Friday , April 21, 2017 - 12:00 AM2 comments
The winter’s ample snowfall is now melting, sending much-needed water downhill to a withered Great Salt Lake. But climate experts caution that relief won’t last.
Snowpack levels in the river basins feeding Utah’s largest terminal lake hit between 157 percent and 172 percent of normal by March. The snowy winter followed four years of drought. Water levels in the Great Salt Lake dropped to near-record lows while raising concerns about impacts on air quality, migrating birds and the future of lake-based businesses.
As of last week, the Great Salt Lake’s south arm sat at nearly 4,195 feet, nearly a foot higher than the same time last year.
Meanwhile, the top of Logan Canyon — part of the Bear River Basin — had 9.5 feet of snow and the equivalent of around five feet of water, a positive sign that the lake could continue to rise.
“What does the Great Salt Lake mean? It’s kind of an indicator of what’s going on around it,” said Scott Jones, a professor of environmental soil physics at Utah State University, during a recent snow survey. “We have wet years and dry years, and the Great Salt Lake shows to some degree when those happen.”
USU’s Utah Climate Center has taken historical data of the lake levels along with tree-ring data to model the lake’s fluctuating levels going back hundreds of years. Combing that with historical coral data from the Pacific, they’re able to make predictions on when the lake will rise and fall. That helps water managers prepare for future years of drought and surplus.
“By predicting lake level, you’re predicting climate,” said Simon Wang with the Utah Climate Center.
Using models based on the historic climate data, Utah Climate Center scientists predicted back in 2010 that the Great Salt Lake’s levels would dip to their lowest point in 2016, then start climbing again in 2017. Turns out, that’s exactly what’s happening.
Great Salt Lake level predictions
Source: Utah Climate Center
“If this were the stock market, I’d bet my money on it,” Wang said.
Levels are predicted to continue climbing until 2020.
The timing couldn’t be better for the lake’s industries and ecosystem. Last December, state officials and Union Pacific breached a railroad causeway that had severed the north arm of the lake from any fresh water. It dropped 3.5 feet lower than the north arm.
Once the breach was completed and water began flowing to the north arm, scientists worried dropping levels in the larger south arm would expose more lakebed and stir up dust.
They also worried it would drive up salinity levels and impact brine shrimp populations, which feed migrating birds and a multi-million dollar harvesting industry.
Others worried about boats left high and dry, and about land bridges to remote nesting islands.
With all that snowmelt flowing to the lake this spring, however, south arm water managed to bump up by 2 feet since the December breach, even while water flowed through the causeway and boosted the north arm elevation by nearly 4.5 feet.
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Great Salt Lake levels, south arm
Great Salt Lake levels, north arm
While conditions seem to be improving, scientists studying the lake remain cautious.
“You can never tell with the weather what the future of climate’s going to be,” said Jim Van Leeuwen, an ecosystem biologist with the Great Salt Lake Ecosystem Program. “It could be just a blip, hopefully it’s more than that.”
While Utah Climate Center forecasters predict the lake will continue to rise over the next few years, climate change and human diversions throw a wrench into the works.
A 2016 study by Utah State University and the Utah Division of Water Resources found the lake would be 11 feet higher if not for humans damming and tapping its tributary rivers — the Weber/Ogden, the Bear and the Provo/Jordan.
Plus, there’s a warming trend in the region that’s expected to get worse.
“Continued warming means evaporation, and the only way for the water to go out (of the lake) is evaporation,” Wang said. “So yes, the lake can continue to drop.”
To understand the effect of warming on lakes in Northern Utah, one only need to look at the shoreline from ancient Lake Bonneville that rims the mountains of the Wasatch Front.
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“The very last period of time, about 10,000 years ago, when lake continued to get lower and lower, it was because we were in an interglacial period. The translation is, that’s warming,” Wang said. “Gradual warming caused the lake to shrink continuously. Now we are having accelerated warming, (but) the physics still apply.”
Big snow years likes the 2016-2017 season often give people false hope that there’s plenty of water, Wang said. But looking at past climate records, Utah’s most stable condition is a state of drought. A warming global climate will likely accelerate the Northern Utah’s extremes.
For the non-climate scientist, Wang understands it can be difficult to understand how climate cycles 3,000 miles away in the Pacific influence water sources in Utah.
“Imagine you have this super typhoon pop up in the Western Pacific,” he said. “One Category 5 hurricane can produce around 100 times (the amount) of the Hiroshima bomb energy.”
That energy has to go somewhere. Often times, it moves into the jet stream and makes its way to the Western U.S.
“It’s all compound, it’s not precise,” Wang said. “We might have bad weather anyway, but a tropical cyclone ramming into the jet stream can amplify this bad weather to become worse or stay longer.”
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Those global changes will likely cause Northern Utah to see a slight increase in precipitation, Wang said, but the amount of precipitation coming down as snow will decline.
“The warming trend is very solid — all the evidence suggests the warming trend, especially in the springtime, is accelerating,” he said. “How that effects water managers or reservoir operators, I can’t answer that. They’ve got a lot of difficult decisions to make.”
With Utah’s growing population and plans to build a large diversion on the Bear River sometime in the future, the Great Salt Lake could take the biggest hit.
“I would say, really, ... with climate and human developments, it’s not impossible the lake can go dry,” Wang said. “We just don’t know when.”
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