Warm springs north of Durango come from faults in the Animas Valley

North of Durango, the Animas River runs through a broad valley, and a few warm springs surface along it. The Colorado Geological Survey has studied this area and describes two main groups of thermal springs in the valley: the Pinkerton springs to the north and the Tripp-Trimble-Stratten springs a few miles south.

These are not random warm puddles. The survey explains that the springs are fault-controlled, meaning cracks in the rock let water move deep underground, warm up, and rise back toward the surface. The recharge water comes off the high mountains nearby, and the warmed water travels largely through an old limestone layer before reaching the valley. The temperatures are warm rather than scalding compared with some Colorado hot springs.

For a new resident, this is mostly a nice piece of “why is the ground warm here” geology, but it has a practical side too. Geothermal and fault settings affect groundwater chemistry and how water moves underground, which can matter for wells and water quality in the valley. It is the same fault-and-aquifer story that shapes where good well water is found.

If you want the real science rather than folklore, the Colorado Geological Survey’s geothermal assessment of the Animas Valley is the place to read about these springs.