Eastsound Constructed Wetland Stormwater Treatment Facility

Stormwater runoff is one of the largest sources of pollution entering Puget Sound and the Salish Sea. The Herrera-designed Eastsound constructed wetland on Orcas Island now treats a portion of the town of Eastsound’s stormwater runoff before it reaches marine waters. The facility consists of a sedimentation basin and a constructed wetland with the capacity to treat 370,000 gallons of stormwater at one time. By slowing the flows, the sedimentation basin allows pollutants and particles to settle out of the stormwater. It then enters the wetland and meanders through vegetation and soil to be further treated by a variety of plants providing a range of capacities for toxin and nutrient uptake, and by infiltration through the soil. The treated stormwater is discharged into the existing downstream piping system.

Seventeen years after San Juan County purchased the 0.9-acre “Mount Property” next to the Village Green in 1994 to create a facility to treat surface water runoff from Eastsound, the Eastsound Constructed Wetland designed by Herrera was completed. During the first 12 years, a number of studies were completed to evaluate stormwater treatment options best suited for the site. The final concept was designed into a three phased project. A grant from the Environmental Protection Agency funded the construction of phase 1 in 2010 which included the installation of pipe from the treatment facility to Fishing Bay. Phase 2 included the installation of the constructed wetland treatment facility. The final phase of the project included piping to convey stormwater runoff from A Street, and part of the Prune Alley and North Beach Road drainages, into the constructed wetland.

A community-based aesthetic design review committee was created to assist with Phase 2 Design of the Constructed Wetland. Among the modifications Herrera made, based on this committee’s recommendations, were the addition of a perimeter trail and retention of an existing ‘tree wedge’ for its aesthetic and habitat value. The committee coordinated the participation of the Orcas Island School Leadership Class for some of the wetland plantings. Another school class developed interpretative and informational signs that were installed.