Sheep Creek Bridge Hot Spring
Sheep Creek Bridge Hot Spring surfaces at 142 degrees Fahrenheit alongside Middle Fork Road in Boise County, making it one of the hotter roadside springs in the Boise National Forest. USGS analysis shows a pH of 9.5 with zero magnesium — unusually pure alkaline water that reflects deep geothermal circulation through granitic rock.
The spring emerges just 278 feet from Middle Fork Road at 3,540 feet elevation, where the Middle Fork Boise River cuts a forested canyon through central Idaho. Ponderosa pine and Douglas fir line the slopes above the road. Steam rises from the source in cooler months, and mineral residue marks the rocks near the outflow. The river runs nearby, providing a cold-water contrast during warmer seasons.
The spring taps into the same deep geothermal system that feeds numerous thermal features along the Middle Fork Boise River corridor. Its strongly alkaline chemistry — very low calcium, no magnesium, moderate sodium — indicates water that has circulated through the Idaho Batholith for potentially thousands of years before surfacing here. The area saw mining activity in the nineteenth century around nearby Idaho City.
Water at the source is dangerously hot at 142 degrees. Look for spots where it mixes with cooler creek water. The road can be rough and seasonal — check conditions before driving. Ninemeyer Campground is about 10 km away but has limited amenities due to past wildfire damage. Best visited mid-May through late September.
Is Sheep Creek Bridge Hot Spring worth visiting?
Best for
- Observing powerful hot springs
- Easy day trips
- Overnight camping trips
Not ideal for
- Casual soaking
The water at Sheep Creek Bridge Hot Spring is alkaline (pH 9.5).
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Overview:Due to a wildfire, there are no amenities at the campground. Currently there are no developed campfire rings therefore when Stage 1 fire restrictions area in effect, no fires are permitted.A stay at Ninemeyer Campground enables guests to enjoy all the beauty and recreation offered along the (Middle Fork Boise River Road) Forest Service (FS) Road 268. Weather is usually good from mid-May through late September and is easily accessible by car in good weather, although the road is some...