Evaluation of Flushing Flows in the Fraser River and Its Tributaries

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EVALUATION OF FLUSHING FLOWS IN THE FRASER RIVER AND ITS TRIBUTARIES

Prepared for

Trout Unlimited

Prepared by

Brian P. Bledsoe, Ph.D., P.E. Professor

Johannes C. Beeby, M.S. Research Associate

Kyle W. Hardie, M.S., E.I.T Research Assistant

September 19, 2013

Colorado State University Department of Civil and Environmental Engineering Daryl B. Simons Building at the Engineering Research Center Fort Collins, Colorado 80523

EVALUATION OF FLUSHING FLOWS IN THE FRASER RIVER AND ITS TRIBUTARIES

Prepared for

Trout Unlimited

Prepared by

Brian P. Bledsoe, Ph.D., P.E. Professor

Johannes C. Beeby, M.S. Research Associate

Kyle W. Hardie, M.S., E.I.T Research Assistant

September 1, 2013

Colorado State University Department of Civil and Environmental Engineering Daryl B. Simons Building at the Engineering Research Center Fort Collins, Colorado 80523

EXECUTIVE SUMMARY

The Fraser River has a storied history as a trout fishery, and trout have been identified as a key indicator of its ecological health. Sustaining trout and their food base in the Fraser River requires the long-term maintenance of physical habitat quality and ecosystem characteristics on which they depend. In addition to adequate streamflows, spawning fish and aquatic invertebrates depend on open interstices in the river bed. Field reconnaissance performed in the Fraser River watershed over the last decade has indicated that fine sediment storage is occurring in several locations in the main stem and tributaries. Evidence of sediment storage includes bars, other deposits of sand and very fine gravel, and embedded substrates that lack interstitial space.

Streamflow depletions in the Fraser River watershed have increased the risk of habitat degradation associated with sediment deposition and clogging of the river bed. The proposed Moffat Collection System Project could alter the capacity of the Fraser River and its tributaries to flush fine sediment and maintain physical habitat for fishes and aquatic insects. By further reducing streamflows, the proposed project would decrease the number of days on average that flows exceed the thresholds necessary to clean and rejuvenate the river bed. If there are longer multi-year periods between flushing events, more sediment could accumulate at time scales relevant to the reproductive cycles of trout and aquatic insects. Recent research conducted in comparable river segments in the upper Colorado River has documented habitat degradation and negative impacts to aquatic life in the absence of high flows that clean the river bed.

The key to evaluating whether sediment accumulation is likely to be exacerbated by a proposed reduction in streamflow is to examine and quantify potential changes in the “flushing flows” that primarily influence cleaning and rejuvenation of the river bed. These flows may also be termed substrate maintenance flows. Flushing flows can achieve multiple objectives that include removing surface veneers of fine sediment, scouring algae, and opening-up interstitial space in the river bed that would otherwise remain continuously embedded with fine sediment.

In developing management recommendations for flushing flows, it is advisable to avoid “single factor ecology” approaches that focus exclusively on one element of the streamflow regime for one type of organism. Given that trout are a highly-valued amenity and primary indicator of ecological health in the Fraser River, maintenance of their food base is also an important consideration. Trout depend on aquatic insects at all life stages from rearing to death, and production of aquatic insects depends on the quantity and quality of habitat available in the river substrate. Therefore, flushing flows are important for riffle habitats used by aquatic insects in addition to trout spawning and rearing habitats.

The potential effects of additional high-flow alterations on aquatic habitat in the Fraser River cannot be thoroughly assessed until the flows that mobilize and clean coarse substrates are more explicitly quantified and understood. The overall goal of this study was to evaluate and quantify

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flushing flows that maintain sediment sizes on the bed and their mobility in the Fraser River and its major tributaries. Improved quantification of flushing flows can inform decision-making focused on the potential long-term environmental impacts of further flow extraction. The specific objectives of the study were to:

 Characterize spatial variability in channel morphology and grain-size distributions in the bed of the Fraser River, Ranch Creek, and other significant tributaries.  Perform a sediment entrainment (shear-stress based) analysis at each bed material sampling and survey location to assess the likelihood of two types of flushing flows: 1) flows required to remove surface deposits of fines, and 2) flows required to mobilize appreciable amounts of coarse gravel and cobble at the surface of the river bed to remove surface veneers of fine sediment and perform the additional function of opening-up interstitial space deeper in the bed that would otherwise remain continuously embedded with fine sediment.  Estimate critical discharges for flushing flows with explicit consideration of uncertainty and describe resulting estimates of critical discharges for substrate maintenance as probability distributions to inform decision-making.  Combine the sediment entrainment analysis with existing hydrologic data to estimate the magnitude, frequency, and duration of dimensionless shear stress values for the baseline condition vs. the tentatively-selected plan for the Moffat Collection System Project at each survey location.  Identify flushing flows that are likely to perform substrate maintenance across the range of variable conditions observed in the field, based on the best available information from this and other studies.

We established sixteen study sites and used a weight-of-evidence approach to estimate critical discharges for flushing flows of varying effectiveness. Shear stress analyses based on highly-detailed characterizations of the channel substrate (including riffle habitats) were performed at each site. Key evidence used to estimate flushing flows included:

 pre- vs. post-2013 runoff evidence of flushing based on field substrate characterization;  tracer rocks;  post-2013 runoff evidence of sediment flushing, based on highly-detailed field characterizations of the river bed at each site;  magnitudes and durations of 2013 peak flows as measured by the U. S. Geological Survey (USGS) (where available);  sediment entrainment computations including relative confidence as quantified by uncertainty analysis;  sediment entrainment information available in the Grand County Stream Management Plan (GCSMP); and  convergence of evidence between this study and the GCSMP.

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Overall, the results of the sediment entrainment analyses revealed variation along the river system in the magnitude of flushing flows required for coarse substrate mobilization. Despite this variability, there is considerable convergence between the estimates generated in this study and the GCSMP. Flushing flows identified in this study are, in some instances, higher than the GCSMP recommendations because sediment entrainment analyses and field observations indicate that some of the GCSMP values have a low probability of providing substantial surface flushing and/or coarse substrate mobilization. Based on multiple lines of evidence for each segment, the flushing flows summarized in Table ES.1 are, in our judgment, the most probable estimates of minimum streamflow required for coarse substrate mobilization and flushing surface veneers of fine sediment.

Minimum Estimated Minimum Estimated GCSMP Flushing Flow for Coarse Flow for Flushing Surface Recommended Site Substrate Mobilization Veneer s of Fine Sediment Flushing Flow (cfs) (cfs) (cfs) Fraser above Diversion 45-100 – – Fraser below Diversion to 100 – 80 Vasquez Creek Fraser between Vasquez Creek 200 200 – and St. Louis Creek Fraser River between St. Louis – 280 200 Creek and Ranch Creek Fraser River between Ranch 370 280 – Creek and Crooked Creek Fraser River between Crooked 470-640 400 400 Creek and Granby Upper Ranch Creek 55 – 40 Lower Ranch Creek 150 – 150 Vasquez Creek 70 – 50 St. Louis Creek 100 – 70

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Flushing flows for surface removal of fine sediments are recommended for every year. The recommended minimum frequency for coarse substrate mobilization flows is every other year (2- year return period over long-term average). A tentative duration of 3 days is recommended for both types of flows. In practice, an event that mobilizes the coarse substrate on a strict interval of every other year is not likely to be feasible under the current management infrastructure given inter-annual variability and the inevitability of multi-year dry spells. Accordingly, an average return period of 2 years is a reasonable target over time. Assessing the feasibility of achieving these frequency and duration characteristics under the Alt 1a scenario is beyond the scope of this study.

Flow frequency analyses comparing the Current Use vs. Alt 1a flow scenarios (1946-1991) indicate that the proposed Alt 1a scenario substantially decreases the frequency that median flushing flow values are met. The number of continuous spells greater than 1 year of non- flushing and the average length of non-flushing spells substantially increase under the proposed Alt 1a flow regime. Final estimated flushing flow values also occur less frequently (35 to 66% reduction) under the proposed Alt 1a flow regime. The number of continuous spells greater than 1 year of non-flushing and the average length of that non-flushing spell also substantially increase under the proposed Alt 1a flow regime in several river segments (Table ES.2). Alterations of flushing flows are most pronounced in the Fraser River main stem between the Denver Water diversion and the confluence with Ranch Creek, and in Vasquez Creek.

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Table ES.2. Frequency that estimated flushing flow values were exceeded for 3 days (consecutive or non-consecutive) within a year under Current Use and Alt 1a flow scenarios (1946-1991).

Current Alt 1a % Difference % Difference Average Maximum No. of Average Maximum No. of Average Maximum Length Length Intervals Length Length Intervals Length Length % Difference Estimated Consecutive Consecutive >1 Year Consecutive Consecutive >1 Year Consecutive Consecutive No. of Intervals Flushing Years Non- Years Non- Non- Years Non- Years Non- Non- Years Non- Years Non- >1 Year Non- Site Flow Flushing Flushing Flushing Flushing Flushing Flushing Flushing Flushing Flushing (cfs) Fraser Winter 100 2.30 5 6 4.00 8 6 74% 60% 0% Park Gage

Fraser Angling 280 1.80 4 5 2.78 6 5 54% 50% 0%

Fraser below 370 1.56 3 4 1.67 3 6 7% 0% 50% Ranch

Ranch Angling 150 1.63 3 4 1.89 3 6 16% 0% 50%

Ranch above 150 1.63 3 4 1.89 3 6 16% 0% 50% Meadow Ranch below 150 1.63 3 4 1.89 3 6 16% 0% 50% Meadow

Vasquez 70 1.70 3 5 2.30 6 5 35% 100% 0%

St. Louis 100 1.63 3 4 1.90 3 6 17% 0% 50%

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We estimate with confidence that implementing the flushing flows identified in this study for mobilizing coarse substrates would reduce the extent of fine sediment deposition and accumulated algae, as well as decrease the likelihood that physical habitat will continue to degrade to a level that produces additional, detectable biological impacts. In the absence of flushing flows, existing physical habitat will be negatively affected in the future as the river channel and its substrate characteristics (e.g., extent of interstices clogged with fine sediment, amount of algae) evolve with ongoing changes in water management. This response is likely to occur irrespective of base flows for fish habitat because such low flows are incapable of rejuvenating the river bed to maintain habitats required for trout reproduction and aquatic insects.

These analyses and previous studies collectively indicate that the frequency and effectiveness of flows that flush fine sediment and rejuvenate river-bed habitats required by trout and their food base are substantially reduced in the Moffat Collection System Project Alt 1a flow scenario compared to the Current Conditions scenario. Thus, the weight-of-evidence from field observations, previous analyses of effective discharges, and sediment entrainment analyses indicates that fine sediment aggradation and concomitant effects on aquatic habitat would be exacerbated under the current sediment supply by additional depletions of the flushing flows identified in this study for maintaining sediment sizes on the bed and their mobility. Further reductions in the frequency and duration of flushing flows would reduce the availability of clean substrates for trout spawning and production of aquatic insects.

The uncertainty inherent to environmental impact assessment and environmental flow management underscores the need for carefully-designed monitoring and adaptive management programs. When faced with competing estimates of grain size and the shear stresses that provide coarse substrate mobilization, we generally chose flow magnitudes in the lower end of the range as minimum estimates of flushing flows. Experimental bypass flows can be useful in evaluating the accuracy of estimated flushing flow effects and improving management over time. A number of field methods that were not feasible in this study are available for directly measuring scour depths and interstitial removal of fine sediments from gravel/cobble river beds. Direct measurement of scour processes over multiple runoff years as part of a “learning by doing” approach would provide more accurate calibration of flushing flows to inform decision-making.

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ACKNOWLEDGEMENTS

Kristin Bunte (Colorado State University) provided detailed guidance on the substrate sampling methodology. Dr. Bunte also shared field data and relations for predicting critical shear stresses in Colorado and Wyoming streams. Robert Milhous (Retired U. S. Geological Survey) and Peter Wilcock (Johns Hopkins University) provided insights and expert judgment on relationships between the extent of substrate maintenance and dimensionless shear stress. We are grateful to Colorado State University ecologists Kevin Bestgen, Kurt Fausch, Boris Kondratieff, and LeRoy Poff for providing helpful insights on the biological implications of flushing flow frequencies. Gloria Garza provided competent assistance with report preparation.

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TABLE OF CONTENTS

EXECUTIVE SUMMARY ...... i ACKNOWLEDGEMENTS ...... vii LIST OF TABLES ...... xi LIST OF FIGURES ...... xiii LIST OF SYMBOLS, UNITS OF MEASURE, AND ABBREVIATIONS ...... xviii CHAPTER 1 INTRODUCTION ...... 1 CHAPTER 2 GOALS AND OBJECTIVES ...... 3 CHAPTER 3 BACKGROUND ...... 4 CHAPTER 4 METHODS...... 8 4.1 Field Data Collection ...... 8 4.1.1 Grain-size Distributions ...... 17 4.1.2 Pre- vs. Post-runoff Substrate Analysis ...... 18 4.2 Hydraulic Characterization ...... 20 4.2.1 Sediment Entrainment Analysis ...... 23 4.3 Critical Discharge ...... 25 4.4 Monte Carlo Critical Discharge Simulation ...... 26 4.4.1 Frequency Analysis of Flushing Flows ...... 31 4.4.2 Characteristics of 2013 Runoff Hydrographs ...... 32 CHAPTER 5 RESULTS ...... 33 5.1 Cross-section and Longitudinal Characteristics ...... 33 5.1.1 Fraser Highway 40 Site ...... 35 5.1.2 Fraser Robbers Site ...... 36 5.1.3 Fraser above Diversion Site ...... 37 5.1.4 Fraser below Diversion Site ...... 38 5.1.5 Fraser Winter Park Gage Site ...... 39 5.1.6 Fraser below Vasquez Creek Site ...... 40 5.1.7 Fraser Rendezvous Site ...... 42 5.1.8 Fraser Open Space Site ...... 43 5.1.9 Fraser Angling Site ...... 44

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5.1.10 Fraser below Ranch Site ...... 45 5.1.11 Ranch at Gage Site ...... 46 5.1.12 Ranch Angling Site ...... 47 5.1.13 Ranch above Meadow Site ...... 49 5.1.14 Ranch below Meadow site ...... 50 5.1.15 Vasquez Site ...... 51 5.1.16 St. Louis Site ...... 52 5.2 Percent Fines Data ...... 52 5.2.1 Tracer Rocks ...... 55 5.2.2 Flushing Flow Estimates ...... 60 5.2.3 Grand County Flushing Flows...... 65 5.2.4 Flushing Flow Frequency ...... 67 CHAPTER 6 DISCUSSION...... 76 6.1 Flushing Flow Key Evidence for Ten Primary River Segments ...... 77 6.1.1 Fraser River above Diversion ...... 77 6.1.2 Fraser River below Diversion to Vasquez Creek ...... 77 6.1.3 Fraser River between Vasquez Creek and St. Louis Creek ...... 77 6.1.4 Fraser River from St. Louis Creek to Ranch Creek ...... 78 6.1.5 Fraser River from Ranch Creek to Crooked Creek ...... 79 6.1.6 Fraser River below Crooked Creek to Granby ...... 79 6.1.7 Upper Ranch Creek ...... 79 6.1.8 Lower Ranch Creek ...... 80 6.1.9 Vasquez Creek ...... 80 6.1.10 St. Louis Creek ...... 80 6.2 Synthesis across Sites ...... 81 6.3 Frequency and Duration of Flushing Flows ...... 82 6.4 Key Uncertainties ...... 84 6.5 Management Implications ...... 85 6.6 Enhancing Predictive Ability in the Future ...... 86 CHAPTER 7 CONCLUSIONS ...... 87 LITERATURE CITED ...... 89

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APPENDIX A CROSS SECTIONS OF STUDY SITES ...... 94 APPENDIX B HYDRAULIC DATA USED TO CALCULATE AT-A-STATION HYDRAULIC GEOMETRY ...... 103 APPENDIX C GRAIN-SIZE DISTRIBUTION – NO TRUNCATION ...... 115 APPENDIX D GRAIN-SIZE DISTRIBUTIONS – TRUNCATED AT 2 MILLIMETERS ...... 137 APPENDIX E GRAIN-SIZE DISTRIBUTIONS – TRUNCATED AT 8 MILLIMETERS ...... 159 APPENDIX F PROBABILITY DISTRIBUTIONS OF FLUSHING FLOW ESTIMATES ...... 181

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LIST OF TABLES

Table ES.1. Estimates of minimum flows required for coarse substrate mobilization and flushing surface veneers of fine sediment. Minimum flows for superficial flushing of the river bed are only provided for Fraser River main stem sites with bed slope <1% to reflect higher uncertainty in steeper river segments. Flushing flow magnitudes are compared to values recommended in the GCSMP...... iii Table ES.2. Frequency that estimated flushing flow values were exceeded for 3 days (consecutive or non-consecutive) within a year under Current Use and Alt 1a flow scenarios (1946-1991)...... v Table 3.1. Interpretation of dimensionless shear stress values in terms of states of fine sediment flushing and coarse substrate mobilization at sites with slopes less than approximately 1%...... 6 Table 4.1. Dates for pre- and post-runoff field work...... 19

Table 4.2. Limerinos data set, R/d84 values for total number of measurements (N)...... 22 Table 5.1. Cross-sectional and longitudinal characteristics of each site...... 34 Table 5.2. Surface fines pre- and post-runoff at the study sites. Pebble counts and % fines counts each exceeded 300 observations per site visit...... 53 Table 5.3. Peak Snow Water Equivalent (SWE) and peak streamflow data from 2013...... 55 Table 5.4. Tracer rock results for the Fraser below Vasquez and Ranch above Meadow sites...... 59 Table 5.5. Estimates of coarse substrate mobilization flows for the Fraser River and tributaries. Emphasis was placed on the median with the interquartile/median value indicating relative uncertainty...... 61 Table 5.6. Results from the sediment entrainment analysis of flushing flows recommended in the GCSMP using hydraulic and substrate data reported in the GCSMP...... 66 Table 5.7. Flow frequency analysis of Current Use vs. Alt 1a flow scenarios (1946- 1991)...... 68 Table 5.8. Frequency that various flushing flow values are exceeded for 3 days within a year under Current Use vs. Alt 1a flow scenarios (1946-1991)...... 70 Table 5.9. Frequency that estimated flushing flow values were exceeded under Current Use and Alt 1a flow scenarios (1946-1991)...... 74 Table 5.10. Frequency that estimated flushing flow values were exceeded for 3 days within a year under Current Use and Alt 1a flow scenarios (1946-1991)...... 75 Table 6.1. GCSMP stream reach summaries (after GCSMP (2010))...... 76 Table 6.2. Estimates of minimum average daily flows required for coarse substrate mobilization and flushing surface veneers of fine sediment. Minimum average daily flows for superficial flushing of the river bed are only provided

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for Fraser River main stem sites with bed slope <1%. Surface flushing flows are recommended for every year. The recommended minimum frequency for coarse substrate mobilization flows is every other year (2-year return period over long-term average). Flushing flow magnitudes are compared to values recommended in the GCSMP...... 82 Table B.1. Hydraulic data for the Fraser Highway 40 site...... 104 Table B.2. Hydraulic data for the Fraser Robbers site...... 106 Table B.3. Hydraulic data for the Fraser above Diversion site...... 106 Table B.4. Hydraulic data for the Fraser below Diversion site...... 107 Table B.5. Hydraulic data for the Fraser Winter Park Gage site...... 108 Table B.6. Hydraulic data for the Fraser below Vasquez site...... 109 Table B.7. Hydraulic data for the Fraser Rendezvous site...... 109 Table B.8. Hydraulic data for the Fraser Open Space site...... 110 Table B.9. Hydraulic data for the Fraser Angling site...... 110 Table B.10. Hydraulic data for the Frazer below Ranch site...... 111 Table B.11. Hydraulic data for the Ranch at Gage site...... 112 Table B.12. Hydraulic data for the Ranch Angling site...... 112 Table B.13. Hydraulic data for the Ranch above Meadow site...... 113 Table B.14. Hydraulic data for the Ranch below Meadow site...... 113 Table B.15. Hydraulic data for the Vasquez site...... 114 Table B.16. Hydraulic data for the St. Louis site...... 114 Table F.1. Sample output table from a Monte Carlo critical discharge simulation (first 24 rows of 10,000 rows)...... 182

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LIST OF FIGURES

Figure 4.1. Site locations within the Fraser River watershed (base map was downloaded from the U. S. Geological Survey (USGS) – http://pubs.usgs.gov/wri/wri98- 4255/pdf/wrir98-4255.pdf)...... 9 Figure 4.2. Fraser Highway 40 site location...... 10 Figure 4.3. Fraser Robbers site location...... 10 Figure 4.4. Fraser above Diversion and Fraser below Diversion site locations...... 11 Figure 4.5. Fraser Winter Park Gage site location...... 11 Figure 4.6. Fraser below Vasquez site location...... 12 Figure 4.7. Fraser Rendezvous site location...... 12 Figure 4.8. Fraser Open Space site location...... 13 Figure 4.9. Fraser Angling site location...... 13 Figure 4.10. Fraser below Ranch site location...... 14 Figure 4.11. Ranch at Gage site location...... 14 Figure 4.12. Ranch Angling site location...... 15 Figure 4.13. Ranch below Meadow and Ranch above Meadow site locations...... 15 Figure 4.14. Vasquez site location...... 16 Figure 4.15. St. Louis site location...... 16 Figure 4.16. Pebble count surveys were conducted using a grid sampler in combination with a gravelometer...... 17

Figure 4.17. Percent error (at 95% confidence) surrounding the d50 percentile, based on the number of size classes and number of particles in the pebble count...... 18 Figure 4.18. Percent fines and coarse material were sampled using a grid and bucket viewer...... 19 Figure 4.19. Placing tracer rocks at the Ranch Creek above Meadow site...... 20

