The U.S. Department of Interior has assigned to the US Geological Survey (USGS) the task of conducting an updated assessment of the geothermal resources in the United States. In that connection, we offer an objective analysis of the last such national assessment, made in 1978, and presented in USGS Circular 790, in View of the Industry experience accumulated over the intervening 26 years. Based on this analysis we offer our perspective on how such assessment may be improved.

Thermal springs are widely distributed throughout the world but are most numerous in areas in which there has been volcanic activity in late geologic time. A review of the available literature has revealed much information on the location of the springs, the temperature of the water, the rate of flow, the chemical character of the water and evolved gases, and the uses made of the water. All such information has been tabulated by countries or geographic areas and is present in the first part of this report. Accompanying the tabulated data for each country or geographic area is a brief description of the geology and a map showing the location of the springs. The second part of the report consists of a list of references, some annotated briefly, to the literature on thermal springs. The references are grouped by countries or geographic areas and within each group are arranged in alphabetical order by author. However, for ease of citation throughout the report, the references have been assigned consecutive numbers.