Hot springs are formed when rain and other surface waters drain through faults or cracks in the Earth's surface and reach hot rocks - those found at the bottom of deep chambers, or volcanically heated material closer to the surface. When the water is heated to boiling, it rises, and if it can find a crack or fault to the surface, it will emerge as a hot spring. En route, the water often picks up a host of minerals, such a sulfur, silica, calcium, potassium, ammonia and phosphate. Washington has few hot springs compared with other western states and British Columbia, especially considering the powerful volcanism that boils below. But those that do exist and are accessible to the public are exceedingly popular.
People come from all over.
Most who go there have a pretty good experience. However, problems can arise at the bubbling springs. Most of the time it's pretty mellow. The U.S. Forest Service has struggled for years with Baker Hot Springs, claiming it fails to meet water-quality standards for fecal coliform levels. Because of the easy access, there's been a lot of partying, beer drinking, broken glass, vandalism to cars at the trailhead.