Figure 4.20. Depiction of probabilistic estimation of Qc using varying distributions of input variables slope, grain size, Manning n, and critical dimensionless shear stress...... 28 Figure 4.21. Sample critical discharge distribution resulting from a Monte Carlo critical discharge simulation...... 30 Figure 5.1. Looking upstream at the Fraser Highway 40 site...... 35 Figure 5.2. Looking upstream at the Fraser Robbers site...... 36 Figure 5.3. Looking upstream at the Fraser above Diversion site...... 37 Figure 5.4. Looking downstream at the Fraser below Diversion site...... 38 Figure 5.5. Looking downstream at the Fraser Winter Park Gage site...... 39 Figure 5.6. Looking downstream at the Fraser below Vasquez site...... 40 Figure 5.7. Directly downstream of the confluence of the Fraser River and Vasquez Creek, large amounts of sand and fine gravel (lighter color in the middle of the photograph) can be seen surrounding larger material (pre-runoff)...... 41

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Figure 5.8. Directly downstream of the confluence of the Fraser River and Vasquez Creek, the amount of sand and fine gravel has decreased post-runoff but is still found in appreciable amounts...... 41 Figure 5.9. Looking downstream at the Fraser Rendezvous site...... 42 Figure 5.10. Looking upstream at the Fraser Open Space site...... 43 Figure 5.11. Looking upstream at the Fraser Angling site...... 44 Figure 5.12. Looking upstream at the Fraser below Ranch site...... 45 Figure 5.13. Looking downstream at the Ranch at Gage site...... 46 Figure 5.14. Looking downstream at the Ranch Angling site...... 47 Figure 5.15. Algae present in pool tail-outs seemed to capture fine sediment...... 48 Figure 5.16. Looking upstream at the Ranch above Meadow site...... 49 Figure 5.17. Looking upstream at the Ranch below Meadow site...... 50 Figure 5.18. Looking downstream at the Vasquez site...... 51 Figure 5.19. Looking upstream at the St. Louis site...... 52 Figure 5.20. Deposits of sand and very fine gravel behind larger bed material...... 54 Figure 5.21. Cobbles / gravel substrates embedded with fine sediment...... 54 Figure 5.22. Hydrograph from June 1-30 for the Fraser River at Upper Station near Winter Park gage (USGS 09022000)...... 56 Figure 5.23. Hydrograph from June 1-30 for the Fraser River at Winter Park gage (USGS 09024000)...... 56 Figure 5.24. Hydrograph from June 1-30 for the Fraser River at Tabernash, Colorado, gage (USGS 09027100)...... 57 Figure 5.25. Hydrograph from June 1-30 for the Fraser River below Crooked Creek at Tabernash, Colorado, gage (USGS 09033300)...... 57 Figure 5.26. Hydrograph from June 1-30 for the Ranch Creek near Fraser gage (USGS 09032000)...... 58 Figure 5.27. Hydrograph from June 1-30 for the Vasquez Creek at Winter Park gage (USGS 09025000)...... 58 Figure 5.28. Hydrograph from June 1-30 for the St. Louis Creek near Fraser gage (USGS 09026500)...... 59 Figure 5.29. Tracer rocks at the Ranch above Meadow site...... 60 Figure A.1. Fraser Highway 40 cross section, plotted facing upstream...... 95 Figure A.2. Fraser Robbers cross section, plotted facing upstream...... 95 Figure A.3. Fraser above Diversion cross section, plotted facing upstream...... 96 Figure A.4. Fraser below Diversion cross section, plotted facing upstream...... 96 Figure A.5. Fraser Winter Park Gage cross section, plotted facing upstream...... 97 Figure A.6. Fraser below Vasquez cross section, plotted facing upstream...... 97 Figure A.7. Fraser Rendezvous cross section, plotted facing upstream...... 98 Figure A.8. Fraser Open Space cross section, plotted facing upstream...... 98 Figure A.9. Fraser Angling cross section, plotted facing upstream...... 99

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Figure A.10. Fraser below Ranch cross section, plotted facing upstream...... 99 Figure A.11. Ranch at Gage cross section, plotted facing upstream...... 100 Figure A.12. Ranch Angling cross section, plotted facing upstream...... 100 Figure A.13. Ranch above Meadow cross section, plotted facing upstream...... 101 Figure A.14. Ranch below Meadow cross section, plotted facing upstream...... 101 Figure A.15. Vasquez cross section, plotted facing upstream...... 102 Figure A.16. St. Louis Gage cross section, plotted facing upstream...... 102 Figure C.1. Grain-size distributions not truncated for the Fraser Highway 40 site...... 116 Figure C.2. Grain-size distributions not truncated for the Fraser Robbers site...... 117 Figure C.3. Grain-size distributions not truncated for the Fraser above Diversion site...... 118 Figure C.4. Grain-size distributions not truncated for the Fraser below Diversion site...... 119 Figure C.5a. Pre-runoff grain-size distributions not truncated for the Fraser Winter Park Gage site...... 120 Figure C.5b. Post-runoff grain-size distributions not truncated for the Fraser Winter Park Gage site...... 121 Figure C.6a. Pre-runoff grain-size distributions not truncated for the Fraser below Vasquez site...... 122 Figure C.6b. Post-runoff grain-size distributions not truncated for the Fraser below Vasquez site...... 123 Figure C.7. Grain-size distributions not truncated for the Fraser Rendezvous site...... 124 Figure C.8. Grain-size distributions not truncated for the Fraser Open Space site...... 125 Figure C.9. Grain-size distributions not truncated for the Fraser Angling site...... 126 Figure C.10. Grain-size distributions not truncated for the Fraser below Ranch site...... 127 Figure C.11. Grain-size distributions not truncated for Ranch at Gage site...... 128 Figure C.12. Grain-size distributions not truncated for the Ranch Angling site...... 129 Figure C.13a. Pre-runoff grain-size distributions not truncated for the Ranch above Meadow site...... 130 Figure C.13b. Post-runoff grain-size distributions not truncated for the Ranch above Meadow site...... 131 Figure C.14. Grain-size distributions not truncated for the Ranch below Meadow site...... 132 Figure C.15a. Pre-runoff grain-size distributions not truncated for the Vasquez site...... 133 Figure C.15b. Post-runoff grain-size distributions not truncated for the Vasquez site...... 134 Figure C.16a. Pre-runoff grain-size distributions not truncated for the St. Louis site...... 135 Figure C.16b. Post-runoff grain-size distributions not truncated for the St. Louis site...... 136 Figure D.1. Grain-size distributions truncated at 2 mm for the Fraser Highway 40 site...... 138 Figure D.2. Grain-size distributions truncated at 2 mm for the Fraser Robbers site...... 139 Figure D.3. Grain-size distributions truncated at 2 mm for the Fraser above Diversion site...... 140 Figure D.4. Grain-size distributions truncated at 2 mm for the Fraser below Diversion site...... 141

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Figure D.5a. Pre-runoff grain-size distributions truncated at 2 mm for the Fraser Winter Park Gage site...... 142 Figure D.5b. Post-runoff grain-size distributions truncated at 2 mm for the Fraser Winter Park Gage site...... 143 Figure D.6a. Pre-runoff grain-size distributions truncated at 2 mm for the Fraser below Vasquez site...... 144 Figure D.6b. Post-runoff grain-size distributions truncated at 2 mm for the Fraser below Vasquez site...... 145 Figure D.7. Grain-size distributions truncated at 2 mm for the Fraser Rendezvous site...... 146 Figure D.8. Grain-size distributions truncated at 2 mm for the Fraser Open Space site...... 147 Figure D.9. Grain-size distributions truncated at 2 mm for the Fraser Angling site...... 148 Figure D.10. Grain-size distributions truncated at 2 mm for the Fraser below Ranch site...... 149 Figure D.11. Grain-size distributions truncated at 2 mm for Ranch at Gage site...... 150 Figure D.12. Grain-size distributions truncated at 2 mm for the Ranch Angling site...... 151 Figure D.13a. Pre-runoff grain-size distributions truncated at 2 mm for the Ranch above Meadow site...... 152 Figure D.13b. Post-runoff grain-size distributions truncated at 2 mm for the Ranch above Meadow site...... 153 Figure D.14. Grain-size distributions truncated at 2 mm for the Ranch below Meadow site...... 154 Figure D.15a. Pre-runoff grain-size distributions truncated at 2 mm for the Vasquez site...... 155 Figure D.15b. Post-runoff grain-size distributions truncated at 2 mm for the Vasquez site...... 156 Figure D.16a. Pre-runoff grain-size distributions truncated at 2 mm for the St. Louis site...... 157 Figure D.16b. Post-runoff grain-size distributions truncated at 2 mm for the St. Louis site...... 158 Figure E.1. Grain-size distributions truncated at 8 mm for the Fraser Highway 40 site...... 160 Figure E.2. Grain-size distributions truncated at 8 mm for the Fraser Robbers site...... 161 Figure E.3. Grain-size distributions truncated at 8 mm for the Fraser above Diversion site...... 162 Figure E.4. Grain-size distributions truncated at 8 mm for the Fraser below Diversion site...... 163 Figure E.5a. Pre-runoff grain-size distributions truncated at 8 mm for the Fraser Winter Park Gage site...... 164 Figure E.5b. Post-runoff grain-size distributions truncated at 8 mm for the Fraser Winter Park Gage site...... 165 Figure E.6a. Pre-runoff grain-size distributions truncated at 8 mm for the Fraser below Vasquez site...... 166 Figure E.6b. Post-runoff grain-size distributions truncated at 8 mm for the Fraser below Vasquez site...... 167

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Figure E.7. Grain-size distributions truncated at 8 mm for the Fraser Rendezvous site...... 168 Figure E.8. Grain-size distributions truncated at 8 mm for the Fraser Open Space site...... 169 Figure E.9. Grain-size distributions truncated at 8 mm for the Fraser Angling site...... 170 Figure E.10. Grain-size distributions truncated at 8 mm for the Fraser below Ranch site...... 171 Figure E.11. Grain-size distributions truncated at 8 mm for Ranch at Gage site...... 172 Figure E.12. Grain-size distributions truncated at 8 mm for the Ranch Angling site...... 173 Figure E.13a. Pre-runoff grain-size distributions truncated at 8 mm for the Ranch above Meadow site...... 174 Figure E.13b. Post-runoff grain-size distributions truncated at 8 mm for the Ranch above Meadow site...... 175 Figure E.14. Grain-size distributions truncated at 8 mm for the Ranch below Meadow site...... 176 Figure E.15a. Pre-runoff grain-size distributions truncated at 8 mm for the Vasquez site...... 177 Figure E.15b. Post-runoff grain-size distributions truncated at 8 mm for the Vasquez site...... 178 Figure E.16a. Pre-runoff grain-size distributions truncated at 8 mm for the St. Louis site...... 179 Figure E.16b. Post-runoff grain-size distributions truncated at 8 mm for the St. Louis site...... 180

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LIST OF SYMBOLS, UNITS OF MEASURE, AND ABBREVIATIONS

Symbols:

2^sampled value randomly sampled values are transformed out of logarithmic space by raising each value exponentially to the base 2 a constant A cross-section area b constant c constant d50 median diameter of bed material th di diameter of the i percentile grain size of the distribution th d65 65 percentile of the truncated grain-size distribution th d84 84 percentile of the truncated grain-size distribution G specific gravity of sediment ∞ infinity n Manning roughness coefficient N number of measurements Q volumetric flow rate or discharge (independent variable)

Q1.5 peak discharge with a return period of 1.5 years in the annual maximum series Qc critical discharge Qflushing flushing flow rate Q50% median flow in a long-term daily discharge record R hydraulic radius S bed slope

Sf friction slope V cross-section average velocity w effective channel width (dependent variable)

β0 intercept β1 coefficient variable γ specific weight of the water/sediment mixture

γs specific weight of sediment μ mean of input distribution σ standard deviation of input distribution  shear stress

 * dimensionless shear stress

 * ' dimensionless shear stress based on Strickler approximation of skin friction

 *50 dimensionless shear stress referenced to d50 grain size

*c critical dimensionless shear stress (Shields parameter)

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 *i dimensionless shear stress referenced to di grain diameter in the denominator

 c critical shear stress (shear stress at incipient motion) ϕ constant

Units of Measure: cfs cubic feet per second ft foot or feet ft/ft feet per foot mi2 square mile(s) mm millimeter(s) % percent psf pound(s) per square foot SI International System of Units

Abbreviations:

1-D one-dimensional 2-D two-dimensional 3-D three-dimensional CWWTP Consolidated Wastewater Treatment Plant FDC flow duration curve GCSMP Grand County Stream Management Plan N/A not applicable / not available No. number NRCS Natural Resources Conservation Service PACSM Platte and Colorado Simulation Model ® registered SD standard deviation SNOTEL SNOw TELemetry SWE Snow Water Equivalent TM trademark U.S. United States USGS U. S. Geological Survey WPWSD Winter Park Water and Sanitation District XS cross section

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CHAPTER 1

INTRODUCTION

The Fraser River and its tributaries provide people on both sides of the Continental Divide with many amenities including clean water, fisheries, and recreational opportunities. As water supply demands and the extent of streamflow extraction have grown over the last century, contemporaneous changes in land use and sediment supply have also occurred. For example, the Colorado Department of Transportation applies approximately 5,600 tons per year of traction sand mix on the west side of Berthoud Pass (Denver Post, 2010) to facilitate winter travel through the Fraser River watershed. Interactions among historic land use changes, altered streamflows and sediment supplies have changed the river’s ecological characteristics.

The Fraser River has a storied history as a trout fishery, and trout have been identified as a key indicator of the ecological status of the river (Grand County Stream Management Plan (GCSMP), 2010). Sustaining trout and their food base in the Fraser River depends on the long- term maintenance of physical habitat quality and ecosystem characteristics on which they depend. In addition to adequate streamflows, spawning fish and aquatic invertebrates depend on open interstices in the river bed. Fine sediment deposition can reduce or eliminate this habitat (Waters, 1995). For example, fish eggs deposited within the river bed require interstitial space for oxygenation and fry emergence (Reiser et al., 1990). Excessive loading of fine sediments can also impair growth and survival of juvenile salmonids (Suttle et al., 2004).

Field reconnaissance performed in the Fraser River watershed over the last decade has indicated that fine sediment storage is occurring in several locations in the main stem and tributaries (e.g., GCSMP (2010)). Evidence of sediment storage includes bars, other deposits of sand, and embedded substrates that lack interstitial space. Substrate embeddedness is the degree that the larger particles (e.g., boulder, rubble, gravel) are surrounded or covered by fine sediment (Platts et al., 1983; Fitzpatrick et al., 1998).

Post-development streamflow depletions in the Fraser River watershed have increased the risk of habitat degradation associated with sediment deposition and clogging of the river bed. The proposed Moffat Collection System Project could alter the capacity of the Fraser River and its tributaries to flush fine sediment and maintain physical habitat for fishes and aquatic insects. By further reducing streamflows, the proposed project would decrease the number of days on average that flows exceed the thresholds necessary to clean and rejuvenate the river bed (Bledsoe and Beeby, 2012). If there are longer multi-year periods between flushing events, more sediment could accumulate at time scales relevant to the reproductive cycles of trout and aquatic insects. For example, T. Wesche (pers. comm.) has found that trout spawn in clean 25 to 50 mm gravel in the Fraser River. Other studies performed by Colorado State University (e.g., Hurst (2005))

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suggest that consistent levels of deposited fine sediment exceeding 15 to 30% surface coverage result in fewer types of mayflies, stoneflies, and caddisflies.

Sound hydraulic and geomorphic analyses are necessary for assessing the potential for sedimentation impacts to aquatic habitat and river biota in the context of flow extraction. The key to evaluating whether sediment accumulation is likely to be exacerbated by a proposed reduction in streamflow is to quantify and examine potential changes in the “flushing flows” that primarily influence cleaning and rejuvenation of the river bed. These flows may also be termed substrate maintenance flows (Whiting, 2002). Flushing flows can achieve multiple objectives that include removing surface veneers of fine sediment, scouring algae, and opening-up interstitial space in the river bed that would otherwise remain continuously embedded with fine sediment.

In developing management recommendations for environmental flows, it is advisable to avoid “single factor ecology” approaches that focus exclusively on one element of the streamflow regime for one type of organism (Bunn and Arthington, 2002). River baseflows that support survival of trout in the Fraser River and its tributaries have been previously studied in some detail; however, the moderate and high flows that prevent excessive accumulation of fine sediments and perform important geomorphic and ecologic functions including habitat, channel, riparian, and hyporheic maintenance have received less attention.

Evaluation and quantification of flushing flows is important for informing decisions about future flow management and impact assessments. The efficacy of flushing flows previously recommended for the Fraser River and its tributaries for flushing surface deposits of fine sediment, as well as fine sediments clogging interstices within the river bed to the depth of the coarse gravel and cobble, remains uncertain. The potential effects of additional high-flow alterations on aquatic habitat in the Fraser River cannot be thoroughly assessed until the flows that perform this coarse substrate mobilization function are more explicitly quantified and better understood. This study attempts to thoroughly assess the potential impacts of additional high- flow alterations on substrate mobilization through the application of accepted hydraulic formulae and hydrologic modeling of future high-flow scenarios.

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CHAPTER 2

GOALS AND OBJECTIVES

The overall goal of this study was to evaluate and quantify flushing flows that maintain sediment sizes on the bed and their mobility in the Fraser River and its major tributaries. Improved quantification of flushing flows can inform decision-making focused on the potential long-term environmental impacts of further flow extraction. Although the quantification of flushing flows in this study is focused on maintenance of substrate quality, such flows have concomitant benefits in maintaining habitat, recreation, hyporheic processes, and aesthetics.

The specific objectives of the study were to:

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CHAPTER 3

BACKGROUND

The importance of moderate to high streamflows in maintaining aquatic and riparian ecosystems is widely recognized (Poff et al., 1997; Bunn and Arthington, 2002; Annear et al., 2004; Poff and Zimmerman, 2010). Moderate to high flows in Rocky Mountain snowmelt rivers provide several types of amenities, physical processes, and ecological functions. Whiting (2002) summarized eight types of management objectives associated with environmental flows in these systems:

1) maintain recreation and aesthetics, 2) maintain sediment sizes on the bed and their mobility, 3) channel maintenance flows, 4) maintain longitudinal continuity of the channel, 5) maintain features and habitat, 6) floodplain maintenance, 7) hyporheic zone maintenance, and 8) maintain riparian vegetation.

In some instances, multiple environmental maintenance flows have been deemed necessary to protect trout populations (Petts, 1996), and include a channel maintenance flow near bankfull discharge, a flushing flow to prevent excessive siltation, and habitat flows to provide usable areas for spawning, longitudinal connectivity, and refuge from temperature extremes. This study is focused on the range of flows that control the size and arrangement of sediment particles comprising the river bed, a major determinant of aquatic insect communities and fish reproduction.

There are a variety of approaches for identifying flushing and substrate maintenance flows; however, such flows are typically estimated using one of three methods: 1) self-adjusted channel methods, 2) sediment entrainment methods, and 3) direct calibration methods. Sediment entrainment methods (the primary approach employed in this study as described below) involve estimation of the discharges that result in motion of fine sediment in a gravel-cobble matrix, and of the gravels and cobbles themselves. Such methods provide a reasonable surrogate for flushing in the absence of direct calibration estimates based on long-term, intensive field measurements with bedload samplers, scour chains, tracer particles, and other empirical methods (Reiser et al., 1985; Milhous, 1990; Kondolf and Wilcock, 1996). The entrainment approach has a physical and empirical basis, and is therefore more general and robust than self-adjusted methods that rely on relatively-vague definitions of channel equilibrium and bankfull conditions. The entrainment

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approach is based on the physics of the existing channel, sediments, and hydraulics which need not be in any particular state.

Useful estimates of flushing flows require a clear statement of objectives so that the flow(s) necessary to achieve those objectives can be identified (Kondolf and Wilcock, 1996). Substrate maintenance can be defined in terms of one or more of the following specific objectives:

1) remove fine sediment from the bed surface, 2) remove fine sediment from interstices, and 3) maintain gravel/cobble looseness.

The shear stress required to remove a surface veneer of fine sediment is somewhat less than that required to mobilize the coarse framework or armor layer of the river bed. Flushing fine sediment from interstices deeper than approximately one coarse grain diameter requires at least some motion of the gravels themselves and, therefore, a higher dimensionless shear stress than what is required for surface flushing (Beschta and Jackson, 1979; Diplas and Parker, 1985; Kondolf and Wilcock, 1996). Interstitial sand and fine gravel become mobile upon entrainment of the coarse particles in the river bed. The third objective, gravel looseness, is recognized as an important attribute for aquatic life (e.g., salmonid spawning); however, there is at present no standard method for its quantification. Nevertheless, experience suggests that this objective is likely to be satisfied if the coarse substrate is periodically mobilized to an extent that removes fine sediment from interstices (Kondolf and Wilcock, 1996).

Dimensionless shear stress ( * ) is the fundamental hydraulic variable used to predict mobility of sediments in rivers and is defined as:

 RS  *i   Eq. (3.1)  s  di 1.65di where

 *i = dimensionless shear stress referenced to di grain diameter in the denominator; τ = shear stress;

γs = specific weight of sediment; γ = specific weight of the water/sediment mixture;

di = represents the grain diameter to which the shear stress is referenced (hereafter the dimensionless shear stress is referenced to d50 grain size in the denominator and

denoted as  *50 ). R = hydraulic radius; S = bed slope; and

In situations where few or no bedload data are available, the critical shear stress that produces gravel / cobble entrainment can be reasonably estimated as a function of the median size of the

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coarse substrate and channel hydraulic characteristics based on reach-averaged values (Andrews, 1984; Milhous, 1990; Parker, 2008; Ferguson, 2012). Variability in estimates of the critical value of dimensionless shear stress for particle motion (*c ) arise from many factors including varying definitions as to what constitutes initiation of the bed, channel slope, particle shape, and arrangement (Buffington and Montgomery, 1997).

The majority of studies aimed at understanding incipient motion of mobile armors in gravel- bed rivers has focused on lower gradient (less than ca. 1%) streams and rivers. In such systems, the dimensionless shear stresses that span the spectrum from surface flushing of veneers of fine sediment to full mobilization of a coarse armor layer typically range from 0.02 to 0.06. Values based on scour data from several gravel-bed rivers in the western United States (U.S.) are summarized in Table 3.1 (after Milhous (2000, 2003, 2009), Parker (2008), and Wilcock (1998)).

