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Program description
A stormwater capital needs assessment completed by Stormwater Services (SWS) in 2012 identified over 64 small streams/lakes in unincorporated King County considered to be degraded as a likely result of stormwater runoff from developed land because of (1) fair to poor biological health and/or a water quality impairment documented through County or State monitoring, and (2) the extent and age of development within the basin. This program will identify the stormwater retrofit sites necessary and feasible to match the flow durations of peak discharges as low as 8% of the forested 2-year peak discharge (ECY8%). This goal is referred to as "ECY8%" because of its focus on matching flow durations of peak discharges as low as 8% of the forested 2-year peak discharge. Use of this performance goal for stormwater retrofitting was derived from another planning effort completed by King County in 2012, called the Stormwater Retrofit Analysis and Recommendations for Juanita Creek Basin in the Lake Washington Watershed.

Small stream basin retrofit program map
King County map of small stream basins targeted for retrofit (pdf)

Program goal
The program goal is to do landscape-level planning with a small stream basin to identify the stormwater retrofit sites necessary and feasible to match the flow durations of peak discharges as low as 8% of the forested 2-year peak discharge (ECY8%).  

Summary milestone schedules

  • Prepare Pre-Design Reports and Basin Plans for Ecology Stormwater Grant applications due in the Fall of every year.

Small Stream Basin Retrofit Projects

For more information about the Small Stream Basin Retrofit Program, please contact Matthew (Matt) McNair, Project Manager, WLR Capital Services Unit.