Editor’s note • This story from the Great Salt Lake Collaborative is part of day two of our series, “At the Water’s Edge: Finding Solutions at the Great Salt Lake’s Sister Lakes Beyond the Great Basin.” The detailed project involves the work of several journalists from several Utah news organizations. Read more stories and view photos, videos and interactive maps https://greatsaltlakenews.org.
Owen’s Dry Lakebed, California • The dust swirls on the expanding dry lakebed of the Great Salt Lake, raising concerns about the air breathed by millions along the Wasatch Front.
Just a few states away, the Los Angeles Department of Water and Energy has spent decades figuring out how to deal with its own dangerous sand and salt storms blowing off Owens Lake.
Until recently, the lake, dried to dust by LA’s water diversions, was the nation’s largest source of man-made PM10 pollution.
Today the problem is largely under control.
[To view photos, videos and interactive maps, click here.]
“What’s most remarkable is that we don’t have to look far to understand what impact other terminal lakes have had,” said Laura Vernon, Great Salt Lake coordinator for the Utah Division of Forestry, Fire and State Lands. “And we don’t have to look long for solutions either.”
Vernon’s department manages the Great Salt Lake bed, and she said that if it also becomes a major source of dust, her team will likely be tasked with finding contractors and developing mitigation plans.
A key lesson from Owens Lake’s efforts is that there is no one-size-fits-all solution to massive pollution of the lake floor. At Owens Lake, LADWP has created a mosaic of control measures that work better under different conditions in different locations. It’s a place of amazing engineering that Utahns may one day have to draw on.
This is what the environmental protection measures look like on site:
Restoring the dried up lake bed with water is the most obvious solution to healing a dried up lake. But for LADWP, water is a precious commodity and the idea is to use as little as possible.
Because of this, crews built berms across the lake — which used to be up to 50 feet deep — which they fill with a few inches of water. It’s a method called shallow flooding.
“In the beginning we had really tight deadlines,” said Arrash Agahi, who oversees regulatory compliance at the Owens Lake utility. “The easiest thing was to build a big bathtub and turn on the water.”
About two-thirds of the lake’s abatement area is used by stagnant water or wet soil during the dusty season, which lasts from mid-October to late June.
The downside to shallow floods, at least from LADWP’s perspective, is that they still require a lot of water. On average, the utility uses 60,000 acre-feet per year for dust control, enough to power all of Long Beach’s businesses and residents. That’s also about a third of the freshwater supply available in the Owens Lake area, instead the city’s water could be piped to its 4.3 million residents.
“We had to see how much water we were using out here,” Agahi said, “…to come to the realization that that’s unsustainable in the face of climate change.”
And it’s something those dealing with dust at the Great Salt Lake may need to consider, especially as a exploding population and the current “mega-drought” threaten Utah’s future water supply.
But re-irrigating the lake had the admittedly unplanned side effect of bringing back beetles, long-dormant Artemia and migratory birds.
“It wasn’t on purpose,” Agahi said. “But when the birds were here, [they] became our responsibility for management.”
To tap less water, LA borrowed an idea from an employee with an agricultural background.
Crews wet the bottom of the lake, then a tractor pulls a plow to create a landscape of furrows and ditches not unlike a farmer’s field in spring. They call the method “cultivation”.
The roughened surface slows the surface wind speed and the clods of earth are less likely to decompose into dust.
LA officials like tillage because it’s cost-effective at around $500,000 per square mile (although monitoring costs more than $1 million a year). It also requires little to no water to maintain – as long as the clods and ridges remain intact.
“When it rains,” Agahi said, “sometimes it washes out and we have to do some maintenance.”
But Phill Kiddoo, environmental protection officer for the Great Basin Unified Air Pollution Control District, is less enthusiastic about tillage, noting there are “mixed results.”
“Tilling is a tough nut to crack,” said Kiddoo, whose district is tasked with overseeing mitigation efforts and ensuring LADWP meets state air quality standards. “It worked very, very well in certain spots that had a shelf life of 12 years. It failed miserably in certain spots because they are too sandy.”
