Puget Sound Olympia

Municipal Stormwater

Phase I Municipal Stormwater Permit

On August 1, 2012, Ecology issued an updated 2013-2018 Phase I Permit, that became effective on August 1, 2013. The permit was first modified on December 17, 2014 and the first modification went into effect on January 16, 2015. The permit was modified a second time on July 20, 2016 and the second modification will go into effect on August 19, 2016.

See the permit history page for redlined versions of the permit issued August 1, 2012.

The National Pollutant Discharge Elimination System (NPDES) and State Waste Discharge General Permits cover discharges from municipal separate storm sewer systems (MS4s). The Phase I Municipal Stormwater Permit regulates the discharges from MS4s owned or operated by Clark, King, Pierce and Snohomish Counties; and the cities of Seattle and Tacoma (incorporated cities with a population over 100,000 and unincorporated counties with populations of more than 250,000 according to the 1990 census). The permit also applies to MS4s owned by public entities located in a Phase I city or county; including the Ports of Seattle and Tacoma.

The files below are the permit as modified in July 2016.

  • 2013-2018 Phase I Municipal Stormwater Permit - Clean* | Redline
  • Appendix 1. Minimum Technical Requirements or New Development and Redevelopment - Clean
  • Appendix 2. Total Maximum Daily Load Requirements - Clean
  • Appendix 3. Annual Report Questions for the Port of Seattle and the Port of Tacoma - Clean
  • Appendix 4. Annual Report Questions for Secondary Permittees - Clean
  • Appendix 5. Notice of Intent - Clean
  • Appendix 6. Street Waste Disposal - Clean
  • Appendix 7. Determining Construction Site Sediment Damage Potential - Clean
  • Appendix 8. Businesses and Activities that are Potential Sources of Pollutants - Clean
  • Appendix 9. Stormwater Discharge Monitoring - Clean
  • Appendix 10. Equivalent Programs for Runoff Controls for New and Redevelopment and Construction Sites - Clean | Redline
  • Appendix 11. Structural Stormwater Controls Project List - Clean
  • Appendix 12. Annual Report Questions for Cities and Counties - Clean
  • Appendix 13. Adaptive Management Requirements - Clean
  • Response to Comments for Permit Modification Effective August 19, 2016
  • Errata issued February 2015

*This clean version corrects a minor formatting error where the citation to the Structural Stormwater Control was missing. No changes to permit requirements/language.

NEW 7/8/2016 2018 Western Washington Permit Reissuance

Regional Stormwater Monitoring Program

2016 Permit Modification

2014 Permit Modification

2012 Municipal Stormwater Permit Appeals

2012 Permits Reissuance Process

Annual Report Forms and Guidance

Permit History