Oregon DEQ: Water Quality Permit Program - Regulatory Mixing Zone in NPDES Permits

Consistent with policy from the federal Environmental Protection Agency (EPA), DEQ is not requiring a National Pollutant Discharge Elimination System permit or other water quality permit for pesticide applications provided the application is performed according to the approved label instructions.

Note: Recent U. S. Ninth Circuit Court cases have required NPDES permits for pesticide and herbicide applications made directly over and into surface waters. EPA has since clarified its position in rulemaking that an NPDES permit is not required. For more information on EPA's final rule, please see below.

EPA Rulemaking

EPA Final Rulemaking - November 27, 2006
The Environmental Protection Agency (EPA) has issued a final rule clarifying two specific circumstances in which a Clean Water Act permit is not required before pesticides are applied. The two situations are when: 1) pesticides are applied directly to water to control pests, including mosquito larvae, aquatic weeds and other pests in the water; and 2) pesticides are applied to control pests that are present over or near water where a portion of the pesticide will unavoidably be deposited to the water in order to target the pests effectively. The action puts into effect a rule that confirms EPA's past operating approach that pesticides legally registered under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) for application to or near aquatic environments, and legally applied to control pests at those sites, are not subject to NPDES permit requirements. The rule becomes effective January 26, 2007.
EPA Proposed Rulemaking and Notice of Interpretative Statement on Application of Pesticides to Waters of the U.S. in Compliance with FIFRA - February 2005 PDF

EPA Guidance

Pesticide Applications into Surface Waters