The U.S. Supreme Court has upheld a U.S. Environmental Protection Agency (EPA) regulatory interpretation that exempted from permitting stormwater runoff from roads built for timber harvesting purposes. Decker v. Nw. Envtl. Def. Ctr., No. 11-338 (U.S. 3/20/13). So ruling, the court reversed a Ninth Circuit decision reinstating a citizen suit after its dismissal by a district court.

The plaintiff had asserted that logging roads require discharge permits under the Clean Water Act’s (CWA’s) National Pollutant Discharge Elimination System (NPDES). EPA and relevant state regulators had not required such permits for an Oregon state forest timber harvesting operation. The CWA exempts from NPDES requirements discharges “composed entirely of stormwater” unless they are from “industrial activities.” The statute does not define the term “industrial activity,” and EPA supplied the applicable definition in its so-called silvicultural rule. That rule required permits only for operations associated with manufacturing, processing or raw material storage areas at an industrial plant, and EPA interpreted it to exclude road runoff, which is related to raw material harvesting only.

EPA revised its regulations to expressly exclude logging roads before the U.S. Supreme Court issued its opinion. Still, the Court determined that the case was not moot, holding that EPA’s earlier rule was a reasonable interpretation of the statutory provision and that EPA’s interpretation of its own rule deserved deference.