It is also destructive, which is why utilities and regulators avoid tilling in archaeologically and culturally sensitive areas.
In some sections of Owens Lake, LADWP workers spread an amazing amount of gravel, covering several square miles in places. They found that a 4-inch layer of rocks placed directly on the ground, or a 2-inch layer placed on cloth, prevented emissive salts from rising to the surface.
LA officials called it the “best” measure they’ve tried.
“If done right and well protected, it’s probably one of our least-maintenance dust control tools,” Agahi said. “So it’s a huge benefit that way.”
Remarkably, it also requires no water.
But gravel also has major limitations. It’s expensive, Agahi said, coming in at about $36 million per square mile.
This huge gravel landscape also absorbs a lot of desert heat and creates an uncomfortable microclimate.
“It doesn’t have an aesthetic component,” Kiddoo said. “It’s of no use to wildlife.”
And it doesn’t work everywhere. A large section is slowly sinking into the lake bed near a brine pool in the middle of the lake, Kiddoo said, which is an expensive lesson.
Meadows with native, drought-tolerant plants protect the surface of the lake floor from wind and catch passing dust. But using vegetation as a dust control isn’t as easy as it sounds. The plants need a few years to establish themselves. They need to be watered in the meantime, and rodents tend to chew up drip lines.
“The voles absolutely love it,” Kiddoo said.
Managed vegetation begins to seed and spread across Owens Lake in areas where the plants are best suited, including areas with springs and soils that are not overly saline.
“Those surrounding the lake still don’t know that the lake has disappeared,” Kiddoo said, “and that artesian pressure from the subsurface is still pushing water onto the lake level. … It’s great for vegetation.”
But LADWP views the naturally spreading greenery as a mixed bag. The plants can trick satellites used to monitor mitigation efforts into believing that wet areas are actually dry. And the grasses and shrubs don’t necessarily spread in dense densities to meet dust control criteria.
Brine and brine pool
In the heart of Owens Lake there is still water – it’s just super salty and covered in a mineral hoarfrost.
“Like the Great Salt Lake, there will always be water to some degree,” Kiddoo said. “The water becomes so hypersaline that it doesn’t evaporate, so it creates this brine pond or brine pool.”
The brine basin and its salt crust also prevent a significant portion of the lake floor from becoming emissive. Because of this, LADWP only had to mitigate about half of the dry lake’s footprint.
LADWP attempted to reproduce this effect at the edges of the mitigation area, flooding ponds with brine instead of fresh water and encouraging crust formation. But the salts can turn into environmentally harmful dust in the time before the brine dries completely. This means the utility must use valuable fresh water as a backup control.
How Would Utahns Pay for an Engineering Dust Control at the Great Salt Lake?
None of these methods are particularly cheap. To date, LADWP has spent $2.5 billion cleaning the air at Owens Lake and installing a staggering 4,200 miles of pipe, and the utility will likely be there for monitoring and maintenance in perpetuity.
The colossal effort rehabilitated about 50 square miles of lake bed, roughly the size of San Francisco. But the Great Salt Lake has currently uncovered about 800 square miles.
Vernon’s department raises approximately $7 million annually from the salt and mineral exploration business at the Great Salt Lake. It’s money the state can use to heal the lake, but it also depends on these companies staying profitable.
The Owens Lake effort shows that water works best in reviving a drying lake, Vernon said, and restoring water to the Great Salt Lake is the only method Utah is currently focused on.
“It’s really the simplest solution,” Vernon said. “This is better than all expensive alternative solutions.”
This article is published by the Great Salt Lake Collaborative, a solutions journalism initiative that brings together news, education and media organizations to educate people about the plight of the Great Salt Lake — and what can be done to help make a difference before it’s too late. Read all of our stories below greatsaltlakenews.org.
https://www.sltrib.com/news/environment/2022/10/10/what-utah-can-learn-monumental/ Can the Utahns fix the looming GSL dust problem?