This report follows the study to recognize, characterize, and delineate mineralized environments in the Wallace and Choteau quadrangles of Idaho and Montana.

From introduction: The overall purpose of this study were twofold: (1) To determine where greatest yielding wells at shallowest depths would produce water of suitable quality for municipal and industrial supplies; and (2) to determine regional effects of additional water development on the hydrologic system.

From purpose and scope: The purpose of this report is to summarize and evaluate water-quality data acquired from streams within the study area from October 1975 through September 1981. This report updates data collected at 9 stations during the initial study and provides new data for 14 stations.

From purpose and scope: The purpose of this report is to present biological data and to compare the physical, chemical, and biological data to water-quality criteria that are desirable for the proposed reservoir uses.

The present study sought to falsify three distinct hypotheses about how the interactions of freshet clay turbidity with Flathead Lake may be affecting its trophic state: 1) that freshet-derived turbidity causes precipitation of organic detritus from the water column by flocculation and/or coagulation of dissolved and colloidal organic carbon and seston; 2) that flocculated clay-organic detritus complexes become increasingly infested with microbial biomass as they sink through the water column; and 3) that primary productivity is reduced and subsequently maintained at low levels throughout the summer and fall because of the phosphorus stripping action of sedimenting clay particles. In addition, this study attempted to firmly document mass balances for some ecologically important elements, nutrient loading rates, steady state nutrient concentrations and annual lake primary productivity. It was also necessary to assess the trophic status of the lake in light of any new findings from this research, especially related to the ecological role of freshet turbidity.

A comparative study was made of environmental variables and the density, biomass, diversity, and species composition of macroinvertebrates in areas downstream from a dam with a hypolimnetic release (Hungry Horse Dam on the Flathead River) and a dam with a selective withdrawal system (Libby Dam on the Kootenai River). A major objective of this study was to examine the response of macroinvertebrate communities to defined environmental gradients in temperature, flow, substrate, and food-related variables (periphyton, particulate organic carbon in the seston). In addition, the effects of experimental manipulations in discharge on macroinvertebrate drift and stranding were assessed, and the effects of temperature on the growth rates and emergence of five species of insects were measured.

From Purpose and Scope: "The Gillette 1º x 2º Quadrangle, Wyoming, and South Dakota was evaluated to find volumes of rock considered favorable for uranium deposits and which could contain at least at 100 mt tons U3O8 with an average grade of 0.01 percent U3O8 or more. All geologic environments to a depth of 1,500 m (5,000 ft) evaluated through the use of surface investigations and subsurface information."

The following plates depict the geology of the Ekala quadrangle in Montana, North and South Dakota.

Simultaneous size fractionation of plankton populations associated with NaH^14CO_3 and ^3H-glucose uptake was employed in eutrophic Lake Texoma (Texas and Oklahoma) and oligotrophic Flathead Lake (Montana). Autoradiography was utilized to determine the role of specific microorganisms in community metabolism. Ultraplankton (0.45-10 μm) dominated plankton numbers and metabolic activity in both aquatic systems. Many of the most abundant species were not the most productive, in terms of inorganic C fixation. Rates of heterotrophic uptake of ^3H-glucose were small in comparison to photolithotrophic uptake in both lakes, Photoheterotrophy was more extensive in Flathead Lake, Autoradiographs indicated that bacteria were responsible for observed photoheterotrophy. Oscillatoria sp. exhibited. mixotrophy in Lake Texoma,

Single record data listings taken during aerial gamma-ray and magnetic surveys of the Glasgow quadrangle in Montana.

Report discussing an investigation of the stratigraphy of the Phosphoria formation in Montana. The investigation took from 1949 to 1950, and this report includes about half of the data collected. Analytical data and abstracts of several locations' stratigraphic sections are included.

A report about gold mineralization at the Golden Sunlight breccia pipe, southwestern Montana, is related to emplacement of Late Cretaceous alkali-calcic rhyolite and subsequent collapse of the Belt Supergroup wallrock and rhyolite in the pipe.

Abstract: The Farlin Creek Wilderness Study Area (MT-076-034) is in the south-central Pioneer Mountains about 24 miles west-northwest of Dillon, Beaverhead County, southwestern Montana. At the request of the U.S. Bureau of Land Management, an area of 610 acres (less than 1 square mile) was investigated by the U.S. Geological Survey and the U.S. Bureau of Mines in 1984. The area contains no mines or prospects, no visible evidence of mineralization, and no identified mineral resources. Geophysical evidence suggests that three parts of the area have moderate mineral resource potential for undiscovered resources of molybdenum. The entire area has a low resource potential for all other metals and for all nonmetals, fuels, and geothermal energy.

Results of reconnaissance surveys of the Havre quadrangle to determine the likelihood of uranium deposits of the area, and additional information about the location and classification of any deposits.

Report documenting the results of chemical analysis for 1580 water and 1720 sediment samples in the Elk City quadrangle, Idaho/Montana. It includes an overview of the area, methods, data analysis, and evaluation.

From purpose and scope: The purpose of this study was to describe existing hydrologic systems, to obtain data on the water quality in the area, and to assess potential impacts of surface coal mining on local water resources.

Report discussing the U.S. Geological Survey's investigation of the stratigraphy of the Phosphoria formation in Montana. Abstracts of stratigraphic sections and analytical data is included.

This report follows the evaluation of uranium resources in the Ekalaka 1°x 2° Quadrangle, Montana and North and South Dakota to a depth of 1,500 m (5,000 ft) using available subsurface geologic information.

Final report regarding the National Logging Program for the National Uranium Resource Evaluation

"Field and laboratory data are presented for 397 water samples and 746 sediment samples from the Ekalaka Quadrangle, Montana. Uranium values have been reported by Los Alamos National Laboratory in Report GJBX-55(78). The samples were collected by Los Alamos National Laboratory; laboratory analysis and data reporting were performed by the Uranium Resource Evaluation Project at Oak Ridge, Tennessee." (Abstract)

"Field and laboratory data are presented for 965 water samples and 1,102 sediment samples from the Glendive Quadrangle, Montana. The samples were collected by Los Alamos National Laboratory; laboratory analysis and data reporting were performed by the Uranium Resource Evaluation Project at Oak Ridge, Tennessee."

Single record data listings taken during aerial gamma-ray and magnetic surveys of the Hamilton quadrangle in Idaho and Montana.

From abstract: A mineral resource survey was conducted in 1987 by the U.S. Geological Survey and the U.S. Bureau of Mines to evaluate mineral resources (known) and mineral resource potential (undiscovered) of the Sleeping Giant Wilderness Study Area (MT-075-111) in Lewis and Clark County, Montana. The only economic resource in the study area is an inferred 1.35-million-ton reserve of decorative stone (slate); a small gold placer resource is subeconomic. A high resource potential for decorative slate exists directly adjacent to the area of identified slate resource and in the northeastern part of the study area. The rest of the study area has a low potential for decorative slate. The westernmost part of the study area has a moderate resource potential for copper and associated silver in strata-bound deposits in green beds and limestone; potential is low in the rest of the study area.

Single record data listings taken during aerial gamma-ray and magnetic surveys of the Billings quadrangle in Montana.