Freshwater heads and ground-water temperatures in aquifers of the Northern Great Plains in parts of Montana, North Dakota, South Dakota, and Wyoming

Abstract

Potentiometric surfaces of the Tertiary aquifer, the Upper Cretaceous aquifer, and the Lower Cretaceous aquifer in the Northern Great Plains of Montana, North Dakota, South Dakota, and Wyoming generally follow land-surface gradients except in areas where geologic structure or lithologic change cause large differences in transmissivity, flow path, or both. Ground-water temperatures generally are controlled by the burial depth of the aquifer.