Court of Appeals Overrules EPA Decision Not to Regulate Perchlorate

On May 9, 2023 a U.S. Court of Appeals overruled EPA’s July 21, 2020 published decision not to regulate perchlorate in drinking water. Many news outlets are reporting this decision. Link to AP News article:
AP News Article

Link to US Court of Appeals Decision
US Court of Appeals_Perchlorate Decision_2023-05-10

In February 2011 EPA made a determination to regulate perchlorate in drinking water. In October 2016, the US District Court for the Southern District of New York entered a consent decree (with EPA and the Natural Resources Defense Council, NRDC) requiring EPA to “sign for publication in the Federal Register” a proposed Maximum Contaminant Level Goal (MCLG) and an MCL by the end of October 2018. The consent decree requires EPA to publish a final MCLG and MCL by December 19, 2019.

On June 26, 2019 EPA proposed the perchlorate MCLG and MCL at 56 ppb. The 60-day public comment period closed on August 26, 2019. In addition, EPA requested public comment on the following three alternatives:

1. MCLG and MCL at 18 ppb.
2. MCLG and MCL at 90 ppb
3. Withdrawing EPA’s February 2011 determination to regulate perchlorate in drinking water “…based on new information that indicates that perchlorate does not occur in public water systems with a frequency and at levels of public health concern and there may not be a meaningful opportunity for health risk reduction through drinking water regulation.”

On July 21, 2020 EPA published its decision not regulate perchlorate in drinking water (EPA_Fed Reg_Perchlorate Final No MCL_2020-07-21 ).

Following EPA’s July 21, 2020 Federal Register notice indicating that the Agency will not establish an MCL for perchlorate, on September 3, 2020, the NRDC filed suit in the U.S. Court of Appeals (DC Circuit) challenging EPA’s decision.