Bacterial Indicators and Epidemiological Studies at Beaches; Implications for Stormwater Management

Based on epidemiological studies at beaches in the U.S., the USEPA has recommended for a number of years that states use enterococci as the bacterial indicator for marine waters and either enterococci or E. coli as the indicator for freshwaters (USEPA 1986). The Massachusetts Department of Environmental Protection (DEP) recently completed a comprehensive review and critical analysis of the more recent (mostly non-EPA) published epidemiological studies that were conducted subsequent to EPA's original recommendation. The purpose of the review was to evaluate the more recent epidemiological studies to determine whether the findings were consistent with the 1986 EPA guidance. In addition, DEP considered the following questions as part of the review:How much of a risk does wet weather stormwater/urban runoff pose to recreational water users?Can a single indicator adequately predict a range of illnesses in swimmers in marine waters?