THE BUZZ 2: Dam Concerns

By on May 24, 2017

Officials discuss potential for flooding as massive snowmelt ensues in the valley.

 

JACKSON HOLE, WY – If you’re not building the next Noah’s Ark, you might be in trouble once the weather warms up and the snow melts. That was the sentiment of one audience member at a public meeting with the Bureau of Reclamation and the state engineer’s office last Thursday. His worries, though not shared by local officials, at least raised important questions about the consequences of this winter’s historically high snowfall.

He pointed to the water levels in Jackson Lake and the Bureau of Reclamation’s apparent inaction in the face of imminent flooding. According to his estimations, the lake could fill up in as few as 10 days of heavy runoff. If enough water hasn’t already been released from the dam by peak runoff, Teton County will end up under water, he argued. His proposed solution was to release as much water from Jackson Lake as possible now in anticipation of the devastating snowmelt.

But it’s not that simple, says Bureau of Reclamation water manager Corey Loveland. His job is a balancing act. Releasing all the water now would deprive essential irrigation systems in Idaho down the road (err, river). They must release enough water, Loveland said, to make room for future snowmelt without running the dam dry. And that’s precisely what they’re doing. “We’re balancing filling the reservoir with not flooding people downstream,” he said.

Loveland says he and his team are acting according to a flood control curve, which measures water levels against forecast to mitigate flooding. It’s the same technique they use in the Palisades, but the needs are different in each reservoir. Certain tributaries that feed into the Snake will certainly have “at least high flows, if not flood flows”—but those are out of his control.

As for Jackson Lake Dam, the Bureau of Reclamation is releasing 2,200 cubic feet per second (CFS). That’s already more than the average daily discharge for this time of year. For visual reference, Loveland compared a cubic foot to a basketball. That’s 2,200 liquid basketballs per second. By the end of the month, he anticipates increasing that flow to as high as 5,000 CFS.

In relation to the flood control curve, “we’re right where we need to be,” Loveland said.

Jackson Hole has no doubt seen record snowfall this winter, and the more snow falls, the more there is to melt. According to data collected from the Bureau of Reclamation, the United States Geological Survey and Mountain Weather, snow precipitation this winter is the highest on record at 600 inches. The water content of the snow is also approximately 165 percent of average. And because winter continues to overstay its welcome, cold temperatures have delayed most of the run-off for the season. The combination of conditions led the National Weather Service to predict a moderate to high snowmelt flood potential in the Snake River.

Indeed, conditions do look a lot like they did the last two times the valley flooded in 1997 and 2011. “It’s not like we’ve never seen this before,” said MountainWeather.com meteorologist Jim Woodmency.

Woodmency recalled that in 1997, “all of Idaho was flooded.” It was a little tamer in 2011, and more closely resembled this year’s conditions, but parts of the valley still flooded.

From a meteorologist’s perspective, Woodmency’s biggest concern is temperature. Temps are still low enough in the mountains to maintain a steady, slow snowmelt—last week’s little snow storm was actually a beacon of hope for flood fearers. Once temperatures reach 70 degrees in the valley and 50 in the mountains for about three days straight, “then you can see pretty significant run-off happening,” Woodmency said. That usually doesn’t happen until mid-June, but Woodmency noted there is still a “significant amount of water contained” in the snowpack, and snowmelt has “barely made a dent above 8,900 feet.”

If, or when, tributaries and surrounding areas do flood, Teton County Commissioner Paul Vogelheim says the county is braced to respond. Flooding, he said, “should be a concern for all of us.”

As far as prevention is concerned, there’s really nothing the county can do, he said. Idaho owns the water rights on the dam and in the Snake. Instead, the county’s job is crisis control. “We focus our energies on the response,” Vogelheim said. However, he continued, “there have been times when we have as a commission voiced rather aggressively our concerns [to the Bureau of Reclamation].” This spring may be one such time.

 “Our priority is public safety,” Vogelheim said. “We’ll be voicing our concerns along the way if we get indications from our staff of a specific tactic. But we also have to respect areas of responsibility.”

Electeds cannot, Vogelheim said, act on every predicted crisis brought before them. “You’d lose all credibility.”

The concerned citizen at the meeting has since given up trying to convince electeds and government agencies of the gravity of the issue, claiming that it is a waste of his time to warn deaf ears. He is still not convinced that the Bureau of Reclamation’s flood control curve is enough given the unusual winter.

But unusual weather, Vogelheim says, is as intrinsic to Wyoming as rapids are to rivers. It comes with the territory. “As citizens, we’ve all decided to move to this place that is unpredictable in terms of rain, snow, sleet, floods … all sorts of things,” he said. “No matter how much we think we’re in control, we’re not.” PJH

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