Lisbon Valley Mine Aquifer Connectivity

Starting in Fall 2017, WHEM Senior Hydrogeologist Dr. Chandler Noyes began conducting his Master’s research at the Lisbon Valley Mining Company (LVMC) in La Sal, UT. LVMC is a copper mine located within the geologically-complex and resource-rich Paradox Basin. While LVMC currently mines copper using traditional open-pit, heap leach, solvent extraction-electrowinning (SX-EW) methods, they are in the permitting process to expand their operations to use modern in-situ recovery (ISR) techniques. In order to move forward in their permitting process, State and Federal regulators required that LVMC conduct a thorough geochemical assessment to evaluate the potential of cross-formational flow and aquifer connectivity from the mined Burro Canyon Aquifer (BCA) to the Navajo Aquifer (NA), an important water-bearing unit for much of the region.

While routine sampling of major ion chemistry is conducted on a quarterly basis, and much of the structural geology of LVMC was characterized, regulators required that LVMC provide more geochemical data to demonstrate minimal connectivity between the BCA and NA. To accomplish this, Dr. Noyes designed a sampling scheme which employed the use of a suite of water and solute isotopic tracers including: stable water isotopes (δ¹⁸O and δD), stable sulfate isotopes (δ³⁴S-SO₄ and δ¹⁸O-SO₄), carbon-13 of dissolved inorganic carbon (δ¹³C-DIC), radiocarbon (¹⁴C), tritium (³H), and the strontium isotope ratio (⁸⁷Sr/⁸⁶Sr). A combination of these isotope tracers was sampled from twenty-one (21) different wells distributed across LVMC and installed in different aquifers.

All geochemical and isotopic results showed distinct groupings between the aquifers, suggesting minimal hydraulic connection. Groundwater from the BCA is meteoric in origin, has residence times that indicate recharge during the Holocene, and has a geochemical and isotopic signature reflective of its carbonate lithology. Groundwater from the NA inherits its signature from the host eolian sandstone, with possible minor input from underlying salt-derived brines, and is characterized as meteoric in origin, with residence times that indicate late Pleistocene recharge. While major ion chemistry alone was never able to definitively explain anomalous chemistry in several wells at LVMC prior to this research, the data provided by the suite of isotopes sampled by Dr. Noyes was able to provide strong evidence of complex geochemical reactions such as methanogenesis occurring at select locations.

Over the years, Dr. Noyes presented the results of his work to regulators from the Utah Department of Environmental Quality, Utah Division of Oil, Gas, and Mining, and U.S. Environmental Protection Agency. His research was presented at several research conferences and garnered a number of awards. As of October 2025, based on the work of Dr. Noyes, LVMC has recently been granted project approval from the U.S. Bureau of Land Management. WHEM continues to provide LVMC with expert advice on aquifer connectivity.

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