Recent studies suggest a 7% loss of volume in the Bonneville Salt Flats salt crust since 2003. The salt laydown project began in 1997 to add salt to the BSF by pumping brine from an adjacent potash mining area. Though an estimated 6.2 million tons have been added to the BSF since the beginning of the project, no notable gains in salt thickness have been observed. This project aims to increase the amount of salt being laid down, monitor the effects of the laydown project, and improve our understanding of how the salt crust forms and is removed.

- Monitor the shallow groundwater to better understand the interactions of salt crust formation, pumping, mineral extraction, salt laydown, and climate. - Install a dedicated monitor well to measure the storage and transmissive properties of the deep and shallow aquifers, to evaluate the long-term sustainability of pumping that supports the laydown and mineral extraction. - Work with Intrepid Potash to quantify groundwater pumping, to enable evaluation of aquifer sustainability and analysis of groundwater monitoring data - Analyze satellite and/or UAV imagery to quantify surface water extent and movement and, perhaps, salt crust texture and composition..

Inaction, or continued progress down the same path, could lead to continued degradation of the BSF, and loss of the resource entirely.

Pony Express Resource Management Plan and Rangeland Program Summary for Utah County * Minerals Program o Decision 3: The closure of 104,814 acres of Federal mineral estate within the Bonneville Salt Fiat Recreation Area will continue until further studies clearly indicate that the closure could be modified without disrupting the natural hydrologic pattern of the entire basin north of 1-80. Once definitive information is available, BLM will reevaluate the existing activities (including existing leases) on and adjacent to the Salt Fiats. Future activities to be allowed will be based on the results of that evaluation. This closure affects further mineral leasing for potash, salts, and other similar brines. This closure does not affect existing leases, including Reilly's leases, so long as they remain in effect and all lease requirements are met.  Rationale: The purpose of this closure is to protect the Bonneville Salt Flats from possible damage that could result from extraction of brines. The closure will protect the area until sufficient scientific information is available to determine whether the closure area should remain the same, be expanded, reduced, or eliminated. Leases held by Reilly Tar and Chemical Company within the closure area are valid existing leases that are not affected by the closure. * Recreation Program o Priorities: Highest priority will be given to the ORV plan and the SRMA plans. The SRMAs are listed in order of priority. ERMA plans will be a lower priority. o Decision 1: Manage the following areas as Special Recreation Management Areas (RMAs):  Bonneville Salt Flats Special RMA, 30,203 acres.  Knolls Special RMA, 37,760 acres.  Pony Express Route Special RMA, 21,120 acres.  North Deep Creek Special RMA, 24,960 acres.  Payson Motocross Track Special RMA, 100 acres. These areas are shown in Figure 6. The remainder of the Pony Express Resource Area would be managed as an Extensive Recreation Management Area (ERMA).  Rationale: The purpose of RMAs is to establish a basis for determining priority for management and funding, and to delineate units that will require activity planning. The above SRMAs are all areas where a commitment has been made, within the parameters of multiple use, to provide specific recreation activity and experience opportunities on a sustained yield basis. These areas require a  higher level of recreation investment and/or management than the ERMA requires. The ERMA possesses several other management objectives outside of recreational use. This extensive area provides unstructured types of recreational activities. * Areas of Critical Environmental Concern o Highest priority is to continue the Bonneville Salt Flats ACEC and to designate Horseshoe Springs as an ACEC. o Decision 1: This decision is to continue to manage 30,203 acres on the Bonneville Salt Flats as an ACEC. The Bonneville Salt Flats were designated as an ACEC in 1985. The 30,203 acre ACEC will be unavailable for ownership adjustment The ACEC will be closed to leasing for potash, salts and other brines. The area is also proposed for a mineral withdrawal The ACEC Is in Fluid Mineral Category 3, No Surface Occupancy. The ACEC is also a Special Recreation Management Area. The VRM Classes are II and III.  Rationale: The unique saline plains of the Bonneville Salt Flats (BSF) have been intensively managed for the past few decades for high speed automobile testing and racing. A Recreation Area Management Plan was completed in 1977 and revised in 1985. In 1985, 30,203 acres of the BSF were also designated as an ACEC to perpetuate and protect the values and resources of the area. This decision is brought forward from the Tooele Management Plan, 1984. Objectives of the plan are to (a) preserve the unique visual, historic and geological resources, (b) minimize and manage mineral uses and other surface disturbing activities to avoid resource damage, (c) coordinate management of 51 the BSF ACEC with other landowners and (d) recognize and manage racing and filming activities on the Salt Flats. The BSF contain three "relevant" resources. The salt's potential for land speed racing was recognized in 1986 and has become known as the "world's fastest mile." Thousands of records have been set there. Unique vistas are offered by the contrast between the white salt flats and a distant blue horizon broken only by various mountains. The BSF are rated as a Class A Scenic Quality Unit. The VRM resources were designated Class II. The BSF are a unique area, directed by geophysical processes that are highly sensitive to interruption by human activity. The area is estimated to have once covered 96,000 acres of crystalline salt, but presently covers about 30,000 acres. Because of their sensitivity and unique character, the BSF are a nationally and internationally significant resource and meet importance and relevance criteria for an ACEC. Recreation Area Management Plan for the Bonneville Salt Flats Special Recreation Management Area and Area of Critical Environmental Concern * IV. The Management Program o A. Area of Critical Environmental Concern  4. Special Management Requirements: Preservation of the salt (morphologic resource} is a key factor in managing the BSF ACEC. Special management attention is also identified to ensure continuance of filming (scenic resource} and racing in the future. Both racing and filming are short term and are considered as non-surface disturbing activities, thus are compatible with the plan. Other human activities have contributed to problems on the salt. Without proper management, indiscriminate surface disturbances could be detrimental to the unique resource base.  5. Compatible Uses: Uses in the BSF which would be compatible with the ACEC designation include, but are not limited to: * b. Scientific uses (nonsurface disturbing): automobile testing, environmental study and experimentation.

