| Abstract: | Shallow ground-water resources in western Montana have been developed primarily in Quaternary alluvium and Tertiary deposits, although bedrock supplies water to wells locally. Well-yield and trans- missivity values were largest (medians of 40 gallons per minute and 970 feet squared per day, respec- tively) in alluvium and smallest (medians of 15 gallons per minute and 130 feet squared per day, respectively) in bedrock. Chemical composition of ground water was dominated by calcium, magnesium, and bicarbonate derived from dissolution of carbonate minerals. Other water types may be the result of ion exchange (increased sodium) and mixing of geothermal water or leachate from mine wastes (increased sulfate). Although concen- trations of arsenic were relatively small (maximum of 20 micrograms per liter), they were somewhat larger in alluvium within 300 feet of the Clark Fork. Elevated concentrations of cadmium (maximum of 6 micrograms per liter) were measured in water from one well downgradient from tailings ponds. Although mining and smelting activities have resulted in widespread distribution of contami- nants in the Clark Fork valley, this study indicates that ground water contains elevated concentrations of trace elements only locally. Streamflow data indicate significant ground-water inflow to the Clark Fork in two reaches. Between Racetrack and Garrison, irrigation-return flow probably augments naturally occurring ground-water discharge. Between Jens and Cramer Creek, geo- thermal water from bedrock flows through alluvium to the river. In the Clark Fork, the maximum arsenic concentration was 8.1 micrograms per liter; copper and manganese concentrations were largest at Warm Springs (maximums of 14 and 350 micrograms per liter, respectively) and decreased downstream. |
| Genre: | USGS Numbered Series |
| ProdID: | 28896 |
| Citation Author: | Nimick, D. A. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | v, 63 p. :ill., maps (some col.) ;28 cm. |
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| Citation Publisher: | U.S. Dept. of the Interior, U.S. Geological Survey ;
Earth Science Information Center, Open-File Reports Section [distributor], |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 93-4052 |
| Citation Search Results Text: | Hydrology and water chemistry of shallow aquifers along the upper Clark Fork, western Montana; 1993; WRI; 93-4052; Nimick, D. A. |
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| Citation Year: | 1993 |
| Type: | citation/reference |
| Text: | Hydrology and water chemistry of shallow aquifers along the upper Clark Fork, western Montana; 1993; WRI; 93-4052; Nimick, D. A. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1993/4052/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1993/4052/report.pdf |
| URL (PLATE): | http://pubs.usgs.gov/wri/1993/4052/plate-1.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Dept. of the Interior, U.S. Geological Survey ;
Earth Science Information Center, Open-File Reports Section [distributor], |
