In a 7-1 decision overruling the Ninth Circuit, the U.S. Supreme Court today upheld the Environmental Protection Agency’s (“EPA”) long-standing interpretation that stormwater run-off from logging roads are exempt from NPDES permitting requirements.

In Decker v. Northwest Environmental Defense Center, U.S. No. 11-338 (March 20, 2013), the Court concluded that under the Clean Water Act, 33 U.S.C. §1342(p)(2)(B), timber operators would be required to secure an NPDES permit for only for those stormwater discharges “associated with industrial activity.” The Court held that the EPA’s interpretation of the definition of “industrial activity” in its Industrial Stormwater Rule (40 CFR §122.26(b)(14)) to exclude logging roads from NPDES permitting was reasonable under the Act and under the deference afforded to agencies interpreting their own regulations. The EPA interpreted “industrial activity” as referring to traditional industrial buildings such as factories and associated sites, as well as other relatively fixed facilities. The Court also recognized that the EPA’s interpretation must be viewed against the background of the extensive state regulatory regimes that impose best practices to manage stormwater runoff from logging roads.