N/A

Water quality at the BSF is very poor. The salt laydown uses groundwater from beneath the BSF to make the brines, and returns it back to the BSF, so theoretically there is zero change to the quantity of water.

An environmental assessment for the salt laydown project was completed on June 16, 1993. Given three of the four original wells are no longer operable, the addition of a well is within the scope of the originally proposed project. Additional permitting and compliance for the installation of a new well will be completed prior to work beginning. The scientific studies proposed are considered casual use, and therefore no additional compliance is required for those actions.

Part of the project will fund the installation of a new well to replace one of the three wells that are no longer operable. The research to follow will be conducted as outlined below: 1. Hydrogeology: shallow groundwater monitoring to better understand the interactions of salt crust formation, pumping, mineral extraction, salt laydown, and climate. a. Support the Ph.D. work of Jeremiah Berneau (UDGG) on characterizing the shallow brine and deeper aquifers and understanding how they influence salt crust growth and are affected by climate fluctuations, regional and local pumping, salt laydown, and racetrack maintenance. b. Establish a consistent, thorough, long-term groundwater monitoring network, to capture effects of climate fluctuations and possible variations in pumping and laydown strategy. c. Establish a station ("eddy-covariance flux station") to measure evaporation and other gas and energy exchange fluxes across the salt pan surface, to better understand the climatic and hydrologic conditions that influence salt growth and dissolution. 2. Install a dedicated monitor well to measure the storage and transmissive properties of the deep and shallow aquifers, to evaluate the long-term sustainability of pumping that supports the laydown and mineral extraction. 3. Work with Intrepid Minerals to quantify groundwater pumping, to enable evaluation of aquifer sustainability and analysis of groundwater monitoring data. 4. Analyze satellite and/or UAV imagery to quantify surface water extent and movement and, perhaps, salt crust texture and composition.

Future studies to quantify the volume and extent of the salt crust will be conducted. Previous efforts have been conducted on ~10-year intervals, and it is assumed that this will continue into the future.

Utah Geological Survey, University of Utah Department of Geology and Geophysics, Intrepid Potash

Applications have been submitted to acquire funding through the Lands & Water Conservation Fund to consolidate land ownership, and acquire active mineral leases on the BSF. If lands or leases are acquired, they will be incorporated into the ACEC/SRMA boundary and mineral withdrawal area to contribute to the conservation efforts of the BSF.

This project aims to increase the quantity and quality of salt crust at the BSF, enabling enjoyment for future generations.

07/01/2023

06/30/2024

2024

UGS used these funds, along with funds appropriated by the Utah legislature, for three main objectives: 1) support the Ph.D. thesis of Mark Radwin at the University of Utah; 2) collect groundwater level and salinity data to support Mark's thesis work and continue the analyses of the effects of groundwater pumping and ditch drainage for mining on salinity and groundwater levels of the shallow brine aquifer and salt crust; and 3) maintain the BFLAT weather and eddy-covariance flux station. The expense report states our expenses during FY24 from the funds appropriated by the Utah Legislature. We have spent nothing from those funds so far in FY25, recognizing the need to bill out the funds from this project. To date we have spent $669,260 of the original $1,000,000 appropriation.

Mark Radwin's Ph.D. thesis is nearly complete. Mark used novel techniques of analyzing multispectral data, collected by both satellites and UAVs, to investigate hydrologic and surficial processes on the Salt Flats. Mark is currently completing revisions to his thesis and will share the results with the BLM-UGS-U of U working team when his thesis is completed. Erin Brinkman manages the current groundwater level and salinity monitoring, visiting the sites three times per year to measure depth to water, download water level transducer data and measure water density (a proxy for salinity). This work is designed to track trends established by past work (Jeremiah Bernau P..D. and postdoctoral work) and measure changes that may result from future management/operational changes. UGS installed a new weather station on the Bonneville Salt Flats in 2022, replacing the previous station on the same footprint. This station collects standard weather data plus other heat and humidity measurements that allow calculation of evaporation. Data are available from Mesowest.

Future management of the Bonneville Salt Flats is still undecided. At this time we plan to continue existing groundwater monitoring, and working with the BLM, U of U, and other stakeholders to plan future research that may include future additional brine laydowns, alteration or cessation of mining-related activities, an experimental summer laydown in a limited area, and investigating new methods to more efficiently estimate salt crust thickness.