FAQ: Do I Need An NPDES Permit To Apply Pesticide That Is Not Approved For Water Application?
Possibly. According to US EPA, some pesticide labels refer to “water” and not “waters of the United States.” It is possible that some pesticide products that are not approved for use in “water” may result in discharges to waters of the United States.
For example, waters of the United States may be dry at the time of pesticide application, and there may be situations where pesticides are applied to temporarily dry waterbodies using pesticides labeled for terrestrial or seasonally-dry use. The National Pollutant Discharge Elimination System (NPDES) permit requirements apply regardless of whether the waters of the United States are wet or dry at the time of the discharge.