The Yampa River basin, Colorado and Wyoming : a preview to expanded coal-resource development and its impacts on regional water resources

Expanded coal production and conversion in the western United States may have substantial impacts on water resources, environmental amenities, and socioeconomic conditions. The U.S. Geological Survey currently (1978) has completed a 3-year assessment of the Yampa River basin, Colorado and Wyoming, where the impacts of expanded coal-resource development are beginning to affect the environment and people in the basin. The objectives of this assessment are: (1) To evaluate the environmental and economic impacts of alternative development plans for regional water and energy resources, and (2) to apply and document various assessment methodologies that might be readily transferable to other regions of the United States with abundant energy resources and limited water resources. Preliminary results are given of the following basin-assessment investigations: (1) An evaluation of surface-water and ground-water resources using available data, (2) a modeling analysis of the waste-load assimilative capacity of a reach of the Yampa River affected by municipal wastewater-treatment plant effluents, and (3) semiquantitative descriptions of ambient airand water-quality conditions. Aspects of the following facr tors also are discussed briefly: (1) Possible constraints on proposed development due to basin compacts and laws regulating water resources, (2) possible changes in environmental-control regulations, and (3) policies on energy-resource leasing and land use that will influence regional economic development. INTRODUCTION Increasing concern for greater national independence with regard to energy resources has generated interest in coal as a resource for meeting a larger part of the overall national energy demands. In contrast, there are continuing concerns regarding the water demands associated with coaldevelopment alternatives (Davis and Wood, 197*0. Anticipated direct environmental impacts associated with coal mining, processing, conversion, and transportation and also indirect impacts associated with shifts in economic activities, such as from agriculture to industry and commercial services in regions affected by such development, are important considerations (Diemer and Wengert, 1977)These impacts are of particular interest in the Rocky Mountain States which have small populations, limited water resources, and relatively abundant coal reserves (U.S. Department of the Interior, 1976a; VanDerwalker, 1975; and Thomas and Anderson, 1976). The major energy resource in the Yampa River basin is the near-surface coal deposits. However, other energy resources, consisting of oil and gas, oil shale, uranium, and geothermal springs, occur in the basin. Since the early 1900's, about 70 small coal mines have operated in the basin; however, current (1977) coal-mining operations involve 8 surface and 2 underground mines. Total coal production in 1977 was nearly ~l.k million tons (6.7 million t) which was double the production for 197^, and coal production is expected to increase to 20 million tons (18 million t) per year by 1990. Increased production will be obtained primarily from lands controlled by federally leased mineral rights. The increasing rate of coal-resource development in the Yampa River basin will result in several environmental stresses on land, water, air, and other natural resources. Examples include changes in land and water use and increased levels of discharged residuals (noneconomic byproducts) to be assimilated in the environment. In addition, potential impacts of impending oil-shale and coal development in nearby areas may affect water availability in the Yampa River basin. As a result of increased coal-resource and economic development, population in the basin is anticipated to nearly triple in 16 years (from 18,000 in 197^ to as many as 53,500 by 1990), causing water-resources impacts of an indirect nature (that is, in addition to water demands directly due to coal mining, transport, or conversion to other energy forms). The bulk of withdrawals and consumptive use of water in the basin traditionally has involved surface-water diversions for irrigated croplands. Given the limited availability of water in the region, increasing competition is anticipated among agricultural, mining-related, and municipal-industrial uses in the near future. Assessment Objectives Objectives of the Yampa River basin assessment are: (1) To evaluate the environmental and economic impacts of regional energyand water-resource development for existing and feasible alternative policies, and (2) to describe the assessment methodologies used so that they may be applied to other energy-rich regions of the Western United States where water resources are 1imited. The Yampa River basin assessment is concerned with evaluating the direct and indirect impacts of this development on the basin's water resources. Identification of hydrologic-information needs and delineation of existing or potential problem areas which suggest the need for further in-depth investigations are of primary concern. Regional Setting The Yampa River basin is located in northwestern Colorado and southcentral Wyoming (fig. 1) and encompasses an area of approximately 8,080 mi 2 (20,900 km2 ). Major references to the basin's regional setting are depicted on figure 1. The assessment studies involve that part of the basin lying to the east of Dinosaur National Monument. Approximately three-fourths of the basin lies in Colorado and one-fourth in Wyoming. Included in the basin boundaries are parts of seven counties: Garfield, Grand, Moffat, Rio Blanco, and Routt Counties in Colorado, and Carbon and Sweetwater Counties in Wyoming. The combined basin areas in Moffat and Routt Counties constitute about two-thirds of the total drainage area of the basin. Moreover, the majority of the population and economic activity within the basin is located in these two counties. The basin averages 75 mi (120 km) in width and extends about 100 mi (160 km) from the Continental Divide in the east to Dinosaur National Monument in the west. The Yampa River basin constitutes the first three cataloging units of accounting unit H0500 of the Upper Colorado River region as defined by the U.S. Water Resources Council (1970). The Yampa River lies within the Green River division [subbasin of the Upper Colorado River (region) Basin (lorns and others, 1965)]. Between 1930 and 1960, the population of the Yampa River basin ranged from about 13,000 to slightly more than 16,000 (Colorado Water Conservation Board and U.S. Department of Agriculture, 1969, table 7, p. ^6). The basin had been losing population from the 19^0's until recent years, primarily as a result of reduced coal mining in Routt County. Starting in the early 1970's, the declining population trend was reversed. Recreational development in the Steamboat Springs area and considerable coal mining and powerplant construction activities in Routt and Moffat Counties caused the basin population to increase to between 17,000 and 18,000 in 197^ and to more than 20,000 by the end of 1975 (adjusted data from U.S. Department of the Interior, 1976a; Colorado Water Conservation Board and U.S. Department of Agriculture, 1969; and Wyoming State Engineer's Office, 1970). Population distribution is highly variable over the basin. The major population centers are indicated on figure 1. The county seats of Steamboat Springs in Routt County and Craig in Moffat County serve as major urban centers. Using 1975 population estimates, about two-thirds of the basin inhabitants (a combined population of 13,870 out of 20,720) live in these two towns (U.S. Department of the Interior, 1976a, table RII-37, PI 1-121). Other towns in the Yampa River basin with 1975 population estimates are: Hayden (1,8^0), Oak Creek (1,290), Yampa (360), Milner (200), Baggs (200), and Dixon (70). A recently completed census in Routt County (The Steamboat Pilot, May 5, 1977) indicated that the population was less than that indicated for 1975-~^1 percent less for Oak Creek, and 5 percent less countywide. This discrepancy reflects to a large extent the seasonal nature of population in the basin and the dependence of recreational activity in the basin on favorable climate and national economic conditions. The remaining inhabitants live in other small communities or on ranches scattered throughout the basin.