2016 Surface Water Design Manual Update


The Surface Water Design Manual regulates the design, construction, and maintenance of all new and/or redevelopment projects.

Currently the City uses the 1998 and 2009 King County Surface Water Design Manual (KCSWDM). The Department of Ecology requires that stormwater standards, codes, policies, and practices incorporate Low Impact Development practices into storm and surface water management.

This requirement means that the City must adopt and incorporate these changes by December 31, 2016 to meet Washington State National Pollutant Discharge Elimination System (NPDES) Permit requirements.

Major Changes

Some of the major changes the 2016 Surface Water Design Manual will incorporate include (but are not limited to): Low Impact Development (LID) techniques for all new and/or replaced impervious surfaces, possible requirements of formal flow control and water quality facilities for certain sized projects, and stricter requirements for development draining to landslide hazard areas.


The City's Planning Commission recommended adoption of the 2016 KCSWDM with the addition of a Sammamish Addendum.

We are currently looking for public feedback on how we can clarify the design manual. Our next steps include Technical Stakeholders meetings and incorporation of Public/Stakeholder comments into the Sammamish Addendum, and implementation of Education and Outreach Programs.

Public Involvement

Upcoming meetings open to the public:

Planning Commission

  • September 1, 2016 - Work Session
  • September 15, 2016 - Work Session/Public Hearing
  • October 6, 2016 - Public Hearing/Deliberation

City Council

  • November 8, 2016 - Planning Commission Hand Off
  • November 15, 2016 - Work Session
  • December 6, 2016 - First Reading, Public Hearing
  • December 13, 2016 - Second Reading, Council Adoption


Staff Contact