Stormwater Design Manual Update

Qa Qad Stormwater Park - ManchesterAs 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 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.

2019 Update

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 forconsistency. 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.  The scope of work includes:

Task 1—SDM Update:  The Herrera team will update the content and hyperlinks in the Kitsap County Stormwater Design Manual (SDM) for consistency with the 2019 Stormwater Management Manual for Western Washington (SWMMWW). The Herrera team will review the existing SDM and the 2019 SWMMWW and prepare a matrix identifying recommendations for manual updates to ensure consistency with the SWMMWW; if any changes are warranted for Kitsap County Code Title 12 Stormwater Drainage, those will be identified as well.  Herrera will work with a Core Manual Team made of representatives from the Kitsap County Department of Community Development, Public Works, and a representative of the Kitsap Building Association, Bernie Kenworthy, PE.

Task 2—Online SDM:  For Task 2, the Herrera team will develop an online version of the 2019 SDM using MadCap Flare software.  The MadCap Flare is the searchable format the Department of Ecology developed for the SWMMWW.

Task 3—SDM Training:  Herrera and RKI will develop training materials and facilitate trainings on the 2019 SDM for internal County staff and interested external stakeholders after the SDM has been adopted (in 2021).


​   Important Meeting dates and Materials

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

​May 19, 2020
​Planning Commission Work-Study Briefing

​June 2, 2020
​Planning Commission Public Hearing

​June 16, 2020
​Planning Commission Deliberation/Findings of Fact

​July 1, 2020
​Board of County Commissioners Work-Study Briefing

​July 13, 2020
​Board of County Commissioners Public Hearing

​July 22, 2020
​Board of County Commissioners Work-Study Deliberation

​August 10, 2020
​Board of County Commissioner Adoption

​September 2020
​Training Workshops

​January 1, 2021
​Ordinance Effective Date

Draft Proposal Timeline


Local Resources:

Kitsap County Stormwater Design Manual
(effective December 31, 2016)

Kitsap County Stormwater Plans

Water Policy Update Resolution 
(Resolution 134-2016, August 8, 2016)


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.