"The purpose of this report is to summarize geology, coal resources, and coal reserves in the Montana Powder River Basin (MTPRB) assessment area in southeastern Montana. This report represents the fourth assessment area within the Powder River Basin to be evaluated in the continuing U.S. Geological Survey regional coal assessment program. There are four active coal mines in the MTPRB assessment area: the Spring Creek and Decker Mines, both near Decker; the Rosebud Mine, near Colstrip; and the Absaloka Mine, west of Colstrip. During 2011, coal production from these four mines totaled approximately 36 million short tons (MST). A fifth mine, the Big Sky, had significant production from 1969--2003; however, it is no longer in production and has since been reclaimed. Total coal production from all five mines in the MTPRB assessment area from 1968 to 2011 was approximately 1.4 billion short tons (BST). The Rosebud/Knobloch coal bed near Colstrip and the Anderson, Dietz 2, and Dietz 3 coal beds near Decker contain the largest deposits of surface minable, low-sulfur, subbituminous coal currently being mined in the assessment area. A total of 26 coal beds were identified during this assessment, 18 of which were modeled and evaluated to determine in-place coal resources. The total original coal resource in the MTPRB assessment area for the 18 coal beds assessed was calculated to be 215 BST. Available coal resources, which are part of the original coal resource remaining after subtracting restrictions and areas of burned coal, are about 162 BST. Restrictions included railroads, Federal interstate highways, urban areas, alluvial valley floors, state parks, national forests, and mined-out areas."
Geological Survey (U.S.); United States. Department of the Interior
Haacke, Jon E.; Scott, David C.; Osmonson, Lee M. . . .