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Stormwater code and manual

Clark County has a National Pollution Discharge Elimination System (NPDES) permit effective August 1, 2013 through July 31, 2018. The Washington Department of Ecology permit is part of the federal Clean Water Act. Clark County has operated under such a permit since 1999.

Code and Manual update (2013-2015)

This permit, among other things, specifies regulations for managing the quantity and quality of stormwater discharged from the county’s stormwater system. To comply with the permit, the county will update applicable development codes, such as 40.385 Stormwater and Erosion Control and the stormwater manual.

Clark County will pursue updates that are:

  • Flexible and tailored to multiple project types, including making Low Impact Development (LID) the mandatory approach for stormwater management in site development.
  • Compatible with other state and local regulations to protect the environment and support an economically vibrant and liveable community.

For this project, refer to the follow sections for more information:

Update (October 2014)

The Washington State Department of Ecology has delayed the review of Clark County's Final Draft of the Stormwater Manual. Additional time is needed to complete their review. Clark County will update the project schedule late fall 2014 with key milestones. The delay will also potentially push the adoption of the stormwater code and manual date. The original implementation date of July 1, 2015 will be updated accordingly. For more information on DOE's updates to state NPDES Phase I permit and stormwater manual, visit their web page.

Final Draft - Municipal Code and Stormwater Manual

For Department of Ecology review and comment (June 30, 2014)

Document Type
Document Name Downloadable file
Municipal Code 13.26A - Clean version .pdf file
  13.26A - strikeout / underline .pdf file
Municipal Code 40.386 - Clean version (replaces 40.385) .pdf file
  40.386 - strikeout / underline .pdf file
Document Type
Document Name
Downloadable file
Stormwater Manual Introduction to manual / TOC .pdf file (2.2 MB)
  Book 1 with appendices .pdf file (24.1 MB)
  Book 2 with appendices .pdf file (13.1 MB)
  Book 3 with appendices .pdf file (3.2 MB)
  Book 4 with appendices .pdf file (6.1 MB)


Review Draft - April - May 2014

Public comments were received on the Review Draft and incorporated in the Final Draft. Here is the County response to public comments received.

Tentative schedule for updates

  • April 11 - May 5, 2014: Public comment period for the Review Draft of code and manual language.
  • May 14, 2014: Work session with Board of County Commissioners to review draft language and public comments (check the Grid for audio recording).
  • June 30, 2014: Final Draft sent to the Washington State Department of Ecology (DOE) for 90-day review period.
  • June 2014 - April 2015: Revise code and manuals per Ecology comments. Continue public outreach, trainings and workshops with stakeholders and citizens.
  • April 2015 - June 2015: Finalize documents and approvals Board of County Commissioners adoption of code and manual by June 30, 2015.


The following documents will be referenced throughout the update process.

Document NPDES Permit Requirement
NPDES Permit from the Department of Ecology Clark County is a Phase 1 permittee.
Phase 1 permittee special conditions are required unless otherwise noted.
Clark County Stormwater Manual - November 2009 (PDF 1MB)
- Appendix A (PDF 1MB)
- Appendix B (PDF 7MB)
- Appendix C (PDF 1MB)
- Appendix D (PDF 14MB)
Minimum requirements 1, 2, 5, 6, 7 and 8
Clark County Pollution Control Manual; Best Management Practices
for Businesses and Government Agencies
- January 2009 (PDF)
Minimum requirement 3
Clark County Stormwater Facility Maintenance Manual - January 2009 (PDF) Minimum requirement 9
Stormwater Management Manual for Western WashingtonAugust 2012 Minimum requirements 2, 4, 5, 6, 7 and 8
Washington State Department of Transportation - 2014 Highway Runoff Manual Publicly funded road projects


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