The Tri-State Compact That Could Destroy the Great Salt Lake

An agreement signed in 1958 and amended in 1980 divvies up the Bear River between Wyoming, Utah and Idaho. If the states find a way to use all their allotted water, the Great Salt Lake could turn into toxic dust.

Written by Emma Penrod Published on Read time Approx. 6 minutes
A herd of mule deer walk along the Great Salt Lake. Water diversions could reduce flows in the largest water source feeding the lake, Bear River, and greatly shrink the lake’s footprint, impacting wildlife and neighboring communities.Prisma by Dukas/UIG via Getty Images

Some time ago, engineer and hydrologist Craig Miller awoke from a nightmare. In it, he said, he envisioned a scenario in which the state of Idaho built a massive pipeline from the Bear River to the more populous Snake Valley, decimating the Great Salt Lake.

The Bear River is the Great Salt Lake’s single most important source of water. In any given year, 53–56 percent of the water to arrive at the Great Salt Lake comes from the Bear, which is shared by three states – Utah, Idaho and Wyoming – according to the terms of the 1958 Bear River Compact.

The Bear River is also one of the few remaining water sources in the western United States where large quantities of unclaimed water may be available. So with demand mounting in neighboring communities, Miller’s fear that someone is going to figure out how to use that water may become reality. If that happens, he said, it could reduce the Great Salt Lake to dust – toxic dust.

“It’s a slow-moving train,” said Miller, who models water levels in the Great Salt Lake for the Utah Division of Water Resources. “We can step off the tracks, but we have to take action. We can’t sit back and say that will never happen.”

Miller’s not alone in his concern. At a June conference in Salt Lake City, environmental advocates, academics, government officials and even industry groups openly worried about the implications of the Bear River Compact for the Great Salt Lake – and lamented the fact that neither Wyoming nor Idaho had sent representatives to participate in a dialog about the lake’s future. But even with concern for the lake mounting, solutions that everyone can agree on will be hard to find.

A Growing Region

A 1980 amendment to the Bear River Compact took essentially all the remaining water in the Bear and assigned a portion to each of the three states it passes through. But the Bear River is remote and not easily accessible to population centers, so large-scale development was long assumed unfeasible.

Demand isn’t expected to increase within the immediate vicinity of the Bear River. But Miller worries that prolonged drought in more populous river basins, particularly along the Colorado River to the south, and rapid growth in both Utah and Idaho could put pressure on the Bear.

The Bear River winds its way just north of Preston, Idaho. (Jimmy Emerson, DVM, via Flickr)

The Bear River is sandwiched between two growing valleys – the Snake Valley, where Boise is located, and the Wasatch Front, home to Salt Lake City. Both areas have considered importing Bear River water to stave off water shortage concerns.

In 1991, the Utah legislature passed a law authorizing the construction of a series of dams on the Bear River to provide water for the Wasatch Front, already one of the fastest-growing regions in the nation. Although no new dams have yet been built, the law remains on the books, and the Wasatch Front is on the verge of another growth spurt fueled by an influx of tech companies.

In Idaho, officials are eyeing Bear River water as a means to fuel growth they believe has been stymied by the absence of readily available water. State officials there, in tandem with leaders in Utah, recently filed an application to claim up to 200,000 acre-feet of water out of the Bear River.

And it is possible that agriculture, the leading user of Bear River water, could actually grow in the region as a direct result of the loss of farmland elsewhere. Farmers who have been displaced by growth on the Wasatch Front have already begun to move into the desert southwest of the Bear River, Miller said – water is the sole factor limiting additional agricultural expansion there.

A Shrinking Lake

Under the terms of the original Bear River Compact, Utah and Idaho were expected to jointly manage the lower third of the Bear River as though they were basically one state, dividing up the water on a first-come, first-served basis, said Don Barnett, head engineer and manager of the Bear River Commission, which oversees the compact. When the compact was amended, the remaining unclaimed water in the lower Bear River was officially assigned. Idaho was awarded at least 200,000 acre-feet of additional water; Utah got a minimum of 350,000 acre-feet.

