Hot springs in Colorado

Most of Colorado's thermal springs follow two belts of faulted crust. The Rio Grande Rift, a zone where the continent is slowly pulling apart, runs north from New Mexico through the San Luis Valley and continues into the upper Arkansas River valley between the Sawatch Range and the Mosquito Range. Rain and snowmelt sink along the rift faults, warm at depth and rise again along the same fractures. A second group lies in the faulted volcanic terrain of the San Juan Mountains in the southwest, and scattered springs occur along faults in the central and northern ranges.

Undeveloped springs in Colorado are mostly on national forest land. The White River National Forest manages the Maroon Bells-Snowmass Wilderness, where the Forest Service requires an overnight permit, reserved through Recreation.gov, for camping anywhere in the Conundrum Creek valley between Silver Dollar Pond and Triangle Pass. The San Isabel National Forest covers the slopes above the Arkansas valley, and the San Juan and Rio Grande national forests cover the southwest. The Bureau of Land Management manages lower valley land, while many springs inside towns sit on private property.

Seasonal access is set by high passes. The Colorado Department of Transportation closes Colorado 82 over Independence Pass, between Aspen and Twin Lakes, each fall, usually in late October or November, and reopens it the week before Memorial Day weekend, weather permitting. Cottonwood Pass west of Buena Vista typically closes from November to May. On Interstate 70 between Dotsero and Morrison, the state traction law is in effect from September 1 through May 31, and it can be applied to any state highway during storms. Wilderness trails above timberline usually hold snow well into early summer.