Table 3.1. Interpretation of dimensionless shear stress values in terms of states of fine sediment flushing and coarse substrate mobilization at sites with slopes less than approximately 1%.

Dimensionless Shear Stress ( * )

Referenced to d50 ( *50) Sediment Movement State Lower Bound Upper Bound Fines and sand are stored or in partial motion – 0.021 Surface cleaning 0.021 0.035 Movement of coarse armor 0.035 0.06-0.084

For steeper channels, a number of recent investigations focused on incipient motion of gravel / cobble river beds have underscored the dependence of critical shear stress on channel bed slope (Lamb et al., 2008; Ferguson, 2012; Bunte, pers. comm.). For example, Lamb et al. (2008) suggested that critical dimensionless shear stress required for incipient motion of coarse beds 0.25 increases with S . The effect of bed slope on  *c is primarily detectable above a slope of approximately 1% (Ferguson, 2012). An extensive set of bedload data collected in Colorado and

Wyoming snowmelt streams has been compiled to examine relationships between critical  *50 and slope in streams steeper than 1% (Bunte et al., 2010). These data indicate that *c increases with slope above 1%; however, the effect is mediated by the relative submergence of d50 based on bankfull flow (ratio of bankfull depth to d50) such that the influence of slope on *c varies non-linearly and is most pronounced at intermediate levels of relative submergence (K. Bunte, pers. comm.).

Scientific literature on thresholds of particle mobility in gravel-bed rivers has also established that incipient motion is a spatially patchy phenomenon as many natural stream channels have irregular cross sections and patches of locally coarser or finer sediment (e.g., Ferguson (2012), Haschenburger (1999), and Bigelow (2005)). As such, there is not a discrete threshold at which

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the entire river bed becomes active in transport and scour/fill. Instead, a flushing flow of given magnitude and duration will produce variable depths of scour on different streambed patches and geomorphic units, e.g., riffles as compared to pools. In entrainment (i.e., shear-stress based) approaches to quantifying flushing flows, average boundary shear stress is typically used to estimate the mobility of coarse particles. Because it is based on an average description of channel geometry, channels that are non-prismatic with irregular cross sections inevitably contain variable zones of shear stress and transport intensity that are higher than average in some locations and lower in others. Despite the fact that particle entrainment processes are complex and three-dimensional (3-D), it is rarely practical and feasible to perform two-dimensional (2-D) or 3-D modeling of shear stresses at many sites, given the extent of detailed data required. In addition, the need to evaluate flushing flows at relatively-large spatial scales (along ~10s of kilometers of channels) precludes the use of 2-D modeling approaches.

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CHAPTER 4

METHODS

We used a weight-of-evidence approach to estimate critical discharges for flushing flows of varying effectiveness with explicit consideration of uncertainty. Field surveys, hydraulic characterizations, and highly-detailed substrate sampling were performed at sixteen sites along the Fraser River main stem, Ranch Creek, Vasquez Creek, and St. Louis Creek. Sediment entrainment analyses were based on critical shear stress values that were ascertained from multiple sources of local field data, scientific literature on similar systems, flume studies on the behavior of fine sediments in armored river beds, and expert judgment. An explicit analysis of uncertainty was performed using Monte Carlo methods to account for parameter uncertainty in grain size, slope, Manning n, and critical shear stress values. We also combined the shear stress analysis with existing hydrologic data to estimate the magnitude, frequency, and duration of dimensionless shear stress values for the baseline condition vs. the tentatively-selected plan for the Moffat Collection System Project at each survey location. The following sections provide detailed descriptions of the various methodological approaches employed in the study.

4.1 Field Data Collection

Sixteen sites were selected along the Fraser River and its tributaries (Figure 4.1). Ten sites were located on the Fraser main stem, four on Ranch Creek, one on Vasquez Creek, and one on St. Louis Creek (Figures 4.2 through 4.15). Site locations were chosen on the Fraser River and Ranch Creek to represent the range of physical, geomorphological, and hydrological conditions occurring in channels with less than a 4% slope. We chose site locations between major water inputs and outputs to the Fraser River and Ranch Creek main stems to account for possible changes in substrate composition due to variations in sediment delivery and transport associated with tributaries/diversions and changes in streamflow (Rice et al., 2001). Plots of the selected cross sections are provided in Appendix A. Hydraulic data used to calculate at-a-station hydraulic geometry for all sites are tabulated in Appendix B.

Total station surveys of channel cross-sections and longitudinal profiles of bed slope, existing water surface slope, and bankfull water surface slope were performed between July 12 and 15, 2013 at each site to provide the necessary inputs for the hydraulic analyses described below. A systematic point grid frame method was used in combination with a gravelometer to collect substrate data at each site along transects spanning the bankfull channel (Bunte and Abt, 2001) (Figure 4.16). The systematic point grid frame method was used to obtain N > 300 pebble count observations with the gravelometer, as well as an additional N > 300 observations aimed at

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quantifying % surface fines. Transects were split between riffles and pool tail-outs as these areas are commonly used to assess the status of aquatic ecosystems and monitor changes in fine bed material within mountain gravel-bed streams (Bunte et al., 2012). Substrate sampling was not focused solely on fish redds per the previous work, as other habitats provide essential food sources for trout and native fishes (Huryn and Wallace, 1987). Transect locations within the riffles and pool tail-outs were chosen based on their representativeness of the overall sediment variability found longitudinally within the reach. Increasing the number of points sampled from the standard 100 to ca. 400 decreased the error in estimated d50 values from 15% to 8% (Bunte and Abt, 2001).

1. Fraser Highway 40 7. Fraser Rendezvous 13. Ranch above Meadow 2. Fraser Robbers 8. Fraser Open Space 14. Ranch below Meadow 3. Fraser above Diversion 9. Fraser Angling 15. Vasquez 4. Fraser below Diversion 10. Fraser below Ranch 16. St. Louis 5. Fraser Winter Park Gage 11. Ranch at Gage 6. Fraser below Vasquez 12. Ranch Angling

Figure 4.1. Site locations within the Fraser River watershed (base map was downloaded from the U. S. Geological Survey (USGS) – http://pubs.usgs.gov/wri/wri98- - ).

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Figure 4.2. Fraser Highway 40 site location.

Figure 4.3. Fraser Robbers site location.

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Figure 4.4. Fraser above Diversion and Fraser below Diversion site locations.

Figure 4.5. Fraser Winter Park Gage site location.

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Figure 4.6. Fraser below Vasquez site location.

Figure 4.7. Fraser Rendezvous site location.

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Figure 4.8. Fraser Open Space site location.

Figure 4.9. Fraser Angling site location.

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Figure 4.10. Fraser below Ranch site location.

Figure 4.11. Ranch at Gage site location.

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Figure 4.12. Ranch Angling site location.

Figure 4.13. Ranch below Meadow and Ranch above Meadow site locations.

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Figure 4.14. Vasquez site location.

Figure 4.15. St. Louis site location.

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Figure 4.16. Pebble count surveys were conducted using a grid sampler in combination with a gravelometer.

4.1.1 Grain-size Distributions

Field data were used to calculate three grain-size distributions for each site: 1) one with all grain sizes (tabulated and plotted in Appendix C), 2) one containing all observations >2 mm (tabulated and plotted in Appendix D), and 3) one containing all observations >8 mm (tabulated and plotted in Appendix E). Grain-size distributions were truncated at 2 mm and 8 mm to estimate a median particle diameter (d50) that best characterizes the coarse framework of the river bed. Truncation is a common procedure to counter bias introduced by fines in standard pebble count procedures (Rice, 1995; Bunte and Abt, 2001). Final d50 values used in the flushing flow analyses were truncated at 2 mm. The standard deviation of the d50 estimate, used in the sediment entrainment and uncertainty analyses described below, was based upon a multinomial distribution approach to identifying confidence intervals around particle size classes in a cumulative frequency distribution curve from pebble count data (Petrie and Diplas, 2000). For each site the standard deviation of d50 was estimated as follows:

d  d 58 42 Eq. (4.1) 4 where th d58 = diameter of the 58 percentile grain size of the distribution; and nd d42 = diameter of the 42 percentile grain size of the distribution.

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th The multinomial approach indicates that the error of the d50 estimate at the 95 confidence level (±2 standard deviations (SDs)) is approximately 8 percentiles away from d50 for ~400 sample points and fifteen grain-size classes used in the distribution (Bunte and Abt, 2001) (Figure 4.17).

Figure 4.17. Percent error (at 95% confidence) surrounding the d50 percentile, based on the number of size classes and number of particles in the pebble count.

4.1.2 Pre- vs. Post-runoff Substrate Analysis

Substrate samples were taken for pre-2013 runoff (at five sites) and post-2013 runoff (at all sites) (hereafter referred to as pre-runoff and post-runoff, respectively). Substrate samples were taken prior to spring runoff at five of sixteen sites (see Table 4.1 for specific pre-runoff sites and dates) to quantify changes in bed material composition as a result of the magnitude and duration characteristics of the 2013 snowmelt hydrograph. The remaining eleven sites could not be sampled due to snow, high flows, and/or turbid water. Percent fines (<2 mm and <8 mm) and coarse bed material data were also taken along the same transects used for sediment sampling after runoff. Over 300 points were sampled at each of the five sites using a systematic point grid frame method and viewing bucket (Bunte et al., 2012) (Figure 4.18). Tracer rocks were also placed before runoff at two sites (Ranch above Meadow and Fraser below Vasquez) to explore whether the magnitude and duration of 2013 peak flows were competent to mobilize the coarse substrate (Figure 4.19). The rocks were spray-painted orange and placed at small intervals along a transect perpendicular to the flow within the wetted channel of the stream. Forty rocks were placed at the Ranch above Meadow site. Rock sizes were split into two groups of approximately

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64 mm (~d68) and 32 mm (~d43). Twenty rocks were placed at the Fraser River site. Rock sizes were split into two groups of approximately 128 mm (~d65) and 64 mm (~d48).

Table 4.1. Dates for pre- and post-runoff field work.

Site Pre-runoff Date Post-runoff Date Fraser Highway 40 7/11/13 Fraser Robbers 7/11/13 Fraser above Diversion 7/13/13 Fraser below Diversion 7/13/13 Fraser Winter Park Gage 5/7/13 7/14/13 Fraser below Vasquez 5/7/13 7/13/13 Fraser Rendezvous 7/14/13 Fraser Open Space 7/14/13 Fraser Angling 7/13/13 Fraser below Ranch 7/14/13 Ranch at Gage 7/12/13 Ranch Angling 7/12/13 Ranch above Meadow 5/7/13 7/12/13 Ranch below Meadow 7/12/13 Vasquez 5/8/13 7/11/13 St. Louis 5/8/13 7/13/13

Figure 4.18. Percent fines and coarse material were sampled using a grid and bucket viewer.

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Figure 4.19. Placing tracer rocks at the Ranch Creek above Meadow site.

4.2 Hydraulic Characterization

Other variables necessary to conduct the sediment entrainment analysis include flow resistance, slope, hydraulic geometry, and critical dimensionless shear stress. Manning n values were estimated using well-established empirical relations and multiple lines of evidence. The Limerinos (1970) relationship was used as a base estimate of grain resistance at sites with th relative submergence R/d84 >2, where R is hydraulic radius and d84 is the 84 percentile of the truncated grain-size distribution. Nominal form roughness was added to the base Manning n values from Limerinos (1970), following Arcement and Schnieder (1989). Field photographs were compared with calibrated photographs (Hicks and Mason, 1999; Jarrett, 1984) and evidence of bedforms in longitudinal profile surveys were also examined in estimating total Manning n values. Roughness values were also assessed by comparison with previously-reported estimates of Manning n for sites in the Fraser River watershed that were computed using the Jarrett (1984) equation (Tetra Tech et al., 2010). Finally, Manning n values for steep gradient sites were assessed based on Yochum et al. (2012). Based on these multiple lines of evidence, a standard deviation reflecting variability in the final estimated Manning n was identified for inclusion in the uncertainty analysis of critical discharge described below in Section 4.3. Slope values were calculated from total station surveys of bankfull elevations (based on field evidence of annual high water / flat depositional features) along each reach. Three sites had bed slopes approaching

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or exceeding 3% with longitudinal profiles showing substantial bedforms and step-like features. To account for the steep slope values and flow resistance added by step formations, average slopes between pronounced steps were calculated. These slope values may be more of an accurate representation of actual friction slopes that bed material would need to be transported over in these channels. These slopes were used instead of bankfull water surface slopes at the higher gradient sites due to the greater quantity of survey points in the thalweg profile and fewer water surface indicators.

At-a-station hydraulic geometry relationships describe the change in a dependent hydraulic variable as it relates to changes in another independent hydraulic variable (usually discharge) at a given “station” or cross section of river channel. For this study, we developed a relationship equating effective flow width to changes in volumetric flow rates for a given cross-sectional geometry. Effective flow width is identified as the average depth-integrated width to account for potential errors in using cross-section averaged values. The Manning formula was chosen as the flow resistance equation and takes the form:

 V  R2/ 3S1/ 2 Eq. (4.2) n f where V = cross-section average velocity; ϕ = constant (1.49 English, 1 International System of Units (SI)); n = Manning roughness coefficient; R = hydraulic radius; and

Sf = friction slope.

The Limerinos (1970) relationship, an empirical relative roughness equation applicable to coarse, mobile-bed streams, was employed to estimate Manning’s roughness coefficients (n) for each cross section. Limerinos (1970) related Manning’s roughness (n) to hydraulic radius (R) and particle size (d84), using fifty current-meter measurements from eleven stream channels with bed material ranging from small gravel to medium sized boulders. Limerinos selected stream sites based on the following criteria: 1) minimal vegetation on the bank and in the channel, 2) relatively-straight channel alignment, 3) stable banks and bed, and 4) relatively-wide trapezoidal shape that contains the entire discharge without flows spilling onto the floodplain. This last site- selection criterion permitted Limerinos (1970) to use one roughness relationship across an entire range of flows, neglecting changes in roughness due to flows spilling onto the floodplain. The Limerinos (1970) relationship takes the form:

c R1/ 6 n  Eq. (4.3)  R  1.16  2.0 Log    d84 

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where n = Manning roughness coefficient; c = constant (0.0926 English, 0.1129 SI); R = hydraulic radius; and

d84 = particle size for which 84 percent of the sediment mixture is finer.

However, the Limerinos (1970) relationship becomes invalid at small values of R/d84. Examining the original data set from Limerinos reveals that approximately 73% of the original forty-nine measurements contained R/d84 values greater than two (Table 4.2). This value was deemed adequate to establish the lower limits of the Limerinos relationship for this hydraulic geometry analysis.

Table 4.2. Limerinos data set, R/d84 values for total number of measurements (N).

R/d84 N > % of N above 4 22 45% 3 30 61% 2 36 73% 1 48 98%

All Manning roughness values for R/d84 values less than two were assigned a unique constant value for each cross section, based on the analysis of flow resistance described above and best engineering judgment. The criteria for calculating Manning roughness coefficient (n) for each cross section in this hydraulic geometry analysis then takes the form:

R n  constant for  2 Eq. (4.4) d84

c R1/ 6 R n  for  2 Eq. (4.5)  R  d84 1.16  2.0 Log    d84  where R = hydraulic radius;

d84 = particle size for which 84 percent of the sediment mixture is finer; and c = constant (0.0926 English, 0.1129 SI).

Volumetric flow rates and effective flow widths were calculated for each cross section at depth increments of 0.01 ft. Calculations were continued for each cross section until the flow depth exceeded the lower of the maximum elevations between the right and left banks (i.e., water must be contained within the cross-sectional survey extents). Following Limerinos’ original site selection, a constant roughness value was assumed across the entire cross section. The logarithmic values (base 10) of volumetric flow rates and effective flow widths were then taken

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for each flow depth increment, and the logarithmic value of effective flow width was plotted against the logarithmic value of volumetric flow rate (both base 10). A linear regression analysis was then performed on the log-transformed data to obtain the following linear relationship between the dependent (w) and independent (Q) variables:

Log10 w  1 Log10 Q  0 Eq. (4.6) where w = effective channel width; and Q = volumetric flow rate.

The results of the linear regression analysis provide values of the intercept (β0) and the coefficient variable (β1). The resulting values are then transformed out of logarithmic space as follows:

w 100 Q1 Eq. (4.7)

The finalized relationship follows the form:

w  a Qb Eq. (4.8)

Dimensionless shear stress ( * ) referenced to d50 ( *50) was used in the sediment entrainment analysis:

 RS *50   Eq. (4.9)  s   d50 1.65d50 where τ = shear stress;

γs = specific weight of sediment; γ = specific weight of the water/sediment mixture;

d50 = median diameter of bed material; R = hydraulic radius; and S = bed slope.

The rationale for selection of  *50 values used in the sediment entrainment analysis is described in the following section.

4.2.1 Sediment Entrainment Analysis

We used a weight-of-evidence approach to estimate critical discharges for flushing flows. Critical shear stress values were ascertained from existing data from the Fraser River basin, scientific literature on similar systems, flume studies on the behavior of fine sediments in

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armored river beds, and expert judgment. An explicit analysis of uncertainty was performed using Monte Carlo methods to account for parameter uncertainty in grain size, slope, Manning n, and critical shear stress values. The resulting estimates of critical discharges for substrate maintenance are described as ranges and probability distributions to inform risk-based decision- making and adaptive management of environmental flows.

In addition to performing a literature review to support the selection of shear stress thresholds for the Fraser River and its tributaries, we elicited expert opinion from three recognized experts in sediment mechanics of gravel-bed rivers to identify thresholds of dimensionless shear stress associated with varying degrees of substrate flushing and scour (personal communications with Dr. Kristin Bunte, Colorado State University; Dr. Robert Milhous, Retired – U. S. Geological Survey; and Dr. Peter Wilcock, Johns Hopkins University). Based on the best available information from the scientific literature on sediment movement in gravel-bedded river systems similar to the Fraser and its tributaries, including expert judgment elicited from K. Bunte, R. Milhous, and P. Wilcock; critical dimensional shear stress values of 0.021 to 0.06 referenced to d50 were chosen for their efficacy in predicting substrate mobility on a spectrum from surface flushing to full mobilization of a coarse armor layer in lower gradient reaches (Buffington and

Montgomery, 1997; Ferguson, 2012; Milhous, 2000, 2003; Parker, 2008). We selected a τ*50 value of 0.021 ± a SD of 0.0015 as a threshold for surface flushing at low-gradient sites per analyses performed by Milhous (2003, 2009) based on scour data from Colorado rivers. To estimate flows that initiate motion of coarse particles and interstitial flushing to the depth of the surface layer, we evaluated a range of fixed values in increments of 0.005 up to the maximum plausible value for initiation of coarse substrate mobilization or to the point where the 25th percentile estimate exceeded the highest point in the survey cross section and maximum reliable discharge.  *50 values ≥ 0.035, representing the lower threshold for movement of the coarse armor, were identified based on studies in comparable systems (Andrews, 1983; Andrews and Nankervis, 1995; Milhous, 2000, 2003, 2009; Parker, 2008; Wilcock, 1998) and were adjusted for the effects of channel slope and relative submergence based on Lamb et al. (2008), Ferguson (2012), Bunte et al. (2010), and K. Bunte (pers. comm.).

Roughness estimates used to calculate shear stresses were primarily based on Limerinos (1970) as described above. The Limerinos (1970) data set and relation provide estimates of Manning n that largely reflect grain roughness. In finalizing flow resistance values, we compared estimated discharges based on low-flow Manning n values with discharges recorded at proximate USGS gages on the day of field surveying. Absolute differences between estimated low-flow discharges and gage records on the Fraser River ranged from 6 to 29%; however, primary emphasis was placed on accurate estimation of Manning n at much higher discharges in the range of flushing flows.

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4.3 Critical Discharge

Critical discharge (Qc) describes the volumetric flow rate at which an appreciable amount of sediment located on the river bed begins to move. The derivation for Qc involves manipulation of the following four relationships:

1) The Manning formula, describing flow resistance:

 V  R2/ 3S1/ 2 Eq. (4.10) n f where V = cross-section average velocity; ϕ = constant (1.486 English, 1 SI); n = Manning roughness coefficient; R = hydraulic radius; and

Sf = friction slope.

2) Critical dimensionless shear stress, describing incipient motion of channel-bed material:

 c RS f *c   Eq. (4.11) ( s   ) d50 (G 1) d50

where

*c = critical dimensionless shear stress (Shields parameter);

τc = critical shear stress (shear stress at incipient motion); γs = specific weight of sediment; γ = specific weight of the water/sediment mixture; R = hydraulic radius;

Sf = friction slope; G = specific gravity of sediment; and

d50 = median diameter of bed material.

3) At-a-station hydraulic geometry relationship, relating effective channel width to discharge as described above:

w  a Qb Eq. (4.12)

where w = effective channel width; a, b = constants; and Q = volumetric flow rate.

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4) The flow continuity relationship, describing the conservation of fluid quantity in transport:

Q VA Eq. (4.13)

where Q = volumetric flow rate; V = velocity; and A = cross-section area.

Using the shear stress identity, τ = γRSf, and assuming wide channel geometry such that R is approximately equal to flow depth, the following relationship is developed:

1/(1b)  a  Q    (G 1)d 5/ 3  Eq. (4.14) c nS 7 / 6 *c i  f  where

Qc = critical discharge; a, b = constants; ϕ = constant (1.486 English, 1 SI); n = Manning roughness coefficient;

Sf = friction slope;

 *c = critical dimensionless shear stress (Shields parameter); G = specific gravity of sediment; and th di = diameter of the i percentile grain size of the distribution.

This relationship describes critical discharge as a function of friction slope, Manning roughness coefficient, critical dimensionless shear stress, sediment size, and the constants from at-a-station hydraulic geometry.

Using the channel hydraulic geometry and slopes estimated from field surveys in conjunction with site-specific grain-size distributions, we used this relationship to estimate critical discharges that correspond to ecologically-relevant thresholds of dimensionless shear stress for each study site.

