Monday , January 22, 2018 - 5:15 AM
Biologists, state officials and lake-dependent industries also braced themselves for a flood of unknowns.
The railroad spur running across the lake from Promontory Point to its west desert shore has divided the Great Salt Lake for decades, apart from two bridge-like culverts that allowed water to pass through. Union Pacific closed those culverts in 2012 and 2013 as the structure became unstable.
Then they delayed opening their newly engineered breach as the lake’s elevation began to drop, which effectively created two lakes. Cut off from the lake’s tributary rivers, the north became artificially low and salty. The south became artificially high and fresh with water flowing in from the Bear, Weber and Jordan rivers.
A tug-of-war ensued about how best to reunite the two arms.
Brine shrimpers worried an influx of super salty northern water would shock the shrimp that still thrived in the south, hurting their multi-million dollar harvest. Minerals industries on the north worried about the millions they’d need to spend digging canals to reach the rapidly receding brine. Biologists worried about the ripple effects it would have across the entire lake ecosystem and up the food chain to migrating birds.
The breach came on Dec. 1, 2016. Then came last winter’s phenomenal snowfall.
“We would’ve hit a (record) low on the south arm last year, except we delayed that breach until December, then we had a lot of snow and a fairly wet spring,” said John Luft with the Utah Division of Wildlife Resources Great Salt Lake Ecosystem Program.
Last winter’s runoff alleviated many concerns about the Great Salt Lake in the short term. But its future still looks murky.
First, the good news.
Delaying the breach until December ended up being the right call, Luft said. The brine shrimp industry had a healthy harvest. Snowmelt replenished the south arm as its water rushed through the causeway to fill the salty north.
There were even a few surprises.
“The funny thing is, everybody expected the south arm to increase in salinity. I expected that,” Luft said. “It actually decreased because of all of that flow.”
The wall of water running through the causeway blocked the north’s pink, hyper-saline water from flowing south. Before the causeway breach, the blue-green south arm water was around 17 percent salt. Today, it’s at around 12 percent, Luft said. The north arm’s salinity hasn’t changed — it’s still at 27 percent, the point where water is so saline, salt settles out. The north will likely always be saltier than the south.
“I think the only way to restore one lake with one salinity is to take the causeway out, which I don’t think will happen,” said Bonnie Baxter, director of the Great Salt Lake Institute and a biology professor at Westminster College.
The lake’s elevation is almost at equilibrium and scientists are starting to see the north’s water flowing to the south. But their waters aren’t exactly mixing. The north arm water is so heavy with salt that it sinks when it mingles with south arm water.
“It’s almost like oil and water,” Luft said. “That more dense water, it just doesn’t mix into the fresher water.”
Biologists were also surprised by their counts of eared grebes. Those unique waterbirds double their weight gorging on brine shrimp as they prepare for a southern migration. Following the breach, they visited the Great Salt Lake in record numbers, Luft said. His team counted 5 million of them — around 90 percent of the entire population made their stopover at Great Salt Lake. In years past, only around half of the grebe population staged in Utah.
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Now the bad news.
Those same eared grebes are likely in Utah in record numbers because it’s the only place with food.
“It is good in the sense that our management of the brine shrimp population has taken into account their need and been able to sustain that large of a number,” Luft said. “However, it is disturbing that almost an entire population of a species is dependent on one place.”
Salty lakes throughout the West are withering away, including the Great Salt Lake.
While the grebes visited the Great Salt Lake in droves, other birds seem to be suffering as habitat disappears along with the water.
Gunnison Island in the lake’s north arm, for example, is one of the largest breeding grounds for American white pelicans in the world. Breaching the causeway should’ve benefited that habitat, in theory, with an influx of water covering land bridges and preventing predators and people from disturbing the birds.
But last season’s runoff wasn’t enough.
Luft’s team only counted half the breeding adults on Gunnison Island that they’ve seen in years past. They spotted coyotes on the island. Wildlife cameras caught multiple people visiting the site, too, on ATVs — which is illegal but hard to enforce.
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“We just lost so much habitat there and a huge forage base for these birds,” Luft said. “They’re still trying to come here but they’re here for a shorter amount of time ... it’s had a huge impact on numbers of birds and the diversity, too.”
The lack of mixing between dense north arm water and fresher south arm water is causing issues, too. When the heavy salt water flows through the causeway breach and sinks, it creates what scientists call a “deep brine layer.”
“The deep brine layer goes anoxic, so there’s no oxygen. That’s when you begin to see the methylation of mercury,” said Cory Angeroth with the U.S. Geological Survey Utah Water Science Center.
Methylmercury is a highly toxic type of mercury that impacts the nervous system. Past research suggests the deep brine layer is where mercury accumulates and can be taken up by organisms like brine shrimp.
In November 2016, if the causeway in the Great Salt Lake had completely disappeared, the lake would’ve hit a record low — it had an average elevation of 4,191.3 feet. Even with the breach and last season’s phenomenal runoff, the south end of the lake currently sits at 4,194 feet, well below its historical average elevation of 4,200 feet.
The Great Salt Lake’s decline is partly due to drought, but mostly caused by the water habits of Wasatch Front residents. Diversions on the lake’s tributary rivers have lowered its elevation by as much as 11 feet and reduced the water volume by half.
And with a dismal start to this year’s winter, things look bleak.
“There’s a feeling we won’t recover from this desiccation and it’s not just my feeling. It’s largely based on the data we have in hand,” Baxter said. “I think it’s easy to be in the moment and say, ‘Hey there’s a lot of powder this year,’ and it’s a lot harder to look forward and think about the bigger trends.”
Looking forward, the causeway might be the key to helping the lake endure. Union Pacific designed its new breach to be adjusted — it can be filled in again to keep the south arm less salty or deepened and widened to bring more water north if the lake continues to shrink. The railroad company is responsible for any breach modificaitons for the next four years, then the responsibiltiy falls to the Utah Division of Forestry, Fire and State Lands.
“I think it’s a brilliant solution and I hope it will work,” Baxter said. “I think if the precipitation and amount of water going to the lake remains constant, it’s going to be really important. If we continue to suck water out of our watershed, it’s going to be hard to use the breach to control salinity.”
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