Donlay Ranch Hot Spring flows at 131 degrees Fahrenheit just 115 feet from Southfork Road in the Boise National Forest, combining serious geothermal heat with convenient roadside access in the South Fork Payette River drainage near Idaho City. The water's pH of 9.2 makes it among the more alkaline springs in this already alkaline corridor.
At 3,200 feet elevation, the spring occupies a transitional zone between the dry, open foothills and the denser forest of the higher canyon. Ponderosa pine stands nearby, and the South Fork Payette River runs through the valley below. The mineral outflow traces pale lines across dark rock. Annual snowfall of nearly nine feet keeps the area white through winter and into spring, and steam rises from the source in any month when air temperatures drop below the water temperature, which is most of the year given the 82-degree differential.
History of Donlay Ranch Hot Spring
The highly alkaline pH of 9.2 with low calcium at 2.0 mg/L and sodium at 75 mg/L is characteristic of water that has circulated through the silica-rich granitic rocks of the Idaho Batholith. Donlay Ranch's name recalls the homesteading era when settlers along the South Fork Payette claimed land near thermal features, sometimes using the hot water for agricultural purposes. USGS records confirm a source temperature of 54.5 degrees Celsius.
At 131 degrees Fahrenheit, the source water requires significant cooling before any contact. Look for downstream mixing zones where cold creek water brings temperatures into a tolerable range. Hot Springs Campground is about 3.5 miles away along the Banks-Lowman Highway and takes reservations. Southfork Road is accessible but unpaved in sections. The spring is on Forest Service land with open access and no fees.
Is Donlay Ranch Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
Donlay Ranch Hot Spring offers an accessible hot spring experience — great for a day trip.
Annual Precip: 30.9 in
Annual Snow: 105.6 in
December
Air 27°F · Water 131°F · +104° contrast
January
Air 28°F · Water 131°F · +103° contrast
February
Air 32°F · Water 131°F · +99° contrast
December offers 48°F more contrast than July
Recent Temperature
130.1°F
(54.5°C)
Measured Nov 27, 1978
The water at Donlay Ranch Hot Spring is alkaline (pH 9.2).
pH influences mineral absorption through skin
May support bone density and joint health
Known for muscle relaxation and stress relief
Supports circulation and skin hydration
Traditionally used for skin conditions and inflammation
Natural antiseptic with skin health benefits
Overview
Hot Springs Campground is located just east of Garden Valley, Idaho along the Banks-Lowman Highway at an elevation of 3169 feet. Visitors enjoy rafting, kayaking, fishing on the South Fork Payette River, and soaking in the hot springs at the river's edge.
Recreation
The South Fork Payette River is across the road from the campground, offering fishing, whitewater rafting, and kayaking.
A natural hot springs soaking pool is located on the river directly across the road and down a...
Reserve on Recreation.gov →
Swimsuit & towel
Water bottle
Stay hydrated, especially in hot water
Camping gear
Nearby camping at Hot Springs
Trash bag
Pack out what you pack in
Water shoes
Hot ground near source
27 miles from Idaho City, ID
USGS Quad: (GARDEN VALLEY 15) · NOAA: 43.0 · AMS Map: CHALLIS
What is the water temperature at Donlay Ranch Hot Spring?
Donlay Ranch Hot Spring has a water temperature of 131°F (55°C). This is considered a hot spring, well above body temperature.
Where is Donlay Ranch Hot Spring located?
Donlay Ranch Hot Spring is located in Boise County, Idaho at 3,200 feet elevation, near Idaho City. Coordinates: 44.0440°N, 115.8510°W.
How do I get to Donlay Ranch Hot Spring?
Donlay Ranch Hot Spring has Roadside road access, with the nearest road being Southfork Road (115 ft from the road).
Is Donlay Ranch Hot Spring free to visit?
Donlay Ranch Hot Spring has Open access. It is managed by US Forest Service.
Can I camp near Donlay Ranch Hot Spring?
Yes, Hot Springs is located nearby (3.5 miles away).
What minerals are in the water at Donlay Ranch Hot Spring?
Water chemistry analysis shows the presence of pH, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 9.2 (alkaline).
Is it safe to soak at Donlay Ranch Hot Spring?
At 131°F, Donlay Ranch Hot Spring is hot enough to require caution. Enter slowly, limit soaking sessions to 15–20 minutes, and stay hydrated. Always tell someone your plans before visiting remote hot springs.
Is Donlay Ranch Hot Spring crowded?
Donlay Ranch Hot Spring is accessible from a paved road, making it easy to reach. Weekends and holidays may be busier — consider visiting on a weekday for a quieter experience.
What should I bring to Donlay Ranch Hot Spring?
Essentials for Donlay Ranch Hot Spring: swimsuit, towel, water bottle, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.