The Safe Drinking Water Act (SDWA) authorizes the U.S. Environmental Protection Agency (EPA) to regulate contaminants in public water supplies. EPA regulates lead specifically through the 1991 Lead and Copper Rule (LCR; 40 C.F.R. Part 141 Subpart I). In the wake of detections of elevated lead levels in tap water in Flint, Michigan, and elsewhere, questions emerged regarding (1) the adequacy of SDWA authorities, and (2) the effectiveness of the LCR in limiting lead exposures and protecting public health.