The NPS released a formal findings report on October 3rd, 2026, authored jointly by Dr.
Marcus Reev and Dr. Kenneth Hartley titled Recovery of Missing Person, Daniel A. Voss. Findings: Geothermal Context and recommended search protocol revisions for backcountry terrain with secondary thermal activity.
The report ran to 67 pages. Its essential argument was this that Yellowstone’s secondary hydrothermal terrain, the diffuse vent areas, the steam fissures, the unstable riolyte formations in the offtrail zones between major basin areas represented a category of backcountry hazard that was systematically under represented in both the park’s visitor safety materials and its search and rescue protocols.
The fummeral zone where Daniel Voss had died was classified following the investigation as a restricted backcountry thermal hazard zone.
One of 34 such zones newly designated across the park’s northern sector following a comprehensive survey conducted in August and September of 2026.
The report recommended mandatory thermal hazard awareness training for all backcountry permit applicants. It recommended the implementation of a real-time ground penetrating radar survey of the Tower Creek drainage and and six similar drainage zones with known secondary thermal activity.
