Research Meeting Report: Knowledge and Gaps in Developing Microbial Criteria for Inland Recreational Waters Samuel Dorevitch,1 Nicholas J. Ashbolt,2 Christobel M. Ferguson,3,4 Roger Fujioka,5 Charles D. McGee,6 Jeffrey A. Soller,7 and Richard L. Whitman 8 1University of Illinois at Chicago School of Public Health, Chicago, Illinois, USA; 2Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA; 3Ecowise Environmental, Penrith, New South Wales, Australia; 4Australian National University, Canberra, Australian Capitol Territory, Australia; 5University of Hawaii, Water Resources Research Center, Honolulu, Hawaii, USA; 6Orange County Sanitation District, Fountain Valley, California, USA; 7Soller Environmental, Berkeley, California, USA; 8U.S. Geological Survey, Lake Michigan Ecological Research Station, Porter, Indiana, USA The U.S. Environmental Protection Agency (EPA) has committed to issuing in 2012 new or revised criteria designed to protect the health of those who use surface waters for recreation. For this purpose, the U.S. EPA has been conducting epidemiologic studies to establish relationships between microbial measures of water quality and adverse health outcomes among swimmers. New methods for testing water quality that would provide same-day results will likely be elements of the new criteria. Although the epidemiologic studies upon which the criteria will be based were conducted at Great Lakes and marine beaches, the new water quality criteria may be extended to inland waters (IWs). Similarities and important differences between coastal waters (CWs) and IWs that should be considered when developing criteria for IWs were the focus of an expert workshop. Here, we summarize the state of knowledge and research needed to base IWs microbial criteria on sound science. Two key differences between CWs and IWs are the sources of indicator bacteria, which may modify the relationship between indicator microbes and health risk, and the relation- ship between indicators and pathogens, which also may vary within IWs. Monitoring using rapid molecular methods will require the standardization and simplification of analytical methods, as well as greater clarity about their interpretation. Research needs for the short term and longer term are described. Key words: Clean Water Act, environmental epidemiology, environmental microbiology, indica- tor bacteria, inland waters, predictive modeling, waterborne pathogens, water recreation. Environ Health Perspect 118:871–876 (2010). doi:10.1289/ehp.0901627 [Online 25 January 2010] Recreational Water Quality Criteria Ambient water quality criteria. Viral, bacterial, and protozoan pathogens are responsible for infectious disease outbreaks among recreators at coastal and inland sur- face waters (Yoder et al. 2008). To protect the public from recreational waterborne illness, the U.S. Environmental Protection Agency (EPA) established ambient water quality crite- ria (AWQC; U.S. EPA 1986). The epidemio- logic studies on which the current AWQC are based suggest that at freshwater beaches, the rate of acute gastrointestinal illness attribut- able to swimming should be about 8 cases per 1,000 swimmers when monthly geo- metric mean (GM) density (concentration) of Escherichia coli is < 126 colony-forming units (CFU)/100 mL), or if the monthly GM density of enterococci is < 33 CFU/100 mL (EPA 1984). For marine waters, the gastro- intestinal illness rate should be about 19 per 1,000 swimmers when monthly GM entero- cocci densities do not exceed 35 CFU/100 mL (U.S. EPA 1983). Additionally, single-sample maximum values were established to aid in day-to-day beach management. For freshwater beaches, these maxima are 235 CFU/100 mL for E. coli or 61 CFU/100 mL for enterococci; for marine beaches, the single sample maxi- mum for enterococci is 104 CFU/100 mL. Nonetheless, final implementation guide- lines for the 1986 AWQC were never issued, and prior to the passage of the Beaches Environmental Assessment and Coastal Health Act (BEACH Act 2000), only 11 states applied the criteria to their marine or Great Lakes recreational waters [herein referred to collectively as coastal waters (CWs)] (U.S. EPA 2006). Indicators and their limitations. Fecal indicator bacteria (FIB), such as enterococci and E. coli, are measured because they are thought to indicate the presence of fecal matter, and potentially pathogens, in sur- face waters. Compared with the pathogens that cause recreational waterborne infections, FIB are easier to detect and enumerate using well-established and inexpensive methods. Epidemiologic studies support the use of FIB as predictors of illness rates among swimmers (Wade et al. 2003). Culture techniques for FIB require a min- imum of 18–24 hr to perform. Thus, beach managers evaluate information that is, at best, 1 day old when deciding to issue swimming bans or advisories. By the time FIB results become available, the microbial water qual- ity may have changed substantially (Boehm 2007; Hou et al. 2006; Whitman et al. 2004). Illness rates at beaches that are impacted by human sewage are related to FIB, which are Environmental Health Perspectives • volume 118 | number 6 | June 2010 measured by culture (U.S. EPA 1983, 1984) or by rapid molecular methods (Wade et al. 2006, 2008), but at beaches without point sources of human fecal pollution, this may not be true (Calderon et al. 1991; Colford et al. 2007). If the environmental sources and persistence of FIB were similar to those of pathogens, FIB should be good predictors of human illness. However, FIB may per- sist or even regrow in soil, plants, sand, and sediments (Byappanahalli and Fujioka 2004; Byappanahalli et al. 2006; Davies et al. 1995; Desmarais et al. 2002)—environments that, without a suitable host organism, do not sup- port the replication of human viral or proto- zoan pathogens. Boehm et al. (2009) recently reviewed these and other limitations of FIB as indicators. Inland water recreation, risk, and regu- lation. Inland flowing (riverine) waters are surface waters with a net directional current and are confined by banks and stream beds. Lacustrine waters are freshwater bodies gener- ally confined to a basin (lakes). According to the U.S. EPA ATTAINS database (2009), the United States has > 3.5 million miles of inland flowing waters and more than 41 mil- lion acres of inland waters (IWs). The 1986 AWQC were based almost entirely on epidemiologic studies conducted at coastal beaches, with a small portion of Address correspondence to S. Dorevitch, UIC School of Public Health, 2121 W. Taylor, M/C 923, Chicago, IL 60612 USA. Telephone: (312) 355-3629. Fax: (312) 413-9898. E-mail: sdorevit@uic.edu We acknowledge all workshop participants for their efforts. Many thanks to S. Briggs, Michigan Department of Environmental Quality, for her com- ments. We acknowledge the Water Environment Research Foundation (WERF) and the U.S. EPA for organizing the expert workshop. R.L.W.: Contribution 1583 of the U.S. Geological Survey Great Lakes Science Center. This manuscript has been reviewed by the U.S. Environmental Protection Agency (EPA) and by the U.S. Geological Survey (USGS). The views expressed by the authors are not necessarily policy nor the views of U.S. EPA or the USGS. S.D. currently receives research support from the WERF and the Metropolitan Water Reclamation District of Greater Chicago. J.A.S. is employed by Soller Environmental, Berkeley, CA. The remaining authors declare they have no actual or potential com- peting financial interests. Received 26 October 2009; accepted 25 January 2010. 871