Prototype stormwater solutions for waterfront

Effects of Waterfront Stormwater Solution Prototypes on Water Quality Runoff

Researchers designed and constructed an innovative, multifunctional stormwater treatment system that may significantly reduce pollution and serve as a model for Puget Sound communities.

Principal Investigator

Nancy Rottle, University of Washington, Landscape Architecture

Co-Principal Investigator

Richard Horner, University of Washington, Civil & Environmental Engineering


This project assessed the capacity of a multi-functional water treatment feature to simultaneously reduce contamination and environmental degradation caused by stormwater runoff and provide high-quality public space. Initial plans were to test the prototype in Coupeville, located on Whidbey Island’s shellfish-rich Penn Cove. However, delays in construction led to using an alternative location in Manchester, Kitsap County. The project trained residents and student researchers and deepened public understanding of shoreline and aquatic issues. If successful, this innovative design approach could help other coastal communities find ways to capture the economic, aesthetic, and environmental benefit of green shoreline infrastructure.

Research Updates

Washington Sea Grant-sponsored researchers assessed waterfront GSI at Manchester Beach, Washington, where bioretention cells filled with Filterra soil media treat stormwater and a spiral raingarden treats lower base flows. The project sampled winter flows into and out of the system; state and county labs analyzed water quality in both. Researchers presented the park design directly to the public and in an online video.

Repeated testing found that the GSI system reduced dissolved metals in runoff by varying degrees and achieved dramatic reductions, ranging from 42 to 99 percent, in fecal coliform bacteria.