Meeting the Source Assessment Requirement under the RTCR: A Wisconsin Pilot Project

The goal of this project was to develop a sampling and testing algorithm to support the new site assessment requirements under the Revised Total Coliform Rule (RTCR) consistent with the “find and fix” goals of the Wisconsin Department of Natural Resources (WDNR). Because of the large number of public water supplies falling into the category of Transient Non-Community Water Systems (TNCWS) in Wisconsin, the WI DNR has elected to conduct both Level 1 and Level 2 Assessments under the RTCR for these systems. The final proposed process involves (1) sanitary surveys, (2) measurement of a suite of microbial indicator organisms, and (3) corrective action. The first two components of the protocol were developed at the Wisconsin State Laboratory of Hygiene and the last component is the responsibility of the Water Supply Section in collaboration with the property owners/well operators. The algorithm recommended for implementation as a State program involves a tiered sampling and analysis approach. In Tier 1, a site will be sampled and tested for coliforms, E. coli, enterococci, and adenosine triphosphate (ATP). Should any of the indicator enumerations return positive, the organisms will be speciated using the API 20E analytical profile index to determine if the species are of predominantly fecal or environmental origin or both. These results coupled with a sanitary survey and RTCR system Assessment, the decision to conduct large volume sampling and concentration followed by fecal source tracking analyses will be made. The source remediations achieved through implementation of this protocol is intended to provide a long-term solution that is sustainable, holistic, and economical for each public water supply investigated. The final analysis algorithm for transfer to a Wisconsin State Laboratory program was refined and is set for implementation in Fiscal Year 2017.