Mormon Ranch Warm Spring

Custer County, Idaho · Near Challis
44.9510°N, 114.7040°W · 4,300 ft
Hot 41°F air · Good soaking weather 4,300 ft Open Hike US Forest Service Camping nearby (11.2 mi)
Aerial view of the ground around Mormon Ranch Warm Spring LiDAR bare-earth view of the same ground around Mormon Ranch Warm Spring
Aerial LiDAR bare earth

Drag the handle to compare the two views. The orange dot marks the spring, in a frame about three quarters of a mile wide.

Mormon Ranch Warm Spring is a Forest Service spring in Custer County, three miles by foot from the closest road and nearly forty miles from Challis. The name says warm and the survey note says hot, and no temperature was written down, so take the name lightly. The water, sampled decades ago, came back strongly alkaline. Salmon National Forest land, listed open to the public.

Location

Mid-elevation mountain country, a bit over four thousand feet, with snowfall approaching eight feet in a typical winter and moderate precipitation. That much snow closes the approach for a long stretch of the year. The three-mile hike in is the defining fact of the place. No road name is on file. Nothing in the record describes the trail or the ground around the source.

No best months are listed, so go by the snow. Summer into early fall is the realistic window, and confirm with the forest before heading out. Overnight options on file come down to Yellowjacket Guard Station, some eleven miles distant. No fee appears in the record. Because the temperature is unrecorded, check the water carefully before getting near it. It might be a soak or it might be hotter than skin can take.

Terrain

Aircraft with laser scanners measured this ground to within inches. The scan strips out trees and buildings, leaving the bare shape of the land around Mormon Ranch Warm Spring.

Setting
Canyon floor
Steep ground climbs away on both sides of the spring.
Highest ground nearby
679 ft above the spring
Within a quarter mile, to the northeast
Cross-section through the spring

A slice through the ground from southwest to northeast, about 0.6 miles end to end.

Elevation data: USGS 3D Elevation Program. Aerial imagery: USGS The National Map. Public domain.

Heat Below
104 milliwatts per square meter of heat flow

That's about 1½ times the US average of 65. It's higher than at 53% of the springs on this site.

Heat flow measures the warmth working its way up through the ground from deep inside the earth. Where it runs high, rain and snowmelt that seep down through cracks in the rock come back up hot.

Heat flow estimate: Stanford Thermal Earth Model (Aljubran & Horne, 2024), CC BY 4.0.

Monthly Climate
26°
Jan
29°
Feb
36°
Mar
41°
Apr
50°
May
61°
Jun
72°
Jul
71°
Aug
61°
Sep
46°
Oct
32°
Nov
24°
Dec
Annual Precip: 21.7 in Annual Snow: 92.1 in
Current Conditions
41°F
WSW 0.0 mph 90% Good soaking weather
Today 74° Low 45° Sunny
Wednesday 79° Low 49° Sunny
Thursday 75° Low 48° Rain then Showers And Thunderstorms 79% precip
Friday 71° Low 46° Chance Light Rain then Showers And Thunderstorms Likely 55% precip
Saturday 76° Low 47° Sunny 10% precip
Water Chemistry Sampled 1980-06-29

The water at Mormon Ranch Warm Spring is alkaline (pH 9.4).

pH 9.4 Alkaline
pH influences mineral absorption through skin
Calcium 3 mg/L
May support bone density and joint health
Sodium 50 mg/L
Supports circulation and skin hydration
Sulfate 29 mg/L
Traditionally used for skin conditions and inflammation
Chloride 5 mg/L
Natural antiseptic with skin health benefits
Where to Stay

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Nearby Camping
Yellowjacket Guard Station 11.2 mi away

Overview Yellowjacket Guard Station is a historic Forest Service Ranger Station and Work Center. Originally constructed in 1925 and remodeled in 1934 by the Civilian Conservation Corps, the structure is eligible for listing on the National Register of Historic Places. Recreation Hikers, horseback riders, mountain bikers and off-road enthusiasts will find many trails in the surrounding area. Hunting is also a popular activity. Click here for an Idaho OHV safety messageFacilities The spacious...

Reservable Yes
Reserve on Recreation.gov →
Temperature
Hot
Warm Hot Boiling
Avg Air Temp 46°F
Access
Open
Road Access Hike
Distance to Road 3.0 mi
Land
Ownership Federal
Agency US Forest Service
Designation National Forest
Unit Salmon National Forest
Manager US Forest Service
Protection 3 - Protected, subject to extractive use
Frequently Asked Questions
What is the water temperature at Mormon Ranch Warm Spring?
Mormon Ranch Warm Spring is classified as hot. An exact temperature measurement has not been recorded.
Where is Mormon Ranch Warm Spring located?
Mormon Ranch Warm Spring is located in Custer County, Idaho at 4,300 feet elevation, near Challis. Coordinates: 44.9510°N, 114.7040°W.
How do I get to Mormon Ranch Warm Spring?
Mormon Ranch Warm Spring has Hike road access (3.0 mi from the road).
Is Mormon Ranch Warm Spring free to visit?
Mormon Ranch Warm Spring has Open access. It is managed by US Forest Service.
Can I camp near Mormon Ranch Warm Spring?
Yes, Yellowjacket Guard Station is located nearby (11.2 miles away).
What minerals are in the water at Mormon Ranch Warm Spring?
Water chemistry analysis shows the presence of pH, Calcium, Sodium, Sulfate, Chloride. The pH is 9.4 (alkaline).
Sources: USGS NWIS