Hydrologists play balancing game with Boise's reservoirs

There is still a lot of snow in the mountains.

Idaho's brutal winter is still impacting many parts of the state, this as record snow in the mountains still has yet to melt.

"Above 6,000 feet the snowpack mostly held on and didn't really begin melting in March," Danny Tappa with the National Resources Conservation Service said.

Currently, the Boise River Basin is about 140-145 percent above normal and estimate there's still about 2.6 million acre feet of snow in it.

"It's the most combined mountain precipitation that we've seen based on our SNOTEL sites since at least 1981 because that's when we put the sites in," Tappa said.

Some of that water remaining in the snowpack will evaporate or go into ground water, but a large portion will make its way into the reservoir system, which why the Bureau of Reclamation is working to save any remaining space for that water.

"Right now, it looks like we're in good shape we can maintain these flows, and with some of the analysis we've done we can pass the rest of the water when it comes," Brian Sauer with the Bureau of Reclamation said.

Currently, the reservoir system is two-thirds of the way full, but the current mountain snowpack can fill up that remaining space six times over again.

"We have time on our side. So we try and stretch the run-off season out and maintain enough space," Sauer said.

If the reservoir system were to reach capacity, with snow still melting, Sauer says we could see uncontrolled flooding, where what comes in must got out. It's something the Bureau of Reclamation says they're trying to avoid.

"We're going to do everything we can to avoid getting into the situation," Sauer said. “We’d ramp up higher, but only as high as we needed to to get through the crisis."

On Wednesday, the Boise River flows were around 8,500 cubic feet per second. However, engineers say levels could go higher without serious flooding.

"It's been over 9,000 historically back in the early 1980s, but we won't go there unless it's absolutely necessary," Sauer said.

According to the Ada County Emergency Management website, 9,000 cubic feet per second is on the cusp of moderate flooding.

"Ideal from here would be a normal spring, gradual increase in temperature," Tappa said.

© 2017 KTVB-TV


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