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. Data source: USGS Groundwater Atlas.
Click on the map for a larger version (in a new pop-up window) or download a high resolution jpeg version of this map (see link below).
Right-click and Save As to download
