Fecal Indicator Bacteria (FS-22-04)

Fecal indicator bacteria (FIB) assays are used as surrogate measures of the sanitary quality of surface waters and industrial discharges. Most states have recreational water quality criteria (RWQC) that specify limits for FIB, with total coliform, fecal coliform, Escherichia coli (E. coli), and enterococci classified as FIB. Limits vary depending on the designated use of the water body, time of year, and other local factors. To ensure that treated pulp and paper mill effluents do not pose a risk to human health and to protect recreational use (e.g., swimming, fishing, boating) in receiving waters, National Pollutant Discharge Elimination System (NPDES) permits may include limits or monitoring requirements for FIB. NPDES permits specify the FIB endpoint to be measured, the frequency and timing of testing (e.g., year-round or seasonal monitoring), and the acceptable analytical test methods.

Historically, fecal coliform was the most common FIB monitoring endpoint in NPDES permits. However, in response to EPA’s RWQC recommendations, there has been a shift to monitoring for E. coli in freshwaters and enterococci in marine/estuarine waters because results from these assays provide a more robust association with illness rates in epidemiological studies than other FIB endpoints. As states update their RWQC criteria to be consistent with EPA’s recommendations, mills that previously had fecal coliform limits and/or monitoring requirements in their NPDES permits are more likely to see E. coli and enterococci limits and/or monitoring requirements in the future. Despite this change, the Food and Drug Administration (FDA) continues to require fecal coliform monitoring in shellfish harvest zones, and fecal coliform may also be required if the receiving water has a Total Maximum Daily Load (TMDL) for fecal coliform.

This fact sheet provides an overview of the analytical methods commonly used to test for FIB in pulp and paper mill effluents and implications for the industry.

Keywords: fecal indicator bacteria, recreational water quality criteria