Report issued by the U.S. Bureau of Mines discussing the mining procedures and minerals of Fergus County, Montana. History, geology, and mineral production of the Fergus County mines are presented. This report includes tables, and maps.

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.

From introduction: This report details the results of a geological survey of the Libby Quadrangle, Montana.