4.4 Monte Carlo Critical Discharge Simulation

Founded on the principles of repeated random sampling from a specified distribution, Monte Carlo simulations evaluate the sensitivity of potential outcome values for a given relationship to potential changes in the input parameters by statistically incorporating the probability distribution of potential input values. Each input parameter is assigned a unique probability

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distribution function by way of a statistical mean, standard deviation, and probability distribution type (e.g., Gaussian). A random sample of each input parameter is then input into the given relationship, in this case the critical discharge relationship above, to develop a potential outcome value. As this process is repeated, a population of potential outcome values is compiled and characterized by a specific probability distribution function. Figure 4.20 depicts this process conceptually. A probability distribution function is assigned for each input parameter: Manning roughness coefficient (n) assumed to fit a Gaussian distribution with mean centered on the estimated n described above, friction slope (Sf) assumed to fit a Gaussian distribution centered on the estimate from the field survey, and d50 fit to a log-normal (base 2) distribution based on visual inspection of grain-size distributions with d50 values taken from the post-runoff grain-size distributions truncated at 2 mm for each site. For surface veneer flushing flows with  *50of 0.021, critical dimensionless shear stress values were also assumed to fit a Gaussian distribution. For coarse substrate mobilization flows, values ≥ 0.03 were held constant in increasing increments of 0.005 with the slope, grain size, and Manning n varying according to the distributions described above.

A random sample of each parameter is obtained using MicrosoftTM Excel®’s built-in ‘NORMINV’ function, utilizing a random probability generator (RAND() function), a mean, and standard deviation. Since the median grain-size data were assumed to fit a log-normal distribution, each of these randomly-sampled values are transformed out of logarithmic space by raising each value exponentially to the base 2 as follows: (2^sampled value). Next, each sample value is input into the above critical discharge relationship. This process is repeated for 10,000 iterations to ensure the sample of critical discharge values (N = 10,000) accurately represent the entire population of potential critical discharge values (N  ∞). Standard statistical analyses are then performed on the distribution of critical discharge values to describe the range of variability and uncertainty in estimates at all study sites.

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µ  µ µ   1 1−푏 1/(1b)  푎휙 5  푄 = a 휏 퐺 − 1 퐷 5 /3 3 Q푐   7  ∗푐(G 1)d 푠  c 푛nS푆 7 /66 *c 50  푓f 

µ  µ 

where μ = mean of input distribution; σ = standard deviation of input distribution; Qc = critical discharge; a, b = constants; ϕ = constant (1.486 English, 1 SI); n = Manning roughness coefficient; Sf = friction slope;

 *c = critical dimensionless shear stress (Shields parameter); G = specific gravity of sediment; and d50 = median diameter of bed material.

Figure 4.20. Depiction of probabilistic estimation of Qc using varying distributions of input variables slope, grain size, Manning n, and critical dimensionless shear stress.

In evaluating the central tendencies of the resulting estimates of Qc, we primarily focused on median values given the asymmetrical distributions that result from inputting the naturally- skewed distributions of grain size (Figure 4.21). Confidence intervals were calculated in addition to statistical mean, median, and standard deviation for each sample (N = 10,000) of critical discharge values. The upper and lower bounds for each confidence interval were calculated using the built-in PERCENTILE function, using a two-tail confidence interval approach, such that the area between the upper and lower bounds for the 98% confidence interval equals 98% (i.e., total area greater than the 98% confidence interval upper bound equals 1%). Figure 4.21 depicts a sample asymmetrical distribution of critical discharge values resulting from a Monte Carlo critical discharge simulation. A sample output table from a simulation is provided in Appendix F.

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The relative uncertainty associated with the resulting non-symmetrical distributions of Qc was assessed using the interquartile range (25th percentile to 75th percentile) divided by the median. This metric is analogous to a coefficient of variation and was used to assess relative confidence in flushing flow estimates.

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Critical Discharge 300

250

200 25th Median 75th Percentile Percentile 150

Frequency 100

1.2 8.1

15.0 22.0 28.9 35.9 42.8 49.8 56.7 63.7 70.6 77.5 84.5 91.4 98.4

230.3 105.3 112.3 119.2 126.2 133.1 140.0 147.0 153.9 160.9 167.8 174.8 181.7 188.7 195.6 202.5 209.5 216.4 223.4 237.3 244.2 251.2 258.1 Flow (cfs)

Figure 4.21. Sample critical discharge distribution resulting from a Monte Carlo critical discharge simulation.

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4.4.1 Frequency Analysis of Flushing Flows

We combined the results of the sediment entrainment analysis with existing hydrologic data to estimate the magnitude, frequency, and duration of dimensionless shear stress values for the baseline condition vs. the tentatively-selected plan for the Moffat Collection System Project at each study site.

A frequency analysis of flushing flows was conducted for eleven sites (six locations on the Fraser River main stem, three on Ranch Creek, one on Vasquez Creek, and one on St. Louis Creek). We compared two Platte and Colorado Simulation Model (PACSM) scenarios of Base 285 existing flows (Current Conditions) vs. Alt 1a Moffat Tunnel Collection System Project (Projected Conditions). The frequency analysis could not be conducted on the remaining five sites due to missing hydrologic data. Analyses of the overall numbers of years that flushing occurred and multi-year periods without flushing were also performed for each value of dimensionless shear stress and its associated discharge.

The frequency analyses required a hydrologic foundation that allowed comparisons of estimated streamflows under both current and future with-project conditions. The hydrologic foundation used in this analysis was the same as used in a previous study by Bledsoe and Beeby (2012). Denver Water provided time series of mean daily discharge data at selected nodes in the Fraser River drainage network for the period October 1, 1946 to September 30, 1991 (April 11, 2012 e-mail from Scott Franklin, U. S. Army Corps of Engineers). These streamflows were estimated by Denver Water with the PACSM and were used in the shear stress and effective discharge analyses performed in this study.

Two PACSM scenarios were used for comparison of current and with-project conditions:

1) Base 285 existing supply, existing demand – run 0030 (Current Conditions) 2) Alt 1a gross 114,000 (42,000 + 72,000) – run 0032 reflecting the tentatively-selected plan for Moffat Collection System Project (with-project conditions)

For Ranch Creek, time series of PACSM data were provided for two node locations: 1) below Denver Water's North Fork Ranch and Dribble Creek diversions (node 2490), and 2) below Denver Water's Main Ranch Creek diversion (node 2500). Streamflow data for the PACSM node 2520 below Denver Water’s Diversion from Middle and South Fork of Ranch Creek were not provided. Downstream segments of Ranch Creek with lower gradients are relatively susceptible to geomorphic change from flow alteration compared to steep headwater reaches. To examine the potential influence of future flow alterations on relatively responsive downstream segments of Ranch Creek, it was necessary to approximate the two flow series using a combination of USGS streamflow data and the two available PACSM nodes in the headwaters of Ranch Creek.

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For locations on lower Ranch Creek where PACSM data describing the project’s influence were not provided, PACSM data from upstream nodes 2490 and 2500 were used along with data from USGS 09033100, 09032500, and 09032000 gages to synthesize streamflows at the Ranch Creek study site near Tabernash upstream of Meadow Creek. Two approaches to generating a synthetic streamflow record were utilized. In the first case, streamflows were estimated by comparing USGS 09032500 and 09032000 gages over the overlapping period of 1934-1960. The difference in these two USGS records was used to estimate the streamflow contribution of the basin below USGS 09032000 gage to the location of USGS 09032500 gage. The PACSM data from nodes 2490 and 2500 were then substituted for the historical gage record at USGS 09032000 gage and added to the difference between USGS 09032500 and 09032000 gages for the overlapping period of the two USGS gages and PACSM (1946-1960). This approach provided a 15-year daily streamflow series. This series reflects the modeled flow contributions / diversions from the vast majority of the upper basin combined with the measured flow contribution of the lower watershed to the point of the site located adjacent to USGS 09032500 gage. In the second case, a series of synthesized flows for Ranch Creek was developed using a dimensionless flow duration curve (FDC) approach (Natural Resources Conservation Service (NRCS), 2007; Soar and Thorne, 2001). FDCs based on the sum of the two flow records for PACSM nodes 2490 and 2500 were calculated for current and with-project Alt 1a conditions. These two FDCs were then non-dimensionalized using regional estimates of median annual flow (Q50%) from the USGS (Capesius and Stephens, 2009). An estimated Q50% was also computed for 1) the F-RC2 Tetra Tech site using a drainage area of 65.7 mi2 and 2) at the location of the survey performed adjacent to the discontinued USGS 09032500 gage at a drainage area of 51.1 mi2, using the Capesius and Stephens (2009) relationship. These values were then used to transfer the dimensionless FDC from the upstream PACSM nodes to the downstream study sites based on a consistent scaling using Q50%.

4.4.2 Characteristics of 2013 Runoff Hydrographs

Gage data (15-minute time increments) from six USGS stations were downloaded to examine magnitudes and durations of 2013 peak runoff hydrographs. The 2013 snowmelt hydrographs were used to calculate high-flow duration at increments of  *50, to aid interpretation of pre- vs. post-runoff substrate characteristics measured in the field and to aid in evaluating flushing flow magnitudes and durations necessary for substrate maintenance.

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CHAPTER 5

RESULTS

5.1 Cross-section and Longitudinal Characteristics

Cross-sectional and longitudinal characteristics of each site are presented in Table 5.1. Field measured slopes ranged from 0.0025 at the Ranch Angling site to 0.0365 at the Fraser Highway

40 site, underscoring the need for evaluating different values of *c as it relates to channel gradient. Bed slopes based on thalweg surveys and water surface slopes based on high water and depositional indicators in the field showed close correspondence (within 12%) at the majority of sites. As expected, exceptions primarily occurred at sites with relatively-steep slopes and higher thalweg variability. A basic description of each site and the spatial variability of the substrate within each reach are described in the following sections.

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Table 5.1. Cross-sectional and longitudinal characteristics of each site.

Standard Standard Bankfull Deviation Highest Post Diversions Deviation Water Bankfull Bed Reliable b Site w = aQ Q1.5 n-value n-value Slope Water Slope Slope d50 Q (cfs) (mm) Fraser Highway 40 3.059Q0.302 117 0.075 0.0038 0.022 0.005 0.0365 59 1200 Fraser Robbers 5.372Q0.264 117 0.045 0.002 0.0137 0.0007 0.0121 48 165 Fraser above Diversion 5.580Q0.269 117 0.04 0.002 0.0101 0.0005 0.0081 51 250 Fraser below Diversion 3.278Q0.312 0.04 0.002 0.0151 0.0008 0.0149 42 100 Fraser Winter Park Gage 3.617Q0.317 158 0.055 0.0028 0.017 0.0008 0.0215 104 1000 Fraser below Vasquez 5.372Q0.264 0.05 0.002 0.0195 0.001 0.0192 55 220 Fraser Rendezvous 6.265Q0.269 0.045 0.002 0.0122 0.0006 0.0087 53 200 Fraser Open Space 3.603Q0.408 0.045 0.0023 0.009 0.0005 0.0097 96 200 Fraser Angling 5.588Q0.351 0.05 0.0025 0.0082 0.0004 0.0098 112 350 Fraser below Ranch 5.134Q0.350 0.045 0.002 0.005 0.0003 0.0051 52 750 Ranch at Gage 4.029Q0.298 132 0.075 0.0038 0.018 0.0035 0.027 71 170 Ranch Angling 11.424Q0.153 0.045 0.002 0.0028 0.0001 0.0025 31 140 Ranch above Meadow 4.534Q0.332 0.04 0.002 0.0061 0.0003 0.0055 44 170 Ranch below Meadow 4.927Q0.295 0.04 0.002 0.0091 0.001 0.0224 51 550 Vasquez 7.450Q0.195 130 0.075 0.0038 0.0347 0.0017 0.0311 87 120 St. Louis 3.599Q0.390 147 0.045 0.0023 0.0178 0.0009 0.0175 54 200

Where a and b = constants; d50 = median diameter of bed material; n = Manning roughness coefficient; Q = volumetric flow rate; Q1.5 = peak discharge with a return period of 1.5 years in the annual maximum series; and w = effective channel width.

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5.1.1 Fraser Highway 40 Site

The Fraser Highway 40 site (Figure 5.1) begins downstream of the road culvert. The channel is steep and narrow with some step-pool formations. Dense willows (Salix spp.) and occasional large boulders line the channel banks. The middle of the channel consists of larger boulders creating step formations with more of a cobble and gravel mix between the steps. Gravel (2 to 8 mm) is depositing out behind the larger bed material in most areas. Where boulders are not present along the channel banks, the substrate consists of finer gravel and sand. Direct input of sand and gravel appears to be coming from Highway 40 material being pushed onto the steep channel banks and eventually washing into the channel itself.

Figure 5.1. Looking upstream at the Fraser Highway 40 site.

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5.1.2 Fraser Robbers Site

The Fraser Robbers site (Figure 5.2) is located directly east of the Robbers Roost Campground. The Fraser River here gently meanders through a flat meadow with pool-riffle sequencing. There is evidence of historic beaver dams crossing the channel here with large deposits of sand along the banks and floodplain in areas. Willows (Salix spp.) line the channel through most of the reach. Substrate in the middle of channel consists of cobble and gravel, while the edges and point bars are more mixed with cobble, gravel, and sand. There are a few smaller sand bars present along the edge of the channel as well. Sand and gravel are depositing out behind the larger bed material especially along the channel edges.

Figure 5.2. Looking upstream at the Fraser Robbers site.

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5.1.3 Fraser above Diversion Site

Located approximately 500 ft upstream of the Denver Water diversion, the Fraser above Diversion site (Figure 5.3) consists of pool-riffle sequencing through a narrow meadow. The banks are grass-lined with occasional willows (Salix spp.) present. Channel substrate consists of cobble and gravel with some fine gravel and sand surrounding the larger material, especially near the channel edges. Point bars are either a mix of cobble, gravel, and sand or just fine gravel and sand.

Figure 5.3. Looking upstream at the Fraser above Diversion site.

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5.1.4 Fraser below Diversion Site

The Fraser below Diversion site (Figure 5.4) is located approximately 600 ft downstream of the Denver Water diversion. The sinuosity of the river has increased compared to upstream as it winds through open forest. The banks are grass-lined upstream with denser willows (Salix spp.) present downstream. Pool-riffle sequencing is occurring with a large amount of sand and fine gravel deposited in the pools. The middle of the channel consists of cobble and gravel with finer gravel and sand deposited within the larger material. A small tributary enters at the downstream end of the reach and appears to be inputting a large amount of fine gravel and sand into the main stem. Upstream point bars are more dominated by cobble and gravel, while downstream they are more sand and gravel dominated.

Figure 5.4. Looking downstream at the Fraser below Diversion site.

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5.1.5 Fraser Winter Park Gage Site

Located directly upstream of the USGS 09024000 gage on Fraser at Winter Park, the Fraser Winter Park Gage site (Figure 5.5) consists of a plane-bed channel that runs steeply through dense forest. The banks are lined with grass and willow (Salix spp.) with large boulders in areas. The middle of the channel consists of large boulders and cobbles with gravel stored behind the larger bed material. Where boulders are not present along the edge, the substrate consists of sand and fines.

Figure 5.5. Looking downstream at the Fraser Winter Park Gage site.

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5.1.6 Fraser below Vasquez Creek Site

The Fraser below Vasquez site (Figure 5.6) is located approximately 500 ft downstream of the confluence of Vasquez Creek and the Fraser River. Here the river runs relatively straight and consists of a plane-bed channel. The banks are lined with grass and willow (Salix spp.) with occasional large boulders near the banks in areas. The middle of channel consists of large boulders and cobbles with gravel and sand stored behind larger bed material. Where boulders are not present along the edge, the substrate consists mostly of cobbles and large gravel, but fine gravel and sand also becomes more prevalent here. Upstream of the reach, closer to the confluence, the larger bed material is highly embedded with sand and fine gravel. The amount of sand and fine gravel decreased post-runoff but was still found in appreciable amounts (Figures 5.7 and 5.8).

Figure 5.6. Looking downstream at the Fraser below Vasquez site.

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Figure 5.7. Directly downstream of the confluence of the Fraser River and Vasquez Creek, large amounts of sand and fine gravel (lighter color in the middle of the photograph) can be seen surrounding larger material (pre-runoff).

Figure 5.8. Directly downstream of the confluence of the Fraser River and Vasquez Creek, the amount of sand and fine gravel has decreased post-runoff but is still found in appreciable amounts.

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5.1.7 Fraser Rendezvous Site

The Fraser Rendezvous site (Figure 5.9) is located approximately 500 ft upstream of where Rendezvous Road crosses the Fraser River. The river here has a plane-bed morphology. The banks are mostly lined with dense willow (Salix spp.). The middle of channel is dominated by cobbles and gravel with some larger boulders. Sand is depositing behind the larger bed material, especially in the upstream area of the reach. Point bars are largely unvegetated and consist mostly of gravel with some sand.

Figure 5.9. Looking downstream at the Fraser Rendezvous site.

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5.1.8 Fraser Open Space Site

The Fraser Open Space site (Figure 5.10) is located in Cozens Ranch Open Space. The river is more characteristic of a pool-riffle system and meanders through an open space with dense willow (Salix spp.) Multiple beaver dams are present throughout the open space, creating ponded areas. Fine sediment can be found above bank levels in areas, indicating the historical presence of beaver dams within the reach. The middle of channel consists of boulders, cobbles, and small gravel depositing out behind the larger material. Point bars consist of a mix of boulder, cobble, gravel, and sand.

Figure 5.10. Looking upstream at the Fraser Open Space site.

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5.1.9 Fraser Angling Site

The Fraser Angling site (Figure 5.11) is located within the Rocky Mountain Angling Club property, approximately 500 ft downstream of where County Road 83 crosses the Fraser River. The river runs relatively straight through a large floodplain of willow (Salix spp.) stands. The channel is characteristic of a plane bed. The middle of channel consists of boulders and cobbles with small gravel depositing out behind the larger material. Some sand was present along the channel edges. Downstream of the reach a scour pool, created by an eddy, had over a foot of sand lining the bottom of the pool.

Figure 5.11. Looking upstream at the Fraser Angling site.

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5.1.10 Fraser below Ranch Site

The Fraser below Ranch site (Figure 5.12) is located directly downstream of the confluence of Ranch Creek and the Fraser River. The river runs relatively straight before entering the canyon downstream. Dense willows (Salix spp.) and large boulders line the banks. The middle of channel consists of boulders and cobbles with fine gravel depositing out behind the larger material. Fines <2 mm were present along the banks below bankfull. The left side of the channel (Fraser River side) substrate is a mix of gravel and cobble, while the right side (Ranch Creek side) consists of boulders and cobbles. Directly below the confluence a depositional area of sand and fine gravel was also present along the Fraser River side.

Figure 5.12. Looking upstream at the Fraser below Ranch site.

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5.1.11 Ranch at Gage Site

Located directly downstream of the USGS streamflow gage (USGS 09032000), the Ranch at Gage site (Figure 5.13) is straight and relatively steep here with some step-pool formations. Dense willows (Salix spp.) and many large boulders line the banks. The middle of channel consists of boulders and cobbles with fine gravel depositing out behind the larger material. The left side of the channel substrate consists of cobbles and gravel, while the right side consists of boulders with fine gravel and sand deposits. Sand was more prevalent at bankfull elevations on both sides of the channel.

Figure 5.13. Looking downstream at the Ranch at Gage site.

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5.1.12 Ranch Angling Site

The Ranch Angling site (Figure 5.14) is located within the Rocky Mountain Angling Club property approximately 500 ft upstream of where County Road 843 crosses Ranch Creek. The river planform is sinuous with riffle-pool sequencing. The floodplain consists of willow (Salix spp.) dominated stands although the channel banks are mostly grass-lined. The middle of channel consists of cobble and gravel with some sand. Point bars consist of gravel and sand. Pool tail- outs were largely covered in algae, which seemed to trap finer sediment (Figure 5.15).

Figure 5.14. Looking downstream at the Ranch Angling site.

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Figure 5.15. Algae present in pool tail-outs seemed to capture fine sediment.

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5.1.13 Ranch above Meadow Site

The Ranch above Meadow site (Figure 5.16) is approximately 2,000 ft upstream of the confluence of Meadow Creek and Ranch Creek. The river runs a sinuous path with pool-riffle sequencing through a floodplain dominated by willow (Salix spp.) stands. The channel banks are mostly grass-lined. The middle of the channel consists of cobble and gravel with some sand. Most point bars consist of large and small gravel and sand.

Figure 5.16. Looking upstream at the Ranch above Meadow site.

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5.1.14 Ranch below Meadow site

The Ranch below Meadow site (Figure 5.17) is approximately 500 ft downstream of the confluence of Meadow Creek and Ranch Creek. The river is relatively straight and transitions from pool-riffle sequencing upstream to a plane-bed morphology downstream. The channel banks are lined with willows (Salix spp.) and boulders in areas. The middle of the channel consists of mostly cobble and gravel with the occasional boulder. Fine gravel deposits are found behind the larger bed material. Fines <2 mm are more prevalent along the channel edges and directly upstream of the bridge where backwater conditions may exist under higher flows. In general, the substrate was noticeably larger here compared to the two lower Ranch Creek sites upstream.

Figure 5.17. Looking upstream at the Ranch below Meadow site.

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5.1.15 Vasquez Site

The Vasquez Creek site (Figure 5.18) is located approximately 1.25 miles upstream of the Arapaho Road bridge. The channel is relatively straight with some step-pool formations. Banks are lined with willows (Salix spp.) and boulders. The middle of channel consists of boulders forming the steps with gravel and cobble stored in between. Gravel and sand deposits are found along the channel margins. Woody debris is present in areas and acting like a sediment trap for fine gravel and sand.

Figure 5.18. Looking downstream at the Vasquez site.

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5.1.16 St. Louis Site

The St. Louis Creek site (Figure 5.19) is located just upstream of the USGS streamflow gage (USGS 09026500). The creek is characteristic of a plane-bed channel. Mid-channel is dominated by boulders and cobbles with fine gravel deposits behind the larger material. Fines <2 mm are depositing over boulders along the channel margins. Upstream of the reach, a beaver dam crosses the channel; which has created some side channels that enter the main stem below the dam.

