This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library. For additional information about this document and the document conversion process, please contact WRDS at [email protected] and include the phrase “Digital Documents” in your subject heading. To view other documents please visit the WRDS Library online at: http://library.wrds.uwyo.edu Mailing Address: Water Resources Data System University of Wyoming, Dept 3943 1000 E University Avenue Laramie, WY 82071 Physical Address: Wyoming Hall, Room 249 University of Wyoming Laramie, WY 82071 Phone: (307) 766-6651 Fax: (307) 766-3785 Funding for WRDS and the creation of this electronic document was provided by the Wyoming Water Development Commission (http://wwdc.state.wy.us) Levell Reoonnaissance Study KIRBY DAM AND RESERVOIR Wyoming Water Development Commission January, 1990 in association with Western Research Corporation Level I Reconnaissance Study KIRBY DAM AND RESERVOIR Prepared for the WYOMING WATER DEVELOPMENT COMMISSION Prepared by HDR Engineering, Inc. Omaha, Nebraska and Western Research Corporation Laramie, Wyoming January, 1990 TABLE OF CONTENTS Chapter 1 Introduction Purpose of report.......................................... 1 Summary of conclusions ..................................... 1 Authori zat ion. .. 3 Acknowl edgments. .. 3 Chapter 2 Description of site Site physical features ..................................... 4 Basin hydrology ............................................ 7 Bas in economy.............................................. 9 Site development goals and objectives ...................... lO Chapter 3 Technical analysis of alternatives Development alternatives ................................... 12 Flood routing studies ...................................... 13 Reservoir operations studies ............................... 16 Hydropower potential studies ............................... 18 Embankment alternatives .................................... 19 Relocation alternatives .................................... 20 Concl us ions ................................................ 24 Chapter 4 Economic analysis Project development costs .................................. 26 Hydropower development ..................................... 30 Project development benefits ............................... 32 Break-even analysis ........................................ 39 Innovative recreational development possibilities .......... 40 Conclusions ................................................ 43 Chapter 5 Potential environmental issues Federal concerns ........................................... 44 State concerns ............................................. 44 Local concerns ............................................. 47 Conclusions ................................................ 47 REFERENCES ................................................................ 49 i i LIST OF TABLES 2.1 Mean monthly flows passing Wind River gauge near Boysen Reservoi r, in cfs........................................ 8 2.2 Bighorn River demands upstream of proposed Kirby Dam ................ 7 2.3 River demands downstream of dam site ................................ 9 3.1 Gauging stations used for flood flow analysis ....................... 14 3.2 Calculated 100-year peak discharge and volumes at the Kirby Dam site .................................................. 14 3.3 Flood routing results, selected alternatives ........................ 16 3.4 Summary of reservoi r operat ions stud i es ............................. 17 3.5 Summary statistics, May through September flows below Lower Hanover Canal, in cfs ........................................... 18 3.6 Power and energy potential for two reservoir alternatives ........... 19 3.7 Assumed sections for roadway and railroad cut and fill .............. 24 4.1 Estimated project costs, alternative no. 1 .......................... 27 4.2 Estimated project costs, alternative no. 2 .......................... 28 4.3 Estimated project costs, alternative no. 3 .......................... 29 4.4 Hydropower economic analysis ........................................ 31 4.5 Net present values of hydropower costs and revenues assuming private financing, in $1000 ..................................... 32 4.6 Visitor activities and participation rates at Wyoming State Parks ... 35 4.7 Traditional recreational benefits, scenario #1 ...................... 36 4.8 Recreational activity for Big Horn Basin reservoirs ................. 39 4.9 Trad it i ona 1 recreat i ona 1 benefi ts, scenari 0 #2 ...................... 39 4.10 Benefit-cost comparison for Kirby Dam, in $1,000 .................... 40 4.11 Break-even requirements for retirement housing ...................... 42 5.1 Impact of instream flow on Kirby Reservoir .......................... 47 LIST OF FIGURES 2. 1 Locat i on map........................................................ 5 2.2 Reservoir stage-area-volume curves .................................. 6 3. 1 Proposed Kirby Reservo i r ............................................ 20 3.2 Embankment layout ................................................... 21 3.3 Relocation alignments ............................................... 22 4.1 Potential economic development ...................................... 34 iii Level I Reconnaissance Study KIRBY DAM AND RESERVOIR iv CHAPTER 1 INTRODUCTION Purpose of report The development of the Kirby Dam on the Bighorn River near Kirby, Wyoming, would create the opportunity for recreation, power production, economic development, and other related uses of the Bighorn River. This potential dam site was among those suggested for study in the Guidebook for Water Resources Management and Development (WWDC, 1988) as a means of more fully developing the resources of the river, including the future expansion of irrigated lands west of the river. The purpose of this study has been to conduct a preliminary assessment of the technical and economic issues facing site development. Principally, these issues include potential size of the reservoir and embankment, the costs associated with the relocation of U.S. Highway 20 and the Burlington Northern Railroad, both of which traverse the western edge of the proposed reservoir, and the potential direct and indirect benefits associated with development. To address these issues, preliminary calculations have been made to determine the height and size of the embankment and related dam features, the size of a potential run-of-the-river hydropower plant which would utilize reservoir releases for downstream irrigation, and a conceptual layout of the proposed development area. These calculations are described in this report. In addition, a preliminary assessment of the fisheries potential has been made by the Wyoming Game and Fish Department, together with an assessment of the potential impacts to terrestrial wildlife. Summary of conclusions A major purpose of the Level I Study is to determine if any fatal flaws exist which would preclude further study of the proposed project. It is the conclusion of this report that no such flaws exist, and that further, more detailed studies would be justified should the Commission be inclined to authorize such studies. The proposed development would entail the construction of an embankment dam across the Bighorn River upstream of the existing Hanover Diversion Dam near the Town of Winchester. The embankment would rise about 89 feet above the existing flood plain, and would be comprised of compacted earth and roller compacted concrete (RCC). The RCC section, which would be about 1,000 feet long, would serve as the spillway for passage of periodic flood flows. Controlled releases to meet downstream irrigation water rights would be made through a steel or pre-stressed concrete cylinder pipe having a diameter of approximately 10 feet. These releases would pass through a small hydroelectric power plant, which would generate an average of about 5,590 kilowatts of power and 39,371,000 kilowatt-hours of energy each year if the pool elevation is held constant at 4260 feet above sea level. Power and energy from this facility would be sold to local energy utilities. - 1 - The reservoir would be operated in a manner to maintain a constant pool elevation; fluctuations would be minimized in order to enhance the overall recreational use of the reservoir. For this report, it has been assumed that releases from the Boysen Dam would serve as the primary source of water for the reservoir, and that streamflows from smaller drainages beween Boysen and Kirby would provide adequate supplies to meet water demands within this reach. Development of the site would require a water right to replace losses caused by lake evaporation and seepage. Development of the site would include the relocation of about five miles of u.s. Highway 20 and about 7 miles of the Burlington Northern Railroad. These major transportation routes would be moved to the western side of the reservoir. Because of grade and alignment restrictions, the relocation of the railroad poses the greatest constraint to development; hence, its longer relocation length. However, from examination of the site and available topographic maps, it appears that both features could be located within the same general corridor. If the final reservoir pool elevation is greater than 4,250 feet above sea level, site development would also require relocation of the Town of Kirby. For this report, it has been assumed that the community would be moved to a new location