Development and Evaluation of Flushing Flow Recommendations for the Bighorn River Donald E. Wiley Thomas A. Wesche Wayne A, Hubert Phase I Report 1995 WWRC-95-02 Phase I Report Submitted to Wyoming Water Resources Center University of Wyoming Laramie, Wyoming and U.S.D.I. Bureau of Reclamation and The Wyoming Department of Game and Fish Donald E. Wiley and Thomas A. Wesche Wyoming Water Resources Center and Department of Range Management University of Wyoming Laramie, Wyoming Wayne A. Hubert Wyoming Cooperative Research Unit University of Wyoming Laramie, Wyoming 1995 Contents of this publication have been reviewed only for editorial and grammatical correctness, not for technical accuracy. The material presented herein resulted from research sponsored by the Wyoming Water Resources Center, U.S. Department of Interior Bureau of Reclamation, and Wyoming Department of Game and Fish, however views presented reflect neither a consensus of opinion nor the views and policies of the Wyoming Water Resources Center, U.S. Department of Interior Bureau of Reclamation, Wyoming Department of Game and Fish or the University of Wyoming. Explicit findings and implicit interpretations of this document are the sole responsibility of the author(s). The Big Horn River near Thermopolis, Wyoming is rated as a Class 1 fishery from Wedding of the Waters to Kirby Creek. The Wyoming Game and Fish Department and the Bureau of Reclamation are concerned about the flow regime in this stretch of river as controlled by the operation of Boysen Reservoir. The goal of this study was to assess the need for flushing flows to enhance the natural recruitment of rainbow trout and brown trout in the Bighorn River. I have assessed the effects of a March 1994 flushing flow on substrate and spawning habitat in the Bighorn River. Data from this test flushing flow provided insight about the magnitude, duration, and timing of flushing flow regimes needed to scour pools, clean spawning gravel, maintain side channels, and remove fine sediment from the reach of the Bighorn River managed as a "blue ribbon" trout fishery. ACKNOWLEDGEMENTS The authors wish to thank the Wyoming Game and Fish Department and the U.S. Bureau of Reclamation personnel for providing equipment and assistance with field work. A special thanks to Mike Welker and Tim Fuchs for days spent in the field and locating study sites. For assistance in the field, thanks to Chris Goertler, Andy Wiley, Travis Bray, Colin Jacobsen and Kale Gullett. For computer and technical support, thanks to Dr. Bob Henszey, Andy Wiley and Kale Gullett. The authors would like to extend their appreciation to Dennis Jones for his outstanding help during this project. Funding for this report was provided by the Wyoming Water Resources Center, the Wyoming Game and Fish Department and the U.S.D.I. Bureau of Reclamation. TABLE OF CONTENTS Page ACKNOWLEDGMENTS ......................................... ii LISTOFFIGURES ............................................. v LISTOFTABLES ............................................. viii CHAPTER I -INTRODUCTION .................................. 1 CHAPTER 11 .DESCRIFITONOFSTUDYAREA ...................... 8 CHAPTERIII .METHODS ...................................... 13 SurfaceHydrology ........................................ 15 SedimentTransport ....................................... 15 BedMaterial Dynamics .................................... 17 TributaryStudy .......................................... 18 ReddAnalysis ...........................................19 SpawningFlows ......................................... 22 LabAnalysis ............................................ 23 Statistical Analysis ........................................ 23 CHAPTER IV-RESULTS ...................................... 24 Surface Hydrology ........................................ 24 Sediment Transport ....................................... 29 Suspended Sediment ................................. 29 Bedload .......................................... 37 BedMaterial Dynamics .................................... 42 iii Substrate Samples ................................... 42 Cross-section channel profiles ........................... 46 Pool Analysis ...................................... 52 TributaryStudy .......................................... 59 ReddAnalysis ........................................... 59 SpawningFlows ......................................... 71 CHAPTER V .DISCUSSION ................................... 73 Spawning Habitat ........................................ 73 Sediment Dynamics ....................................... 76 Suspended Sediment ................................. 76 Bedload .......................................... 77 Streambed ........................................ 