This map displays dissolved-solids concentrations in water from Lower Paleozoic aquifers in the Northern Great Plains aquifer system. Lower Paleozoic aquifers contain freshwater only in two small areas (under the Bighorn Mountains and Black Hills). A large area of brine with a dissolved-solids concentration of 100,000 milligrams per liter (mg/L) underlies eastern Montana and much of North Dakota. At the aquifer outcrops, surface water recharges these units and becomes part of the deep, very slow, regional flow patterns that propagate from the southwest to the northeast beneath the project area. Total dissolved solids are very high in Paleozoic units underlying most of the study area and therefore hold potential for CO2 storage.
Data Sources: USGS Groundwater Atlas and Downey and Dinwiddie, 1988