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Geoff Dates, rv V r.R NETWORK ,.~ en you swim in lakes and streams, you run. the risk of swallowing water laced with disease-causing organisms w (pathogens). So, what is the risk of getting sick at your favorite swimming hole? That's where bacte- w ria monitoring comes in. Before we start in on the danger of bac- N teria, it's important to remember that many 'o bacteria perform essential functions in nature, o such as decomposition, carbon cycling, and nitro- ii gen rycling. What Are Fecal Bacteria and Why Are They Important.? When people drink, play in, or water their crops with contaminated water, they are exposed to not only bacteria, but other pathogens that are found in human waste, including viruses (like influenza) and protozoans (like cryptosporidium). ~...--~.. Bacteria are single-celled microorgan- isms, some of which are used as indicators of the presence of disease-causing organisms. Because it's too difficult to test for the pathogens themselves (there are too many and they tend to mutate more quickly than tests can be devel- oped), members of two bacteria groups, coliforms and fecal streptococci, are used as indicators of possible sewage contamination. Although they are generally not harmful themselves, they indicate the possible presence of disease causing organisms that live in human and animal digestive systems and are found. in their feces. If you find high levels of fecal indicator bacteria in your swimming hole, jumping in may be a health risk. Monitoring .bacteria is challenging: There are many that are naturally-occurring' in surface water and there are many sources of water "contamination, such as: malfunctioning. septic tanks; untreated poorly treated wastewater; com- a biped sewer overflows; leaking sewer lines; pollut- ed runoff; and wildlife. A good indicator bacteria needs to: ° Be there all the time ° Be consistently and exclusively associated with human feces ° Be easily and quickly detected • Able to be cultured predictably and reliably ° Mimic the survival of pathogens ° Provide a good association with health risk Indicator Bacteria Types and What They Can Tell You The most commonly tested fecal bacteria indica- tors are the groups total coliforms, .fecal coliforms, and fecal streptococci.. All are com- prised of a number of species of bacteria that share common characteristics such as shape, habi- tat, or behavior. Within these groups, enterococci and Escherichid tali (E. colt) are tested. E. tali is a single species in the fecal coliform group. Which bacteria you test for depends on what you want to know. Do you want to know whether swimming in your stream poses a health risk? Do you want to know whether your stream is meeting state water quality standards? Studies conducted by the Environ- mental Protection Agency (EPA) to detemrirte the correlation between different bacterial indicators and the occurrence of digestive system illness at swunrning beaches suggest that the best indicators of health risk from recreational water contact in fresh. water are E. tali and enterococci. Interestingly, fecal coliforms as a group were determined to be a poor indicator of the risk of digestive system illness. However, many states continue to use fecal coliforms as their primary health risk indicator. The Minnesota Pollution :Control Agenry uses both fecal coliforms and E. tali testing as indicators of water quality. In addition to bacteria testing, some ther indicators of the presence of sewage include optical brighteners used in many detergents and genotyping of bacteria, which is a complex and expensive procedure that looks for a genetic "sig- nature"'of a particular bacteria. Which Method? Bacteria'. can be difficult to analyze,. even in a laboratory, primarily because the procedures are complex' "and absolutely sterile conditions are required. (continued on page 12) Page 11