Cow Flats Hot Spring
Cow Flats Hot Spring sits just 86 feet from Milner Trail in Nezperce National Forest, delivering 138-degree Fahrenheit water at 3,440 feet elevation in Idaho County near Grangeville. The roadside location on public forest land makes it one of the more straightforward thermal springs to reach in this remote part of the state.
The spring emerges in a forested drainage where mixed conifers and thick undergrowth line the trail corridor. At 3,440 feet, the area receives over 35 inches of rain and nearly 11 feet of snow annually, creating a lush, damp environment through much of the year. Steam rises visibly from the source on cool mornings. The Salmon River corridor lies within reach to the south, and the surrounding Nezperce National Forest terrain is rugged, steep, and sparsely roaded.
No detailed water chemistry data is recorded for Cow Flats, but its 138-degree temperature and 88-degree differential above ambient air point to significant geothermal heat flow. The spring's location along the western margin of the Idaho Batholith places it in a zone where deep faults channel heated water upward through fractured granitic rock. US Forest Service management ensures continued public access to the site.
Spring Bar Campground on the Salmon River sits about 10 miles away with 18 tent sites available on a first-come, first-served basis. The campground has tables, fire rings, and wheelchair-accessible picnic facilities. At the source, 138-degree water is dangerously hot and requires natural cooling downstream before any contact. Winter snowfall buries the access route, so plan visits between late spring and early fall.
Is Cow Flats Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
A popular take-out point for floaters of the Salmon River, the Spring Bar Campground offers a boat launching ramp and 18 tent campsites. A table and fire ring are provided at all but two of the sites. Spring Bar is situated next to a relatively flat part of the Salmon River with the south end nestled in the shade of various fruit bearing trees. The surrounding area also provides for fishing, swimming, berry picking, and exploring. Wheelchair accessible picnic facilities are available at Allis...