Valles Caldera

From 1959 to 1983, approximately 40 exploratory geothermal wells were drilled into the Redondo Creek Graben as part of the Baca geothermal field, a joint operation by the United States Department of Energy and the Union Oil Company of California. Despite measuring a maximum temperature of 342 °C and having a likely production capacity of 20 MWe, the geothermal field was too small to be economic. Three scientific cores were drilled in Valles Caldera during the mid-1980s as part of the United States Continental Scientific Drilling Program in order to analyze the chemistry of geothermal fluids and the presence of a vapor-dominated cap in the Sulphur Springs region. The maximum bottom hole temperature measured during drilling was 295 °C. Overall, the geothermal reservoir at Valles Caldera is liquid-dominated rather than vapor-dominated and has a neutral-chloride fluid chemistry with a maximum temperature below 300 °C.