Stormwater runoff is one of the leading contributors of pollutants to the Puget Sound; impairing the health, water quality, and its habitats. The stormwater runoff from Freeland Park
was contaminated with trash and other toxins creating a negative impact on water quality and commercial shellfish beds in Holmes Harbor. In an effort to improve the water quality Island County installed a Filterra Bioretention System
designed to reduce the amount of TSS, metals, and nutrients from entering Holmes Harbor.
The specific challenge of this project was to provide a cost effective solution to reduce and remediate the adverse impact the polluted stormwater runoff was having on the water quality and shellfish health in Holmes Harbor. As the problem persisted the State Department of Health required Island County to establish a district wide shellfish protection program designed to promote efforts for cleaning the harbor and improving water quality. Due to the Shellfish Protection District Status, Island County was awarded a grant from the State Department of Ecology to address the aforementioned stormwater impacts.
Island County implemented several substantial drainage improvements to the Freeland Park site including a Filterra Bioretention System as well as various raingarden installations. The purchase and installation of the Filterra system was primarily funded by a grant received from the Washington State Department of Ecology, with additional support from Island County. The Filterra Bioretention System was the logical choice for county officials due the documented third party verification supporting the effectiveness and ability of the Filterra units to provide removal of TSS, metals, and nutrients.
A Thuja occidentalis ‘Hills Dark Green’ Arborvitae was installed in the stormwater systems to assist with pollutant removal, to match the existing landscape, and add aesthetics to the streetscape.