OPINION & ORDER In 2011, the United States Environmental Protection Agency and its Administrator (collectively, “EPA”) decided to regulate the presence of the chemical perchlorate in drinking water, triggering statutory rulemaking deadlines under the Safe Drinking Water Act of 1974 (the “Act”). Five years later, the National Resources Defense Council, Inc. (“NRDC”), a national not-for-profit environmental and public health organization, brought this citizen suit against the EPA for its failure to comply with the rulemaking mandate of the Act. Ultimately, the parties entered a consent decree through which the EPA agreed to propose and issue final standards. Before finalizing its proposed regulations, however, the EPA withdrew its decision to regulate perchlorate at all. Now pending before this Court are the EPA’s motion to terminate the consent decree based on this change of circumstance, and the NRDC’s cross-motion to enforce the consent decree as written. Concurrently, the NRDC is challenging the EPA’s decision not to regulate perchlorate before the D.C. Circuit in NRDC v. Wheeler, No. 20-1335, and the EPA has requested, in the alternative, that this Court stay these proceedings pending the Circuit’s decision. For the reasons set forth below, the Court stays this case pending decision in Wheeler. I. Background In 1974, Congress passed the Act, 42 U.S.C. §300f et seq., authorizing the EPA to issue standards to protect public water systems. Under the Act, the EPA’s Administrator must publish a maximum contaminant level goal (“MCLG”)1 and promulgate a national primary drinking water regulation (“NPDWR”) for any particular contaminant once it determines that (i) the contaminant may have an adverse effect on the health of persons; (ii) the contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern; and (iii) in the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems. §300g-1(b)(1)(A). To make its determination, the Administrator must rely on “the best available public health information” and a database of the occurrence of contaminants in public water systems. §300g-1(b)(1)(B)(ii)(II). If, based on these criteria, the Administrator chooses to regulate a contaminant, she must propose an MCLG and an NPDWR within 24 months and publish them within 42 months. §300g-1(b)(1)(E). “[P]rior to” proposing any contaminant level or regulation, the Administrator must also request comment from the Science Advisory Board (the “Board”).2 §300g-1(e). Consultation with the Board, however, “shall, under no circumstances, be used to delay final promulgation of any national primary drinking water standard.” Id. The Act further specifies that in carrying out the duties enumerated in 300g-1, the Administrator must use “the best available, peer-reviewed science and supporting studies conducted in accordance with sound and objective scientific practices; and data collected by acceptable methods or best available methods[.]” §300g-1(b)(3)(A)(i)-(ii). Citizens may bring a civil action in district court against the Administrator if she “ fail[s]…to perform any act or duty under this subchapter which is not discretionary.” §300j-8(a)(2). Lawsuits otherwise challenging “actions pertaining to the establishment of” NPDWRs and MCLGs must be filed in the D.C. Circuit. §300j-7(a)(1). On February 11, 2011, the EPA decided to regulate the presence of perchlorate in public drinking water under §300g-1(b)(1)(A) (“2011 Determination”). Doc. 1 at
4, 30, 52-53. Perchlorate is a negatively charged inorganic ion consisting of one chlorine atom and four oxygen atoms. Doc. 65-1 at 4. Perchlorate can occur naturally as a result of atmospheric processes and can be found in mineral deposits. Id. It is also a byproduct of the rocket, missile and firework industries and can come from the degradation of hypochlorite solutions used to disinfect water. Id. People are typically exposed to perchlorate in their food or drinking water. Id. Ingesting a certain level of perchlorate can inhibit thyroid hormone production, which may cause changes in fetal brain development in pregnant women. Id. at 4-5. On May 29, 2012, the EPA consulted with the Board on interpreting more recent data on the health effects of perchlorate than had informed its 2011 Determination. 84 Fed. Reg. 30,524, 30,561 (June 26, 2019). One year later, on May 29, 2013, the EPA “received significant input from” the Board and, to address the Board’s recommendations, the EPA collaborated with the Food and Drug Administration scientists to develop models incorporating all available health information about perchlorate. Id. On February 18, 2016, the NRDC filed the instant complaint alleging that the EPA failed to comply with its nondiscretionary duties under the Act to propose and finalize an MCLG and an NPDWR regarding perchlorate following the 2011 Determination. Doc. 1. On September 19, 2016, the Court issued a short order finding that the EPA’s failure to set an MCLG and an NPDWR under §300g-1(b)(1)(E) constituted failure to perform non-discretionary duties. Doc. 24 at 3. On October 18, 2016, the parties entered a consent decree by which the EPA agreed to complete the external peer-review process, propose MCLG and NPDWR by October 31, 2018, and publish final MCLG and NPDWR by December 19, 2019. Doc. 38 at
