U.S. Supreme Court Holds Flow from One Part to Another of Same Waterway is Not a Discharge under the CWA

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In a 9-0 decision in favor of the Los Angeles County Flood Control District (the District), the U.S. Supreme Court reversed an opinion from the 9th Circuit yesterday, holding water flowing from an improved segment of a navigable waterway into an unimproved segment of the same waterway does not constitute a “discharge of a pollutant” under the Clean Water Act.

The District operates a municipal separate storm sewer system (MS4), which requires a National Pollutant Discharge Elimination System (NPDES) permit under the Clean Water Act (CWA) before any storm water discharges into navigable waters. The National Resources Defense Council and Santa Monica Baykeeper (now known as LA Waterkeeper) filed suit against the District for violating its NPDES permit. As certain monitoring stations for the District’s NPDES permit are located in concrete channels, the 9th Circuit held a discharge of pollutants occurred when polluted water at monitoring stations flowed out of such concrete channels and entered downstream segments of the waterways without concrete linings.

Writing for eight of the justices, Justice Ginsburg said the CWA defines a “discharge of pollutant” to mean “any addition of any pollutant to navigable waters from any point source,” and based on “a common understanding of the meaning of the word ‘add,’ no pollutants are ‘added’ to a water body when water is merely transferred between different portions of that water body.” Justice Alito concurred in the judgment.

The Court declined to address any issues beyond the narrow question on which it granted cert and remanded for the issues remaining, including NRDC and Baykeeper’s alternative argument the District violated its NPDES permit based on pollution levels that exceeded water quality standards.

NRDC and Baykeeper will likely push forward in their arguments against the District. In the meantime, the District can continue to operate under its NPDES permit with this clarification from the Court.

The Court’s slip opinion can be read here.

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