Reliable Water-Supply Management Model for Emerging Carbon-Removal Infrastructure: A Case Study in Castle Valley, Utah, USA

A reliable water supply is essential for balancing hydrologic, operational, and institutional constraints and is intensified by the water demands of emerging carbon-removal technologies. This study applies a reliable water-supply framework to Castle Valley, Utah, USA, a region with favorable geologic conditions for carbon storage. Existing municipal, agricultural, and industrial water demands and surface-water, groundwater, and water-rights-based supply were quantified using publicly available datasets. Scenarios were then evaluated to test how a proposed 1 Mt/yr direct air capture (DAC) facility would affect the regional water balance. Results indicate that the existing supply–demand balance in Castle Valley is approximately in equilibrium, and that a 1 Mt/yr DAC facility would require an estimated 7–18% of total municipal water demand, disrupting the balance under several supply scenarios, particularly where supply is based on water rights rather than actual conditions. Retrofitting existing coal-fired power plants with carbon capture and storage (CCS) could double their water consumption. Non-potable water sources, such as brine water, may be necessary to support DAC development without compromising existing water users. The findings suggest that regional water-balance frameworks can help identify where carbon-removal infrastructure is feasible without exacerbating water scarcity, and that similar assessments should precede DAC siting decisions in other water-limited regions.