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New risk of flooding from Howard Hanson Dam could threaten County facilities and require emergency relocations


Metropolitan King County
Council News

New risk of flooding from Howard Hanson Dam could threaten County facilities and require emergency relocations


Authority for Executive to declare a state of emergency before the actual event occurs is sent to full Council


Under a worst-case scenario, major County facilities downstream of the federal Howard Hanson Dam face the threat of flood waters as high as 10 feet and may need to be temporarily relocated this fall, according to the latest information provided today to the Metropolitan King County Council’s Committee of the Whole. Members were briefed on preparations now taking place to alert and protect the public, and provide for the continuity of County services, should heavy rains make it necessary for the U.S. Army Corps of Engineers to release water to avoid overloading the dam.

The full County Council will consider legislation next Monday giving the County Executive the authority to declare a state of emergency for the Howard Hanson flood threat before any flooding actually occurs.

“The likelihood of significant flooding in the Green River Valley is sobering,” said Councilmember Bob Ferguson, chair of the Committee of the Whole. “Of the many challenges facing King County, preparations to safeguard citizens and property in the event of a potentially catastrophic flood must move to the top of our priority list.”

“Potential flooding in the Green River Valley is a reality for which we must prepare now,” said Councilmember Reagan Dunn. “As chair of the King County Flood Control District Executive Committee, we are proactively securing levees, raising public awareness and monitoring emergency preparedness. At the same time we are asking citizens to prepare, King County is leading by example by preparing its own facilities for the possibility of catastrophic flooding.”

Assistant County Executive Pam Bissonnette briefed members on plans to shift the operations of major County facilities that lie in the heart of the historic flood plain, including the potential need to relocate animals from the Animal Shelter, inmates from the Maleng Regional Justice Center, and move the County’s Elections headquarters to prevent any disruption to the November general election. She presented projected high water marks for several of those facilities:

  • Aukeen District Court—up to a foot,
  • Animal Care and Control Shelter in Kent—up to 3 feet,
  • Maleng Regional Justice Center—up to 4 feet,
  • Black River Building—up to 7 feet, and
  • Earlington Center (King County Elections)—up to 10 feet.

“Many homes and businesses in South King County may be devastated by flooding from the Green River,” said Councilmember Julia Patterson, who represents three cities in the Green River Valley and is chair of the King County Flood Control District. “The economic impact has major implications: expert economists have advised that a shutdown of economic activity in King County's floodplains would cost the region millions. That’s why it is critical the County communicate with residents and businesses in the Green River Valley about flood preparation, particularly by low-income households and vulnerable populations.”

“The Snoqualmie Valley has experienced record flooding several times in recent years, so we can share our experience as we deal with this threat in the Green River Valley,” said Councilmember Kathy Lambert, who represents the Snoqualmie Valley. “Residents can respond by preparing themselves for sheltering at home or evacuation. Some items people forget to have on hand are at least a week’s worth of medications, copies of legal documents, and a 72-hour survival kit.”

“We must provide citizens and businesses with certainty and stability both for their daily lives and for the health of our already threatened economy,” said Councilmember Jane Hague. “We can’t afford any other option. We must act now.”

Bissonnette said King County is working across jurisdictions to ensure that a region that has become the major freight distribution center for the Pacific Northwest will continue to operate in the event of flooding. She said the County is working with the cities within the Green River Valley, the U.S. Army Corps of Engineers, FEMA, Washington State Emergency Management and Puget Sound Energy on a strategy to ensure the safety of the business corridor.

“The valley is home to the region’s food distribution center and is the manufacturing hub of the Pacific Northwest,” said Councilmember Larry Gossett, chair of the Council’s Budget and Fiscal Management Committee. “Given our current economic crisis we can ill afford to lose the $46 million a day in economic activity that is generated in the valley. It’s vital we take all the needed steps to prevent this from happening.”

“This is a regional issue – the impact of flood waters will reach far beyond the Green River Valley,” said Councilmember Pete von Reichbauer. “The beginning of flood season is a little over a month away. King County is encouraging everyone to act now in order to maximize preparedness efforts.”

Bissonnette told the committee that it may take $10 million to $35 million to lease replacement facilities; relocate shelter animals, jail inmates, and other County services; and protect buildings from damage. She said FEMA has estimated the property damage to the thousands of homes and businesses in the flood plain at $2 billion to $3 billion.

The Council urged the County Executive to press the federal government, which built and operates the Howard Hanson Dam, to act quickly to make the repairs needed to strengthen the dam and to swiftly reimburse the costs incurred due to the flood preparations.

“I have spoken with Senator Murray, Senator Cantwell, Congressman Smith and other members of our state’s Congressional delegation in the past few days about the Green River flood threat and know that they share a sense of urgency and commitment to action on this potential crisis,” said Council Chair Dow Constantine. “It is critical that we coordinate the tools needed to immediately enact short-term flood control measures that will protect lives and property.”

“The construction of the dam by the federal government in 1962 allowed the extensive commercial development of the Kent Valley,” said Councilmember Larry Phillips. “We need the federal government to step up in not only acting to protect public safety and property, but to put a permanent fix in place immediately.”

Extensive outreach is underway to inform residents and businesses of the potential crisis, according to Carolyn Duncan, Communications Director for the County Executive. She said groups are already working with agricultural interests and underserved populations in the Green River Valley, and that letters with informational brochures have been mailed to 165,000 addresses in the flood plain along with 15,000 distributed to jurisdictions, businesses, and non-profit organizations. She said the County is reaching out to businesses and working with companies on flood plans, ranging from supply issues to transportation for employees impacted by floods.

The U.S. Army Corps of Engineers discovered sinkholes and rapid seepage of water through an earthen abutment next to the Howard Hanson Dam after last January’s record rain. A temporary fix to inject grout into the earthen material to control seepage is underway but dam storage capacity will be limited until the repair can be tested next spring. Bissonnette said a long-term fix could take three to five years and hundreds of millions of dollars.

In order to proactively prepare for the threat of flooding, the Committee of the Whole today sent legislation to the full Council that would allow the County Executive to waive procurement rules in connection with a declaration of emergency specific to the Howard Hanson Dam. The legislation will come before the Council this Monday, August 31.

Further briefings on the Howard Hanson flood threat will be heard in Committee of the Whole. The County is hosting a series of public meetings on the Howard Hanson flood threat, the first of which is on Wednesday, September 9, at 6:00 p.m. at Green River Community College. 

Read more about this legislation on the King County Council’s LEGISEARCH system at  and type in “2009-0447”

Read more about this issue at

View the PowerPoint  presenation from the Committee of the Whole

Read the legislation

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