Pool Creek Hot Spring
Pool Creek Hot Spring holds a secret in its numbers. The surface reads 108 degrees Fahrenheit, but USGS instruments recorded the source at 76 degrees Celsius, or 169 degrees Fahrenheit, revealing a dramatically hotter subsurface feed beneath Boise National Forest. The extremely high pH of 9.6 and near-zero magnesium create exceptionally soft water.
The spring emerges at 3,760 feet along the Middle Fork Road corridor, just 107 meters from the pavement. Ninemeyer Campground sits less than a kilometer away. The Middle Fork Boise River runs nearby, its cold water audible from the spring. Canyon walls of weathered granite rise steeply, covered in Douglas fir and ponderosa pine. This stretch of road winds through one of Idaho's classic river canyons, narrow and shaded, where morning fog often lingers until mid-morning. Annual snowfall tops 10 feet, and average temperatures sit around 47 degrees Fahrenheit.
Ninemeyer Campground is first-come, first-served and currently lacks amenities due to wildfire damage. No fire rings are available, so check current fire restriction status before visiting. Surface water at 108 degrees Fahrenheit is soakable with care, but subsurface vents may reach 169 degrees Fahrenheit. Test thoroughly before entering. Middle Fork Road can be rough and is best traveled in dry conditions from mid-May through September.
The 61-degree temperature gap between surface flow and subsurface source indicates significant cooling as water rises through fractured granite. Total dissolved solids of 245 mg/L are moderate, while the sodium-dominant, calcium-depleted chemistry fingerprints deep circulation through the Idaho Batholith. The Middle Fork corridor hosts a chain of thermal features along a single fault system. Recent wildfire has affected Ninemeyer Campground, removing some of the forest canopy and altering drainage patterns near the spring.
The water at Pool Creek Hot Spring is alkaline (pH 9.6) with 245 mg/L total dissolved solids.
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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...
Pool Creek Hot Spring is road-accessible, so you can bring more gear.
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