Hydrologic Science Vs. Regulatory Policy: USEPA’s Watershed Control Requirements For Cryptosporidium
Pontius, Frederick W. 1
1 Dept. of Civil, Environmental, and Architectural Engineering, University of Colorado, Boulder, Colo.
Watershed control is one option within the US Environmental Protection Agency’s (USEPA’s) Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) microbial toolbox for public water systems to provide extra protection against Cryptosporidium. To receive credit for removal of Cryptosporidium, a watershed control program must meet certain requirements.
Watershed control programs must include an analysis of the system’s source water vulnerability to the different sources of Cryptosporidium. Assessments must include a characterization of watershed hydrology, identification of an “area of influence on source water quality,” sources of Cryptosporidium, seasonal variability, and the relative impact of the sources of Cryptosporidium on the system’s source water quality. An analysis of sustainable interventions and an evaluation of their relative effectiveness in reducing Cryptosporidium in source water is required.
Federal regulatory policy can have both a positive and negative affect on the advancement of science. This review of the state of knowledge regarding Cryptosporidium sources, fate, and transport within a surface watershed demonstrates that USEPA’s presumptive 0.5 log removal ‘credit’ has a weak scientific basis. The implications of this for researchers, regulators, and regulated water utilities will be discussed.
USEPA. 2006, Final Long Term 2 Enhanced Surface Water Treatment Rule. Federal Register, v. 71, p. 653-702.
Davies, C., Kaucner, C., Altavilla, N., Ashbolt, N., Fuerguson, C., Krogh, M., Hijnen, W., Medema, G., and Deere, D. 2005, Fate and Transport of Surface Water Pathogens in Watersheds, AWWA Research Foundation, Denver, Colo.