78 FlushingFIows .......................................... 78 Comparison to Large Tailwaters in Wyoming ..................... 81 Management Recommendations ............................... 84 LITERATURECITED .......................................... 87 ~P~IXA................................................ 93 iv LIST OF FIGURES Page Figure 1. Map of the Bighorn River, Wyoming . 9 Figure 2. Channel profile of the Bighorn River from approximately three miles upstream of Wedding of the Waters to Kirby Creek . 11 Figure 3. Map of the Bighorn River study area, Wedding of the Waters to Kirby Creek ............................................. 14 Figure 4. Location of redd measurements . 20 Figure 5. Mean monthly hydrographs for pre (water years 1912-1952, USGS M259500) and post (water years 1953-1993, USGS #0625900) Boysen Dam, Bighorn River, Wyoming. 25 Figure 6. Normalized (QJQJ flow duration curves using mean daily data for pre and post Boysen Dam, Bighorn River, Wyoming. 26 Figure 7. Mean daily peak flow frequency analysis for pre-Boysen and post-Boysen Dam construction on the Bighorn River, Wyoming. 27 Figure 8. Seven day low flow frequency analysis for pre-Boysen and post-Boysen Dam construction on the Bighorn River, Wyoming. 28 Figure 9. Hourly hydrograph and cumulative acre feet data for the Bighorn River below Boysen Dam during March 1994 test release . 30 Figure 10. Average suspended sediment concentrations (mgll) for the four study sites on the Bighorn River, Wyoming. 31 Figure 11. Mean hourly hydrograph and suspended sediment concentrations (mgll) for Wedding of the Waters, Bighorn River, Wyoming, March 28 - 30, 1994. ............................................. 33 Figure 12. Mean hourly hydrograph and suspended sediment concentrations (ma) for the Red Bluffs Main Channel, Bighorn River, Wyoming, March 28 - 30,1994 ........................................... 34 Figure 13. Mean hourly hydrograph and suspended sediment concentrations (mg.4) for the City Main Channel, Bighorn River, Wyoming, March 28 - 30, 1994 .............................................. 35 V Figure 14. Mean hourly hydrograph and suspended sediment concentrations (ma) for the Mills Main Channel, Bighorn River, Wyoming, March 28 - 30, 1994 .............................................. 36 Figure 15. Sediment mass curves for bedload and suspended sediment transport for the City secondary channel during March 1994 test flow release on the BighornRiver, Wyoming. ............................... 38 Figure 16. Hydrograph and suspended sediment concentrations (mg/l) for the City Secondary Channel, Bighorn River, Wyoming, March 27 - 31, 1994 (n=15) ........................................... 39 Figures 17a. and b. Sediment mass curves for the four study sites during March 1994 test flow release on the Bighorn River, Wyoming .............. 40 Figure 18. Hydrograph and bedload transport (tondday) for City Secondary Channel of the Bighorn River, Wyoming, March 27 .31, 1994 (n = 13) ..... 41 Figure 19. Particle size distributions for bedload samples collected at the City Secondary Channel during March 1994 test release, Bighorn River, Wyoming. ..................................... 43 Figure 20. Particle size distributions for pre and post-release McNeil core samples collected at the Red Bluff, City, and Mills sites, Bighorn River, Wyoming .......................................... 45 Figure 21. Particle size distributions for pre and post-release freeze core samples collected at the Red Bluff, City, and Mill sites, Bighorn River, Wyoming. .......................................... 48 Figure 22. Pre and post-test release (Mmh 1994) channel profiles of the Wind River and Red Bluff main channel, Bighorn River, Wyoming. .......... 50 Figure 23. Pre and post-test release (March 1994) channel profiles of the City and Mills main channel, Bighorn River, Wyoming. ................ 51 Figure 24. Pre and post-test release (March 1994) channel profiles of the Red Bluffs secondary channel, Bighorn River, Wyoming. ................. 53 Figure 25. Pre and post-test release (March 1994) channel profiles of the City secondary channel, Bighorn River, Wyoming. ................. 54 vi Figure 26. Pre and post-test release (March 1994) channel profiles of the Mills secondary channel, Bighorn River, Wyoming. ................. 55 Figure 27. Bed elevation changes in large pl,below confluence of Buffalo Creek, as a result of the March 1994 test release, Bighorn River, Wyoming .......................................... 57 Figure 28. Seasonal bed elevation changes in large plbelow confluence of Buffalo Creek, Bighorn River, Wyoming .......................... 58 Figure 29. Particle size distributions for rainbow trout and brown trout redds at the Red Bluffs, Lunch Island, and City