The report is produced under the cosponsorship of the Montana State Board of Health, North Dakota State Department of Health, Wyoming Department of Public Health, and the Public Health Service. It is based on data available as of January 1, 1952, on sources of pollution, treatment facilities employed, and stream conditions. The report also presents information concerning use of water resources, pollution entering water resources and resulting damages, benefits which may result from pollution prevention and abatement, pollution prevention measures in effect and those which appear to be needed. A sincere effort has been made to present a fair picture of the water pollution problems in the Yellowstone Basin and to present reasonable conclusions and recommendations.