During dust storms, host spots on the lake will pop and emit swirls of dust, collecting particles less than a fraction of the width of a human hair, darkening the sky and propelling them into communities nearby. The smallest particles can remain airborne for weeks at a time.
The lake bed contains pollutants like arsenic, distributed widely across the surface, which could be an indication that some of it occurs naturally, Perry said.
The lake has long been a catchment for industrial pollution. Each area of the lake has its own recipe of toxic metals and other substances, fed by different polluting industries nearby. Researchers are concerned that what’s been stored in the lake will soon be carried on the wind into Salt Lake City and other neighboring communities. -NBC News
Salt Lake City Faces Toxic Dust Storms Amid Declining Water Levels
Salt Lake City, Utah, was already in trouble. Between vast open-pit mining operations in the surrounding areas, oil refineries, and a unique mountain range that traps pollution in a winter 'inversion layer,' the cities surrounding the Great Salt Lake have grappled with air quality issues for years.
"We have 2.5 million residents along the edges of the lake," said Kevin Perry, a University of Utah atmospheric scientist researching the Great Salt Lake dust. "These dust plumes come off and make the air unhealthy regardless of what’s in it."
Now, as NBC News reports, declining water levels in the Great Salt Lake have created new challenges as dust laden with toxic metals threaten the region.
Since Mormon pioneers settled the valley in the mid-1800s, the lake's volume is down 67% - thanks to a combination of irrigation projects, which account for roughly 75% of the loss, and the ongoing megadrought, which accounts for the remainder of the drop, according to research from Utah State University.
This isn't an issue caused by climate change, according to the report. Residents are simply consuming too much water for agriculture, residential use and industry, from overtaxed rivers that feed the terminal lake. Humans diverting water has reduced the Great Salt Lake by around 11 feet - while increased evaporation has added to the problem by around half-a-foot.
In 2018, roughly 9% of the lakebed was a source of dust - with a protective crust covering much of the rest. But wind and weathering is breaking that down.
"The longer the lake bed is exposed, we expect that to increase. It could increase to 24% to 25% of the lakebed," said Perry.
Lawmakers are starting to take notice - but in typical fashion, it's too little, too late. They have passed a series of bills designed to revamp how Utah uses its water. In November, Gov. Spencer Cox closed the basin to new water appropriations. A step in the right direction after years of neglect.
"The entire state has an unhealthy relationship with water," said Perry. "We need to start living like we live in the desert."
Researchers looking into the toxic dust have been examining exactly where it goes - including whether it's easily absorbed into people's bodies, and what risks it may present.
In 2018, scientists with the US Geological Survey placed 18 dust traps throughout the Salt Lake City area - where they trapped dust from the lake, local construction, and local deserts, for a period of several months.
What they found was concerning. At every site, arsenic concentrations exceeded EPA levels of concern for residential soil. One site had a concentration 35x higher.
"We’ve got some bells going off," said USGS hydrologist, Annie Putman, who led the study. "The pieces are there to think we should be concerned."
The Salt Lake City area has long had a reputation for pollution gong back decades. Out of 888 US metro areas, the EPA ranked it the ninth-worst on a 2020 risk screening model that ranks health risks from toxic chemical releases. Last year it ranked 20th for short-term particle pollution by the American Lung Association.
"If you look at Salt Lake, it’s essentially a bowl and the dense emissions are in the lower elevations," said John Lin, an atmospheric research professor at the University of Utah, who noted that pollutants such as black carbon, nitrogen dioxide and other particulate matter "tend to be higher in lower-income neighborhoods."
Residents in the lower portion of the 'bowl' are inundated in a pea soup of refinery emissions, car exhaust and other pollutants.
The researchers suspect that urban, diverse neighborhoods are receiving much of their dust and the toxic metals within that dust from local sources — nearby polluters or construction projects. It’s also possible that dust from the Great Salt Lake and other nearby playas picks up local pollutants from nearby mines, refineries and pesticides as dust travels into the city.
Meanwhile, researchers found the highest levels of dust — and metals — in suburbs outside urban Salt Lake City. Researchers suspect communities north of the city, including areas such as Syracuse, Ogden and Bountiful could be receiving the majority of the dust that blows off the lake. In early October, less than a mile from what was once lakeshore, workers were hammering away to frame new housing. -NBC News
"It irritates the eyes and gives me sinus infections," said 58-year-old George Casillas, who's lived on the west side for 15 years. "It’s hard to be trapped in the valley."
"There’s so much sediment and so much trapped for so long. It’s pulling up stuff that’s been trapped for 100 years," he continued. "Are there carcinogens or other health risks? That’s what I’m worried about."