The Colorado Department of Health's Office of Health Protection began this study in the fall of 1981 when oil shale development seemed inevitable. Since then, the oil shale industry has been dealt some serious blows. Some maintain that the industry's problems are terminal. Others insist that only the timetable for oil shale development has been set back. Our crystal ball is cloudy on the subject, but 2000 (the assessment year for the study) is still seventeen years away. This study makes no attempt to predict the likely level of energy development in the year 2000. The Colorado Department of Health's Office of Health Protection is responsible for air quality, water quality, radiation control, noise control, epidemiology and disease control. consumer protection, and solid and hazardous waste management programs in Colorado.Because of its environmental and health protection responsibilities, the Department finds the potential problems associated with projected energy growth in the six counties of Northwestern Colorado-Garfield, Rio Blanco, Mesa, Routt, Moffat, and Delta-to be of particular concern. The vast majority of Northwest Colorado's oil shale resources are located in two counties, Garfield and Rio Blanco. Together the six counties of the region produce 78% of the coal" 62% of the oil, and 33% of the gas produced in the State. Within this same region are uranium mining and milling operations, a proposed coal gasification (coal-to-hydrogen) project, and several existing major powerplants (with others either under construction or in an advanced planning stage). Nowhere else in Colorado does such a concentration of energy resources exist. Within this same region are a number of particularly sensitive areas including: two wilderness areas, Flat Tops and Mt. Zirkel; two national monuments,Dinosaur and Colorado; one wildlife refuge; habitat for a number of threatened and endangered species; and approximately 534,000 acres of cropland'. The Colorado Department of Health, in association with the U.S. Environmental Protection Agency (EPA),Region VIII, has undertaken this effort to study the cumulative environmental impacts of energy development in Northwestern Colorado in order to develop a better understanding of the potential environmental problems facing the region. This study examines the direct and secondary impacts of energy development on land, air quality, water quolity, solid and hazardous waste disposal and noise in the region. The study is meant as a general overview of these impacts. It is impossible to actually predict the environmental impact of oil shale development with any certainty, because oil shale pollution control technologies have never been tested on a commercial level.However, from work based on pilot projects and existing information some tentative projections can be made. Although the focus of this study is upon the operation phase of these energy operations, the study also attempts to address concerns that may arise during the construction and post-operative phases. One major assumption made throughout the report is that existing State and Federal environmental statutes and regulations will not be relaxed. Major revisions to sequences than those actually projected in this study. This study also assumes that all energy projects in the region will comply, either voluntarily or through various State and Federal enforcement mechanisms, with these laws and permit requirements. It should be noted that forced compliance of environmental laws and regulations could be costly both to Colorado and U.S.taxpayers. The report did not address the possibility that there will be a "crash program" to develop oil shale. It also did not consider the economic costs of compliance with current environmental standards. It is conceivable that compliance could be so costly that industry will attempt to relax environmental standards. These two concerns- a crash program and the relaxation of environmental standards-have been a longstanding concern to many citizens and State and local officials in Colorado. Energy development in the region currently must meet the requirements imposed by the following major Federal and State environmental statutes. Federal Clean Air Act Clean Water Act Endangered Species Act National Environmental Policy Act Resource Conservation and Recovery Act Safe Drinking Water Act Toxic Substances Control Act Colorado Air Quality Control Act Hazardous Waste Act Mined Land Reclamation Act Noise Control Act Solid Waste Act Water Quality Control Act A deliberate attempt was made not to make value judgements as to the relative importance of any particular environmental concern. This report should be useful in identifying areas where further research and planning are needed. More detailed environmental impact studies are being prepared by the U.S. Bureau of Land Management and others. It is hoped that citizens of Colorado will find this report to be an understandable overview of a complex subject.