Unregulated Contaminant Monitoring Regulation for Public Water Systems; Analytical Methods for List 2 Contaminants; Clarifications to the Unregulated Contaminant Monitoring Regulation

The Safe Drinking Water Act (SDWA), as amended in 1996, requires the U.S. Environmental Protection Agency to establish criteria for a program to monitor unregulated contaminants and to publish a list of contaminants to be monitored. In fulfillment of this requirement, EPA published the Revisions to the Unregulated Contaminant Monitoring Regulation (UCMR) for public water systems on September 17, 1999, which included lists of contaminants for which monitoring was required or would be required in the future. These lists included: List 1 for contaminants with approved analytical methods; List 2 for contaminants with methods that were being refined; and List 3 for contaminants with methods that were still being developed. Today's rule approves the analytical methods for thirteen chemical contaminants on List 2, and requires monitoring for those contaminants in drinking water. This rule also sets the schedule for monitoring one microbiological contaminant, Aeromonas, contingent on promulgation of its analytical method. These methods and associated monitoring will be used to support EPA decisions concerning whether or not to regulate and establish standards for these contaminants in drinking water. The intent of regulating and setting standards for any of these contaminants that may be found to occur at levels of health concern is to protect public health. Additionally, in today's rule, EPA includes modifications to the UCMR (published September 17, 1999) that affect the implementation of monitoring for both List 1 and List 2 contaminants.