The Wyoming State Geological Survey has published a new study compiling hydrogeologic information about the Tensleep aquifer and equivalent rock units across Wyoming. The study, titled "Hydrogeologic Parameters for the Tensleep Aquifer in Wyoming," was authored by WSGS hydrogeologists Kurt Hinaman and James Stafford.
The Tensleep Sandstone and equivalent formations constitute a major aquifer system across Wyoming. The study examined porosity, permeability, groundwater recharge, water quality, temperature, and groundwater interaction with oil fields.
The research found that porosity and permeability generally decrease with depth. High estimated long-term groundwater recharge occurs in portions of the Bighorn Mountains, Wyoming Range, and Gros Ventre Range. Throughout much of Wyoming, groundwater salinity generally increases from mountain flanks toward deeper portions of sedimentary basins.
The study also found that sodium-adsorption ratios generally increase farther from mountain fronts, making groundwater from the aquifer less suitable for irrigation in many areas. Lithium concentrations were generally low, though data are limited in deeper portions of sedimentary basins.
One unusual finding occurred in the northeastern Powder River Basin, where groundwater in the Minnelusa Formation—an equivalent of the Tensleep—has exceptionally high salinity but is cooler than expected for its depth. The cause remains unknown.
The report is the first in a planned series of WSGS studies characterizing individual aquifers in Wyoming.