Reduced risk has not slowed preparations for potential flooding from federal Howard Hanson Dam

September 8, 2010

Summary

Council committee briefed on continued planning, outreach in Green River Valley

Story

The Director of King County’s Office of Emergency Management told the Metropolitan King County Council’s Committee of the Whole today that while the risk may be lower, preparations in the event of potential release of water from the federally-owned Howard Hanson Dam continue.

“The Army Corps has provided good information about the current condition of the dam, but the people of the Green River Valley are living in a flood plain,” said Hillman Mitchell. “We need to make sure we are prepared. We want to make sure that everybody stays ready and vigilant this winter.”

Mitchell told the Committee that with expectations of a wetter winter this year, his department is continuing its outreach to communities in the path of a potential flood should water need to be released from behind the dam.

“Now is not the time to relax,” said King County Councilmember Julia Patterson, who represents the Green River Valley. “While the heightened risk of flooding still exists, Valley residents and businesses must continue to prepare. I am pleased to see King County work to prepare the people and commerce for the possibility of flooding.”

“Although a lot of progress has been made and the risk of flooding has been mitigated, we must remain vigilant in our emergency planning efforts while we work with our federal and local partners for additional repairs,” said Council Chair Bob Ferguson.

A grout curtain put in place last winter by the U.S. Army Corps of Engineers has reduced the risk that water would need to be release from behind the structure to relieve pressure on the dam from 1-in-4 to 1-in-60. Additional repairs, which are targeted for completion in 2012, are expected to further reduce the risk of flooding.

Mitchell told the Committee that the regional public notification system, created by King County and the cities in the Green River Valley was tested earlier this year with positive results. Working with State Department of Commerce and local agencies, the Office of Emergency Management has developed a fact sheet for businesses in the Green River Valley to dispel some of the myths surrounding the potential for flooding.

Interagency cooperation between local, state and federal governments continues in the creation of response and recovery plans in the event of flooding in the Green River Valley. Mitchell said that includes the office of Emergency Management working on agreements to ensure there will be mass care facilities available if evacuations are necessary.

“The Army Corps’ comprehensive response to the threat at Howard Hanson Dam has been very reassuring for King County citizens,” said Councilmember Kathy Lambert. “This experience is a good reminder about why we implemented our landmark flood warning system 50 years ago. I look forward to celebrating the success of our system in saving lives and protecting property. The Water and Land Resources Division will have a series of flood update meetings around the county in the coming months.”

“The risk to the cities in the Green River Valley have been reduced, but there is still a risk,” said Councilmember Larry Phillips. “This briefing is a good progress report on what we’re doing to ensure that the people and businesses in the path of the flood remain aware and vigilant until permanent repairs on the Howard Hanson Dam are complete.”

Mark Issacson, Director of the County’s Water and Land Resources Division (WLRD), told the committee that many of the preparations put in place last year remain on the banks of the Green River, including the 26 miles of “supersacks”— oven-sized plastic and fiber bags filled with rock and gravel. Working in conjunction with the Army Corps of Engineers, repairs to the levee system that protects the Green River Valley have also been made.

Isaacson said WLRD’s has maintained its community outreach through an automated flood warning system which has over 3,200 subscribers. It has also updated its flood information brochure, which is available in several languages. The Department continues to work with community groups and the Red Cross to ensure that vulnerable populations and non-English speaking communities also have access to flood preparation information. WLRD will participate in public meetings in the Green River Basin and work with communities along the Snoqualmie and Cedar Rivers to increase awareness on flood preparations.

“Regional cooperation between the County, the cities in the Green River Valley and state and Federal governments have done great work protecting residents and making them aware of the problems caused by the impaired Howard Hanson Dam,” said Councilmember Larry Gossett. “I am pleased to hear that even with a reduced risk of flooding, the outreach efforts to the most vulnerable residents in the flood plain will continue.”


View the PowerPoint presentation given to committeemembers