The criteria are based on levels of bacteria that can indicate the presence of pathogens (harmful bacteria, viruses or protozoa) that can cause human illness. Many such pathogens exist and monitoring for all of them would be impractical. Therefore, “indicator” bacteria have been selected that exhibit, in a given environment, a similar ability to survive as the pathogens of concern. Currently, three bacterial indicators are used to detect the presence of pathogens: E. coli, Enterococci, and Fecal Coliform.

Currently, the analysis for Fecal Coliform (FC) bacteria is the primary indicator of non-point pollution when evaluating ground and surface water quality. FC bacteria exist in the intestines of warm-blooded animals including humans, pets, livestock, birds, wildlife, etc. FC found in water samples can indicate the presence of human sewage and animal waste and their associated pathogens. Assessing contamination associated with this pollution source is the primary focus of the program. FC is the parameter selected to be monitored by the State Department of Ecology in freshwater streams, storm water runoff, seeps, etc.

Chemical and physical parameters that are monitored on a regular basis are Dissolved Oxygen (DO), nutrients (primarily Nitrogen), pH, turbidity, conductivity, and temperature, and are routinely recorded during Ambient Monitoring sampling.