Figure 5.19. Looking upstream at the St. Louis site.

5.2 Percent Fines Data

Results are focused on percent fines <2 mm and <8 mm at each site. Full grain-size distribution results for each site are presented in Appendix C (full distribution), Appendix D (percent fines <2 mm truncated), and Appendix E (percent fines <8 mm truncated). Percent fines post-runoff data show that all sites except for St. Louis Creek had a higher percentage of fines between 2 to 8 mm than <2 mm, indicating a greater presence of fine and very fine gravel than sand (Table 5.2). Field observations also noted the relatively-high percentage of fines <8 mm at most sites (Figures 5.20 and 5.21). Overall percent fines pre-runoff and post-runoff data show

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that four of five sites decreased in fines <2 mm and all five sites decreased in fines <8 mm. However, St. Louis Creek still had 34% and 23% of fines <8 mm and <2 mm remaining after runoff, respectively. Surface flushing occurred for both 2 and 8 mm sized particles at the Fraser Winter Park Gage and Ranch above Meadow sites. The Fraser below Vasquez site flushed 2 mm material more than the 8 mm sized grains. Vasquez Creek did not appear to flush either 2 or 8 mm sized particles. St. Louis Creek substantially decreased in particles both <2 and <8 mm particles, but 34% of particles <8 mm and 23% of particles <2 mm particles remained after runoff, indicating only partial flushing.

Table 5.2. Surface fines pre- and post-runoff at the study sites. Pebble counts and % fines counts each exceeded 300 observations per site visit.

Pre-runoff Post-runoff Pebble % Fines Pebble % Fines Site Grain Size Count Count Average Count Count Average <8 mm 26 31 28 Fraser Highway 40 <2 mm 9 7 8

<8 mm 15 38 26 Fraser Robbers <2 mm 3 10 7

<8 mm 22 28 25 Fraser above Diversion <2 mm 6 6 6

<8 mm 21 28 24 Fraser below Diversion <2 mm 9 11 10

<8 mm 6 37 22 10 13 11 Fraser Winter Park Gage <2 mm 4 21 12 1 1 1 <8 mm 27 32 30 20 23 22 Fraser below Vasquez <2 mm 11 28 19 1 1 1 <8 mm 23 12 18 Fraser Rendezvous <2 mm 10 4 7

<8 mm 6 3 5 Fraser Open Space <2 mm 2 0 1

<8 mm 14 16 15 Fraser Angling <2 mm 3 3 3

<8 mm 21 11 16 Fraser below Ranch <2 mm 9 1 5

<8 mm 25 16 21 Ranch at Gage <2 mm 6 4 5

<8 mm 30 25 28 Ranch Angling <2 mm 16 9 12

<8 mm 24 37 30 17 15 16 Ranch above Meadow <2 mm 10 29 20 4 7 6 <8 mm 14 22 18 Ranch below Meadow <2 mm 3 2 2

<8 mm 7 17 12 8 13 11 Vasquez <2 mm 0 4 2 5 5 5 <8 mm 30 57 43 35 33 34 St. Louis <2 mm 25 57 41 23 23 23

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Figure 5.20. Deposits of sand and very fine gravel behind larger bed material.

Figure 5.21. Cobbles / gravel substrates embedded with fine sediment.

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5.2.1 Tracer Rocks

The snow pack for 2013 was 105% of average at the Berthoud Summit SNOw TELemetry (SNOTEL) site and resulted in an instantaneous peak flow of 193 cfs at the Fraser Winter Park Gage site (Table 5.3). Snowmelt runoff hydrographs from this year are presented below (Figures 5.22 through 5.28). Results from the tracer rock study at the Fraser below Vasquez site showed that five of ten rocks sized between 46 and 64 mm (~d39) moved (Table 5.4). Rocks that moved were less than 4 ft from their original location except for two that were missing. For the rocks sized 91 to 128 mm (d60) two of ten rocks moved. One rock moved 2 ft, while the other was missing. For the Ranch above Meadow site, three of twenty rocks sized between 23 and 32 mm

(d34) moved (Figure 5.29). Two of the rocks that moved were less than 4 ft from their original location and one was missing. For the rocks sized 46 to 64 mm (~d60) ten of twenty rocks moved. Most of the rocks moved less than 4 ft from their original location but two were missing. In both instances, most of the rocks were recovered because they either did not move or were only displaced short distances (<4 ft).

Table 5.3. Peak Snow Water Equivalent (SWE) and peak streamflow data from 2013.

PEAK SWE Average Median SNOTEL Sites 2013 (1981-2010) Percentage (inches) Berthoud Summit 22.9 21.8 105% INSTANTANEOUS PEAK FLOW USGS Recurrence Gaging Stations Gage No. 2013 Interval (cfs) Fraser Winter Park 09024000 193 1.62 Vasquez Creek 09025000 120 1.43 St. Louis Creek 09026500 238 1.93 Ranch Creek 09032000 155 1.57

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Figure 5.22. Hydrograph from June 1-30 for the Fraser River at Upper Station near Winter Park gage (USGS 09022000).

Figure 5.23. Hydrograph from June 1-30 for the Fraser River at Winter Park gage (USGS 09024000).

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Figure 5.24. Hydrograph from June 1-30 for the Fraser River at Tabernash, Colorado, gage (USGS 09027100).

Figure 5.25. Hydrograph from June 1-30 for the Fraser River below Crooked Creek at Tabernash, Colorado, gage (USGS 09033300).

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Figure 5.26. Hydrograph from June 1-30 for the Ranch Creek near Fraser gage (USGS 09032000).

Figure 5.27. Hydrograph from June 1-30 for the Vasquez Creek at Winter Park gage (USGS 09025000).

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Figure 5.28. Hydrograph from June 1-30 for the St. Louis Creek near Fraser gage (USGS 09026500).

Table 5.4. Tracer rock results for the Fraser below Vasquez and Ranch above Meadow sites.

Tracer Rocks Results Site Size Class Placed Remaining Moved % Remain % Moved (mm) 91-128 10 9 2 90% 20% Fraser below Vasquez 46-64 10 8 5 80% 50% 46-64 20 18 10 90% 50% Ranch above Meadow 23-32 20 19 3 95% 15%

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(a) pre-runoff (b) post-runoff

Figure 5.29. Tracer rocks at the Ranch above Meadow site.

5.2.2 Flushing Flow Estimates

Flushing flow estimates are presented in Table 5.5. Focus was placed on the resulting median and quartile values from the Monte Carlo analysis. The range of uncertainty (interquartile range/median) describes variance relative to the magnitude of the median estimate in a non- symmetrical distribution and is analogous to a coefficient of variation. Results indicate that estimates of flushing flows are especially sensitive to the input slope as slope varied with the 7/6 power. The estimated flushing flow value at many of the key sites converged with flushing flow values recommended in the GCSMP.

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Table 5.5. Estimates of coarse substrate mobilization flows for the Fraser River and tributaries. Emphasis was placed on the median with the interquartile/median value indicating relative uncertainty.

Estimated Estimated Grand Range of Minimum Minimum County Flow Flow Standard 25th 75th Interquartile/  *c  *c Flushing Flushing Site *c Mean Median Deviation Percentile Percentile Median Lamb et al. Bunte  *c Flow Flow (cfs) (cfs) (cfs) (cfs) 0.021 2 2 2 1 2 0.86 0.03 5 4 4 2 5 0.82 0.035 6 5 7 4 8 0.82

Fraser 0.04 9 7 10 5 11 0.82 0.066 0.110 >0.065 >25 Highway 40 0.045 12 9 9 6 14 0.84

0.05 15 12 12 8 18 0.83 0.055 19 15 14 10 22 0.83 0.06 23 18 18 12 27 0.82 0.021 8 7 3 6 9 0.49 0.03 18 17 6 14 21 0.43 0.035 26 25 9 20 31 0.44 Fraser 0.04 36 35 12 28 43 0.44 0.045- 0.050 0.046 45-59 Robbers 0.045 48 45 16 36 56 0.44 0.05 0.05 62 59 20 48 73 0.44 0.055 78 74 26 60 92 0.44 0.06 97 92 32 73 114 0.44 0.021 18 17 5 14 21 0.38 0.03 41 40 10 34 47 0.31 0.035 58 57 14 49 66 0.31 Fraser above 0.04 76 73 22 60 88 0.38 0.045 N/A 0.045 100 Diversion 0.045 104 100 25 86 118 0.32 0.05 131 128 31 110 149 0.31 0.055 164 159 38 137 186 0.31 0.06 200 195 47 166 228 0.31

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Gage 0.05 162 153 58 121 193 0.47 0.055 204 192 73 152 242 0.47 0.06 252 237 91 188 299 0.47 0.021 6 5 4 3.4 8 0.86 0.03 14 11 9 8 17 0.83 0.035 19 16 13 11 24 0.83 Fraser below 0.04 26 22 17 15 33 0.85 0.055- 0.056 0.066 55 Vasquez 0.045 35 29 23 19 43 0.83 0.065 0.05 43 36 29 24 54 0.84 0.055 54 45 36 30 68 0.84 0.06 66 55 44 36 82 0.83 0.021 14 14 3 12 16 0.26 0.03 31 31 3 29 33 0.15 0.035 45 44 5 41 48 0.14 Fraser 0.04 61 60 6 56 65 0.14 0.045- 0.046 N/A 80-100 Rendezvous 0.045 80 79 9 74 85 0.14 0.05 0.05 102 101 11 94 109 0.14 0.055 127 126 13 117 135 0.14 0.06 156 155 17 144 166 0.14 0.021 111 102 47 78 135 0.57 Fraser Open 0.03 300 280 113 220 359 0.50 0.035- 1,2 0.047 0.038 >200 Space 0.035 463 434 170 343 552 0.48 0.045 0.04 673 629 252 496 801 0.48

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Estimated Range of Estimated Grand Minimum Minimum County Flow Flow Standard 25th 75th Interquartile/  *c  *c Flushing Flushing Site *c Mean Median Deviation Percentile Percentile Median Lamb et al. Bunte  *c Flow Flow (cfs) (cfs) (cfs) (cfs) 0.021 208 199 65 162 245 0.42 Fraser 0.03 515 499 128 424 588 0.33 0.035- 2 0.047 0.039 >500 200 Angling 0.035 767 740 193 629 877 0.34 0.045 0.04 1079 1046 267 890 1234 0.33 0.021 78 70 37 52 95 0.62 0.03 191 176 82 133 231 0.56 Fraser below 0.035 287 263 123 201 346 0.55 0.04 401 370 171 278 490 0.57 0.040 N/A 0.04 370 Ranch 0.045 544 501 232 380 660 0.56 0.05 706 648 301 490 861 0.57 0.055 912 836 393 637 1110 0.57 0.021 6 4 2 1.3 3.0 0.89 0.03 13 10 4 3.1 7 0.83 0.035 19 15 5 4.3 10 0.84 0.04 27 21 7 6.2 14 0.83 0.045 35 27 10 8.1 18 0.83 0.05 45 35 13 10 23 0.83 Ranch at 0.055 56 44 15 13 29 0.85 0.06- 0.061 0.087 55-125 40 Gage 0.06 70 54 19 16 36 0.83 0.085 0.065 84 65 23 19 43 0.83 0.07 101 78 28 23 52 0.83 0.075 118 93 32 27 62 0.84 0.08 137 106 37 32 71 0.82 0.085 159 124 43 36 82 0.86 0.09 182 142 51 42 95 0.84 0.021 54 52 15 43 63 0.38 Ranch 0.03 109 106 27 90 125 0.33 0.034 N/A 0.035 140-150 150 Angling 0.035 147 143 36 121 168 0.33 0.04 191 186 47 157 219 0.33 0.021 30 28 11 22 35 0.46 Ranch above 0.03 72 69 22 56 84 0.41 0.035 106 100 32 83 123 0.40 0.041 N/A 0.04 140-150 150 Meadow 0.04 147 140 45 115 173 0.42 0.045 197 189 60 154 231 0.41

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Estimated Range of Estimated Grand Minimum Minimum County Flow Flow Standard 25th 75th Interquartile/  *c  *c Flushing Flushing Site *c Mean Median Deviation Percentile Percentile Median Lamb et al. Bunte  *c Flow Flow (cfs) (cfs) (cfs) (cfs) 0.021 26 20 20 13 32 0.96 0.03 59 47 44 31 74 0.91 0.035 84 68 62 43 106 0.93 Ranch below 0.04 117 94 88 61 146 0.91 0.055- 1 0.058 0.075 200 150 Meadow 0.045 155 125 116 80 193 0.90 0.06 0.05 201 163 147 104 251 0.91 0.055 250 203 183 130 315 0.91 0.06 306 248 222 159 384 0.90 0.021 4.7 4.5 1.2 3.8 5.4 0.35 0.03 9.8 9.6 2.1 8.3 11 0.29 0.035 13 13 2.8 11 15 0.28 0.04 18 17 3.7 15 20 0.28 0.045 23 22 4.9 19 26 0.29 0.05 28 26 6.0 24 32 0.29 0.055 34 34 7.2 29 39 0.28 0.06 41 40 8.8 35 46 0.29 0.065- 1 Vasquez 0.063 0.097 50-100 50 0.065 49 47 10 41 54 0.28 0.095 0.07 57 55 12 48 64 0.28 0.075 65 64 14 55 73 0.28 0.08 74 73 16 63 84 0.28 0.085 85 83 18 72 96 0.29 0.09 95 93 20 81 107 0.28 0.095 107 104 23 90 120 0.29 0.1 118 115 25 100 133 0.28 0.021 5 5 1 4 6 0.33 0.03 15 13 8 9 19 0.71 0.035 23 20 13 14 29 0.72 0.04 34 30 20 21 43 0.73 0.055- 1 St. Louis 0.055 0.061 70-90 70 0.045 46 40 26 28 58 0.74 0.06 0.05 62 54 35 38 77 0.72 0.055 81 70 47 49 100 0.72 0.06 102 89 58 62 127 0.73 N/A = Bunte estimate not available for slopes < 1%. 1 Estimate subsequently adjusted based on additional field evidence as described in Section 6.1. 2 Estimate exceeds maximum reliable discharge that can be estimated with field survey.

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5.2.3 Grand County Flushing Flows

Flushing flows recommended in the GCSMP produce a range of  *50 values from 0.012 to 0.059, indicating varying degrees of flushing potential (Table 5.6). This reflects, in part, differences in methodology as flushing flow estimates in the GCSCM plan were based on visual inspection of bedload rating curves, as well as the range of variability in historic hydrographs.

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Table 5.6. Results from the sediment entrainment analysis of flushing flows recommended in the GCSMP using hydraulic and substrate data reported in the GCSMP.

Shear Average Slope Used in Stress at Channel Shear Stress Slope at  Site Qflushing d50 Qflushing Slope Analysis Qflushing *50 Comments (cfs) (mm) (psf) (ft/ft) (ft/ft) (ft/ft)

F-RC1, Ranch Creek 40 67 1.33 0.058 0.010-0.028 0.022 0.059 Flushing recommendation achieves  *50 of 0.059.

F-RC2, Ranch Creek 150 32 0.44 0.007 0.002-0.005 0.004 0.041 Flushing recommendation achieves  *50 of 0.041. F-StL, St. Louis Creek 70 82 1.29 0.015 0.02 0.02 0.046 Flushing recommendation achieves of 0.046. Achieving minimum of 0.021 would require F-VC, Vasquez Creek 50 105 0.42 0.024 0.006 0.006 0.012 Q >112 cfs, beyond bounds of data. F3, Fraser River 80 77 1.09 0.019 0.017 0.017 0.042 Flushing recommendation achieves of 0.042. Achieving minimum of 0.021 requires ~280 F6, Fraser River 200 80 0.486 0.007 0.005 0.005 0.018 cfs, of 0.03 requires Q >360 cfs, beyond bounds of data. No grain-size data available, highest modeled flow

of 213 cfs would transport ~40 mm d50 at  * of F7, Fraser River 213 N/A 0.41 0.006 0.005 0.005 N/A 0.03, and ~58 mm d50 at  * of 0.021. Median grain size is larger than these values upstream and downstream. Flushing recommendation achieves of 0.028, of 0.03 requires 470 cfs, of 0.035 F9, Fraser River 400 70 0.66 0.005 0.006 0.006 0.028 requires 640 cfs, of 0.04 requires Q >640 cfs, beyond bounds of data. N/A = grain-size data not available.

Where: d50 = median diameter of bed material; Q = volumetric flow rate; Qflushing = flushing flow rate;  * = dimensionless shear stress;  *50= dimensionless shear stress referenced to d50 grain size.

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5.2.4 Flushing Flow Frequency

Flow frequency analyses comparing the Current Use vs. Alt 1a flow scenarios (1946-1991) indicate that the proposed Alt 1a scenario substantially decreases the frequency that median flushing flow values are met (Table 5.7). The number of continuous spells greater than 1 year of non-flushing and the average length of non-flushing spells substantially increase under the proposed Alt 1a flow regime (Table 5.8). Final estimated flushing flow values also occur less frequently (35 to 66% reduction) under the proposed Alt 1a flow regime (Table 5.9). The number of continuous spells greater than 1 year of non-flushing and the average length of that non- flushing spell also substantially increase under the proposed Alt 1a flow regime in several river segments (Table 5.10). Alterations of flushing flows are most pronounced in the Fraser River main stem between the Denver Water diversion and the confluence with Ranch Creek, and in Vasquez Creek.

Under the Current Use flow scenario, the flow with an exceedence frequency of 1% at the Fraser Winter Park Gage site is approximately 237 cfs. In contrast, the flow with an exceedence frequency of 1% at this same location in the Alt 1a flow scenario is 119 cfs. The largest degree of flow alteration at the Fraser Winter Park Gage site occurs between 66 to 199 cfs (-64%) which includes the estimated flushing flow of 100 cfs. The average length of consecutive years of non- flushing at Winter Park also nearly doubles (average ~90% difference) between Current Use and Alt 1a flows for 66 to 199 cfs. The frequency of a 100 cfs flushing flow (for the Fraser Winter Park Gage site) decreases by 64% and the average length of consecutive years non-flushing increased 74% under the Alt 1a flow regime.

The frequency of the estimated flushing flow value for the St. Louis Creek (100 cfs) and Fraser Angling site (280 cfs) both decrease substantially under the Alt 1a flow regime with reductions of 66% and 54%, respectively. For Vasquez Creek, the maximum length of consecutive years non-flushing doubled from 3 to 6 years under the Alt 1a flow scenario. The frequency of days exceeding the estimated flushing flow value for the lower Ranch Creek sites (150 cfs) decreases by 34% under the Alt 1a flow scenario.

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Table 5.7. Flow frequency analysis of Current Use vs. Alt 1a flow scenarios (1946-1991).

Current Use Alt 1a % Days Flow % Days Flow Median Exceeded Exceeded Site *c Flow (1946-1991) (1946-1991) % Difference (cfs) 0.021 19 4.5% 2.5% -44% 0.03 45 3.5% 1.4% -60% 0.035 66 3.3% 1.2% -64% Fraser Winter Park 0.04 91 2.8% 1.0% -65% Gage 0.045 119 2.3% 0.9% -64% 0.05 153 1.7% 0.7% -61% 0.055 192 1.2% 0.5% -61% 0.06 237 0.7% 0.3% -51% 0.021 5 99.2% 64.3% -35% 0.03 11 50.3% 37.9% -25% 0.035 16 39.1% 27.1% -31% Fraser below 0.04 22 24.1% 13.4% -44% Vasquez 0.045 29 13.5% 9.3% -32% 0.05 36 10.1% 6.6% -35% 0.055 45 8.0% 4.6% -42% 0.06 55 6.6% 3.7% -44% 0.021 14 40.4% 31.9% -21% 0.03 31 11.1% 7.2% -35% 0.035 44 7.3% 4.2% -43% 0.04 60 6.0% 3.1% -49% Fraser Rendezvous 0.045 79 5.1% 2.3% -55% 0.05 101 4.6% 2.0% -57% 0.055 126 4.2% 1.8% -58% 0.06 155 3.8% 1.5% -60% 0.021 102 4.6% 2.0% -57% 0.03 280 2.2% 0.9% -59% Fraser Open Space 0.035 434 0.8% 0.4% -53% 0.04 629 0.2% 0.1% -48% 0.021 199 5.2% 2.7% -48% 0.03 499 2.0% 0.9% -54% Fraser Angling 0.035 740 0.8% 0.4% -52% 0.04 1046 0.1% 0.0% -65% 0.021 70 19.7% 16.2% -18% 0.03 176 8.4% 5.9% -30% 0.035 263 6.8% 4.3% -37% Fraser below Ranch 0.04 370 5.6% 3.3% -42% 0.045 501 4.5% 2.6% -42% 0.05 648 3.4% 1.9% -44% 0.055 836 2.2% 1.1% -48% 0.021 52 8.5% 6.2% -27% 0.03 106 6.5% 4.2% -35% Ranch Angling 0.035 143 5.4% 3.6% -34% 0.04 186 4.5% 3.0% -34%

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Current Use Alt 1a % Days Flow % Days Flow Median Exceeded Exceeded Site *c Flow (1946-1991) (1946-1991) % Difference (cfs)

0.021 28 10.5% 8.2% -22% 0.03 69 7.7% 5.4% -30% Ranch above 0.035 100 6.7% 4.4% -34% Meadow 0.04 140 5.5% 3.6% -34% 0.045 189 4.4% 2.9% -34% 0.021 20 22.8% 21.8% -4% 0.03 47 9.6% 7.3% -24% 0.035 68 8.4% 6.1% -27% Ranch below 0.04 94 7.6% 5.3% -30% Meadow 0.045 125 6.8% 4.5% -34% 0.05 163 6.0% 3.9% -35% 0.055 203 5.1% 3.4% -34% 0.06 248 4.3% 2.8% -34% 0.021 4.5 54.0% 19.2% -64% 0.03 9.6 23.3% 9.5% -59% 0.035 13 13.5% 7.0% -48% 0.04 17 9.8% 5.2% -47% 0.045 22 7.9% 4.2% -47% 0.05 26 7.0% 3.7% -47% 0.055 34 6.2% 3.2% -48% 0.06 40 5.9% 3.0% -49% Vasquez 0.065 47 5.7% 2.8% -51% 0.07 55 5.4% 2.6% -52% 0.075 64 5.1% 2.2% -57% 0.08 73 4.7% 2.1% -55% 0.085 83 4.4% 1.9% -57% 0.09 93 4.1% 1.8% -56% 0.095 104 3.8% 1.7% -55% 0.1 115 3.4% 1.5% -56% 0.021 5 76.5% 76.4% 0% 0.03 13 31.7% 30.9% -3% 0.035 20 19.9% 19.0% -5% 0.04 30 12.8% 11.4% -11% St. Louis 0.045 40 9.9% 7.8% -20% 0.05 54 7.8% 5.6% -28% 0.055 70 6.5% 4.4% -33% 0.06 89 5.8% 3.6% -39%

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Table 5.8. Frequency that various flushing flow values are exceeded for 3 days within a year under Current Use vs. Alt 1a flow scenarios (1946-1991).

