The Hawaiʻi Department of Health (HDOH) issued the National Pollutant Discharge Elimination System (NPDES) Permit No. HI S000625 (MS4 NPDES Permit) to the Hawaiʻi Department of Transportation (HDOT), Oʻahu District. The MS4 NPDES Permit requires the HDOT Oʻahu District Storm Water Management Program (SWMP) to reduce the discharge of pollutants from the MS4 to the maximum extent practicable (MEP), and is the backbone of HDOT efforts to continue reducing pollutants in storm water runoff.
The MS4 NPDES Permit became effective on October 1, 2026, and will expire at midnight, September 30, 2031. Read more about this on our About Page.
