Cataloguing through sedimentation
Great Salt Lake has had pressure on its water resources since the Mormon pioneers began settling in Utah beginning in 1847. In fact, Professor and Department Chair of Geology & Geophysics Gabriel Bowen tells us a pretty clear story of human influence on the lake. Bowen looks at sedimentation of Great Salt Lake, the terminal point for not only water but solid particles (sand, mud, organic bits), and he catalogues events impacting the lake via that sedimentation.
During the mid 19th century, Mormon settlers arrived in the Salt Lake Valley via Emigration Canyon. Upon their arrival, irrigation projects of a grand scale were planned and installed. Wetlands gave way to canals which delivered water to freshly tilled farmland. The valley that was once a desert turned green. Bowen found that around this time, an unprecedented amount of organic matter reached the lake — a clear indication of an increase in agricultural runoff.
Then, in 1959 the Lucin Cutoff was constructed by Union Pacific Railroad. This feat of engineering split the lake into the North and South Arm. Prior to 1959, the sediments deposited indicate that the South Arm had equal ratio of water evaporation to input—a state of equilibrium.
However, after 1959 these levels lowered substantially creating two different systems: a South Arm that now acts like an open system (exorheic) and a North Arm that remains a terminal lake (endorheic). As a result, the South Arm remains fresher with levels today hovering around 12.5 percent salinity while the North Arm is nearly three times as salty—around 33 percent.
Water can hold approximately 350-360 grams of salt per liter. Currently, salt levels in the North Arm hover around 330 grams per liter. But, in certain parts of the North Arm this saturation level has already been reached and halite salt crystals can be seen floating in the water.
Extreme conditions still harbor life
We are reaching a level of extreme that feels beyond extreme. That’s why it’s so hard to believe that this lake can still harbor aquatic life and plenty of it. For a long time, we have known that brine shrimp and brine flies were capable of surviving in Great Salt Lake. But in 2024, U postdoctoral researcher Julie Jung and faculty member Michael Werner discovered a new species of nematode, a microscopic worm commonly referred to as a “roundworm,” hiding right under our nose.
Found in the South Arm, the species likes to reside in the reef-like microbialite structures that cover about one-fifth of the lakebed. This is the most saline environment where nematodes have ever been discovered. Recently, Werner officially described the new species as a tribute to the ancestral lands of the nearby Shoshone tribe Diplolaimelloides woaabi—cementing this discovery permanently.
Even the hypersaline North Arm contains life. Its waters are pink due to halophilic bacteria which we have known of for years. As waters in the North Arm receded, many gypsum crystals, which can be capsules of life, were exposed. The outer layer of these crystals has been known to protect and enclose microbial ecosystems. Current U doctoral candidate Paulina Martinez-Koury and Westminster University Professor Bonnie Baxter decided to investigate what life may live inside those ecosystems. Within the minerals they found microbes, pollens, and a staggering 200 bacteria species—a testament to life’s innate ability to survive. Scientists say it may hold clues for life on other planets, too, especially Mars, which was once replete with salty lakes that dried up as the Red Planet lost its atmosphere and magnetism.
Dust in the wind
The newly dried lakebed, also known as “playa,” provides fascinating opportunities for discovery, but at its core it is its own issue. The playa emits high levels of particulate matter PM10 and PM 2.5, the latter of which can penetrate deeply and be fully absorbed by our lungs to deleterious effect. Kevin Perry, U atmospheric science faculty member who has surveyed dust hotspots around the lake, found that every playa soil measurement of arsenic was ten times beyond the EPA’s recommendations.
But work is being done to understand the implications here as well. Perry has worked alongside his colleague Derek Malia to understand where the dust is likely to impact. Farmington, West Valley City, and Salt Lake City are hit the hardest leaving more than a million people at risk.
Perry is trying to figure out how to prevent this dust from becoming airborne in the first place. It turns out that if you water the playa, the crust can re-form—trapping the dust in place. Interestingly enough, this water could even come from below the lake itself. The presence of phragmites, an invasive grass species on the playa, suggests that there is groundwater present. Geology and Geophysics Professor Bill Johnson confirmed the presence of groundwater using airborne electromagnetic surveys . The water is contained within tightly packed sediments that start at 30 feet below the surface of the lake and descend to 10,000 feet. But more work needs to be done to determine if there is water across this entire range or just a portion.