NEWS RELEASE: Wyoming Geological Survey Publishes Report on Groundwater Salinity in the Powder River Basin

WSGS Publishes Report on Groundwater Salinity in the Powder River Basin

The Wyoming State Geological Survey (WSGS) recently published a report on groundwater salinity in the Powder River Basin (PRB) of northeastern Wyoming. This report examines the salinity of groundwaters that occur at depths of 7,000 feet or less in the PRB where significant oil and gas activity has taken place in recent years. In this report, special emphasis is placed on the location of naturally occurring saline groundwaters with total dissolved solids (TDS) levels greater than 5,000 parts per million (ppm) that may be suited to some industrial uses thereby conserving higher-quality water for domestic, agricultural, and livestock uses.

“As oil drilling continues in the Powder River Basin, the need for industrial-use water will become increasingly important,” says WSGS Director, Dr. Erin Campbell. “This report is a first step toward locating subsurface water that is not suitable for human consumption, livestock, or agriculture.”

Groundwater quality varies widely throughout Wyoming’s geologic basins. An aquifer may produce high-quality groundwater suited for human consumption at a basin’s edge while water pumped from the same aquifer a few miles further into the basin may be unfit for livestock usage.

One measure of water quality is its “salinity,” or TDS, which is the amount of dissolved material that remains as residue after the liquid portion of a water sample evaporates. Salinity, measured in ppm, is one constituent, among others, used by the Wyoming Department of Environmental Quality (WDEQ) to determine if groundwater resources are suited for human consumption, agricultural application, or livestock watering. Although salinity provides a general measure of water quality, it does not specify the type or amounts of particular chemical compounds present.

“The results of this study show that naturally occurring moderately saline groundwaters first appear in a few locations in the west-central PRB at 1,000 feet below the surface and are widely scattered throughout the entire basin at depths exceeding 5,000 feet,” says Karl Taboga, WSGS hydrogeologist.

For this report, WSGS geologists examined thousands of water quality analyses from the U.S. Geologic Survey (USGS) and geophysical well logs from the Wyoming Oil and Gas Conservation Commission.

The 23-page report, “Groundwater Salinity in the Powder River Basin, Wyoming: Open File Report 2018-5,” is available as a free download on the WSGS website. The online report includes an explanation of groundwater salinity and maps of water quality by depth interval throughout the Powder River Basin.

This report is the second of a series of studies examining the occurrence of industrial-grade groundwaters in Wyoming’s structural basins. The first report in the series examined the salinity of groundwater in the Denver-Julesburg Basin in southeastern Wyoming. The newest report supplements the recently released USGS report, "Brackish Groundwater in the United States," available as a free download on the USGS Publications website.