Stormwater documents 

Surface Water Design Manual - 2009 update
Requirements and standards for designing surface and storm water management systems in King County to mitigate the impacts of new development and redevelopment on natural and existing man-made drainage systems.

• Archived versions
  Older versions of the Surface Water Design Manual are available for municipalities who have referenced them in stormwater managementcodes.

Stormwater Pollution Prevention Manual
2009 guide describing best management practices for businesses, residents, managers, and owners of property in unincorporated King County to apply to reduce the contamination of stormwater, surface water, and groundwater.

The Integrated Pond
Design ideas to improve the asthetic quality of stormwater retention/detention ponds built in King County neighborhoods.

Drainage Maintenance Standards
Guide for property owners, developers, engineers, or field crews overseeing, specifying, or conducting the maintenance on commercial and multifamily drainage facilities.

2012 Post Construction Monitoring Report (13.1 Mb Acrobat pdf)
King County received a grant from the State of Washington Department of Ecology to retrofit stormwater facilities owned and operated by King County.  This report includes the photographs and field check summary of each retrofit site constructed in 2011 to evaluate the success of the retrofit improvement.  These facilities include a mix of stormwater detention and treatment facilities, nearly all of which were constructed by past subdivision development projects to mitigate stormwater flow and water quality degradation from land development.

Model Low Impact Development Strategies for Big Box Retail Stores
Describes methods for designing stormwater systems for big retail stores using a more natural approach to land development and stormwater management that uses a site's natural features, applies best management practices to mimic natural hydrologic patterns to limit stormwater runoff and pollution sources.

Green River Stormwater Retrofit Project documents 
Results of an ongoing study working to develop best practices for improving stormwater management and reducing non-point source pollution in areas that have already been developed.

Stormwater Retrofit Analysis and Recommendations for Juanita Creek Basin in the Lake Washington Watershed
Strategies to improve flow and water quality to support aquatic life in Juanita Creek, including fish.

Storm water & ground water in sewers is regional problem (Acrobat pdf)
Overview of capacity problems created by inflow and infiltration in King County's sewer system and how the County is responding.  Published in 2008.

Highway 520 Bridge Storm Water Runoff Study
Part of a comprehensive evaluation of current and future water quality conditions in Lake Washington to support informed decision-making.

Wetlands and Urbanization: Implications for the Future
The Puget Sound Wetlands and Stormwater Management Research Program (PSWSMRP) was a ten-year regional research effort documenting how urbanization affects wetlands. The studies examined the impacts of stormwater on the five major structural components of wetlands: (1) hydrology, (2) water quality, (3) soils, (4) plants, and (5) animals. The fourteen papers in this monograph are divided into four sections: Program Overview, Descriptive Ecology, Assessment of Stormwater Effects, and Management Guidelines.

Characteristics of the low-elevation Sphagnum-dominated peatlands of western Washington: a community profile
Also known as "the bog book", this publication provides a compilation of data and findings about Sphagnum-dominated peatlands from existing local sources, most of which are unpublished as of November, 2001.

For questions about the stormwater services website, please contact Dale Nelson, Engineer, King County Stormwater Services Section.