Current Alt 1a % Difference % Average Maximum Average Maximum Average Difference % Length Length No. of Length Length No. of Length Maximum Difference Consecutive Consecutive Intervals Consecutive Consecutive Intervals Consecutive Length No. of Years Years >1 Year Years Years >1 Year Years Consecutive Intervals >1 Non- Non- Non- Non- Non- Non- Non- Years Year  *c Q Flushing Flushing Flushing Flushing Flushing Flushing Flushing Non-Flushing Non-Flushing (cfs) 0.021 19 1.44 3 3 1.89 4 4 31% 33% 33% 0.03 45 2.10 5 6 3.22 8 7 53% 60% 17% 0.035 66 2.10 5 6 4.00 8 6 90% 60% 0% Fraser Winter 0.04 91 2.20 5 6 4.00 8 6 82% 60% 0% Park Gage 0.045 119 2.40 5 6 4.71 10 6 96% 100% 0% 0.05 153 4.00 10 7 5.83 10 6 46% 0% -14% 0.055 192 3.75 10 7 6.50 11 6 73% 10% -14% 0.06 237 6.00 14 6 10.25 14 4 71% 0% -33% 0.021 5 0.00 0 0 0.00 0 0 0% 0% 0% 0.03 11 0.00 0 0 0.00 0 0 0% 0% 0% 0.035 16 0.00 0 0 0.00 0 0 0% 0% 0% Fraser below 0.04 22 1.00 1 0 1.00 1 0 0% 0% 0% Vasquez 0.045 29 1.20 2 1 1.29 2 2 7% 0% 100% 0.05 36 1.29 2 2 1.30 2 3 1% 0% 50% 0.055 45 1.44 2 4 1.45 3 4 1% 50% 0% 0.06 55 1.50 3 4 2.10 4 6 40% 33% 50% 0.021 14 0.00 0 0 0.00 0 0 0% 0% 0% 0.03 31 1.20 2 1 1.29 2 2 7% 0% 100% 0.035 44 1.44 2 4 1.45 3 4 1% 50% 0% Fraser 0.04 60 1.60 3 4 2.33 6 5 46% 100% 25% Rendezvous 0.045 79 1.70 3 5 2.30 6 5 35% 100% 0% 0.05 101 1.70 3 5 2.30 6 5 35% 100% 0% 0.055 126 1.80 4 5 2.78 6 5 54% 50% 0% 0.06 155 1.80 4 5 3.38 8 5 88% 100% 0%

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Current Alt 1a % Difference % Average Maximum Average Maximum Average Difference % Length Length No. of Length Length No. of Length Maximum Difference Consecutive Consecutive Intervals Consecutive Consecutive Intervals Consecutive Length No. of Years Years >1 Year Years Years >1 Year Years Consecutive Intervals >1 Non- Non- Non- Non- Non- Non- Non- Years Year  *c Q Flushing Flushing Flushing Flushing Flushing Flushing Flushing Non-Flushing Non-Flushing (cfs) 0.021 102 1.70 3 5 2.30 6 5 35% 100% 0% Fraser Open 0.03 280 2.50 5 7 4.00 8 6 60% 60% -14% Space 0.035 434 5.00 11 7 8.00 14 5 60% 27% -29% 0.04 629 10.50 25 4 22.00 36 2 110% 44% -50% 0.021 199 1.70 4 4 2.10 4 6 24% 0% 50% 0.03 499 2.40 5 6 3.88 9 6 61% 80% 0% Fraser Angling 0.035 740 6.33 11 6 10.25 14 4 62% 27% -33% 0.04 1046 10.50 25 4 22.00 36 2 110% 44% -50% 0.021 70 1.00 1 0 1.00 1 0 0% 0% 0% 0.03 176 1.38 2 3 1.56 3 4 13% 50% 33% 0.035 263 1.50 2 4 1.78 3 6 19% 50% 50% Fraser below 0.04 370 1.56 3 4 1.67 3 6 7% 0% 50% Ranch 0.045 501 1.60 4 4 2.00 4 6 25% 0% 50% 0.05 648 1.82 4 5 2.27 6 6 25% 50% 20% 0.055 836 2.67 4 6 2.80 6 6 5% 50% 0% 0.021 52 1.50 2 3 1.83 3 4 22% 50% 33% 0.03 106 1.50 3 3 1.56 3 4 4% 0% 33% Ranch Angling 0.035 143 1.63 3 4 1.89 3 6 16% 0% 50% 0.04 186 1.75 4 4 1.73 3 6 -1% -25% 50% 0.021 28 1.33 2 1 1.20 2 1 -10% 0% 0% 0.03 69 1.43 2 3 1.63 3 4 14% 50% 33% Ranch above 0.035 100 1.38 2 3 1.56 3 4 13% 50% 33% Meadow 0.04 140 1.50 3 3 1.78 3 5 19% 0% 67% 0.045 189 1.67 4 4 1.73 3 6 4% -25% 50%

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Current Alt 1a % Difference % Average Maximum Average Maximum Average Difference % Length Length No. of Length Length No. of Length Maximum Difference Consecutive Consecutive Intervals Consecutive Consecutive Intervals Consecutive Length No. of Years Years >1 Year Years Years >1 Year Years Consecutive Intervals >1 Non- Non- Non- Non- Non- Non- Non- Years Year  *c Q Flushing Flushing Flushing Flushing Flushing Flushing Flushing Non-Flushing Non-Flushing (cfs) 0.021 20 1.00 1 0 1.00 1 0 0% 0% 0% 0.03 47 1.20 2 1 1.60 3 2 33% 50% 100% 0.035 68 1.50 2 3 1.71 3 4 14% 50% 33% Ranch below 0.04 94 1.43 2 3 1.63 3 4 14% 50% 33% Meadow 0.045 125 1.38 2 3 1.56 3 4 13% 50% 33% 0.05 163 1.50 3 3 1.56 3 4 4% 0% 33% 0.055 203 1.63 3 4 1.89 3 6 16% 0% 50% 0.06 248 1.67 4 4 1.73 3 6 4% -25% 50% 0.021 4.5 0.00 0 0 0.00 0 0 0% 0% 0% 0.03 9.6 0.00 0 0 1.25 2 1 0% 0% 0% 0.035 13 1.50 2 1 1.29 2 2 -14% 0% 100% 0.04 17 1.29 2 2 2.00 4 4 56% 100% 100% 0.045 22 1.71 3 4 1.78 4 4 4% 33% 0% 0.05 26 1.56 3 4 1.78 4 4 14% 33% 0% 0.055 34 1.50 3 4 1.73 4 5 15% 33% 25% 0.06 40 1.50 3 4 2.33 6 4 56% 100% 0% Vasquez 0.065 47 1.60 3 4 2.30 6 5 44% 100% 25% 0.07 55 1.60 3 4 2.30 6 5 44% 100% 25% 0.075 64 1.70 3 5 2.30 6 5 35% 100% 0% 0.08 73 1.70 3 5 2.30 6 5 35% 100% 0% 0.085 83 1.70 3 5 2.50 6 5 47% 100% 0% 0.09 93 1.80 4 5 2.50 6 5 39% 50% 0% 0.095 104 1.80 4 5 2.70 6 5 50% 50% 0% 0.1 115 1.82 4 5 2.70 6 5 49% 50% 0%

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Table 5.9. Frequency that estimated flushing flow values were exceeded under Current Use and Alt 1a flow scenarios (1946-1991).

Current Use Alt 1a Estimated % Days Flushing % Days Flushing Flushing Flow Exceeded Flow Exceeded Site Flow (1946-1991) (1946-1991) % Difference (cfs) Fraser Winter Park Gage 100 2.6% 1.0% -64% Fraser Angling 280 4.2% 1.9% -54% Fraser below Ranch 370 5.5% 3.2% -42% Ranch Angling 150 5.3% 3.5% -35% Ranch above Meadow 150 5.3% 3.5% -35% Ranch below Meadow 150 5.3% 3.5% -35% Vasquez 70 5.2% 2.4% -54% St. Louis 100 5.4% 1.8% -66%

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Table 5.10. Frequency that estimated flushing flow values were exceeded for 3 days within a year under Current Use and Alt 1a flow scenarios (1946-1991).

Fraser Angling 280 1.80 4 5 2.78 6 5 54% 50% 0%

Fraser below 370 1.56 3 4 1.67 3 6 7% 0% 50% Ranch

Ranch Angling 150 1.63 3 4 1.89 3 6 16% 0% 50%

Ranch above 150 1.63 3 4 1.89 3 6 16% 0% 50% Meadow Ranch below 150 1.63 3 4 1.89 3 6 16% 0% 50% Meadow

Vasquez 70 1.70 3 5 2.30 6 5 35% 100% 0%

St. Louis 100 1.63 3 4 1.90 3 6 17% 0% 50%

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CHAPTER 6

DISCUSSION

The results of the sediment entrainment analysis reveal longitudinal variation along the river system in the magnitude of flushing flows required for coarse substrate mobilization. Despite this variability, there is convergence between the estimates generated in this study and the Grand

County Stream Management Plan. Where competing estimates of Qc occur longitudinally in the same river segment, flushing flow estimates were based on multiple lines of evidence:

 pre- vs. post-runoff evidence of flushing based on field substrate characterization (where available);  tracer rock results (where available);  post-runoff evidence of flushing and embeddedness based on field substrate characterization;  magnitude and durations of 2013 peak flows as measured by USGS (where available)  sediment entrainment computations including relative confidence as quantified in the Monte Carlo uncertainty analysis;  sediment entrainment information available in the GCSMP (F-RC1, F-RC2, F-StL, F-VC, F3, F6, F7, and F9; Table 6.1); and  convergence of evidence between this study and the GCSMP.

Table 6.1. GCSMP stream reach summaries (after GCSMP (2010)).

GCSMP Site Location Description Winter Park Water and Sanitation District (WPWSD) intake to Town of F3 Fraser River Winter Park Fraser Consolidated Wastewater Treatment Plant (CWWTP) to Ranch F6 Fraser River Creek F7 Fraser River Ranch Creek to mouth of Canyon F9 Fraser River Canyon to Granby F-VC Fraser River Tributary Vasquez Creek diversions to Fraser River F-RC1 Fraser River Tributary Ranch Creek (upper) F-RC2 Fraser River Tributary Ranch Creek (lower) F-StL Fraser River Tributary St. Louis Creek

The following sections summarize key evidence available for ten primary river segments in the Fraser River watershed.

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6.1 Flushing Flow Key Evidence for Ten Primary River Segments

6.1.1 Fraser River above Diversion

Upstream of Winter Park the substrate still contained 24 to 28% fines <8 mm and 6 to 10% fines <2 mm post-runoff despite high flows exceeding 92 cfs for over 6 days at this location in 2013. This likely reflects the very high sediment supply to this reach, which appears to include abundant very fine gravel in addition to sand sizes. Based on our sediment entrainment analysis, the most probable estimates of minimum flows necessary for coarse substrate mobilization are 45 to 59 cfs at the Fraser Robbers site and 100 cfs at the Fraser above Diversion site. Overall confidence in the sediment entrainment analysis is lower in this segment than in downstream segments given the prevalence of steep bed slopes and the high sensitivity of d50 estimates to variable sand and gravel content.

6.1.2 Fraser River below Diversion to Vasquez Creek

The USGS gage at Winter Park recorded peak flows exceeding 91 cfs and 98 cfs for 2.3 days and 1.6 days, respectively. Appreciable flushing approaching 90% removal of surface fines was observed at this site in pre-runoff vs. post-runoff substrate samples. In contrast, both our sediment entrainment analysis and the GCSMP analysis estimate minimum flows necessary for coarse substrate mobilization in excess of 140 to 150 cfs. It is possible that the high levels of surface sand observed at this site prior to runoff may have temporarily reduced the shear stress required for at least partial mobilization of the coarse substrate (Wilcock and Kenworthy, 2002). Given compelling field evidence indicating that substantial surface flushing occurred during the 2013 runoff, we adjusted our estimate of a minimum flushing flow down to 100 cfs at this location. This value slightly exceeds a  *50 value of 0.04 in our analysis and equates with a  *50 value of approximately 0.047 at GCSMP site F3 (described in the GCSMP).

6.1.3 Fraser River between Vasquez Creek and St. Louis Creek

We established three study sites (Fraser below Vasquez, Fraser at Rendezvous, and Fraser Open Space) in this segment. Peak streamflows in 2013 based on the sum of the USGS 09025000 Vasquez Creek at Winter Park, Colorado, and USGS 09024000 Fraser River at Winter Park, Colorado, gages exceeded 100 cfs and 132 cfs in this segment for 7.7 days and 3.3 days, respectively. As a result, the Fraser below Vasquez site also experienced significant flushing of surface sand despite marginal to no movement of exposed tracer rocks at this location. Post- runoff substrate samples indicated average surface fines <2 mm of 1 to 7% and average fines <8 mm of 5 to 18%. The sediment entrainment analysis suggests that river substrates in the two upper sites of this main stem segment of the Fraser River are relatively mobile as a result of a substantial reduction in sediment size below Vasquez Creek. The Fraser at Rendezvous site appears to be the limiting reach of the two upper sites with respect to bed mobility, and the most probable estimates of minimum flows necessary for coarse substrate mobilization at this site

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range from 79 to 101 cfs. As such, a flow of 100 cfs for 3 days at Winter Park plus flow from Vasquez Creek could potentially exceed the minimum flushing flow for the Fraser below

Vasquez and Fraser Rendezvous sites; however, this is complicated by the fact that the d50 estimate at the Fraser below Vasquez site increases from 55 mm to 111 mm when fines are truncated at <8 mm. This means that the estimated flushing flow is very sensitive to the inclusion of 2 to 8 mm bed material in calculating d50. Removing the 2 to 8 mm material from the grain-size distribution at this site would lead to a twofold increase in d50 and a twofold the shear stress required for mobilization. The extent of fine and very fine gravel packed around coarser particles could at least partially explain why the bed was not more mobile at this location during the 2013 runoff. Uncertainty analysis of the sediment entrainment calculations indicates higher confidence at the Fraser Rendezvous and Fraser Open Space sites compared to the Fraser below Vasquez site.

In contrast to the two upstream sites, the Fraser Open Space site appears to be highly armored and the limiting reach in this segment, in that the streamflow associated with maximum extent of our field survey (200 cfs) does not produce a  *50 value of 0.03. Nevertheless, a flow of 200 cfs would provide surface flushing and some mobility in patches of high shear stress. This location is also the upstream-most site with a bed slope <1%, which is within the range of applicability of Table 3.1. The estimated range of flows for surface flushing at this site is 102 to 280 cfs. Therefore, a flow of ~200 cfs would likely provide both surface flushing at this site and coarse substrate mobilization at the two upstream sites. A flow of 200 cfs would also be more likely to mobilize embedded coarse material in the bed, based on the results of the tracer rock experiment.

6.1.4 Fraser River from St. Louis Creek to Ranch Creek

This segment contains the Fraser Angling site and GCSMP site F6. Both appear to have highly-armored beds similar to the next site upstream (Fraser Open Space site). Based on the USGS gage 09027100 Fraser River at Tabernash, Colorado, these sites experienced flows exceeding 200 cfs and 257 cfs for 4.6 days and 1.1 days, respectively, during the 2013 runoff. Post-runoff estimates of fine sediment on the surface of the river bed were 9% <2 mm and 25% <8 mm. The estimated minimum flow for surface flushing at the Fraser Angling site is 200 cfs. The maximum estimate of flow in our survey cross section is 350 cfs. At GCSMP site F6, achieving a minimum  *50 of 0.021 requires flows ~280 cfs and a  *50 of 0.03 requires flows >360 cfs, beyond the bounds of the GCSMP survey data. As such, the estimated minimum flow for removing surface fines at both sites is 280 cfs. Extensive mobilization of the coarse substrate at these sites probably only occurs during overbank flooding events of at least 400 to 500 cfs.

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6.1.5 Fraser River from Ranch Creek to Crooked Creek

This segment contains the Fraser below Ranch site. Post-runoff substrate sampling indicated 5% surface fines <2 mm and 16% surface fines < 8 mm. Based on the sediment entrainment analysis, the minimum flow that likely achieves coarse substrate mobilization is

370 cfs at a  *50 value of 0.04. Estimated minimum streamflows that provide surface flushing of fine sediment in the main stem segment just upstream (200 to 280 cfs) are very likely to be adequate for surface flushing in this reach.

6.1.6 Fraser River below Crooked Creek to Granby

The present study did not establish any study sites on the Fraser River main stem below Crooked Creek. Two sites included in the GCSMP (sites F7 and F9) provide data required for a sediment entrainment analysis. No grain-size data are available at site F7; however, available hydraulic data indicate that the highest modeled flow of 213 cfs would transport a d50 of ~40 mm at a  *50 of 0.03 and a d50 of ~58 mm at a  *50 of 0.021. Median grain size is larger than 58 mm both upstream and downstream of this location; therefore, flows greater than the highest flow examined (213 cfs) are necessary to achieve the minimum shear stress associated with effective surface flushing. GCSMP site F9 is located below the canyon segment and both grain-size and hydraulic data are provided in the GCSMP. Based on these data, a flushing flow of 400 cfs as recommended in the GCSMP achieves a shear stress that exceeds the minimum value for surface flushing ( *50 of 0.021 at 200 cfs). For coarse substrate mobilization at this site, we estimate that a minimum flow of 470 to 640 cfs is probably necessary based on the data available in the GCSMP.

6.1.7 Upper Ranch Creek

The Upper Ranch Creek site near the gaging station has a 2 to 4% channel gradient with substantial bedform roughness. During the 2013 runoff, flows at this site exceeded 58 cfs for 4.1 days and 79 cfs for 1.5 days. Post-runoff substrate sampling indicated 5% fines <2 mm and 21% fines <8 mm. Based on the sediment entrainment analysis, the minimum flow likely to initiate motion of the coarse substrate in this steep gradient site is ~55 cfs at a lower bound  *50 value of 0.06. The Lamb et al. (2008) and Bunte predictions of critical dimensionless shear stress for bed motion span a wide range of  *50 values from 0.061 to 0.087. High relative uncertainty is introduced through the estimation of slope due to a complex bed profile and associated bedform roughness. The GCSMP site F-RC1 in this location yielded similar slope and d50 estimates. The

GCSMP recommended a flushing flow of 40 cfs at a  *50 of 0.059.

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6.1.8 Lower Ranch Creek

This study established three study sites (Ranch Angling, Ranch above Meadow, and Ranch below Meadow) on lower Ranch Creek. Sediment entrainment analyses for all three sites produced consistent results that agreed with the flushing flow of 150 cfs recommended in the GCSMP. For the downstream-most site, Ranch below Meadow, the sediment entrainment analysis suggests that a higher flow is required for coarse substrate mobilization; however, this site is potentially affected by a downstream bridge crossing and there is higher confidence in the estimates at the Ranch Angling and Ranch above Meadow sites. Reliable estimates of peak discharge at these sites during the 2013 runoff are not available. The tracer rocks emplaced at the Ranch above Meadow site indicated some marginal movement (1 to 4 ft) downstream despite greater exposure than most other particles on the streambed.

6.1.9 Vasquez Creek

Similar to the Range at Gage site, the Vasquez site has a 2 to 4% channel gradient with substantial thalweg variability and form roughness. During the 2013 runoff, flows at this site exceeded 58 cfs for 7.2 days and 72 cfs for 3.0 days. Pre- vs. post-runoff substrate samples indicated that average % fines <8 mm remained constant at 11 to 12% and % fines <2 mm increased slightly from 2 to 5%. The estimated minimum flow for coarse particle entrainment is bracketed by Lamb et al. (2008) and Bunte predictions of critical dimensionless shear stress spanning a range of  *50 values from 0.065 to 0.097. These values of  *50 correspond to flushing flows of 47 cfs to more than 100 cfs. High relative uncertainty is introduced through the estimation of slope given the complex bed profile and associated bedform roughness. The GCSMP provides hydraulic and substrate data at a nearby site on upper Ranch Creek (F-VC). Our analysis of this information indicates that flushing flow of 50 cfs recommended in the GCSMP for Vasquez Creek only yields a of 0.012, based on their hydraulic outputs.

Further, a minimal  *50 value of 0.021 for flushing lower gradient channels would require Q > 112 cfs according to the GCSMP data, a flow level that is beyond the bounds of their channel survey. Until additional information is available on the characteristics and behavior of various locations in this segment, we tentatively identify a middling value of 70 cfs as reasonably likely to provide coarse substrate mobilization.

6.1.10 St. Louis Creek

Both pre- and post-runoff substrate surveys indicated that St. Louis Creek contained very high levels of sand and very fine gravel. Average estimates (pebble count and fines survey) of pre- vs. post-runoff % fines <2 mm were 41% and 23%, respectively; and pre- vs. post-runoff % fines <8 mm were 43% and 34%, respectively. Although there were consistent reductions in fine sediment after the 2013 runoff, the extent of fine sediment remained at a level that is detrimental to aquatic life despite nearly 7 days of flow exceeding 95 cfs according to the USGS gage. At

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present, it is not possible to ascertain whether sediment supply in 2013 was representative of typical conditions, given the episodic nature of sediment delivery and the presence of beaver activity in upstream reaches. The sediment entrainment analysis indicates that likely minimum values of flushing flows for coarse particle entrainment are in the range of 70 to 90 cfs.

