Stormwater Design Manual Update

 Draft - Design Manual

Kitsap County Stormwater Design Manual

(2nd draft redline/stikeout version)

Kitsap County Stormwater Design Manual List of Figures 

(2nd draft redline/stikeout version)

Kitsap County Code Title 12 - Stormwater Drainage

(redline/stikeout version)

Summary of changes to Kitsap County's Stormwater Design Manual 

(final 2016 SDM to 2020 SDM + KCC Title 12)

Planning Commission Findings of Fact Corrections Memo (July 14, 2020)

1st Draft Documents

1st draft

Kitsap County Stormwater Design Manual

1st draft

Kitsap County Stormwater Design Manual List of figures 

1st draft

Kitsap County Stormwater Design Manual 

(redline/stikeout version)

1st draft

Summary of changes to Kitsap County's Stormwater Design Manual 

(final 2016 SDM to 2020 SDM)

State Environmental Policy Act (SEPA) determinations

The SEPA Determination will be noticed and published as required under law, and the comment period for the SEPA Programmatic Determination of Non-significance is closed.

If there are questions regarding SEPA, contact Scott Diener at:

SEPA Programmatic Determination of Non-significance

​Comment period concluded July 6, 2020

SEPA Environmental Checklist


In 2019, Ecology revised its stormwater design manual for Western Washington communities.  As such, Kitsap County is mandated to update it’s Stormwater Design Manual and relevant development codes for consistency. Kitsap County Departments of Public Works and Community Development have collaboratively embarked on a review and update process, with the assistance of a consulting firm.

Scope of Work

In April 2019, Herrera Environmental Consultants (Herrera) was contracted by Kitsap County to update the Kitsap County Stormwater Design Manual (SDM), develop an online version of the SDM, conduct focused review of the Kitsap County Code (KCC), and assist with any necessary revisions to the KCC.  The revised manual and any code changes will not be effective until
January 1, 2021, or later if the Board determines a later date would be beneficial. 

​Important Meeting dates and Materials

All the information listed below is tentative and subject to change.

​May 19, 2020
​Planning Commission Work-Study Briefing
(available on Planning Commission site)
June 16, 2020
​Planning Commission Public Work Study

(available on Planning Commission site)
​July 7, 2020
​Planning Commission Public Hearing

​July 21, 2020
​Planning Commissioner Deliberation and Finding of Fact

(available on Planning Commission site)
​August 3, 2020

​Board of County Commissioners Work Study

​Executive Summary

September 14, 2020

​Board of County Commissioners Public Hearing
Agenda Summary
​September 21, 2020​Board of County Commissioners DeliberationAgenda Summary
​October 19, 2020
​Board of County Commissioners Deliberations Continued
Agenda Summary
June 28, 2021

​Board of County Commissioners Ordinance Adoption

​Ordinance Effective Date


State Resources:

Executive Summary of the 2019 Revisions

The Stormwater Management Manual for Western Washington (SWMMWW) provides guidance on the measures necessary to control the quantity and quality of stormwater. Local municipalities use this manual to set stormwater requirements for new development and redevelopment projects. Land developers and development engineers use this manual to design permanent stormwater control plans, create construction stormwater pollution prevention plans, and determine stormwater infrastructure. Businesses use this manual to help design their stormwater pollution prevention plans.

The development and administration of the Clean Water Act National Pollutant Discharge Elimination System (NPDES) municipal stormwater permits in Washington.

This document gives a brief summary of changes.  Appendix 1 contains the development regulations starting at page 84, ending at page 90.

Ecology has provided the crosswalk below to help you identify where content has been moved and/or renamed between the 2014 and 2019 manuals. Note that during the 2019 update some sections were merged together and/or edited for clarity. Therefore, you may not find the exact language from the 2014 manual in the linked sections of the 2019 manual indicated below. The links below will lead you to where the updated content is contained in the 2019 manual, providing updated guidance on the topic from the 2014 manual.


As part of the United States Clean Water Act and National Pollutant Discharge Elimination System (NPDES) permit program, Kitsap County is required to develop and implement a stormwater management program.  This program is intended to reduce discharge of pollutants to the maximum extent practicable and protect water quality. The Washington State Department of Ecology is the responsible agency for permit issuance to local jurisdictions.

Kitsap County is considered a Phase II NPDES permit jurisdiction and is located within census-defined urbanized areas and includes Urban Growth Areas defined by the Washington State Growth Management Act. As a Phase II jurisdiction, stormwater runoff and associated codes must comply with Ecology's rules to prevent and control the impacts of stormwater runoff from new development, redevelopment and construction activities.

Kitsap County's Title 12 and Stormwater Design Manual provides guidance and standards in stormwater management planning and design for development.

Additionally, in 2009,  the Kitsap County Board of County Commissioners approved Resolution No 134-2016 "Water as a Resource" policy.  This policy, in addition to requirements noted above, provide guiding principles to stormwater asset management, implementing development codes, public outreach and reporting needs.