Reservoir-development impacts on surface-water quantity and quality in the Yampa River basin, Colorado and Wyoming

Content Provider	Semantic Scholar
Author	Adams, Douglas B. Bauer, Daniel Dale, Robert H. I. Steele, Timothy Doak
Copyright Year	1983
Abstract	The Yampa River basin in northwestern Colorado and south-central Wyoming is an area in which development of the coal resources and associated economy is accelerating. This development includes increased use of the water resources of the area, which will have a direct impact on the quantity and quality of the water resources. Current (1979) regulation of the basin's surface water by reservoirs is minimal. As part of 18 surface-water projects, 35 major reservoirs have been proposed with a combined total storage of 2.18 million acre-feet (2,688 cubic hectometers), which is 41 percent greater than the mean annual outflow from the basin. Three computer models were used to demonstrate a method of evaluating future impacts of reservoir development in the Yampa River basin. Four different reservoir configurations were used in the analysis in order to simulate the effects of different degrees of proposed reservoir development. A multireservoir-flow model included both within-basin and transmountain diversions. Simulations indicated that in many instances the proposed diversion amounts would not be available for either type of diversion. For example, a proposed industrial diversion of 130 cubic feet per second (3-64 cubic meters per second) from the proposed Blacktail Reservoir would not be possible from 85 to 93 percent of the time. A corresponding frequency analysis of various reservoirstorage levels indicated that most reservoirs would be operating with small percentages of total capacities, and, in most instances, with less than 20 percent of conservation-pool volumes. Simulations using a dissolved-solids model indicated that extensive reservoir development could increase average annual concentrations at most locations. At Steamboat Springs, Colo., for example, most upstream water could be diverted, which could result in increased dissolved-solids concentrations during an average water year. Extensive reservoir development could reduce the larger May or June maximum mean monthly flows at Deerlodge Park, Colo., which is located downstream from the confluence of the Yampa and the Little Snake Rivers, from 460,000 to 250,000 acre-feet per month (56? to 308 cubic hectometers per month) and could increase the mean annual dissolved-solids concentrations by 60 percent. Simulations using a single-reservoir model indicated that no significant water-temperature stratification would occur in most reservoirs because of limited reservoir storage. The model simulation also indicated that there could be a reduced range in water temperatures in most of the proposed reservoirs, such as the proposed Juniper Reservoir, where the inflow water temperature could range from 0°C to 26°C, while the unregulated outflow water temperature could range from 4°C to 18°C. In addition, the model simulations indicated that the range of specificconductance values could be less in reservoir outflows than in reservoir inflows. INTRODUCTION The Yampa River basin in northwestern Colorado and south-central Wyoming (fig. 1) is being affected by accelerated rates of coal-resource and associated economic development, which will have a direct impact on the quantity and quality of the water resources of the basin. The projected water demands from this development will not only increase the water-supply requirements but redistribute the timing of demands from the traditional water-use patterns. Several potential impacts will result as a consequence of mining, processing, transport, and withinbasin conversion of coal and the associated residential and commercial growth (Steele and others, 1979; Weatherford and Jacoby, 1975; Udis and Hess, 1976). To meet these projected demands, considerable interest has been expressed and plans proposed for additional development of the surface waters of the Yampa River basin (fig. 1). Currently (1979), there is little regulation of streamflow by reservoirs in the basin. The main use of surface water during April, May, and June, when 60 to 70 percent of the annual stream runoff occurs, is for irrigation of hay meadows, grasslands, and grain fields. As part of 18 surface-water projects, 35 major reservoirs (larger than 2,000 acre-feet or 2.^7 hm 3 ) have been proposed. The overall effect of these proposed reservoirs on the Upper Colorado River Basin is not known and will not be addressed in this report. Different Federal and State agencies, however, including the U.S. Bureau of Reclamation (1976; 1980), have written planning documents for the Upper Colorado River Basin, for which these report results may serve as useful input. The total proposed reservoir capacity in the Yampa River basin is about 2.18 million acre-feet (2,690 hm 3 ), which is ^1 percent greater than the mean annual outflow from the basin. This contrasts to a current (1979) aggregate storage capacity of 5^,000 acre-feet (66.6 hm 3 ) or approximately 2.5 percent of the total proposed reservoir capacity. This report describes the results of an investigation in which three computer models were used to evaluate different levels of the proposed reservoir development. One model simulated streamflow conditions with alternative multireservoir configurations; a second model simulated the dissolved-solids concentrations at various locations in the basin; and a third model used streamflows and dissolvedsolids concentrations to simulate the water-quality conditions within certain proposed reservoirs. This study was designed to demonstrate the application of computer-modeling techniques in evaluating impacts of proposed reservoirs. Hence, the configurations of proposed reservoirs considered in the analysis were not exhaustive; rather, reservoirs were selected to depict a range of potential locations and storage capacities. This is one of several investigations evaluating the E X P L A N A T IO N ^ P fl P R O P O S E D R E S E R V O IR * * > T R A N S M O U N T A IN D IV E R -
File Format	PDF HTM / HTML
DOI	10.3133/wri8130
Alternate Webpage(s)	https://pubs.usgs.gov/wri/1981/0030/report.pdf
Alternate Webpage(s)	https://doi.org/10.3133/wri8130
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article