Washington’s Green River Valley Prepares for a Flood

Washingtons Green River Valley Prepares for a Flood

Months before flood season begins in western Washington, government officials have already declared a state of emergency and, even as they worry about the viability of a pivotal dam, have encouraged residents to buy flood insurance immediately.

When the Howard Hanson Dam was first built on the Green River in western Washington in 1962, the concrete behemoth was hailed as the new protector of the valley below. Until that point, the Green River Valley was regularly inundated during the flood season, which runs from late October through March. “We had an almost annual flood,” recalls Governor Christine Gregoire, who grew up in the valley. “Only when I was in high school and they built the Howard Hanson Dam did we see an end to the flooding.” Now, should the water rise to dangerous levels, engineers will be forced to release the dam, all but ensuring a flood of the valley below.

That is likely to affect the cities of Auburn, Kent, Renton and Tukwila, all located along the river, which runs from the Cascade Mountains to Elliott Bay, north of Seattle. It is an area where industry and real estate bloomed as its population surged — by 68% between 1980 and 2000 alone, according to the Washington State Department of Transportation. Some 350,000 people are estimated to live in the Green River Valley. Last January, because of torrential rains, the river rose 10 ft. higher than it ever had before and severely damaged the dam. This winter, with the likelihood of just as much rain, there will be some 35,000 residents in danger. If authorities try to make do with the crippled dam and it fails, “you’re talking about a biblical wall of water swimming down the valley,” says Kurt Triplett, interim executive of King County, home to the Green River Valley. So a controlled release may be the only way to regulate a catastrophe, even if it leads to flooding.

Engineers are frantically working to strengthen the dam, installing a “grout curtain,” or, as Triplett explains, basically applying huge amounts of caulk, to firm up where the edges of the dam anchor into gravel. Because the engineers can’t be sure that the patched dam will hold — and there is even a real possibility that the repair work could just ensure that the gravel collapses in one chunk, as opposed to failing in pockets — should the anticipated rains arrive, the only relatively safe option will be to deliberately release the dam. “What is crystal clear is that there will be a devastating impact if the water is released,” Triplett says. The Federal Emergency Management Agency estimates that if the dam needs to be released, the resulting damage could cost $3 billion. County officials estimate that the ensuing shutdown of business could cost the area another $46 million per day. The odds of needing to release the dam, according to the Army Corps of Engineers, are about 1 in 3. “That’s a huge number,” Triplett says.

And it was ultimately that grim reality that prompted Triplett to declare a state of emergency in early September, likely months before the dreaded event. Government officials have requested $40 million in federal funding to prepare — the dam is a federal facility — in addition to another $16 million from the Army Corps of Engineers devoted specifically to bolstering levees down the river. While Washington’s congressional delegates fight for the money in the nation’s capital, preparations and public-awareness campaigns are already under way — including driving home the importance of purchasing flood insurance, and buying it right away.

How do you buy flood insurance when there’s a 1 in 3 chance that you’ll need to use it That’s generally not a gamble insurers like to take. Fortunately for Green River Valley, King County belongs to the National Flood Insurance Program, which means that residents cannot be turned down for flood insurance , and that effectively, even though some 90 insurance companies administer the policies, it is the government providing the insurance itself. “There is nobody in the Green River area that should not be able to get flood insurance,” says Jeff Woodward, the region’s insurance-program specialist for FEMA. How much people have to pay for flood insurance — premiums vary from about $250 to $1,900 a year, Woodward says — depends on where they live in the floodplain and what risk level that area has, as determined by a complicated federal flood map.

In addition to understanding the complexities of flood insurance, homeowners should act quickly. The waiting period for policies to become active is 30 days, and experts believe the major floods will likely happen in mid- to late November, leaving just weeks for homeowners to get everything in order. Hence, the current government battle cry. “Buy flood insurance,” Governor Gregoire says. “I know we’re at a very difficult time financially for many families but should this dam fail, while FEMA will step up, it will never replace individual homes.”
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