Puget Sound Olympia

Municipal Stormwater

Phase I Municipal Stormwater Permit

NEW, updated 05/18/2016 Ecology is proposing a second modification to the Phase I Permit to incorporate Ecology's determinations of equivalency for the Phase I manuals/programs. On May 18, 2016, Ecology made draft permit documents available for public comment.

On August 1, 2012, Ecology issued an updated 2013-2018 Phase I Permit, that became effective on August 1, 2013.

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 December 2014.

  • 2013-2018 Phase I Municipal Stormwater Permit - Clean | Redline
  • Appendix 1. Minimum Technical Requirements or New Development and Redevelopment - Clean | Redline
  • Appendix 2. Total Maximum Daily Load Requirements - Clean | Redline
  • Appendix 3. Annual Report Questions for the Port of Seattle and the Port of Tacoma - Clean | Redline
  • Appendix 4. Annual Report Questions for Secondary Permittees - Clean | Redline
  • 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 | Redline
  • 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 | Redline

  • Response to Comments for Permit Modification Effective January 16, 2015

  • Errata issued February 2015

Regional Stormwater Monitoring Program

2014 Permit Modification

2012 Municipal Stormwater Permit Appeals

2012 Permits Reissuance Process

Annual Report Forms and Guidance

Permit History