How can geothermal development affect groundwater and surface water supplies?

Geothermal development can impact water supplies through several mechanisms related to extraction, cooling, and drilling processes:

• Water Scarcity: Many geothermal power plants require significant volumes of water for cooling or operational purposes. In regions where water is already limited, this demand can create conflicts with other essential uses, such as supporting fish spawning and rearing habitats.1
• Groundwater Contamination: While closed-loop systems are designed to prevent contamination by circulating fluids in sealed pipes, improper drilling or system failures can lead to issues. Geothermal fluids often contain dissolved solids, including toxic heavy metals like arsenic, mercury, and nickel, as well as sulfur and chlorides. If these substances leak from deep wells or fracture systems into groundwater, they can degrade water quality.231
• Surface Water Impacts: Discharges from geothermal systems may contain concentrated minerals and gases. If released into the environment, these discharges can harm local ecosystems and contribute to wildlife mortality.1
• Overpumping: Excessive extraction of geothermal fluids can lead to water scarcity in the surrounding area, potentially affecting local aquifers.1

While Enhanced Geothermal Systems (EGS) use water to create fissures in hot rock, they generally avoid the chemical additives used in traditional oil and gas fracking. However, they still carry risks of groundwater contamination and require careful management to protect water resources.231