Lessons from the first year of compliance sampling under Michigan's revised Lead and Copper Rule and national Lead and Copper Rule implications

In 2018, Michigan revised its Lead and Copper Rule (LCR) compliance sampling requirements to better represent the potential lead contribution from lead service lines (LSLs). The first year of sampling results under the new requirements were analyzed to determine their impact on lead sampling results. The dataset reveals statistically significant higher detected lead levels, both at individual sample sites and in some water system 90th percentiles. Michigan's LCR results reveal the percentage of public water systems with LSLs exceeding the lead action level (15 ppb) increasing to 13% compared to 2% under the previous sampling protocol. Michigan's experience demonstrates that solely collecting first-liter data, consistent with current LCR requirements, is inadequate for detecting the higher range of lead concentrations commonly found in LSL samples. As the 2021 EPA LCR revision includes fifth-liter and removes first-liter compliance sampling, Michigan's lessons portend national implications. This paper evaluates Michigan's novel 2019 LCR results, compares the results to previous sampling periods, and shares lessons learned for timely national policy decisions.