Elkhorn Warm Spring
Elkhorn Warm Spring emerges at just 72 degrees F on BLM land in Madison County, making it a warm spring rather than a hot one. It sits at 5,283 feet elevation near Rexburg in eastern Idaho, running only 27 degrees above ambient air temperature. A 600-foot walk separates the spring from the nearest road access.
The spring surfaces in open rangeland typical of the Upper Snake River Plain, where sagebrush and native grasses extend to the horizon under wide skies. The terrain is flat to gently rolling, with the Snake River Range visible to the east. The area feels exposed and wind-swept, without the sheltering canyon walls that characterize many Idaho thermal features. Cottonwood trees may mark the water's course downstream. Annual snowfall is moderate at 45 inches, and the landscape dries out considerably by late summer.
The Upper Snake River Plain sits atop the track of the Yellowstone hotspot, where the North American plate has migrated southwest over a deep mantle plume. This geologic history left behind fractured volcanic rock that allows groundwater circulation, though Elkhorn's modest 72-degree temperature suggests a shallower system or greater mixing with cold surface water than the region's hotter springs. The BLM manages this area under multiple-use principles as part of the Upper Snake Field Office.
Kelly Island Campground is about 4 miles away along the South Fork of the Snake River, with free first-come sites, vault toilets, and water. The campground has a 5-day stay limit and is open roughly mid-May through September. At 72 degrees F, the spring is tepid and not suitable for traditional hot soaking. The short walk crosses open terrain. Bring sun protection, as shade is scarce.
Is Elkhorn Warm Spring worth visiting?
Best for
- Overnight camping trips
Scenic, semi-developed camping in a cottonwood gallery forest along the South Fork of the Snake River with views of the Snake River Range foothills. Excellent trout fishing along with hiking, boating, wildlife viewing and OHV riding opportunities nearby. Approximate use season: Mid-May to mid/late September. The Kelly Island Campground has no electrical hook-ups and ATV's are not allowed to be ridden in the campground. This site is equipped with a central spicket for water, vault toilets, pul...