Hydrogeology of the Fort Peck Indian Reservation, northeastern Montana
- Geological Survey, Helena, MT (United States)
The Fort Peck Indian Reservation, which encompasses about 3,300 square miles in northeastern Montana, is characterized by three major types of terrain: Missouri River bottom lands, badlands, and topographically higher benchlands. The reservation lies on the western flank of the Williston Basin, a large, petroleum-rich structural depression in Montana, North and South Dakota, and Saskatchewan and Manitoba, Canada. Structurally, the area is not complex, although the Poplar Anticline trends northwest through the central part of the reservation. The East Poplar Oil Field lies astride this structure and produces from the mississippian Madison Group. Geologic units that crop out in the reservation are the Upper Cretaceous Bearpaw Shale, Fox Hills Sandstone, and Hell Creek Formation; the Tertiary Fort Union and Flaxville Formations; and Quaternary glacial and alluvial deposits. Most ground water is produced from alluvial deposits, glacial deposits, Flaxville Formation, Fort Union Formation, Hell Creek Formation, and Fox Hills Sandstone. Well depths range from about 15 to 300 feet below land surface; depth to water ranges from about 5 to 160 feet. Units deeper than the Fox Hills Sandstone are not important aquifers because of the underlying, thick Bearpaw Shale, and because the water is too mineralized for most uses. Background dissolved-solids concentrations of water from major aquifers is in the range of about 300 to 3,000 milligrams per liter. However, in the East Poplar Oil Field, water in the alluvial and glacial deposits has been contaminated near brine-disposal facilities; dissolved-solids concentration of water is as much as 114,000 milligrams per liter.
- OSTI ID:
- 5128831
- Report Number(s):
- CONF-9305259-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AQUIFERS
GEOLOGY
HYDROLOGY
GROUND WATER
WATER CHEMISTRY
MONTANA
ALLUVIAL DEPOSITS
BRINES
CHEMICAL COMPOSITION
CRETACEOUS PERIOD
GEOLOGIC FORMATIONS
INDIAN RESERVATIONS
SITE CHARACTERIZATION
WATER POLLUTION
CHEMISTRY
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
HYDROGEN COMPOUNDS
MESOZOIC ERA
NORTH AMERICA
OXYGEN COMPOUNDS
POLLUTION
USA
WATER
580000* - Geosciences