However, the grain-size distribution and estimate of d50 is highly influenced by the prevalence of very fine gravel remaining in the streambed after runoff. For example, if the grain-size distribution is truncated at 8 mm, as is commonly done in studies of spawning habitat (e.g.,

Burke et al. (2006)), the d50 increases 48% from 54 to 80 mm. Given that critical shear stress for coarse substrate mobilization scales linearly with the estimated d50, it follows that a higher discharge would be necessary for coarse particle entrainment when the fine sediments accumulated in this reach have been more effectively evacuated. The GCSMP includes substrate and hydraulic outputs for site F-StL and thereby provides another line of evidence. Based on the GCSMP site information for F-StL, St. Louis Creek achieves the minimum shear stress for coarse substrate entrainment at a flow of 100 cfs. Given this additional evidence and the lack of effective flushing in 2013, we tentatively identify a flow of 100 cfs as a minimum value for achieving coarse substrate mobilization. If sediment delivery in 2013 was indeed representative of normal conditions, a flushing flow of 100 cfs may prove insufficient based on the post-runoff substrate characteristics we observed in the field.

6.2 Synthesis across Sites

Based on the evidence described above for each segment, the flushing flows summarized in Table 6.2 are, in our judgment, the most probable estimates of minimum average daily streamflow required for coarse substrate mobilization and flushing surface veneers of fine sediment. Flushing flows identified in this study are, in some instances, higher than the GCSMP recommendations because sediment entrainment analyses indicate that some of the GCSMP values have a low probability of providing substantial surface flushing and/or coarse substrate mobilization. Given that the short duration peaks recorded by USGS in 2013 approached some of these magnitudes, it is important to note that although appreciable surface flushing was observed at some sites, we did not obtain conclusive evidence of widespread coarse substrate mobilization in 2013. Hence, the coarse substrate mobilization flows should be regarded as likely minimum values as described throughout this report.

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Table 6.2. Estimates of minimum average daily flows required for coarse substrate mobilization and flushing surface veneers of fine sediment. Minimum average daily flows for superficial flushing of the river bed are only provided for Fraser River main stem sites with bed slope <1%. Surface flushing flows are recommended for every year. The recommended minimum frequency for coarse substrate mobilization flows is every other year (2-year return period over long-term average). Flushing flow magnitudes are compared to values recommended in the GCSMP.

Fraser below Diversion to 100 – 80 Vasquez Creek

Fraser between Vasquez Creek 200 200 – and St. Louis Creek

Fraser River between St. Louis – 280 200 Creek and Ranch Creek

Fraser River between Ranch 370 280 – Creek and Crooked Creek Fraser River between Crooked 470-640 400 400 Creek and Granby

Upper Ranch Creek 55 – 40

Lower Ranch Creek 150 – 150

Vasquez Creek 70 – 50

St. Louis Creek 100 – 70

6.3 Frequency and Duration of Flushing Flows

Implementation of flushing flows necessitates specification of a target frequency and duration. We considered two interrelated lines of evidence with respect to frequency: 1) return periods of high flows to which regional river biota are adapted and 2) the reproductive cycles of trout and aquatic insects. Previous studies of numerous Colorado snowmelt rivers with gravel beds (Andrews, 1984), as well as similar systems in the western U.S. (Emmett and Wolman, 2001) indicate that events which transport appreciable amounts of coarse bed material tend to occur with a return period of less than 2 years in the annual maximum series. Regional river biota (non-native trout not withstanding) have adapted over long time scales to this inter-annual pattern of high flow. Numerous studies also indicate that the non-native trout species that

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dominate the Fraser River and its tributaries depend on high flows that provide suitable habitat conditions as in their native range (Waters, 1995). Recent research conducted in comparable river segments downstream of our study area has clearly documented habitat degradation and negative impacts to aquatic life in the absence of flushing flows (Nehring et al., 2011).

Given that trout are a highly-valued amenity and primary indicator of ecological health in the Fraser River, maintenance of their food base is an important consideration. Trout depend on aquatic insects at all life stages from rearing to death, and production of aquatic insects depends on the quantity and quality of habitat available in the river substrate. Most of the aquatic insects that support the trout fishery in the Fraser River reproduce one or more times per year (Ward and Kondratieff, 1992). As such, current scientific understanding of the ecology of these systems indicates that providing an annual high-flow spate capable of at least flushing surface deposits of fine sediment is a logical precautionary measure.

Widespread mobilization of the coarse fractions of the river bed is a somewhat less frequent occurrence (approximately 2 out of 3 years to 3 out of 4 years) in low-gradient segments of undepleted Rocky Mountain streams and rivers (Emmett and Wolman, 2001). Coarse substrate mobilization may occur less frequently in channels with gradients exceeding 2 to 3%, especially for the relatively coarse materials that form step-like features (Grant et al., 1990; Wohl, 2010). From a biological standpoint, trout reproduction varies considerably from year to year and population maintenance does not require high levels of recruitment every year; however, trout populations in the Fraser River do depend on a substantial recruitment event approximately every 3 years (Kurt Fausch, Professor, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, pers. comm.). Although substrate quality is a critical limiting factor in trout reproduction, other factors such as late summer temperatures can limit recruitment, even when other habitat characteristics are adequate. It follows that a high flow that at least partially cleans interstices in the river bed every 2 years on average, increases the likelihood that the multiple factors supporting reproduction of both trout and aquatic insects are synchronized and maintained over decadal and longer time scales, especially in the middle and lower sections of the Fraser River and Ranch Creek. In practice, an effective flushing event on a strict interval of every other year is not likely to be feasible under the current management infrastructure given inter-annual variability and the inevitability of multi-year dry spells. Accordingly, an average return period of 2 years is a reasonable target over time. Assessing the feasibility achieving this frequency is beyond the scope of this effort.

Specifying the appropriate duration of a flushing flow without some knowledge of inflowing sediment regime is extremely challenging (Wilcock, 1998). Longer flows generally increase the area of the river bed that is mobilized until it asymptotically reaches a limit at long duration. However, extended durations may be counterproductive in systems that lack vegetation reinforcement along streambanks in locations that are vulnerable to toe erosion. In the case of the Fraser River and its tributaries, we must recommend a heuristic approach based on the commonly cited duration of 3 days as a starting point. This duration means that the target

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flushing flow is exceeded for 72 hours (consecutive or non-consecutive) or for 3 days of average daily flow (consecutive or non-consecutive) in a year. There is some support for this duration given our observations of appreciable surface flushing at multiple study sites with 3 cumulative days near recommended high flows during the 2013 runoff. Flushing flow durations of 3 consecutive days with ramping rates comparable to snowmelt hydrographs of less-altered analog systems in the region would be most representative of the conditions to which native aquatic and riparian species in the Fraser River are adapted.

6.4 Key Uncertainties

Key uncertainties in this study include the selection of critical dimensionless shear stress values across a fairly broad range of channel slopes. It is scientifically well-established that  *c values increase with increasing stream gradient; however, when faced with competing estimates of  *c as affected by slope (Lamb et al., 2008; Ferguson, 2012; Bunte et al., 2010) we chose values at the low end of the range as “minimum” estimates of the flows providing coarse substrate mobilization. It is important to recognize, as described in the Background section of this report, coarse substrate mobilization is not an “all or nothing” phenomenon that operates like a switch. Instead, it is a continuous process in which increasing areas of the river bed become activated and flush as flow increases. It is also scientifically well-established that flows beyond the minimum for flushing translate to increasing benefits that include algae scouring, flushing of relatively-shallow sections of the channel such as the tops of bars and channel margins, and providing moisture required by riparian vegetation. As such, the provision of minimum flushing flows is a means of reducing impacts as opposed to avoiding impacts.

Hydraulic variables used in one-dimensional (1-D) sediment entrainment analyses represent channel cross-sectional geometry with average values. In natural channels like those surveyed in this study, cross sections tend to be irregular and topographically complex. As such, it is inevitable that even the most accurate estimates of flushing flows will not achieve a particular management goal at all locations in the river corridor. What is important is that the objective is achieved at enough locations to maintain valued amenities. Assessing the extent to which the management objectives are achieved, necessitates a field-based, long-term effort. Characterization of the river substrate also introduces uncertainty, despite the fact that the river- bed surveys performed in this study included over 600 observations of the substrate for each sampling event at each site. Variable estimates of d50 arise when the extent of fine sediments change over time. In this study, fine and very fine gravel remaining after runoff were included in the calculation of d50. We examined sensitivity of entrainment estimates to the amount of sediments finer than 8 mm at each site and found that the relatively high levels of fine and very fine gravel stored at some locations substantially reduced estimates of d50 and the flows required to mobilize it. These analyses suggest that substrate sampling conducted during periods of

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reduced storage of sand and fine gravel or truncation of the fines

<8 mm could substantially increase estimates of d50 and, therefore, the flushing flow required for its mobilization. Similarly, current sediment-transport theory has established that a sand matrix can reduce the critical shear stress required for mobilization of gravel in low-gradient channels (Wilcock and Kenworthy, 2002). However, it would be irrational from an ecological standpoint to manage a system for high sand content in order to facilitate occasional coarse substrate mobilization. The high levels of very fine gravel remaining after runoff at some sites warrant additional consideration with respect to biological implications (e.g., emergence of trout fry), and effects on the mobility of coarser particles in the river bed.

Future sediment supply is another important consideration and uncertainty. A sedimentation basin, constructed on the Fraser River main stem upstream of Winter Park, has altered downstream delivery of coarse and fine sediments; however, river reaches downstream of the basin (e.g., Fraser River at Winter Park gage) are likely to continue to receive inputs of sand and fine gravel from existing valley storage for at least the next few decades. Fine sediment inputs are reestablished below major tributaries including Vasquez, St. Louis, and Ranch Creeks. As such, the sediment basin does not eliminate the risk of fine sediment accumulation in downstream segments and vulnerability to sedimentation remains a risk, especially given the potential for episodic sediment delivery as a result of fire and other watershed disturbances.

6.5 Management Implications

Despite the aforementioned uncertainties, we estimate with confidence that implementing the flushing flows identified in this study for mobilizing coarse substrates would reduce the extent of fine sediment deposition and accumulated algae, as well as decrease the likelihood that physical habitat will continue to degrade to a level that produces additional, detectable biological impacts. In the absence of flushing flows, existing physical habitat will be negatively affected in the future, as the river channel and its substrate characteristics (e.g., interstices clogged with fine sediment, amount of algae) evolve with ongoing changes in water management. This response is likely to occur irrespective of in-stream flows because such low flows are incapable of rejuvenating the river bed to maintain habitats required for trout reproduction and aquatic insects.

This study and previous analyses (GCSMP, 2010; Bledsoe and Beeby, 2012) collectively indicate that the frequency and effectiveness of flows that flush fine sediment and rejuvenate river-bed habitats required by trout and their food base are substantially reduced in the Moffat Collection System Project Alt 1a flow scenario compared to the Current Conditions scenario. The weight-of-evidence from field observations, previous analyses of effective discharges, and sediment entrainment analyses indicates that fine sediment aggradation and concomitant effects on aquatic habitat would be exacerbated under the current sediment supply by additional depletions of the flushing flows identified in this study for maintaining sediment sizes on the bed

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and their mobility. Further reductions in the frequency and duration of flushing flows would reduce the availability of clean substrates for trout spawning and production of aquatic insects.

6.6 Enhancing Predictive Ability in the Future

The sediment entrainment analyses performed in this study are a rational and physically- based approach for quantifying substrate maintenance flows. Nevertheless, as with the hydrologic models and population projections used to evaluate future streamflow yield and demand scenarios, models of river response to streamflow change will always be imperfect representations of reality with associated uncertainty in their predictions. Decision-makers must weigh a variety of stakeholder interests and the ecological, economic, and societal consequences associated with all policy options in an atmosphere of uncertainty, whether acknowledged or otherwise. Probabilistic scientific predictions like those provided in this study can provide a more rational and transparent basis for prediction and decision-making by explicitly recognizing uncertainty and helping policy-makers understand the likely consequences of policy choices.

The uncertainty inherent to environmental impact assessment and environmental flow management underscores the need for carefully-designed monitoring and adaptive management programs. Experimental bypass flows can be useful in evaluating the accuracy of entrainment based estimates of flushing flow effectiveness. The key is that flushing flow objectives be clearly defined with respect to specific physical changes in the stream channel so that costs, constraints and tradeoffs can be evaluated over time (Kondolf and Wilcock, 1996).

The ideal approach to flushing flow quantification is to integrate the best available scientific information with both a mechanistic understanding of the system and careful field calibration in an overall framework of “learning by doing.” Despite the physical basis of the approach used in this study, our transparent analysis of uncertainty indicates a need for field testing aimed at further refinement and calibration. A number of field methods that were not feasible given the time and resource constraints imposed on this study are available for directly measuring scour depths and interstitial removal of fine sediments from gravel/cobble river beds. For example, river-bed scour and flushing have been measured in situ with scour chains (e.g., Emmett and Leopold (1965), Lisle (1989), Haschenberger (1999), and Bigelow (2005)), sliding-ball monitors (Klassen and Northcote, 1986; Tripp and Poulin, 1986; Nawa and Frissell, 1993), and accelerometers (Gendaszek et al., 2013). Direct measurement of scour processes over multiple runoff years in a “learning by doing” approach could provide more accurate calibration of flushing flows to inform decision-making.

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CHAPTER 7

CONCLUSIONS

The importance of moderate to high streamflows in maintaining aquatic and riparian ecosystems is well-established (Poff et al., 1997; Bunn and Arthington, 2002; Poff and Zimmerman, 2010). River substrate conditions, a major determinant of aquatic insect communities and fish reproduction, are primarily controlled by moderate to high streamflows. Post-development streamflow depletions in the Fraser River watershed have increased the risk of habitat degradation associated with sediment deposition and clogging of the river bed. The proposed Moffat Collection System Project could further alter the capacity of the Fraser River and its tributaries to flush fine sediment and maintain physical habitat for fishes and aquatic insects.

This study evaluated flushing flows that control the size and arrangement of sediment particles comprising the river bed in the Fraser River and three of its major tributaries. The results of this study and the previous study by Bledsoe and Beeby (2012) indicate that projected future changes in streamflow (Current vs. Alt 1a scenarios for the Moffat Collection System Project) would result in substantially-reduced frequencies and effectiveness of the flows that flush surface accumulations of fine sediment as well as the levels of streamflow that open interstitial space in the river bed required by trout and their food base.

Field reconnaissance performed in this study revealed substantial physical heterogeneity along the river corridor. Despite this longitudinal variability, there is general convergence between this study and the flushing flow recommendations provided in the Grand County Stream Management Plan. We estimate with confidence that implementation of the flushing flows identified in this study would reduce the extent of fine sediment deposition and accumulated algae, as well as decrease the likelihood that physical habitat will continue to degrade to a level that produces additional, detectable biological impacts. In the absence of flushing flows, existing physical habitat will be negatively affected in the future as the river channel and its substrate characteristics (e.g., extent of interstices clogged with fine sediment, amount of algae) evolve with ongoing changes in water management. This response is likely to occur irrespective of base flows for fish habitat because such low flows are incapable of rejuvenating the river bed to maintain habitats required for trout reproduction and aquatic insects.

The sediment entrainment analyses performed in this study are a rational and physically- based approach for quantifying substrate maintenance flows in the absence of a thorough field calibration. The uncertainty analysis of flushing flow estimates underscores the need for carefully-designed monitoring and adaptive management programs. Experimental bypass flows

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and direct field measurements of scour are recommended for calibration and evaluating the accuracy of estimated flushing flow effects.

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LITERATURE CITED

Andrews, E. D. (1983). Entrainment of gravel from naturally sorted riverbed material. The Geological Society of America Bulletin 94(10):1225–1231, DOI: 10.1130/0016- 7606(1983)94<1225:EOGFNS>2.0.CO;2. Andrews, E. D. (1984). Bed-material entrainment and hydraulic geometry of gravel-bed rivers in Colorado. Geological Society of America Bulletin 95(3):371–378, DOI: 10.1130/0016- 7606(1984)95<371:BEAHGO>2.0.CO;2. Andrews, E. D., and J. M. Nankervis (1995). Effective discharge and the design of channel maintenance flows for gravel-bed rivers. Geophysical Monograph 89 (Pages 151–164) in Natural and Anthropogenic Influences in Fluvial Geomorphology, J. E. Costa, A. J. Miller, K. W. Potter, and P. R. Wilcock (Eds.), American Geophysical Union, 239 p. Annear, T., I. Chisholm, H. Beecher, A. Locke, P. Aarrestad, N. Burkhart, C. Coomer, C. Estes, J. Hunt, R. Jacobson, G. Jobsis, J. Kauffman, J. Marshall, K. Mayes, C. Stalnaker, and R. Wentworth (2004). Instream Flows for Riverine Resource Stewardship. Revised Edition; Cheyenne, WY: Instream Flow Council; 268 p. Arcement, Jr., G. J., and V. R. Schneider (1989). Guide for Selecting Manning’s Roughness Coefficients for Natural Channels and Flood Plains. U. S Geological Survey Water- Supply Paper 2339; Denver, CO: USGS; 38 p. Beschta, R. L., and W. L. Jackson (1979). The intrusion of fine sediments into a stable gravel bed. Journal of the Fisheries Research Board of Canada 36(2):207–210, DOI: 10.1139/f79-030. Bigelow, P. E. (2005). Testing and improving predictions of scour and fill depths in a northern California coastal stream. River Research and Applications 21(8):909–923, DOI: DOI: 10.1002/rra.863. Bledsoe, B. P., and J. Beeby (2012). Sedimentation Processes and Effects in the Fraser River and Its Tributaries. CSU Technical Report prepared for Trout Unlimited, Winter Park, CO, June, 52 p. Buffington, J. M., and D. R. Montgomery (1997). A systematic analysis of eight decades of incipient motion studies, with special reference to gravel-bedded rivers. Water Resources Research 33(8):1993–2029, DOI: 10.1029/96WR03190. Bunn, S. E., and A. H. Arthington (2002). Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management 30(4):492– 507, DOI: 10.1007/s00267-002-2737-0. Bunte, K., and S. R. Abt (2001). Sampling Surface and Subsurface Particle-size Distributions in Wadable Gravel and Cobble Bed Streams for Analyses in Sediment Transport, Hydraulics, and Streambed Monitoring. General Technical Report RMRS-GTR-74; Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station; 428 p.

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Bunte, K., S. R. Abt, K. W. Swingle, and J. P. Potyondy (2010). Bankfull mobile particle size and its prediction from a Shields-type approach. 2nd Joint Federal Interagency Conference, Las Vegas, NV, June 27 – July 1; URL: http://acwi.gov/sos/pubs/2ndJFIC/ Contents/4B_Bunte_03_ 01_10_paper.pdf. Bunte, K., J. P. Potyondy, K. W. Swingle, and S. R. Abt (2012). Spatial variability of pool-tail fines in mountain gravel-bed stream affects grid-count results. Journal of American Water Resources Association 48(3):530–545, DOI: 10.1111/j.1752-1688.2011.00629.x. Burke, M., K. Jorde, J. M. Buffington, J. H. Braatne, and R. Benjankar (2006). Spatial distribution of impacts to channel bed mobility due to flow regulation, Kootenai River, USA. In: Proceedings of the Eighth Federal Interagency Sedimentation Conference, Reno, NV, April 2–6, 9 p. Capesius, J. P., and V. C. Stephens (2009). Regional Regression Equations for Estimation of Natural Streamflow Statistics in Colorado. U. S. Geological Survey Scientific- Investigations Report 2009-5136, 46 p. Denver Post (2010). Agencies agree to tackle problem of traction-sand deposits in Fraser River by B. Finley. URL: http://www.denverpost.com/search/ci_16613779 (accessed June 2012). Diplas, P., and G. Parker (1985). Pollution of Gravel Spawning Grounds Due to Fine Sediment. St. Anthony Falls Hydraulic Laboratory Project Reports 240, University of Minnesota, Minneapolis, MN, 390 p., URL: http://purl.umn.edu/113315. Emmett, W. W., and L. B. Leopold (1965). Downstream patterns of riverbed scour and fill. Pages 399–409 in Proceedings of the Federal Inter-Agency Sedimentation Conference, Vol. 1, 963, Misc. USDA, 970 p. Emmett, W. W., and M. G. Wolman (2001). Effective discharge and gravel-bed rivers. Earth Surface Processes and Landforms 26(13):1369–1380, DOI: 10.1002/esp.303. Ferguson, R. I. (2012). River channel slope, flow resistance, and gravel entrainment thresholds. Water Resources Research 48(5), W05517, DOI: 10.1029/2011WR010850. Fitzpatrick, F. A., I. R. Waite, P. J. D’Arconte, M. R. Meador, M. A. Maupin, and M. E. Gurtz (1998). Revised Methods for Characterizing Stream Habitat in the National Water- Quality Assessment Program. Water-Resources Investigations Report 98-4052; Raleigh, NC: U. S. Geological Survey. Gendaszek, A. S., C. S. Magirl, C. R. Czuba, and C. P. Konrad (2013). The timing of scour and fill in a gravel-bedded river measured with buried accelerometers. Journal of Hydrology 495:186–196, DOI: 10.1016/j.jhydrol.2013.05.012. Grand County Stream Management Plan (GCSMP) (2010). Draft Report, Stream Management Plan, Phase 3, Grand County, Colorado. Report and Appendices, Draft Report prepared for Grand County, Colorado, August, 37 p., URL: http://co.grand.co.us/WRM/ Draft_Report/draft.html including appendices. Grant, G. E., F. J. Swanson, and M. G. Wolman (1990). Pattern and origin of stepped-bed morphology in high-gradient streams, Western Cascades, Oregon. The Geological Society

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of America Bulletin 102(3):340–352, DOI: 10.1130/0016-7606(1990)102< 0340:PAOOSB >2.3.CO;2. Haschenburger, J. K. (1999). A probability model of scour and fill depths in gravel-bed channels. Water Resources Research 35(9):2857–2869, DOI: 10.1029/1999WR900153. Hicks, D. M., and P. D. Mason (1999). Roughness Characteristics of New Zealand Rivers. Water Resources Publications LLC; ISBN 0-477-026008-7, 336 p. Hurst, B. E. (2005). Conditional Probability Approach for Assessing Fine Sediment Impacts on Aquatic Insects with Consideration of Hydrogeomorphic Context. Unpublished M.S. Thesis, Colorado State University, Department of Civil Engineering, Fort Collins, CO. Huryn, A. D., and J. B. Wallace (1987). Local geomorphology as a determinant of macrofaunal production in a mountain stream. Ecology 68(6):1932–1942, DOI: 10.2307/1939884. Jarrett, R. D. (1984). Hydraulics of high-gradient streams. Journal of Hydraulic Engineering 110(11):1519–1539, DOI: 10.1061/(ASCE)0733-9429(1984)110:11(1519). Klassen, H. D., and T. G. Northcote (1986). Stream bed configuration and stability following gabion weir placement to enhance salmonid production in a logged watershed subject to debris torrents. Canadian Journal of Forest Research 16(2):197–203, DOI: 10.1139/x86- 036. Kondolf, G. M., and P. R. Wilcock (1996). The flushing flow problem: defining and evaluating objectives. Water Resources Research 32(8):2589–2599, DOI: 10.1029/96WR00898. Lamb, M. P., W. E. Dietrich, and J. G. Venditti (2008). Is the critical Shields stress for incipient sediment motion dependent on channel-bed slope? Journal of Geophysical Research 113, F02008, DOI:10.1029/2007JF000831. Limerinos, J. T. (1970). Determination of the Manning coefficient from measured bed roughness in natural channels. Geological Survey Water-Supply Paper 1898-B; Washington, DC: U. S. Geological Survey; 47 p. Lisle, T. E. (1989). Sediment transport and resulting deposition in spawning gravels, north coastal California. Water Resources Research 25:1303–1319, DOI: 10.1029/WR025i006 p01303. Milhous, R. T. (1990). Calculation of flushing flows for gravel and cobble bed rivers. Pages 598–603 in Hydraulic Engineering, Proceedings of the 1990 National Conference, H. H. Chang and J. C. Hill (Eds.), Vol. 1; New York, NY: American Society of Civil Engineers. Milhous, R. T. (2000). Numerical modeling of flushing flows in gravel-bed rivers. Chapter 25 (Pages 579–608) in Gravel-Bed Rivers in the Environment, P. C. Klingeman, R. L. Beschta, P. D. Komar, and J. B. Bradley (Eds.); Littleton, CO: Water Resources Publications, LLC; 832 p. Milhous, R. T. (2003). Reconnaissance – Level Application of Physical Habitat Simulation in the Evaluation of Physical Habitat Limits in the Animas Basin, Colorado. U. S. Geological Survey Open File Report 03-222; Fort Collins, CO: Fort Collins Science Center; 16 p.

