A flood of once-in-a-century proportion inundated homes from Nile to Toppenish, first sending residents scrambling for sandbags and later raising questions about how best to prepare for future floods in a region where nearly every town and city has been built along rivers or in floodplains.
It began when warm storms dumped rain on deep snows across the region — 11 inches of rain hit the Yakima River’s headwaters near Snoqualmie Pass in just three days — sending so much water, ice and debris down the river and its tributaries on Feb. 9, 1996, that it spilled over its banks by more than 6 feet at Union Gap.
It was the second-worst flood to strike the Yakima Basin since record keeping began a century earlier, and the toll was high: 111 homes destroyed and 2,204 damaged; hundreds of people evacuated; and $17 million spent in the following year to repair roads, homes, levees and Yakima’s wastewater plant.
Officials say with 20 years of investment to rebuild bridges, remove homes and businesses from the floodplain and rethink how to manage the river, a flood of similar magnitude would cause far less damage today.
But it doesn’t mean flood risks are a thing of the past in the Yakima Basin.
During the largest floods, conditions become unpredictable. Which creek will have boulders and debris come crashing down? Where will an ice jam form that pushes a raging river over its banks?
In 1996, an unexpected ice jam sent the Yakima River flowing across the Yakima Elks Golf and Country Club in Selah, stranding about 30 people at the country club. The fast-moving water prevented rescue by boat; ultimately, it took a 5-ton military surplus truck to safely evacuate those trapped.
Boulders and gravel tearing down Rattlesnake Creek near Nile nearly dammed the Naches River, pushing the river into one narrow channel with enough power to wash out the highway.
“The roar of large boulders coming down Rattlesnake Creek literally sounded like a freight train, you had to scream just to have a conversation,” recalled Perry Harvester, a habitat specialist with the state Department of Fish and Wildlife who worked on the flood response.
Everyone was in awe of the floodwaters on Rattlesnake, he said, because such events happen so rarely that people forget that they are even possible. In that way, the 1996 floods washed away complacency, too.
“People call us now to ask about the flood history of their properties before they build, and that’s good because that babbling brook behind your house could become a roaring river that you can’t possibly imagine,” Harvester said. “These small streams can turn into raging giants when we have a big rain or snow event.”
A wake-up call
The 1996 flood spurred the county to create its own flood control zone district in 1998, which has the authority and funding to address a wide variety of river management issues across municipal boundaries.“We just focus on making the river work better,” said Joel Freudenthal, natural resource specialist for Yakima County who was hired when the flood control district started up.
“We’re authorized to cooperate with anybody under the sun, including private folks, if we decide that the reduction in flood hazard is worth the costs and time and cooperation needed,” he said.
One of the district’s major successes — relocating a junkyard from the floodplain next to the Donald-Wapato Road Bridge in coordination with a redesigned bridge — means that a future flood shouldn’t inundate Toppenish like it did in 1996.
Floodwaters traveled more than a mile from the river across fields and roads to immerse the northeast side of town, where more than 300 volunteers worked around the clock filling 20,000 sandbags to protect homes and businesses.
“The floodwaters used to just stack up there and go sideways down to Wapato and Toppenish, but now, with the bridge replacement and the wrecking yard moved out of there, the floodwaters would be 8 feet less,” Freudenthal said.
That is, if a similar flood struck today, instead of the river rushing over its banks by 6 or 7 feet and pouring down the valley, it would stay safely in the channel.
Efforts to purchase private property to move people out of high-risk flood zones have been time-consuming and controversial, he said but it makes more sense to give those high-risk areas back to the river.
With the help of state grants, properties have been purchased along Ahtanum and Wide Hollow creeks, in the Lower Naches River, and along the Yakima Greenway near Union Gap.
Other projects include improved flood mapping, updated zoning to limit development in high-risk areas, designing an interagency flood response plan, levee repair and removal, and rerouting roads prone to washout.
The district worked closely with the state Department of Transportation on the replacement of the State Route 24 bridge, which was damaged by the 1996 floods. The new, wider bridge, which was finished in 2007, allows floodwaters to pass below it without building up to unsafe levels, Freudenthal said.
“The bridges have more capacity now, with the dikes pushed back so that water can spread out and slow down and so it just doesn’t have the energy to tear things up like it did in ’96,” Harvester said. “I’m very confident that if we were going to have another flood of that magnitude, the damage would be far less.”
Rethinking rivers
Much of the flood control zone district’s work, along with state and federal partners, represents a changing approach to flood management that gives rivers more space rather than strengthening restrictions, such as levees that can channel floodwaters into fast-moving, destructive forces.Wider bridges, larger culverts, and levees pulled back to provide more floodplain are all part of the effort, but it’s a challenge here because we’ve already built our communities around our rivers.
“We’ve got a highway next to an irrigation diversion next to a levee and they are all fighting each other” and pushing up floodwaters, Freudenthal said. “Then, the energy (of the water) concentrates in certain areas and it chews on your infrastructure.”
The costs of rebuilding around our rivers are high — the Army Corps of Engineers spent $12 million to relocate one of its levees next to Yakima and the state Department of Transportation spent $14 million on the State Route 24 bridge.
But they pay off, Freudenthal said.
Those projects gave the river more space and were successful last December, when heavy rains sent water rushing down the Yakima River at moderate flood levels with little damage, he said.
While Rattlesnake Creek washed out a section of the Nile Road and lots of backyards flooded as the Naches River rose to within 2 feet of the 1996 flood, damage was still minor compared with the havoc of two decades ago.
“Now there’s a lot more space for the river to move around without concentrating its energy to chew on anybody’s infrastructure,” Freudenthal said. “It’s going to be a lot less expensive to maintain and provide more certainty that your infrastructure isn’t going to crumble.”
Slowing down the rivers and giving floodwaters more room has also added more fish and wildlife habitat to the region.
“By doing that we’ve also improved habitat for fish because those high velocity flows can flush spawning gravel and habitat out,” Harvester said.
Some big issues remain, however.
One ongoing challenge is the sediment that builds up behind diversion dams and along levees, Freudenthal said. That extra sediment pushes the rivers up so that it actually takes less water to spill over their banks.
“We know if there was 100-year flood now, it would go beyond the boundaries of what’s mapped as current 100-year flood,” he said.
Working with irrigation diversions to reduce that sediment buildup is going to be a next big priority for the flood control district, he added.
And then, there’s always a risk of a flood larger than the improvements have been designed for. The largest flood recorded in the basin occurred just before Christmas in 1933, and the flow of Naches River filled the entire Naches Valley.
“If we had another 1933 flood, it would still be a major disaster. The Naches River was wall-to-wall across the valley, and there’s just nothing we can do about that,” Freudenthal said.
“We can get rid of a lot of the nuisance things, the 50-year flood-type impacts, but we just can’t prepare for everything.”
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