This list of United States thermal spring locations and temperatures. The list includes natural surface hydrothermal features: springs, pools, mud pots, mud volcanoes, geysers, fumaroles, and steam vents at temperatures of 20C (68F) or greater. It does not include wells or mines, except at sites where they supplement or replace natural vents presently or recently active, or, in some places, where orifices are not distinguishable as natural or artificial.