Beneath the surface just outside Charlotte, North Carolina, lies one of the most extensive lithium deposits in the United States, stretching for approximately 25 miles southward. As a critical component in modern rechargeable batteries and energy storage systems, lithium is globally recognized for its strategic and economic value. The enormous subterranean lithium reserves in this region, primarily contained within pegmatite formations rich in spodumene mineral, have drawn renewed attention amid the soaring global demand for sustainable energy technologies. However, the legacy of historic lithium mining in this area has raised concerns among local communities about the potential impacts on groundwater and surface water quality.
The Carolina Tin-Spodumene Belt, the geological province hosting these lithium deposits, once supported two large-scale lithium mines that ceased operations decades ago. Despite their closure, remnants from these historic mining activities—such as open pits, waste rock piles, and tailings—remain, presenting potential environmental challenges. Contemporary interest by mining companies to tap into this resource has intensified scrutiny of the long-term environmental effects of both past and prospective lithium mining activities, especially regarding drinking water safety for the surrounding populations.
Responding to these concerns, an interdisciplinary research team led by Avner Vengosh, a renowned environmental geochemist at Duke University, undertook a comprehensive investigation into the legacy of lithium mining on water quality in the region. Their recent study focused on analyzing groundwater from domestic wells and surface water near the defunct mines and an operational lithium processing site in Bessemer City, where raw lithium is refined into battery-grade materials. Funded by the North Carolina Water Resources Research Institute and Duke’s Climate Research Innovation Seed Program, this investigation yields critical insights into the complex interactions between geology, mining legacy, and water chemistry.
The researchers employed meticulous sampling strategies, collecting over 190 water samples from wells and streams across the Tin-Spodumene Belt over a three-year timespan. Using advanced geochemical fingerprinting techniques developed in the Vengosh Laboratory, the team identified elemental ratios that serve as markers of water-rock interactions and potential contamination sources. By examining trace metals such as lithium, rubidium, cesium, and arsenic, the team sought to determine whether historic mining activities have measurably influenced water quality as compared to baseline natural geochemical conditions.
Contrary to community apprehensions, the study found no direct evidence indicating that legacy lithium mining has compromised the quality of groundwater accessed by residential wells. Instead, elevated lithium concentrations detected in many well samples were attributed predominantly to natural geochemical processes, specifically the dissolution of pegmatite-hosted minerals like spodumene into groundwater. This discovery emphasizes that naturally occurring lithium and related metals are characteristic of the region’s unique geology rather than symptomatic of anthropogenic pollution, a nuance critical to understanding environmental risk in mining districts.
While groundwater seemed largely unaffected by mining legacy, surface waters presented a different picture. Streams proximate to the historic mines and the active processing facility exhibited increased levels of lithium and rubidium compared to background concentrations. Detailed geochemical analysis suggested that these heightened levels stem from oxidative weathering of mining waste materials, particularly gypsum remnants from lithium extraction processes. Notably, the lithium and rubidium enrichments rapidly diminished downstream due to dilution and natural attenuation, indicating spatially limited impacts of historic mining on surface water systems.
Beyond lithium and related metals, the investigation probed for arsenic, a naturally occurring element of substantial toxicological concern that can leach from arsenic-bearing minerals in mining wastes under certain geochemical conditions. Elevated arsenic levels were detected in a localized cluster of wells in Gaston and Lincoln counties, confirming previous identification of this area as a regional arsenic hotspot. Subsequent geological analysis implicated the close spatial association of pegmatite with mica schist formations rich in arsenic as the probable source of this contamination—underscoring the influential role of local geology in dictating water quality hazards independent of mining activity.
This nuanced understanding of the interplay between bedrock geology and water chemistry has significant implications for future lithium mine development in the region. The potential co-occurrence of pegmatite and arsenic-bearing schist poses a risk factor that must be carefully evaluated during mine site selection to mitigate adverse impacts on groundwater arsenic levels. Integrating detailed geological surveys with hydrological modeling and comprehensive water quality monitoring will be essential to ensuring sustainable resource extraction that safeguards community health and environmental integrity.
Although current regulatory frameworks, including those from the U.S. Environmental Protection Agency, do not establish maximum contaminant levels for lithium, rubidium, or cesium in drinking water, ongoing research into their chronic health effects remains imperative. It is worth noting that lithium is medically administered in doses far exceeding environmental concentrations for psychiatric conditions, yet the implications of long-term low-level exposure through drinking water continue to warrant investigation. The detected magnitude of these elements in well water samples suggests minimal immediate health risk, though continuous surveillance and risk assessment efforts are recommended.
Importantly, the research results provide local stakeholders—including residents, policymakers, and mining companies—with robust scientific evidence to inform decision-making processes. Communities can be reassured that historic lithium mining to date has not caused detectable harm to drinking water supplies, while highlighting the need for vigilance regarding naturally high arsenic levels in select areas. Likewise, mining enterprises can leverage these insights to tailor environmental monitoring protocols and adopt geochemically informed management strategies for waste handling and water protection.
This study exemplifies how modern geochemical detective work can unravel complex environmental questions posed by legacy mining operations. By integrating field sampling with state-of-the-art analytical techniques, researchers effectively differentiated between natural geogenic signatures and anthropogenic influences on water quality. Such approaches set a precedent for assessing emerging lithium mining regions worldwide, many of which grapple with balancing the promise of critical mineral development against ecological stewardship and community well-being.
As the demand for lithium surges in the global push towards renewable energy and electric vehicles, the North Carolina tin-spodumene belt represents both an opportunity and a responsibility. Mining ventures must be underpinned by rigorous environmental assessments and community engagement to preclude unintended consequences. The findings from this detailed water quality study provide a scientific foundation for sustainable resource development, emphasizing the crucial role geology plays in shaping water chemistry profiles and potential contamination pathways.
Ultimately, this research highlights a critical intersection of earth science, environmental chemistry, and public health in the context of mineral resource extraction. It underscores that the legacy of historic mining need not dictate the future if proactive, science-driven approaches guide ongoing and future operations. As lithium mining advances globally, the lessons from North Carolina’s hard-rock deposits stand as a testament to the power of geochemical vigilance in protecting vital water resources amidst a rapidly evolving energy landscape.
Subject of Research: Environmental impacts of legacy hard-rock lithium mining on groundwater and surface water quality in North Carolina.
Article Title: The Water Quality Impacts of Legacy Hard-Rock Lithium Mining and Processing.
News Publication Date: December 2, 2025.
Web References:
- The Water Quality Impacts of Legacy Hard-Rock Lithium Mining and Processing
- Duke University Vengosh Lab
- North Carolina Water Resources Research Institute
- Duke University Climate Research Innovation Seed Program
References:
Williams, GDZ; Petrović, M; Hill, RC; Hall, GA; Vengosh, A. The Water Quality Impacts of Legacy Hard-Rock Lithium Mining and Processing. Environmental Science & Technology 59, no. 49 (Dec. 1, 2025): 26492-26505.
Keywords: Geochemistry, Water resources, Lithium mining, Groundwater contamination, Surface water quality, Arsenic contamination, Pegmatite, Spodumene, Environmental monitoring, Legacy mining impacts, Mining waste management.
