Coyote Hot Spring
Coyote Hot Spring emerges at 135 degrees Fahrenheit on BLM land managed by the Four Rivers Field Office in Elmore County near Glenns Ferry, with water so low in dissolved minerals that calcium and magnesium each register at just 0.1 mg/L. That near-pure thermal water is unusual even among Idaho's soft-water volcanic springs.
The spring sits at 3,885 feet elevation in open sagebrush steppe, just 130 feet from the nearest road. The landscape is dry and exposed, with 16 inches of annual rain and about 41 inches of snow. There is no forest canopy here; instead, the view extends across rolling desert benchlands characteristic of the western Snake River Plain. The thermal outflow cuts a narrow, mineral-stained channel through pale soil. On winter mornings, the steam column is visible from a distance against the brown hills.
Coyote's water chemistry is remarkably stripped of dissolved solids. At 54 mg/L sodium, 10 mg/L sulfate, and 2.7 mg/L chloride, with calcium and magnesium each at 0.1 mg/L, the water has undergone extreme ion exchange and filtration through volcanic rock. This profile suggests circulation through young rhyolitic formations where the rock itself contributes little soluble material. The 84-degree differential above ambient air confirms substantial geothermal heating at depth.
Spillway Campground on Anderson Ranch Reservoir sits about 27 miles away with three first-come, first-served sites and access to fishing and boating. The spring's roadside location on BLM public land makes it accessible year-round, though the source temperature of 135 degrees is dangerously hot. Look for downstream cooling areas where the water may reach comfortable soaking temperatures. Carry water, as this is arid rangeland with no services.
Is Coyote Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
Overview: Spillway Campground is a small campground with 3 campsites along Anderson Ranch Reservoir. The reservoir is a popular destination for fishing, boating, waterskiing and riding personal watercraft. There is excellent fishing in the reservoir for smallmouth bass and kokanee. Also try your luck at fly fishing just below the dam for a trout!Rafting access is at Reclamation Village, just south of the campground.