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National Pollutant Discharge Elimination System (NPDES)

According to a 2009 U.S. Court ruling, any pesticide (herbicide, weed killer, insecticide, algaecide, mosquito adulticide or larvicide, molluskicide, disinfectant, etc.), applied in, over or near waters of the state that results in at least some pesticide residue entering that water is considered a point source discharge of a pollutant and requires NPDES permit coverage to remain in compliance with the Clean Water Act. The NPDES Permit requirement became effective October 31, 2011.

Permits and Pesticide Use


Question: Do I need an NPDES permit to apply a pesticide IN, OVER, or NEAR WATER in Indiana?

Answer: Beginning April 11, 2011, applications for pests such as: Adult Mosquitos, Mosquito Larvae, Aquatic Weeds and Forest Canopy Pests over Water probably require an NPDES permit. View more details about plans for implementing the Pesticide NPDES Permitting under the Clean Water Act. (pdf, 74kb)