Is EPA's Decision the End of the Road on Perchlorate?

The U.S. Environmental Protection Agency (EPA) announced on March 31, 2022, that it did not intend to regulate perchlorate in drinking water, leaving its July 2020 decision in place. EPA concluded that the prior decision was based on the best available science. This has been a long road since Massachusetts was one of the first states to regulate perchlorate in drinking water in 2006. (See Holland & Knight newsletter, "Massachusetts Proposes First-in-the-Nation Drinking Water and Cleanup Standards of 2 ppb for the Chemical Perchlorate.") Ironically, it was the quick and decisive action by states years ago that resulted in EPA's 2020 conclusion that perchlorate occurrence in the environment has decreased over time and does not meet the criteria for regulation under the Safe Drinking Water Act (SDWA).

To recap, in June 2020, EPA announced it had determined that perchlorate does not meet the criteria for regulation as a drinking water contaminant under the SDWA and thus withdrew the 2011 Regulatory Determination. (See Holland & Knight's Energy and Natural Resources Blog, "EPA Finalizes Its Perchlorate Decision," June 23, 2020.) EPA's final decision was published on July 21, 2020. Specifically, EPA determined that perchlorate does not occur "with a frequency and at levels of public health concern" within the meaning of the SDWA and that regulation of perchlorate does not present a "meaningful opportunity for health risk reduction for persons served by public water systems."

EPA specifically reevaluated the 2011 Regulatory Determination over many years of conducting multiple analyses evaluating the occurrence data collected from the Unregulated Contaminant Monitoring Rule (UCMR) and other monitoring by Massachusetts and California. (See Holland & Knight alert, "EPA Proposes Perchlorate Rule After Years of Study," June 10, 2019.) Based on this data reevaluation, EPA concluded that only 15 regulated public water systems in the U.S. would exceed even the lowest proposed value under consideration (18 ug/L). As a result, pursuant to SDWA Section 1412(b)(4)(C), EPA determined that, based on available information, the benefits of establishing a National Primary Drinking Water Regulation for perchlorate did not justify the associated costs. Under the SDWA evaluation and rulemaking process, EPA is required to determine that regulation presents a meaningful opportunity for health risk reductions served by public water systems before proceeding with regulation.

The Natural Resources Defense Council promptly issued a statement condemning the action. Given its prior litigation challenging the 2020 determination, it remains to be seen whether this decision is, indeed, the end of the road. Stay tuned.