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Conservation Leader Says Deal with the Cause or We’ll be Chasing Floods Forever
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Tuesday, May 30, 2017
 

STORY AND PHOTO BY KAREN BOSSICK

Scott Boettger has been working to restore the Big Wood River to its more natural state since he took over as director of the Wood River Land Trust in 1997.

In 2002 he enlisted volunteers to remove old rusted cars and other junk dumped at Lions Park when it was the city dump.

And he and colleagues with Hemingway Chapter-Trout Unlimited were gearing up this summer to act on river restoration recommendations contained in a $180,000 study they had commissioned from the Jackson, Wyo.-based Biota Researching and Consulting, Inc.

The study had suggested such things as using natural materials like root balls and vegetation in the place of riprap to restore meandering in the river, creating riffles and pools and using fill material to return the flood plain to a more natural state.

The river will be surveyed again once this spring’s flooding has ended, Boettger said. But, he added, the flood of 2017 reaffirms that the study’s findings were on the right track.

“If anything, the flooding has made it obvious we’ve got to do even more. We’re going to need more partners,” he said. “If we don’t deal with the cause, we’ll be chasing the flood and its effect forever.”

The fast moving currents that crested at 7.82 on May 7 tore away parts of bank in Lions Park and picked up bed load—big rocks and cobblestones—from the river bottom and deposited them near Heagle Park. That backed up the river, forcing it to rise and find new routes through the preserve and the Sherwood Forest and Della View neighborhoods.

As a result, the neighborhoods have continued to be inundated by up to a foot of sheet flooding, even when the river dropped more than a foot below flood stage of 6 feet between May 18 and 23.

“There’s so much gravel being deposited in the river the flood waters are backed up to the Draper Preserve and flowing through the Della View neighborhood because that’s the only place it can go,” said Mike McKenna, the Land Trust’s community engagement coordinator.

“It’s like a funnel that’s blocked. Sometimes when you’re making home brew sediments get stuck in the bottom of the funnel and you have to remove them. That’s what this is like only we can’t remove what’s been deposited,” he added.

A lot of people seem to think the worst of the flooding is over—some have talked about removing their sandbags.

“But this is far from over. And what’s to come is going to be different because the river has changed,” warned McKenna.

Indeed, the Big Wood River had climbed back up to 5.53 feet by this morning--Tuesday, May 30--and it is expected to reach 6.77 feet by Friday, said Carol Brown, public information officer for the City of Hailey.

A few Wood River Valley residents have asked about building concrete walls or levees—manmade embankments—to prevent the river from overflowing its banks.

That is an extreme measure, said Boettger. Walls would have to be built higher and higher until at some point the river would break through and cause even more severe damage, potentially washing homes away.

Plus, McKenna observed, when you mess with one thing it affects things elsewhere: “Put a wall up and you’re just moving the problem somewhere else.”

When the river is in its natural state, big water moves bed load but in a manner the river can handle, said Boettger. When it’s constricted, it deposits bed load in a problematic manner.

“Nature’s got to be the designer. If you don’t replicate what’s natural, you’re always going to have problem flooding,” said Boettger.

One morning this past week Boettger picked his way around flood water at the north end of Draper Preserve.

The Land Trust got an emergency permit to have Alpine Tree Services cut down a few selectively chosen trees in the Draper Preserve over the weekend to stymie the velocity of the groundwater flowing through the preserve and reduce materials being carried along.

The trail through the Draper Preserve has been funneling water at a high velocity rights towards Cedar Street.

Creating roughness on the ground slows flows, Boettger said. It won’t eliminate flooding but it will cut down on the impact of fast-moving water on the Della View neighborhood.

Boettger continued to the Bow Bridge where he pointed out a dike—an embankment of earth and rock-- built decades earlier on the east side of the river.

Dikes in the river are still constricting the river.

The Land Trust had hoped that high water would spread over parts of Lions Park. But so much material was dumped in that area when it served as a city dump that the bank is still too high despite the restoration work the Land Trust has done so far.

“I hope we can open up some areas in the park to allow more room for the river to expand when we have big water like this,” Boettger said.

Heagle Park is also the site of an old dump, he noted, and the materials that have been dumped there are making it difficult for flood waters to flow through there as they should, causing water to spill over into people’s yards.

Boettger pointed out the remnants of a channel that carried water by gravity from the river to a sawmill in the Lions Park area in the 1880s. The river is now eight feet lower than the channel, showing how much the river has cut a channel in that area.

He pointed to a historic picture at an information kiosk near the Bow Bridge. The picture, taken around 1900, shows a river that snaked its way around China Gardens, resembling an “S” repeated a couple times.

An outline of the current river laid on top shows a river that’s nearly straight—a river that has straightened for 17 miles, having lost two miles in length. The banks have eroded, making the river wider than it used to be and rendering it unable to transport sediment downstream properly

China Gardens is no longer part of the flood plain because the river has cut down, Boettger said. And that’s affecting those downstream in the Della View neighborhood and further down in Bellevue.

“If we keep controlling the river, we don’t have a river. We have a flood channel,” he added.

Every house built near the river displaces the flood plain further, he added.

“That’s why we want places like Colorado Gulch and the Draper Preserve where the river is allowed to take its natural course,” he said.

In fact, the 150 acres of private property that the Land Trust bought in the Colorado Gulch area in December 2016 should allow seasonal flooding to help the river access its historic flood plain.

“And that might not have been possible had it remained in private hands,” said Keri York, the Land Trust’s director of conservation.

The Wood River Valley has experienced hundred-year floods twice in the last 11 years. And with the impacts of climate change and the changes to the natural flow of the river, issues with flooding will only continue to increase unless we can be proactive about making positive changes, said McKenna.

Flooding and high water runoffs in the 1970s and ‘80s were not as extensive as this year’s, he said. But alterations made to the river since, including building dikes, channelizing the river, landscaping the banks and installing riprap, have created many of the current challenges.

The water has sped up, causing more erosion. And the impacts of runoff from two big fires in the past decade have only exacerbated the problem.

“The good news is there is hope. We can make a difference by protecting the undeveloped area along the river, implementing restoration projects and reconnecting floodplains,” he said.

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