Keithly Warm Spring
Keithly Warm Spring surfaces at a mild 86 degrees Fahrenheit near Weiser in Washington County, right off the road at 2,560 feet elevation. Its slightly acidic pH of 6.7 makes it unusual among Idaho thermal springs, which tend strongly alkaline, and its low mineral content suggests a shallow, fast-circulating source.
The spring sits in the western Idaho foothills where the Weiser River drainage opens toward the Snake River and the Oregon border. Rolling grassland and scattered ponderosa pine characterize the terrain. Annual precipitation of 20 inches supports greener vegetation than the desert to the south, and 36 inches of snow falls in a typical winter. The 86-degree water is barely warm enough to register as thermal against the 51.5-degree annual air average, offering only a subtle warmth on cooler days.
The spring is roadside at 2,560 feet and requires no hiking. Water temperature is tepid and best appreciated in cooler weather. Mann Creek Campground sits 17 kilometers away near Mann Creek Reservoir with reservable sites and boating and fishing access. The Weiser area offers services and supplies. Check current land access before visiting as ownership status along the road may vary.
The near-neutral to slightly acidic pH and calcium-magnesium chemistry distinguish this spring from the sodium-alkaline systems of the Snake River Plain. The water's composition suggests circulation through sedimentary or metamorphic formations in the West Central Mountains foothills rather than the volcanic rocks to the east. USGS measurements recorded just 16.9 degrees Celsius, cooler than the historical 86-degree reading, which may indicate seasonal variation or measurement at a different discharge point.
The water at Keithly Warm Spring is slightly acidic (pH 6.7).
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Overview Mann Creek Campground is located near the Mann Creek Reservoir in the foothills of the West Central Mountains in western Idaho near the Payette National Forest. The reservoir is a popular boating and fishing destination. Once on-site, you may be able to pay for your campsite(s) by scanning a QR code using the Recreation.gov mobile app, and the Scan and Pay feature. If this option is available, you will need to first download the free Recreation.gov mobile app https://www.recreation....
Keithly Warm Spring is road-accessible, so you can bring more gear.
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Springs Near Keithly Warm Spring
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Slightly Acidic Springs (pH ~6.7)
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