Flood worries rise for Green River's rural neighbors

The Green River above Auburn looked placid in spots early last week, but walk any stretch and a rowdier, high-running stream emerged.

Mini-waves swamped spawning salmon, and boisterous white caps doused log jams, even with waters tumbling at a mere 1,800 cubic feet per second.

With its swifter velocity and lower banks rarely buttressed by levees, the pastoral section of river above Highway 18 rises faster, with less warning and with more devastating force than it does below.

Yet, as King County and cities downstream spend millions to prepare for the possibility of major flooding this winter because of the weakened Howard Hanson Dam, little is being done to keep this middle section of the Green from swamping the upper valley.

That leaves residents of the 150 or so homes along this 32-mile stretch between Highway 18 and the dam with virtually no defense against potential flooding that would hit them the hardest and first.

"It always seems to be the rural people who are stuck saying, 'What about us?' " said Clarissa Metzler Cross, who raises show horses and grows blueberries several hundred yards from the river. Her property, Canter-Berry Farms, is a little more than 5 miles east of Highway 18.

Fire officials have scrutinized logjams, gone door to door with evacuation plans, urged residents to buy emergency radios, and increased the frequency of white-water rescue training.

But the upper valley's sparse population and the river's more-natural channel have left emergency planners mostly scratching their heads.

"We have to make choices sometimes," said Steve Bleifuhs, who oversees floodplains for King County. "We haven't spent a lot of time on that stretch, in part, because there's really not that much we can do."

Since a January storm damaged an abutment to the Howard Hanson Dam, the Army Corps of Engineers maintains there's a 1-in-4 chance it may have to release enough water to cause significant flooding along the Green.

King County and several cities have spent millions of dollars scrambling to prepare, with most of the effort focused on reducing the threat to the tens of thousands of homes and businesses between Auburn and Tukwila. Even without the Mini-Cooper-sized sandbags that are being stacked along the lower river, downstream levees don't even typically seep until waters rise above 12,000 cubic feet per second (cfs).

But there are virtually no levees upstream, and minor flooding can occur with flows as low as 7,000 cfs. Flood planners warn that, depending on the weather, dam releases this year could drive flows to anywhere from 13,900 to 25,000 cfs — far higher than anything seen since the dam was built nearly 50 years ago.

Some upper-valley residents, like Arnold Horath, who raises heifers on a small farm a couple of miles east of Highway 18 along Green Valley Road, aren't all that worried.

"It won't get that high," he said, resting one foot on a fence post during a work break beside his barn. "If it does, there's a little high ground between the river and here."

But the possibility of flooding is keeping others, including Metzler Cross and her husband, up night after night. When waters last year approached 12,000 cfs, the road near her property was submerged under 8 inches of water.

"The whole thing is absolutely terrifying," she said from her driveway, located across the road from a pasture that adjoins the river. Her property is trapped in a narrow canyon between the Green and a steep hillside. "I mean ... where is the water going to go? We don't know."

Officials don't dispute how potentially dangerous flooding could be for upper-valley residents.

Before the dam began operating in 1961, the Green River regularly spilled its banks, particularly in the upper valley.

But with the dam protecting against the worst floods, many homesteads that dotted the upper valley have been replaced by Kentucky-style horse farms and exotic-livestock ranches. Villas reaching 5,000 square feet have cropped up.

The dam may contribute to the current threat in less-than-obvious ways, too. Much as wildfire suppression has made blazes more explosive in national forests, the dam has prevented the river from migrating as it normally would. That means no one knows precisely how the river will move during high water. Sharp river bends may blow out and create new channels, relieving pressure on the mainstream; or the river may migrate and undercut roads or structures.

"Below, we've got the river contained in a straitjacket," said Tom Bean, a riverplain engineer with the county. "Upstream you'll get a more natural — though not completely natural — channel migration."

Officials with King County Fire District 44 worry that high river flows also will cause nearby creeks to back up and cut off evacuation routes. From the moment water is released from the dam, the easternmost upstream residents will have about three hours to respond; the water won't reach Auburn for about eight hours.

"We hope people leave when we tell them," Chief Greg Smith said.

Fellow Chief Mike Barlow said, "What we know is there'll be water in places where there hasn't been water in a long time, maybe ever."

Perhaps more worrisome to emergency planners and residents are the dozens, perhaps hundreds, of log jams that have built up in the channel over decades. Those logjams, some bigger than houses, potentially will trap debris coming downriver — a good thing. But many county officials also worry those logs could shoot downstream, endangering people and property.

"The Green has been tamed for so long that it seems it would be more like a coiled spring and ready to deliver trees in large number," Bean said.

Metzler Cross, whose family lived in the valley before the dam, now makes blueberry jam and syrup, chutney and vinegar that she and her husband sell at Pike Place Market. They've arranged to move their horses to a farm near Seattle and have made plans to relocate other valuables to higher ground during the rainy season.

But they worry that logs and muddy river water powering through their home and business could cause damage that would take years to repair. She also finds herself driving Green Valley Road, checking to see which low-lying bridges could get wiped out by log torpedoes.

In the meantime, she keeps writing letters to county officials asking for them to try something to prevent the flood, and she and her husband noodle to try to think of any scenarios they might have missed.

"That's what makes it so unnerving," she said. "Anything can happen."

Craig Welch: 206-464-2093 or cwelch@seattletimes.com