The State of Hawaiʻi monitors its marine coastal waters using the U.S. Environmental Protection Agency (EPA) 1986 Ambient Water Quality Criteria for Bacteria. A beach is considered "on alert" for poor water quality if either: (a.) the latest water sample exceeds 104 CFU/100 mL of Enterococcus, or (b.) the geometric mean of the past 30 days of water samples exceeds 35 CFU/100 mL Enterococcus. The State of Hawaiʻi also utilizes Clostridium perfringens as a secondary tracer to help distinguish between sewage and non-sewage sources of elevated Enterococcus levels. If Enterococcus concentrations remain elevated after resampling, a Clostridium perfringens concentration exceeding 50 CFU/100 mL requires a "Waste Water Condition" to be publicly posted.
Enterococcus bacteria has been correlated with the presence of human pathogens (disease-causing organisms) and therefore with human illnesses such as gastroenteritis, diarrhea, and various infections in epidemiological studies. Clostridium perfringens bacteria is a normal component of the human intestinal tract, and its presence in samples of sea water can be used as a tracer of sewage contamination. As such, concentrations of these bacteria are commonly measured in beach water quality monitoring programs.