On April 23, 2020, the U.S. Supreme Court issued a decision in County of Maui v. Hawaii Wildlife Fund, a closely watched case regarding whether the federal Clean Water Act (CWA) applies to discharges of pollutants to groundwater which reach surface waters.

In County of Maui, the plaintiff environmental organizations brought a citizen suit alleging that the defendant-county was in violation of the CWA in regard to the county’s decades-old practice of injecting partially treated wastewater into groundwater wells.  The wells consistently leaked and tracer dye testing confirmed that over 60% percent of the wastewater injected into the wells wound up in the Pacific Ocean within three months of injection.  The trial court granted summary judgment to the plaintiffs and the Ninth Circuit Court of Appeals concluded that the defendant’s “indirect” discharges of pollutants via groundwater into the Pacific Ocean (a “navigable water” under the CWA) was subject to liability under the CWA.

The U.S. Supreme Court considered the issue of whether the CWA “requires a permit when pollutants originate from a point source but are conveyed to navigable waters by a nonpoint source”—in this case, groundwater.  The Supreme Court rejected as too broad the approach taken by the Ninth Circuit (and advocated for by the plaintiffs) in which a CWA permit is required so long as the pollutant is “fairly traceable” to a point source even if the pollutant traveled a significant distance or over a long period of time before it reaches navigable waters.  Conversely, the Supreme Court rejected as too narrow the “bright-line test” proposed by the defendant (and the EPA) that the CWA only applies to point sources that discharge pollutants directly to navigable waters (i.e., that no permit is required if the pollutants travel through any amount of groundwater before reaching navigable waters).

The 6-3 majority of the Supreme Court adopted a middle ground approach and held that a CWA permit is required if the addition of pollutants through groundwater “is the functional equivalent of a direct discharge from the point source into navigable waters.”  The Court held that, in evaluating whether a discharge to groundwater that reaches navigable waters is “the functional equivalent of a direct discharge” and thus subject to CWA jurisdiction, “transit time” and “distance traveled” will be the most important factors in most cases, but that courts may consider numerous other factors such as (i) the nature of the material through which the pollutant travels, (ii) the extent to which the pollutant is diluted or chemically changes as it travels, (iii) the amount of pollutant entering the navigable waters relative to the amount of the pollutant leaves the point sources, (iv) the manner by or area in which the pollutant enters the navigable waters, and (v) the degree to which the pollution has maintained its specific identity.

The Supreme Court’s decision is likely to lead to much debate and considerable litigation as lower courts and litigants seek to apply the Court’s “functional equivalence” test and the numerous technical facts to future cases.  For more information about Clean Water Act or groundwater discharge issues, please contact Andy Thompson.  For a copy of the Supreme Court’s decision in County of Maui, click here.

For more information regarding this decision, please contact SGR’s Environmental Counsel.