other recreational waters.