This report is the result of reconnaissance field work and air photo interpretation conducted during late summer and fall, 1976. The chief purpose of the project was the preliminary assessment of the impact of a prohibition against mining alluvial valley floors on the coal resources of portions of Dawson, Garfield, McCone, and Richland Counties, Montana. A secondary purpose was the assessment of some of the physical and land use characteristics of these areas, and their importance to the local farming and ranching economy. Field work, data compilation, and report preparation were accomplished in less than five months. Thus, it must be emphasized that the report is reconnaissance in nature. The report is no substitute for site specific field work related to a particular mining proposal, which should document ground water levels, surface and subsurface soil and water salinity, aquifer relationships, the economic importance of a particular valley floor to individual ranchers and farmers, and identify specific mining and reclamation problems.