Great Salt Lake expert explains another threat from proposed US Magnesium canal dredging

Potential danger lurks in the lakebed the company plans to disturb.

A proposed canal extension project has stirred up emphatic concern about plans to siphon water from the shrinking Great Salt Lake.

But a retired U.S. Geological Survey scientist says US Magnesium’s proposal could pose disastrous consequences to the lakebed as well.

The company wants to lengthen its two intakes by a collective 3.7 miles, resulting in a lot of displaced sediment. That could choke out important microbes and churn up toxins in the water column, according to Robert Baskin, a hydrologist with more than 30 years of experience studying the lake. He outlined his concerns in a lengthy letter he said he sent to Gov. Spencer Cox late last month.

“MagCorp’s proposed project,” Baskin wrote, using US Magnesium’s old moniker, “would destroy the remaining chance that [Great Salt Lake’s] ecosystem might quickly recover if lake levels were to rebound.”

US Magnesium filed for a dredging permit with the U.S. Army Corps of Engineers in August, arguing the lake’s receding water threatened access to the brine it uses to produce magnesium and other minerals. The project also needs approval from the Utah Division of Water Quality, which recently received a torrent of comments in opposition.

The plan calls for discharging sediment across about 127 acres of lakebed so the company can continue to siphon lake water at the rate of 100,000 gallons per minute. Its application includes the option to dredge even more if the lake continues to shrink, which the extractor says “may be needed” in the next three to five years.

The governor’s Public Lands Policy Coordinating Office previously urged the Army Corps to approve the permit request, arguing US Magnesium provides a critical supply of domestic magnesium.

But after reviewing US Magnesium’s application, Baskin found the proposed dredging activities “unclear, misleading, open-ended or incorrect,” he wrote, questioning why the state supported the idea.

Francisco Kjolseth | The Salt Lake Tribune Small rock like structures formed by bacteria in the Great Salt Lake have become visible along the North shore of Antelope Island. Older structures dry up and collapse as the water recedes leaving dry domes. Known as microbialites, a few of the microbial mounds are being gathered and studied by researchers.

“I don’t do politics except for this letter here,” Baskin said in an interview. “I’m strictly science and try to be as unbiased as possible. But apparently mining laws are written to help mining companies.”

Clouding the lake’s food web

Baskin has done extensive research on the lake’s microbialites — rocky formations created by cyanobacteria that serve as an important part of the brine fly lifecycle, which in turn feed millions of migrating birds.

The microorganisms, which Baskin calls “biohermes,” basically build their own homes by pulling minerals out of the water and cementing them together. They need water shallow enough to photosynthesize, but with the Great Salt Lake so low, many have surfaced and dried out, killing their bacterial colonies.

“[Their] homes are [still] there and ready to be repopulated if the lake comes up,” Baskin explained. “But getting the lake up to where it inundates those now-exposed-bioherms is going to be very difficult, especially if MagCorp plans to pump 100,000 gallons a [minute] out of the existing lake.”

Even microbialites that remain submerged face threats from rising salinity as the lake shrinks and its minerals concentrate. Baskin pointed to the railroad causeway that bisects the lake, which turned the north arm hypersaline. It has killed off roughly 40% of the lake’s microbialite colonies, he said, which built their dome-like and now salt-crusted rock formations over thousands of years.

(Leah Hogsten | The Salt Lake Tribune) The northern arm of Great Salt Lake, Thursday, Aug. 4, 2022. The northern arm of the causeway is hypersalinity, or saturated with salt, and colored pink by the microorganisms that in the hypersaline water.

Baskin is worried, too, about the resulting sludge from excavating US Magnesium’s canals. Because the Great Salt Lake’s water is chock full of minerals, making it denser than freshwater, sediment floats around and moves farther, potentially settling on microbialites.

“Without light,” he said, “they’re not going to live.”

In its application, US Magnesium acknowledges dredging might have a “temporary effect” on the water quality by clouding the lake with sediment in the work area but claims it won’t cause any “long-term or permanent degradation.”

Baskin disagrees.

In his letter to the governor, he attached aerial photos of two previous dredging events around Promontory Point, one near the railroad causeway and one at a marina. They show sediment traveling through the water by waves and currents, he wrote, in some cases settling over microbialites.

(Image courtesy of Robert Baskin) A satellite image shows dredged material placed near a Union Pacific causeway, which spread over microbialites that appear dark green in color, according to hydrologist Robert Baskin.

(Image courtesy of Robert Baskin) A satellite image of a marina on the Great Salt Lake's Promontory Point shows dredged sediment entering the water, appearing as gray streaks, according to hydrologist Robert Baskin.

Carie Frantz, an associate professor of geochemistry and geobiology at Weber State University who also studies the Great Salt Lake’s microbialites, agreed sediment stirred up by dredging is a cause for concern.

“I would expect, long term, sediment would move around and not stay on top of microbialites forever,” Frantz said. “... But that could take years or decades, and in some cases, they might never recover if sediment is deep enough.”

That’s why the structures don’t form in Farmington Bay, she said, even though it has salinity levels needed to support them. All the sediment flowing into the lake there from rivers like the Weber and Jordan settles in the bay, which chokes out the microbialites before they can form.

“In a year you’ll get three feet of muck forming,” Frantz said. “And that’s way, way faster than the microbialites grow.”

Contamination in the lakebed

Baskin worries about the potentially toxic material getting stirred up with the sediment as well. Mercury has been detected throughout the lake. Its southern end is known for issues with selenium, which weakens bird eggs.

Once those contaminants mix in the water column, they could become bioavailable to brine flies, brine shrimp and the birds that eat them.

And US Magnesium itself has had documented releases of PCBs and dioxins, which can cause health complications for people, including cancer, liver damage, reproductive issues and more.

“They’re going to remobilize those materials that are right now sequestered under all the muds,” Baskin said.

That’s why he proposed the state support the lake’s mineral extraction industries in other ways, like offering loans or grants to help them stay in business until the water rises again.

“The damage that will occur ... to the environment and people of the Wasatch Front,” Baskin said, “is much more than the cost of supporting the mining industry through payments … to get them through these low-level years.”

Baskin said he hasn’t received a reply from the governor since sending his letter. Asked for comment, a spokesperson for Cox said she hadn’t seen Baskin’s feedback. The governor’s Public Lands Policy and Coordinating Office did, however, walk back its support for US Magnesium days after news broke of the canal extension proposal in September.

This article is published through The Great Salt Lake Collaborative: A Solutions Journalism Initiative, a partnership of news, education and media organizations that aims to inform readers about the Great Salt Lake.