In-situ recovery (ISR) of uranium is a mining practice that uses groundwater. First, wells are drilled into a uranium-bearing aquifer. Leaching fluids are injected into the wells to dissolve the uranium ore into the groundwater, and then the uranium is recovered by extracting the groundwater. Uranium extraction by ISR accounts for more than 90% of production since the mid-1990s. The uranium deposits where ISR is conducted are typically found in arid areas of the United States, such as Texas, Colorado, and Wyoming. Aquifers near ISR operations may also be vulnerable to contaminants migrating through undetected or mischaracterized faults from the injection zone into any hydraulically connected aquifers. Additional research is needed to identify if contaminants are present at or near ISR sites and understand the potential for migration of contaminants, which would be useful to EPA’s Underground Injection Control (UIC) program.