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Green Island and the Hyporheic Zone: Why Restoration matters
Hockenbury, L., Bart Faulkner, Ken Forshay, AND Reneej Brooks. Green Island and the Hyporheic Zone: Why Restoration matters. U.S. EPA Office of Research and Development, Washington, DC, EPA/600/F-13/340, 2013.
This work describes current research on the benefits of floodplain restoration for ecosystem services. At Green Island, the EPA has focused on three components of water quality: identifying source water, modeling near channel (hyporheic) connectivity, and assessing rates and drivers of nitrogen processing. This combination details an overall story of where the water is coming from, where it's going, what it's doing in the floodplain, and the potential benefits provided. Here, we review each approach and the current results.
Large river floodplains present diverse benefits to communities, yet management strategies often fail to consider the broad suite of ecosystem services provided by these systems. The U.S. Environmental Protection Agency (EPA) is evaluating the benefits associated with restoring large river floodplains, specifically levee setback and revetment removal. This effort will provide scientific support for community-based environmental decision making within our study area on the McKenzie River, a tributary to the Willamette River in Oregon, and support emerging restoration efforts along the Yakima River in Yakima, Washington, and across the nation. The EPA is working with the McKenzie River Trust, the City of Yakima, and the Washington Department of Transportation to bring a more holistic approach to enhance sustainability, with consideration of the ecosystem services offered by dynamic river systems. Restoring hydrologic connectivity in floodplains can enhance the overall ecological condition of riparian systems. We have examined groundwater flow patterns, denitrification rates, and water isotopic signatures for identifying water sources at Green Island, a 1,055 acre restoration effort located at the confluence of the McKenzie and Willamette Rivers in order to identify specific benefits of increased hydrologic connectivity. The Yakima River, which winds through a highly productive agricultural valley, has been identified as having high potential for successful restoration and increased floodplain connectivity. The EPA is undergoing research to assess groundwater flow and denitrification rates occurring within the Yakima River floodplain. With these two case studies, the EPA will present a scientific review of the issues and benefits associated with restoring large river floodplains through levee setback and the influence of hydrologic connectivity.