Flood preparation for the Green River Valley
Green River Valley residents of all ages fill sandbags for use around homes and businesses. Get Ready, Stay Ready
In 2011, the Corps invested around $40 million to improve the safety of Howard Hanson Dam, making repairs due to seepage issues discovered after a flood event in 2009. The rainfall and flow rate during February 2012 flooding landed in the top ten events in Howard Hanson Dam’s history, but many may not have realized the potential impact because the dam functioned according to design. Without Howard Hanson Dam holding back flows, estimated flows on the Green River would have been near 22,000 cubic feet per second, nearly double the river’s maximum design flow of 12,000 cfs measured in Auburn, Wash.
The Corps has confidence that the completed repairs have restored the dam and operations have returned to its designed capacity. However, even a return of full operational capacity of Howard Hanson Dam, in partnership with a functioning levee system downstream, does not eliminate all risks of flooding. The dam and levees only reduce the risk of flooding resulting in a 140-year flood protection level.
Flood barrier (i.e. sandbags) removal has begun along the Green River, with local cities determining the specific timeframe for their area. As always, the Corps encourages everyone living in areas prone to flooding to continue to be prepared for potential flooding during flood season. Although there is increased confidence in the dam’s flood storage capacity given the analyses we have done to date, there is always a residual risk of flooding in the Green River Valley flood plain.
Learn more about the Howard Hanson Dam (from the U.S. Army Corps of Engineers)
If the valley were to experience serious flooding, evacuations in some communities are possible. Key transportation routes and transit service could be disrupted. Power outages and sewer back-ups are possible even outside the immediate flood zone.
Knowing several evacuation routes is just part of your family’s personal preparedness planning. Citizens are also encouraged to register for regional warnings and alerts at www.RPIN.org. This is just one alert tool that’s available to you. Your city may also have its own emergency warning systems.
Most typical home and business insurance policies don’t cover losses from flooding, so flood insurance is an important consideration. Preliminary flood insurance rate maps can be accessed through King County Flooding Services.
Get Ready and Stay Ready to help keep your family and property safe when the rains come.
Frequently asked questions (PDF)
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Prepare now by following the action plan and help keep your family and property safe when the rains come.
Translations - Green River flood preparation (PDF)
    
    
Additional information
Green River flood planning agencies and city Web sites
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Residents, businesses and farms below the Howard Hanson Dam in the Green River Valley should prepare each year for potential 