Stormwater Permits

Stormwater is rain and snow melt that runs off surfaces such as rooftops, paved streets, highways, and parking lots and that does not percolate into the soil. As water runs off these surfaces, it carries pollutants such as sediment, oil, fertilizers, pesticides, trash, animal waste and a variety of other pollutants that can negatively impact water quality. DEQ regulates discharges of stormwater from construction activity, industrial activity and from Municipal Separate Storm Sewer Systems (MS4s) primarily through three Montana Pollutant Discharge Elimination System (MPDES) General permits.

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Stormwater Construction


An authorization under the General Permit for Stormwater Discharges Associated with Construction Activity is required for construction activities that include clearing, excavating, grading, grubbing, or placement/removal of earth material with a total area of one or more acres.