A 21-mile corridor along the Lower Green River is at risk of severe flooding, according to the King County Flood Control District.

Portions of Auburn, Kent, Renton, SeaTac, Tukwila, and unincorporated King County could be inundated with more than one foot of flood water in a major flood, potentially impacting over 27,000 residents and the stability of 28,000 jobs.

The King County Flood Control District (District) has responded to this risk by conducting a study of ways to manage flood risk in the Lower Green River Corridor (Corridor). The District released this study as a final Programmatic Environmental Impact Statement (PEIS) on April 30. The document evaluates three flood hazard management alternatives that substantially reduce flooding across the Corridor. The PEIS analyzes impacts, benefits, and costs of planning-level decisions that affect a large area. Benefits could include providing better habitat for salmon and additional recreation and open space along the river.

“The PEIS process set a high standard for participation and environmental analysis,” said District Chair Reagan Dunn. “This comprehensive document reflects the culmination of extensive study and a robust participatory process. We gained valuable input from Tribes; municipalities along the Lower Green River; county, state, and federal agencies; environmental interests; and people who live, work, and recreate in the area.”

The final draft PEIS evaluates three different approaches (called alternatives) to reducing flood risks in the Corridor. A key finding is that all three alternatives substantially reduce flooding in most areas during a major flood and public feedback indicated broad support for flood risk management that delivers community benefits, recognizing these benefits may result in increased investment and land use changes immediately adjacent to the river. 

“The District can and should achieve our mission of protecting people and property from flooding in a way that honors Tribal interests and treaty rights while also pursuing additional benefits whenever possible, such as restoring salmon habitat, creating greenspaces and recreation opportunities, and fostering a thriving community,” said District Supervisor and King County Councilmember representing the Lower Green area, Dave Upthegrove.

The District Board of Supervisors will discuss the final PEIS at their meetings starting in June. Next steps may include the development of a Flood Hazard Management Plan for the Lower Green River Corridor that would prioritize future projects and integrate multibenefits.

For more information on the final PEIS, please visit LowerGreenSEPA.org. To learn more about the District’s meeting schedules and agendas please visit KingCountyFloodControl.org.

Scott Schaefer

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