Supreme Court Rules that Clean Water Act Covers Groundwater Discharges

6 min read

The Supreme Court ruled on April 23, 2020 that federal law can require a permit for pollutant discharges that travel through groundwater to surface water. The Court’s ruling establishes a new standard by which a Clean Water Act (CWA) permit is required for discharges through groundwater, and rejects the Trump administration’s argument that the CWA does not apply to any discharges through groundwater.  

In an unexpected 6-3 decision in one of the most high profile environmental cases before the Court, the April 23 opinion said that the CWA’s permitting requirements apply to any direct discharge from a point source into federally regulated surface waters or the “functional equivalent of a direct discharge” from a point source to these waters. The Court noted that the hallmark of whether a particular indirect discharge is subject to CWA permitting requirements depends upon how similar it is to a direct discharge. 

In describing this “functional equivalence”, the Court highlighted two factors: (i) the distance pollution must travel to reach a federal waterway, and (ii) the time it takes to get there, but also noted that distinctive circumstances may warrant consideration of other facts. For example, the Court noted,“[w]here a pipe ends a few feet from navigable waters and the pipe emits pollutants that travel those few feet through groundwater (or over the beach), the permitting requirement clearly applies”. On the other hand, “if the pipe ends 50 miles from navigable waters and the pipe emits pollutants that travel with groundwater, mix with much other material, and end up in navigable waters only many years later, the permitting requirements likely do not apply.” The Court also listed the following factors as potentially relevant in determining “functional equivalence”: (i) the nature of the material through which the pollutant travels, (ii) the extent to which the pollutant is diluted or chemically changed as it travels, (iii) the amount of the pollutant entering the navigable water relative to the amount of the pollutant that leaves the point source, and (iv) the manner by or area in which the pollutant enters the navigable water.  

The Court acknowledged that the “functional equivalent” standard leaves some uncertainty about what is covered under the CWA, but noted that “there are too many potentially relevant factors applicable to factually different cases for this Court now to use more specific language.” Owners and operators of facilities with a groundwater connection in particular may now face uncertainty as to when a federal CWA permit is required. Previously unpermitted utilities, pipelines, energy facilities, development projects and green infrastructure with stormwater or wastewater discharges could now be required to maintain federal CWA permits. 

The Court provided additional guidance as to how to interpret its new rule. First, it cautioned lower courts and agencies to take into account the traditional role of states when interpreting the scope of federal authority over discharges through groundwater. Second, recognizing that its ruling will expand the regulatory reach of the CWA, and potentially subject previously unregulated discharges to federal permitting requirements, the Court urged lower courts to be mindful of “any good-faith effort to comply” with the CWA, and “the economic impact of the penalty on the violator” when setting fines and other punishments for violations of the CWA. 

The Court’s opinion came in Cty. of Maui v. Hawai’i Wildlife Fund, which concerns whether Maui was required to hold a CWA permit for its wastewater facility that pumps partially treated sewage through underground wells. This partially treated sewage then migrates via groundwater to the Pacific Ocean. Environmental groups sued Maui in 2012, arguing that Maui was violating the CWA by discharging sewage without a CWA permit. Maui argued it is not subject to CWA permitting requirements because the pollution’s path to the ocean is indirect via groundwater and not conveyed directly from a point source to the ocean. The Court’s April 23 ruling is in response to Maui’s appeal of a 2018 lower court finding that a CWA permit is required when pollutants are "fairly traceable" to a point source. The Supreme Court rejected the lower court’s “fairly traceable test” noting that the test would have allowed “permitting authority over the release of pollutants that reach navigable waters many years after their release.” The Court reasoned that such a sweeping interpretation of the CWA is not in line with the law’s intent or the structure, which indicates that Congress left “substantial responsibility and autonomy” to the states for groundwater pollution. However, with its April 23 ruling, the Court finds that the CWA does not completely relinquish control over groundwater to the states, as discharges that pass through groundwater into waters of the United States can be subject to CWA permitting.

The Supreme Court’s decision comes one day after the Trump administration’s Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers published the Navigable Waters Protection Rule (the NWPR) on April 21, 2020. The NWPR specifically clarified that “waters of the United States” did not include groundwater. The Trump administration’s Solicitor General argued to the Court that the CWA does not apply to any discharges through groundwater. The Court, in a rebuke to the Trump administration, rejected the interpretation that the Solicitor General put forth in the Cty. of Maui v. Hawai’i Wildlife Fund case, noting that it “would open a loophole allowing easy evasion of the statute’s basic purposes”. In rejecting this interpretation, the Court explained that “[i]f that is the correct interpretation of the statute, then why could not the pipe’s owner, seeking to avoid the permit requirement, simply move the pipe back, perhaps only a few yards, so that the pollution must travel through at least some groundwater before reaching the sea?” The Court’s decision could be employed by litigants challenging the NWPR and the exclusion therein of groundwater from the definition of “waters of the United States.”

Litigation is expected over what discharges constitute “functionally equivalent” direct discharges, which litigation may result in more refined principles for what indirect discharges trigger CWA permitting. However, some commentators laud the Court’s decision as a workable middle ground that provides clarity to a difficult legal issue that has evaded resolution for many years and is consistent with the intent of the CWA. 

A copy of the opinion can be found here.

A copy of the NWPR can be found here. The NWPR will become effective 60 days after publication, on June 22, 2020, barring the issuance of a stay or other injunctive relief from litigation challenging the rule.


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