Supreme Court rules that Clean Water Act covers discharges to groundwater

The United States Supreme Court recently ruled that point source discharges to navigable waters through groundwater are regulated under the Clean Water Act.

In what was being referred to as “the Clean Water Act case of the century”, the Court answered the question of whether a release of a pollutant to groundwater that makes its way to navigable waters is regulated by the Clean Water Act. In short, yes, if the groundwater serves as the “functional equivalent of a direct discharge” to regulated waters.

The Clean Water Act prohibits the addition of a pollutant from a point source to navigable waters (also referred to as “waters of the U.S.”) without a National Pollutant Discharge Elimination System (NPDES) permit. In a 6-3 decision, the justices on April 23 affirmed the decision in the Ninth Circuit Court of Appeals in holding that an NPDES permit is required for either a direct discharge of pollutants into federally regulated rivers and oceans or the “functional equivalent of a direct discharge,” thus implicating a discharge into groundwater under certain circumstances.

The Court acknowledged that its decision was not a clear line, but did provide some guidance to federal courts as they wade through the facts specific to future cases in applying the new “functional equivalent” test: “Time and distance will be the most important factors in most cases, but other relevant factors may include, e.g., the nature of the material through which the pollutant travels and the extent to which the pollutant is diluted or chemically changed as it travels.” The Court then laid out seven factors to consider, depending on the circumstances of each case:

1. transit time;
2. distance traveled;
3. the nature of the material through which the pollutant travels;
4. the extent to which the pollutant is diluted or chemically changed as it travels;
5. the amount of pollutant entering the navigable waters relative to the amount of the pollutant that leaves the point source;
6. the manner by or area in which the pollutant enters the navigable waters; and
7. the degree to which the pol­lution (at that point) has maintained its specific identity.

The specific question in the case, County of Maui, Hawaii v. Hawaii Wildlife Fund, concerned whether Maui County violated the Clean Water Act by injecting partially treated wastewater into wells without a permit when that wastewater traveled via groundwater for a half a mile and then into the Pacific Ocean. The county argued their practice does not require an NPDES permit because it is not discharging “directly” into waters of the U.S.

The decision returns the case to the Ninth Circuit to apply the new “functional equivalent” test to the specific facts in the case. In its ruling, the Court disagreed with the Ninth Circuit’s interpretation that a permit is required when “pollutants are fairly traceable from the point source to a navigable water.” The Court’s holding is narrower, stating that a pollutant that took years to reach a navigable water should not be regulated under the Clean Water Act as that is beyond the intent of Congress. However, by including a discharge to groundwater at all, the Court has broadened what has historically been excluded from regulation under the Clean Water Act.