Army Corps of Engineers thinking big about restoring Yakima River

YAKIMA – As it flows from Selah Gap to Union Gap, the Yakima River provides a rare urban habitat for wildlife, opportunities for fishing and boating and plenty of scenery for those walking or biking on the Yakima Greenway.

But those familiar with the river know its peaceful sound of rushing water belies a power capable of devastating destruction.

After the epic flood of 1933, officials began planning a series of levees that artificially channeled the river and protected the immediate surrounding areas in times of high water. But while the levees worked they sometimes required expensive repairs, sometimes failed and harmed wildlife habitat.

In recent years, however, efforts have shifted to bringing back a more natural environment that still protects property but at less of a cost over the long run.

The latest proposal by the Army Corps of Engineers would – at an estimated cost of more than $13 million – restore a more natural flood plain, decrease the risk of flooding and reduce expensive repairs to levees. It would also create a more productive habitat for fish, plants and wildlife.

“We’re taking a more holistic approach on restoring the river function and the flood plains throughout that particular reach, as well as the Naches River,” state Department of Fish and Wildlife biologist Perry Harvester said.

Smarter planning

Levees along the river were designed in the late 1930s, but not built until after World War II. They relied on the simple principle of restricting the river and preventing floods, and were based on limited historic data on flooding, according to Yakima County senior natural resources specialist Joel Freudenthal.

As a result, repairs were regularly needed over the years as the levees were hit by various floods.

But by 2000, work was already underway to make significant changes. Officials realized by taking advantage of the relatively open space on the east bank, they could spread the river over a wider area, greatly reducing the threats to developed urban areas on the river’s west side.

“It took a long time for (the city of Yakima) to understand that, look, you guys are the ones that are benefiting,” Freudenthal said. “There’s $3 billion worth of property value on (the west) side. There’s nowhere near $3 billion worth of property value on this side.”

Freudenthal estimates the county, the Corps and other groups have spent almost $55 million over the past 16 years on various fixes and projects, such as lengthening the State Route 24 Bridge, which once forced the river through a relatively small area.

The Corps’ latest plan would set back levees near SR 24 Bridge and restore a channel in Sportsman’s State Park, creating 320 additional acres of flood plain

That would allow the river to meander more, decreasing its velocity and putting less pressure on critical levees on both sides. Many of the levees have eroded and have needed emergency repairs, such as when the river threatened to spill over into Buchanan Lake during the flood of 1996.

Moving forward

One of the highest priorities is protecting the city of Yakima’s wastewater treatment plant from flooding. That means relocating levees on the opposite side of the river so there would be less velocity against levees on the west bank where the treatment plant is located.

Pushing those east side levees away from the river would also lower the risk of flooding for an area near SR 24, making it more attractive to potential businesses. Freudenthal said major companies have expressed interest in the past only to be deterred by flooding.

New channels in the river’s expanded floodplain will create crucial new spawning grounds for fish, such as steelhead and bull trout, which Harvester said struggle to find rearing areas in narrow, deep channels created by the existing levees.

Fish won’t be the only animals to benefit, as more shoreline and wetlands would attract waterfowl as well as insects.

“Instead of having just primarily one channel of the river, there’ll be a lot more diversity of the river,” Harvester said. “There’ll be a lot more braiding of the channel. The productive capacity of the river will go way up.”

Yakima River Runners Club President Michael Aquilino said the changes won’t necessarily be good for boating with all the additional channels and reduction in energy. Still, he fully supports returning the river to a more natural state.

Freudenthal said a $770,000 feasibility study could conclude by September with work starting next year. However, Corps of Engineers planner Chris Behrens declined to speculate on when construction would start since funding hasn’t yet been allocated.

Other improvements are part of a longer-term plan, including a proposal to widen the Terrace Heights Bridge. Freudenthal said the bridge’s design sent water blasting against a levee immediately downstream, causing it to nearly fail during the 1996 flood.

Freudenthal said more flood plains and less pressure on levees should mean significantly less maintenance costs for the county, but it will take years to finish.

“This is a major structural change,” Freudenthal said. “So when we get done it’ll probably be a couple decades for (the river) to respond and the hope – and I think it’s 99 percent likely – is that while it’s doing that, it’s probably not going to be chewing on the levee system.”