Pothole Spring
Pothole Spring flows at 78 degrees Fahrenheit at 4,855 feet elevation in Modoc County's remote high country, creating moderately warm waters 29 degrees above freezing alpine temperatures.
The spring emerges near Clear Lake Reservoir at the edge of high desert terrain characterized by sagebrush, juniper, and mountain mahogany. The 3,820-foot walk from Clear Lake Reservoir Road crosses open plateau landscape where winters bring 50 inches of snow and annual temperatures average just 49 degrees. This remote location offers few amenities and demands preparation for alpine conditions.
The spring represents geothermal activity occurring at unusual elevation within the broader Modoc Plateau volcanic system. Heat circulation through fractures in volcanic rock sustains the modest warmth emerging at this altitude. The plateau itself formed through ancient lava flows and basaltic volcanism, creating a landscape where thermal features appear sporadically among the sagebrush.
The 3,820-foot hike is moderate but requires caution given the remote location and variable weather conditions. Spring through early fall offers the best access, though snow can linger into June and return by September. Bring water and map—this is genuine backcountry terrain. The modest thermal discharge and alpine setting make this a destination for visitors seeking geothermal features in high, wild country.