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Cardno’s study breaks the Big Wood River down into 20 discreet reaches along its 36-mile scope. Each, such as this stretch near Hailey, engineers say, behaves differently—and may require different approaches.

As development projects—and their impacts—continue to mount along the Big Wood River, stakeholders sat down Wednesday morning in the Old County Courthouse to find a set of common goals for the valley’s main waterway, and to build a new guide that captures the approach.

The “atlas” of the Big Wood will likely be completed sometime later this year, the culmination of Blaine County’s $170,000 contract with international engineering firm Cardno to take an in-depth look at a 36-mile run of the river from Stanton Crossing south of Bellevue to the SNRA headquarters north of Ketchum.

Unlike past studies, this will be captured in a high-gloss product—think a coffee-table book—designed to explain the state of the Big Wood to laymen and engineers alike. County officials hope that package, backed by fresh data, will help foster a big-picture approach to the river—and update its regulation of the waterway, according to county Floodplain Manager Kristine Hilt.

“From the county’s perspective, I think it’s important that the final document applies to all communities up and down the valley—irrigators, engineers and the public at large,” she said during the meeting. “It’s a balance. … We’re starting to see the cumulative impacts of individual projects that have taken place on the river over time. It’s not all about individual details on a certain site.

“We need to step back. We need to understand what’s driving these changes. Hopefully this can guide us.”

But, while the study will compile the freshest possible data, Cardno water resources scientist Jon Ambrose made it clear that he’s not here to argue for any particular policy. He’ll work to put the information in a digestible form, but after that, management practices are up to the county, landowners and local jurisdictions that bank the river.

“There are various stakeholders with various visions,” Ambrose said. “Ultimately, you want to create a shared strategy, with multiple uses and multiple purposes, for the river.”

That’s why the county prioritized clarity with the new reachwide study. Past findings, including those completed by Jackson, Wyo.,-based Biota Engineers in 2016, were either too limited or too difficult to understand, Hilt told the commissioners when they approved the contract in November.

Her interest is policy—particularly, using clear data to support county recommendations for development within the floodplain.

Already, she said, Cardno’s data based on the floods of 2017 show that FEMA’s current mapping for the area—and, therefore, its standards for some buildings along the river—is out of date.

Near Hailey, for instance, images from two years ago show flooding well outside FEMA’s expected boundaries. According to Ambrose, that flood was more likely a 20- to 25-year event, not a 100-year one.

With that in mind, Hilt hopes to use the new material to justify more strident county requirements.

“I think the information that we can get here will be drivers of policy in the future,” she said. “We can regulate above minimum standards, if we have the information to support it. And this information I see as much better and more reliable than what you’ll get from FEMA right now.”

FEMA is currently working to update maps with more modern techniques, Ambrose said. When it does, it will also update requirements for development—including which sites need flood insurance. Those, though, may be years away. Cardno’s data can’t replace FEMA’s when it comes to regulatory practices, but the county can put it to work. Only FEMA can tell landowners to buy flood insurance, but the county can tell them to elevate or anchor their house.

“What is the right approach for addressing bank erosion? What is the right approach for habitat restoration?” Ambrose asked. “I don’t want to suggest there are different sides of the table here—I don’t think there are—but there are different goals. That’s why it’s so important to develop those goals, and that vision, together.

“The way I’ve been seeing this document is it’s a document that represents the community, and how the community interacts with the river—now, and in the future.”

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