In 2025, Mazama Energy achieved a landmark advancement in geothermal technology by developing the world’s hottest Enhanced Geothermal System (EGS) on the western flank of Newberry Volcano, Oregon. The project began with the workover of the existing 55-29 well (3,008 m deep and 331°C BHT) for use as an injector, followed by the drilling and completion of well 55A-29 to the same depth for use as a producer. After stimulation of both wells, initial circulation and diagnostic testing confirmed strong hydraulic connectivity and stable fluid circulation within the newly engineered reservoir. During this first year of operations, Mazama collected extensive geological, geophysical, and geomechanical datasets. Integration of these data with prior site characterization efforts leads to substantial refinement of the subsurface models, which are presented in this work. These achievements demonstrate the technical feasibility of EGS development in hot crystalline formations of various lithologies and represent a critical milestone toward establishing a Superhot Rock (SHR) EGS reservoir at Newberry Volcano. This effort is part of the Newberry SHR EGS Demonstration Project, a multi-institutional collaboration funded in partnership with the U.S. Department of Energy, paving the way for next-generation geothermal power at unprecedented temperatures.

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