The Howard Hanson Dam, which regulates the flow of the Green River to prevent flooding throughout the Green River and Kent valleys, was damaged during the January floods. This damage, caused by depressions, or sinkholes, has prompted an urgent and coordinated response by the U.S. Army Corps of Engineers, King County and the cities of Auburn, Kent, Renton and Tukwila.
The Howard Hanson Dam is located southeast of Enumclaw. During an inspection, corps engineers discovered two sinkholes in the northeast hillside of the dam. Engineers are in the process of studying the sinkholes and they are working to determine what needs to be done to fix them.
The King County Flood District met recently at which time the Army Corps of Engineers reassured county officials that the dam is stable and that they will be able to repair it. They also assured the county that repairing the dam is a top priority.
In the meantime, the corps also acknowledges that there is an increased risk of flooding in the event of a major rain storm before the repairs are made.
Howard Hanson Dam is one of the most important flood-control facilities in the county. Prior to its construction in 1961, the Green River routinely topped its banks from Auburn to Tukwila. Since the dam’s construction, and the flood protection afforded by it, billions of dollars have been invested in homes, public and commercial buildings, and industrial facilities in the valley.
Tens of thousands of people live and work in the areas protected by Howard Hanson Dam. Major employers, including Boeing and Starbucks, have operations in the valley. The region’s largest warehouse and distribution operations – everything from groceries to medical supplies – are located there. State Route 167 and two major rail lines that carry important freight, run from one end of the valley to the other.
Public safety and the protection of property is of paramount importance to the corps, King County and local officials.
Even with the full protection of Howard Hanson Dam, the extensive levee system and other facilities, there is a risk of valley flooding during extreme weather events. Now, with the dam’s water-holding capacity temporarily reduced, is an especially good time for valley residents and business owners to review their own emergency plans and the status of their flood insurance. The good news is, because King County’s flood-management program exceeds national requirements, unincorporated King County residents flood insurance is provided by private carriers at reduced rates.
King County is also taking additional actions to protect people and property during this period:
• The King County Flood Warning Center will open earlier during heavy rains to more closely coordinate information and response.
• Crews will be dispatched earlier to the Green River when higher flows are expected to visually inspect condition.
• King County’s Emergency Coordination Center is coordinating flood planning and response with its counterparts in the cities of Auburn, Kent, Renton and Tukwila.
Fortunately, the King County also has additional financial resources for making flood control investments. In 2007, after witnessing the devastation of Hurricane Katrina in New Orleans, the King County executive and County Council formed a special-purpose government – the King County Flood Control District – to finance accelerated work on the county’s backlog of levee maintenance and repairs.
The King County Flood District levy adds approximately $35 million a year to leverage state and federal flood protection funding. Without it, the 24 projects, including projects on the Green River, that were completed in 2008—constructing and repairing levees and sinkholes—would have taken about 17 years to finish.
Every King County resident, whether they live on the top of a mountain or along a river bank, has a stake in improved flood control. Our access to jobs, schools, friends, and emergency services depends on keeping the roads and bridges open. Our economy depends on keeping regional employment, education, health care and government centers protected from flooding.
U.S. Army Corps of Engineers will continue working with King County officials, local governments and technical experts to repair the damage to the Howard Hanson Dam as quickly as possible and to reduce the risk of flooding.
If you have further questions, please call 206-296-8362 or visit http://kingcounty.gov/environment/waterandland/flooding/warning-system.aspx
Julia Patterson is a King County Council member and chair of the King County Flood Control District. Reagan Dunn is a King County Council member and vice-chair of the King County Flood Control District.