Since 1976, the two states have only used about 10,000 acre feet of that allotment, Barnett said.

As of late June, the elevation of the Great Salt Lake’s south arm was 4,194ft according to the United States Geological Survey. A study published in Nature last year, and coauthored by Miller, found that existing water diversions and development have already reduced the lake’s volume by about 40 percent. If Utah and Idaho find a way to make use of their Bear River allotments, Miller said, his models show that the lake could fall to an average seasonal low of 4,189ft – a huge drop in a wide but shallow lake where depths only reach 4–5ft in some places.

During dry years, Miller said, the lake would essentially disappear if the Bear River is diverted. Only a few shallow areas of water would remain.

(Left) A simulation of the Great Salt Lake with current water use. (Right) A simulation of the Great Salt Lake if all of the Bear River Compact water is taken out. (Courtesy of Utah Division of Water Resources)

Pulling even a portion of the assigned water could have a devastating effect on the Great Salt Lake, which is already poised for ecological collapse, said Bonnie Baxter, director of the Great Salt Lake Institute and a professor of biology at Westminster College in Salt Lake City. As the lake continues to shrink, she said, it concentrates the salts for which the Great Salt Lake is famous. Just a small increase in salinity – which is already on the rise – could kill the algae and brine shrimp that inhabit the lake.

More than 10 million migratory birds are known to rely on those tiny organisms as a food source. If the lake loses its brine shrimp, Baxter said, the U.S. will likely have several newly endangered species on its hands.

The loss of the lake also threatens about 7,000 local jobs that collectively generate about $1.3 billion for Utah’s economy. And due to the area’s history of mining, the lake sediment is thought to contain high levels of mercury and other heavy metals that could become airborne if allowed to dry.

No Easy Solutions

The solution, as Miller sees it, is to amend the Bear River Compact to freeze all development and to dedicate the remaining water to the Great Salt Lake, which the compact currently ignores.

American white pelicans take flight on the Bear River Migratory Bird Refuge at the Great Salt Lake. (Wayne Watson/USFWS)

“There is not one single mention of a lake called the Great Salt Lake in the Bear River Compact,” Miller said. “They never considered it. It was wasted water.”

But anyone seeking to change the tri-state agreement faces an uphill battle. Amendments require unanimous approval from all three states and have to be ratified by Congress. And there is currently little interest in renegotiating the compact.

The Bear River Compact is subject to review every 20 years, but this past April, the commission ended the most recent review by concluding that adjustments are not currently necessary. A public comment period garnered 67 comments about the review, but just five favored reopening the compact. Four of the five cited concern for the Great Salt Lake, prompting the commission to order a study of the lake.

Idaho and Wyoming likely won’t favor giving up water so Utah can keep its lake, Barnett said. If Utah wants the lake full, he said, it should come out of Utah’s allocation.

Even advocates for the lake agree that the compact is likely to remain unchanged.

“The bottom line is, Utah alone is going to have to be burdened with this,” Lynn de Freitas, executive director of Friends of Great Salt Lake. “It’s our lake. It’s not going to come from the compact.”

A more likely solution, according to Steve Clyde, a prominent water rights attorney based in Salt Lake City, is amending state water law to allow interested parties to lease water from farmers in the Bear River to maintain the Great Salt Lake.

It is possible, said Nancy Mesner, a professor of watershed science at Utah State University, that more water is currently diverted from the Bear River for farming than is actually necessary. Modern irrigation and metering technologies, she said, could leave farmers in Utah and Idaho with a surplus of water. Adjusting state law to allow farmers to lease that extra water could give them additional revenue while preserving Bear River flows for the Great Salt Lake.

But whatever it chooses, Utah “has a window of opportunity,” Clyde said. “We have to do something now, before it’s too late.”

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