Elliot Jagniecki

Senior Geologist

Utah Geological Survey


Elliot Jagniecki is a Senior Geologist with the Energy and Minerals Program at the Utah Geological Survey. He worked five years at ConocoPhillips in Houston in research and development and exploration prior to joining the UGS in September 2018. He coordinates research with government, industry, and academic partners on assessing petroleum resources and characterizing Utah’s geology. His expertise includes sedimentology, evaporites, modern and ancient lacustrine systems, and geochemistry. He is actively involved in researching the sedimentary processes, chemical sediments, and brine dynamics in Great Salt Lake and working with graduate students on the Bonneville Salt Flats. He graduated with a B.S. in geology from Central Michigan University and received his Ph.D. from Binghamton University in geology and geochemistry. He is a licensed Professional Geologist in Utah. 

Title: Recent and Seasonal Evolution of Great Salt Lake’s North Arm Brine and Salt Crust

Abstract: (Elliot Jagniecki and Andrew Rupke) Following the construction of the railroad causeway in 1959, a perennial halite (NaCl) bottom crust has been known to exist in the north arm of Great Salt Lake, Utah, but the lake conditions controlling evolution of the crust are not well defined, including how depth-controlled chemodynamic and hydrodynamic factors influence the degree of the halite saturation. Prior to the opening of a new bridge in the causeway in early December 2016 when north arm lake elevation was at a historical low (just above 4189 feet), the north arm lake brine was at halite saturation, and significant halite precipitation occurred during warm months. After the opening, inflow of less saline south arm water mixed with north arm water, raised lake elevation, and diluted the north arm lake brine to undersaturation with respect to halite. The following five years have resulted in annual and seasonal fluctuations of halite saturation states.

Beginning in mid-2019, the Utah Geological Survey began a study of the north arm to better understand and document the transitions of halite saturation state using newly collected data as well as reviewing available past data. We investigated the accumulation of salt in the nearshore environment, utilized underwater photography to observe lake bottom salt crust, deployed buoy stations to observe salt accumulation, took water profile measurements, performed density measurements and experiments, and implemented geochemical modeling to understand mineral saturation states. In parallel, groundwater contribution and influence on the salt crust were investigated. Based on our observations and experimentation, we estimate the halite saturation density of the north arm water is approximately 1.223 g/cm3 at 20°C. Our observations show that the entire north arm water column can reach halite saturation and that coarse halite crystalline growth occurs on the lake bottom in both shallow and deep areas. Using the developed methods, we were also able to observe and document three transitions of saturation state of the north arm brine: 1) halite undersaturation in the second half of 2019 through the first half of 2020 to supersaturated in the second half of 2020, 2) halite undersaturation in very late 2020 through most of the first half of 2021, and 3) halite supersaturation in the late first half of 2021. Notably, in 2020, the north arm did not reach halite saturation until August, but in 2021 the north arm had already reached saturation by late May, which could be a function of lower lake level, the north arm reaching hydrologic equilibrium following the bridge opening, or both. Observations and geochemical modeling indicate that groundwater discharge near the lake margins and nearshore environments appears to influence dissolution of the halite crust as well as the inflow of solutes that contribute to the north arm brine evolution. Dissolution holes within the salt crust at ~20 ft depth also suggests lake bottom groundwater input. Saturation state of the north arm is also seasonally affected by mirabilite precipitation that occurs during winter months and lowers the brine salinity.