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Title: Assessment of selected ground-water-quality data in Montana

Technical Report ·
OSTI ID:5222010

This study was conducted to assess the existing, computer-accessible, ground-water-quality data for Montana. All known sources of ground-water-quality data were reviewed. Although the estimated number of analyses exceeds 25,000, more than three-fourths of the data were not suitable for this study. The only data used were obtained from the National Water Data Storage and Retrieval System (WATSTORE) of the US Geological Survey, because the chemical analyses generally are complete, have an assigned geohydrologic unit or source of water, and are accessible by computer. The data were assessed by geographic region of the State because of climatic and geologic differences. These regions consist of the eastern plains region and the western mountainous region. Within each region, the data were assessed according to geohydrologic unit. The number and areal distribution of data sites for some groupings of units are inadequate to be representative, particularly for groupings stratigraphically below the Upper Cretaceous Fox Hills Sandstone and Hell Creek Formation in the eastern region and for Quaternary alluvium, terrace deposits, glacial deposits, and associated units in the western region. More than one-half the data for the entire State are for the Tertiary Wasatch, Fort Union, and associated units in the eastern region. The results of statistical analyses of data in WATSTORE indicate that the median dissolved-solids concentration for the groupings of geohydrologic units ranges from about 400 to 5000 milligrams per liter in the eastern region and from about 100 to 200 milligrams per liter in the western region. Concentrations of most trace constituents do not exceed the primary drinking-water standards of the US Environmental Protection Agency. The data in WATSTORE for organic constituents presently are inadequate to detect any organic effects of man's activities on ground-water quality. 26 figs., 79 tabs.

Research Organization:
Geological Survey, Helena, MT (USA)
OSTI ID:
5222010
Report Number(s):
USGS/WRI-84-4173; ON: TI86900045
Country of Publication:
United States
Language:
English