Clean Water Service (CWS) is tasked with managing stormwater in portions of Washington County, OR that fall within the Urban Growth Boundary with the goal of protecting waterways and natural resources within stream and wetland corridors. When a new development is proposed, CWS works with the developer to meet regulatory requirements associated with increased runoff from impervious surfaces with the goal of maintaining discharges of stormwater to pre-development conditions. Traditionally, meeting these requirements consists of designing and constructing large, regional stormwater management facilities in upland areas adjacent to the new developments.Given CWS’ dual interest of managing stormwater and protecting and restoring waterways, CWS has developed a pilot to test and evaluate a process whereby stream corridors are improved to restore stream, wetland, and riparian functions while at the same time increasing their ability to attenuate stormwater delivered from urban development. Waterways worked with HDR to develop an innovative stormwater management approach with these goals in mind at two project areas in the North Bethany Area. Waterways’ role was to conduct a geomorphic and restoration opportunities and constraints analysis for each of the project areas and contribute to the development of alternatives and specific restoration design elements. Design elements included off-channel wetlands, integration of channel and floodplain roughness elements, and measures to arrest active channel incision and improve channel and floodplain connectivity.
