|Madison Group, Williston Basin
Water in the area varies significantly in temperature and in dissolved solids concentration, and as a result the density and viscosity vary from area to area. Available data for the ground-water temperature of the Madison Group show variations between 46 °F in or near outcrop areas to about 300 °F in some deeper parts of the basin. The units for the water-temperature map by Downey (1986) (modified from MacCay, 1984) are in degrees Celsius.
Downey, J. S., 1986, Geohydrology of bedrock aquifers in the northern Great Plains in parts of Montana, North Dakota, South Dakota and Wyoming: U.S. Geological Survey Professional Paper 1402-E, 87 p.
Downey, J. S., 1984, Geohydrology of the Madison and associated aquifers in parts of Montana, North Dakota, South Dakota and Wyoming: U.S. Geological Survey Professional Paper 1273-G, 47 p.