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Milhous, R.T. (2009). An adaptive assessment of the flushing flow needs of the lower Poudre River, Colorado: first evaluation. Pages 46–56 in Proceedings of the 29th Annual American Geophysical Union Hydrology Days, J. A. Ramirez (Ed.), AGU Hydrology Days, Colorado State University, Fort Collins, CO, March 25-27, 72 p. Natural Resources Conservation Service (NRCS) (2007). Part 654 Stream Restoration Design – National Engineering Handbook. U. S. Department of Agriculture, NRCS eDirectives – Electronic Directive System, August, 1600+ pp. Nawa, R. K., and C. A. Frissell (1993). Measuring scour and fill of gravel streambeds with scour chains and sliding-bead monitors. North American Journal of Fisheries Management 13(3):634–639, 10.1577/1548-8675(1993)013<0634:MSAFOG>2.3.CO;2 Nehring, R. B., B. Heinold, and J. Pomeranz (2011). Colorado River Aquatic Resources Investigations, Federal Aid Project F-237R-18. Job Progress Report; Fort Collins, CO: Colorado Division of Wildlife, Aquatic Wildlife Research Section; June, 96+ pp. Parker, G. (2008). Transport of gravel and sediment mixtures. Chapter 3 (Pages 165–251) in Sedimentation Engineering: Theories, Measurements, Modeling, and Practice (ASCE Manuals and Reports on Engineering Practice No. 110), M. H. Garcia (Ed.); New York, NY: American Society of Civil Engineers; 1150 p., DOI: 10.1061/9780784408148.ch03. Petrie, J., and P. Diplas (2000). Statistical approach to sediment sampling accuracy. Water Resources Research 36(2):597–605, DOI: 10.1029/1999WR900321. Petts, G. E. (1996). Water allocation to protect river ecosystems. Regulated Rivers: Research and Management 12(4–5):353–365, DOI: 10.1002/(SICI)1099-1646(199607)12:4/5<353:: AID-RRR425>3.0.CO;2-6. Platts, W. S., W. F. Megahan, and W. G. Minshall (1983). Methods for Evaluating Stream, Riparian, and Biotic Conditions. General Technical Report INT-138; Ogden, UT: U. S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. Poff, N. L., J. D. Allan, M. B. Bain, J. R. Karr, K. L. Prestegaard, B. D. Richter, R. E. Sparks, and J. C. Stromberg (1997). The natural flow regime. BioScience 47(11):769–784, URL: http://www.jstor.org/stable/1313099. Poff, N. L., and J. K. H. Zimmerman (2010). Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows. Freshwater Biology 55:194–205, DOI: 10.1111/j.1365-2427.2009.02272.x. Reiser, D. W., M. P. Ramey, and T. R. Lambert (1985). Review of flushing flow requirements in regulated streams. San Francisco, CA: Bechtel Group. Reiser, D. W., M. P. Ramey, and T. A. Wesche (1990). Flushing flows. Chapter 4 (Pages 91– 135) in Alternatives in Regulated River Management, J. A. Gore and G. E. Petts (Eds.); Boca Raton, FL: CRC Press, Inc.; 360 p. Rice, S. (1995). The spatial variation and routine sampling of spawning gravels in small coastal streams. Working Paper 06/1995; Victoria, BC: Research Branch, British Columbia Ministry of Forests; 41 pp.

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Rice, S. P., M. T. Greenwood, and C. B. Joyce (2001). Tributaries, sediment sources, and the longitudinal organisation of macroinvertebrate fauna along river systems. Canadian Journal of Fisheries and Aquatic Sciences 58:824–840, DOI: 10.1139/f01-022. Soar, P. J., and C. R. Thorne (2001). Channel Restoration Design for Meandering Rivers. Technical Report No. ERDC/CHL CR-01-1; Vicksburg, MS: U. S. Army Corps of Engineers, Engineer Research and Development Center, Coastal and Hydraulics Laboratory; September, 437 p. Suttle, K. B., M. E. Power, J. M. Levine, and C. McNeely (2004). How fine sediment in riverbeds impairs growth and survival of juvenile salmonids. Ecological Applications 14:969–974, DOI: 10.1890/03-5190. Tetra Tech, HabiTech, Inc., and Walsh Aquatic, Inc. (2010). Draft Report, Stream Management Plan, Phase 3, Grand County, Colorado. Report prepared for Grand County, Colorado, with support from Denver Water and Northern Colorado Water Conservancy District, August, 29 p. Tripp, D. B., and V. A. Poulin (1986). The Effects of Logging and Mass Wasting on Salmonid Spawning Habitat in Streams on the Queen Charlotte Islands, Land Manage. Report 50; Victoria, BC: British Columbia Ministry of Forest Lands; 29 pp. Ward, J. V., and B. C. Kondratieff (1992). An Illustrated Guide to the Mountain Stream Insects of Colorado. Niwot, CO: University Press of Colorado; ISBN 08-708-12602 and ISBN 08-708-12610, 191 p. Waters, T. F. (1995). Sediment in Streams: Sources, Biological Effects, and Control. American Fisheries Society, Monograph Series, Monograph 7, 251 p. Whiting, P. J. (2002). Streamflow necessary for environmental maintenance. Annual Review of Earth and Planetary Sciences 30:181–206, DOI: 10.1146/annurev.earth.30. 083001.161748. Wilcock, P. R. (1998). Sediment maintenance flows: feasibility and basis for prescription. Chapter 26 (Pages 609–638) in Gravel-Bed Rivers in the Environment, P. C. Klingeman, R. L. Beschta, P. D. Komar, and J. B. Bradley (Eds.); Highlands Ranch, CO: Water Resources Publications, LLC. Wilcock, P. R., and S. T. Kenworthy (2002). A two-fraction model for the transport of sand/gravel mixtures. Water Resources Research 38(10), 1194, DOI: 10.1029/2001WR000684. Wohl, E. (2010). Mountain Rivers Revisited. Water Resources Monograph Series, Vol. 19; Washington, DC: American Geophysical Union; ISSN: 0170-9600, ISBN: 978-0-87590- 323-1, 573 p., DOI: 10.1029/WM019. Yochum, S. E., B. P. Bledsoe, G. C. L. David, and E. E. Wohl (2012). Velocity prediction in high-gradient channels. Journal of Hydrology 424–425:84–98, DOI: 10.1016/j.jhydrol. 2011.12.031.

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APPENDIX A

CROSS SECTIONS OF STUDY SITES

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Figure A.1. Fraser Highway 40 cross section, plotted facing upstream.

Figure A.2. Fraser Robbers cross section, plotted facing upstream.

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Figure A.3. Fraser above Diversion cross section, plotted facing upstream.

Figure A.4. Fraser below Diversion cross section, plotted facing upstream.

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Figure A.5. Fraser Winter Park Gage cross section, plotted facing upstream.

Figure A.6. Fraser below Vasquez cross section, plotted facing upstream.

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Figure A.7. Fraser Rendezvous cross section, plotted facing upstream.

Figure A.8. Fraser Open Space cross section, plotted facing upstream.

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Figure A.9. Fraser Angling cross section, plotted facing upstream.

Figure A.10. Fraser below Ranch cross section, plotted facing upstream.

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Figure A.11. Ranch at Gage cross section, plotted facing upstream.

Figure A.12. Ranch Angling cross section, plotted facing upstream.

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Figure A.13. Ranch above Meadow cross section, plotted facing upstream.

Figure A.14. Ranch below Meadow cross section, plotted facing upstream.

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Figure A.15. Vasquez cross section, plotted facing upstream.

Figure A.16. St. Louis Gage cross section, plotted facing upstream.

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APPENDIX B

HYDRAULIC DATA USED TO CALCULATE AT-A-STATION HYDRAULIC GEOMETRY

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Table B.1. Hydraulic data for the Fraser Highway 40 site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4988.91 0.8 0.0 4993.31 16.0 270.5 4989.01 1.5 0.1 4993.41 16.2 283.1 4989.11 2.2 0.4 4993.51 16.5 296.1 4989.21 2.8 0.8 4993.61 16.7 309.5 4989.31 3.4 1.3 4993.71 16.9 323.3 4989.41 4.1 2.1 4993.81 17.1 337.5 4989.51 4.8 3.2 4993.91 17.3 352.2 4989.61 5.4 4.7 4994.01 17.6 367.2 4989.71 5.9 6.5 4994.11 17.8 382.7 4989.81 6.4 8.6 4994.21 18.0 398.6 4989.91 6.8 10.9 4994.31 18.2 415.2 4990.01 7.2 13.5 4994.41 18.4 432.5 4990.11 7.6 16.3 4994.51 18.7 450.1 4990.21 7.9 19.3 4994.61 18.9 468.2 4990.31 8.3 22.7 4994.71 19.1 486.8 4990.41 8.6 26.2 4994.81 19.3 505.7 4990.51 9.0 30.1 4994.91 19.6 525.2 4990.61 9.3 34.3 4995.01 19.8 545.0 4990.71 9.6 38.8 4995.11 20.0 565.3 4990.81 9.9 43.5 4995.21 20.2 586.1 4990.91 10.2 48.6 4995.31 20.5 607.5 4991.01 10.5 54.2 4995.41 20.7 629.4 4991.11 10.8 60.1 4995.51 20.9 651.7 4991.21 11.1 66.5 4995.61 21.1 674.4 4991.31 11.4 73.1 4995.71 21.4 697.7 4991.41 11.7 80.1 4995.81 21.6 721.4 4991.51 11.9 87.4 4995.91 21.8 745.6 4991.61 12.2 94.9 4996.01 22.0 770.2 4991.71 12.5 102.8 4996.11 22.3 795.4 4991.81 12.7 111.0 4996.21 22.5 821.0 4991.91 12.9 119.4 4996.31 22.7 847.1 4992.01 13.2 128.2 4996.41 22.9 873.7 4992.11 13.4 137.3 4996.51 23.1 900.9 4992.21 13.6 146.7 4996.61 23.4 928.7 4992.31 13.9 156.4 4996.71 23.6 956.9 4992.41 14.1 166.5 4996.81 23.8 985.7 4992.51 14.3 176.9 4996.91 24.0 1011.7 4992.61 14.5 187.6 4997.01 24.3 1037.9 4992.71 14.8 198.6 4997.11 24.5 1064.6 4992.81 15.0 209.9 4997.21 24.7 1092.1 4992.91 15.2 221.6 4997.31 24.9 1120.1 4993.01 15.4 233.6 4997.41 25.2 1148.8 4993.11 15.6 246.0 4997.51 25.4 1178.2 4993.21 15.8 258.3 4997.61 25.7 1208.2

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Water Surface Effective Elevation Width Q (ft) (ft) (cfs) 4997.71 26.0 1070.8 4997.81 26.4 1109.0 4997.91 26.8 1148.0 4998.01 27.2 1187.9 4998.11 27.6 1228.8 4998.21 28.0 1270.8 4998.31 28.4 1313.7 4998.41 28.8 1357.5 4998.51 29.2 1402.1 4998.61 29.6 1445.4 4998.71 30.0 1475.5

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Table B.2. Hydraulic data for the Fraser Table B.3. Hydraulic data for the Fraser Robbers site. above Diversion site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4995.54 2.0 0.1 4996.76 2.7 0.1 4995.64 3.4 0.4 4996.86 5.2 0.4 4995.74 6.0 1.5 4996.96 7.1 1.3 4995.84 7.6 3.1 4997.06 8.4 2.7 4995.94 8.9 5.1 4997.16 9.4 4.5 4996.04 9.9 7.8 4997.26 10.3 6.7 4996.14 10.8 10.9 4997.36 11.0 9.3 4996.24 11.5 14.8 4997.46 11.7 12.3 4996.34 12.2 19.1 4997.56 12.4 15.8 4996.44 12.8 23.8 4997.66 13.0 20.1 4996.54 13.3 29.0 4997.76 13.6 25.3 4996.64 13.9 35.3 4997.86 14.2 31.3 4996.74 14.4 41.1 4997.96 14.8 38.1 4996.84 15.1 45.8 4998.06 15.3 45.5 4996.94 15.9 51.8 4998.16 15.8 53.7 4997.04 16.8 59.2 4998.26 16.3 62.5 4997.14 17.7 69.7 4998.36 16.8 71.8 4997.24 18.6 81.0 4998.46 17.3 81.7 4997.34 19.7 87.8 4998.56 17.8 92.4 4997.44 20.9 104.9 4998.66 18.3 103.3 4997.54 22.0 123.4 4998.76 18.8 114.7 4997.64 23.1 142.2 4998.86 19.3 128.1 4997.74 24.1 159.5 4998.96 19.9 142.8

4999.06 20.3 158.3 4999.16 20.8 174.7 4999.26 21.3 192.0 4999.36 21.8 192.8 4999.46 22.5 190.5 4999.56 23.5 181.4 4999.66 25.0 178.0 4999.76 26.7 200.7 4999.86 28.5 227.2

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Table B.4. Hydraulic data for the Fraser below Diversion site.

Water Surface Effective Elevation Width Q (ft) (ft) (cfs) 4996.30 1.3 0.0 4996.40 2.4 0.3 4996.50 2.9 0.7 4996.60 3.5 1.3 4996.70 4.5 2.3 4996.80 5.4 3.9 4996.90 6.2 5.9 4997.00 6.9 8.4 4997.10 7.5 11.3 4997.20 8.0 15.1 4997.30 8.4 18.7 4997.40 8.9 22.7 4997.50 9.4 28.3 4997.60 9.9 34.5 4997.70 10.3 41.2 4997.80 10.8 48.0 4997.90 11.2 54.8 4998.00 11.7 62.3 4998.10 12.2 70.9 4998.20 12.7 80.7 4998.30 13.2 85.0 4998.40 13.9 92.3

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Table B.5. Hydraulic data for the Fraser Winter Park Gage site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4995.60 1.0 0.0 4998.40 20.2 207.7 4995.70 1.9 0.2 4998.50 20.6 227.6 4995.80 2.6 0.6 4998.60 21.1 248.7 4995.90 3.2 1.1 4998.70 21.5 271.1 4996.00 4.1 1.8 4998.80 22.0 294.4 4996.10 5.4 3.0 4998.90 22.4 318.8 4996.20 6.6 5.2 4999.00 22.8 344.1 4996.30 7.7 7.8 4999.10 23.2 370.4 4996.40 8.7 10.8 4999.20 23.6 397.8 4996.50 9.7 14.7 4999.30 24.0 427.2 4996.60 10.5 19.2 4999.40 24.4 457.5 4996.70 11.3 24.3 4999.50 24.8 489.0 4996.80 12.0 30.1 4999.60 25.1 522.2 4996.90 12.6 36.4 4999.70 25.5 556.4 4997.00 13.2 43.2 4999.80 25.8 591.5 4997.10 13.7 50.6 4999.90 26.2 627.7 4997.20 14.2 58.4 5000.00 26.5 664.9 4997.30 14.7 66.7 5000.10 26.8 702.6 4997.40 15.2 74.2 5000.20 27.2 740.3 4997.50 15.7 82.0 5000.30 27.5 779.1 4997.60 16.2 91.8 5000.40 27.8 818.8 4997.70 16.7 101.9 5000.50 28.1 859.6 4997.80 17.2 112.8 5000.60 28.4 901.4 4997.90 17.7 124.8 5000.70 28.7 944.1 4998.00 18.2 138.6 5000.80 29.0 987.9 4998.10 18.7 153.6 5000.90 29.3 1032.8 4998.20 19.2 170.7 4998.30 19.7 188.7

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Table B.6. Hydraulic data for the Fraser Table B.7. Hydraulic data for the Fraser below Vasquez site. Rendezvous site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4996.36 2.1 0.1 4995.46 3.4 0.1 4996.46 5.9 0.7 4995.56 5.3 0.5 4996.56 7.8 2.0 4995.66 6.7 1.3 4996.66 8.9 3.8 4995.76 7.8 2.6 4996.76 9.7 6.2 4995.86 8.8 4.3 4996.86 10.4 9.0 4995.96 10.1 5.9 4996.96 11.0 12.4 4996.06 11.4 8.7 4997.06 11.5 16.2 4996.16 12.7 12.3 4997.16 12.0 19.9 4996.26 14.0 16.1 4997.26 12.7 23.9 4996.36 15.2 21.5 4997.36 13.3 29.8 4996.46 16.2 27.6 4997.46 13.8 36.2 4996.56 17.2 34.5 4997.56 14.3 43.2 4996.66 18.1 42.1 4997.66 14.8 50.7 4996.76 18.9 50.5 4997.76 15.2 58.7 4996.86 19.6 61.1 4997.86 15.7 67.3 4996.96 20.3 73.5 4997.96 16.1 72.0 4997.06 20.9 86.8 4998.06 16.6 82.1 4997.16 21.4 101.1 4998.16 17.1 92.5 4997.26 21.9 116.2 4998.26 17.6 103.7 4997.36 22.3 132.2 4998.36 18.1 115.4 4997.46 22.8 148.2 4998.46 18.5 127.3 4997.56 23.2 165.1 4998.56 19.0 140.0 4997.66 23.5 182.8 4998.66 19.5 152.9 4997.76 23.9 201.3

4998.76 19.9 169.1 4998.86 20.4 187.6 4998.96 20.8 203.3

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Table B.8. Hydraulic data for the Fraser Table B.9. Hydraulic data for the Fraser Open Space site. Angling site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4997.60 0.6 0.0 4996.74 1.3 0.0 4997.70 1.1 0.1 4996.84 2.4 0.2 4997.80 1.6 0.3 4996.94 6.9 1.6 4997.90 2.9 0.6 4997.04 10.9 3.6 4998.00 4.6 1.5 4997.14 13.8 6.5 4998.10 6.2 2.9 4997.24 16.0 10.1 4998.20 7.8 4.9 4997.34 17.8 14.7 4998.30 9.5 7.4 4997.44 19.3 20.0 4998.40 11.0 11.3 4997.54 20.5 25.9 4998.50 12.5 15.9 4997.64 21.6 32.7 4998.60 13.7 21.2 4997.74 22.5 40.1 4998.70 14.9 27.2 4997.84 23.3 48.2 4998.80 16.0 33.2 4997.94 24.1 57.1 4998.90 17.2 41.2 4998.04 24.7 66.8 4999.00 18.2 50.0 4998.14 25.3 77.0 4999.10 19.2 59.6 4998.24 25.8 87.8 4999.20 20.1 70.0 4998.34 26.2 99.1 4999.30 21.0 81.0 4998.44 26.7 110.7 4999.40 21.8 92.4 4998.54 27.1 122.9 4999.50 22.7 103.4 4998.64 27.5 135.7 4999.60 23.5 115.3 4998.74 27.8 147.1 4999.70 24.4 122.2 4998.84 28.2 158.6 4999.80 25.5 137.9 4998.94 28.7 156.6 4999.90 26.5 154.7 4999.04 29.5 172.3 5000.00 27.5 172.3 4999.14 30.2 186.7 5000.10 28.5 190.8 4999.24 31.1 187.9

4999.34 32.2 193.6 4999.44 33.6 202.9 4999.54 35.1 215.4 4999.64 36.8 231.0 4999.74 38.7 249.5 4999.84 40.7 270.9 4999.94 42.9 294.3 5000.04 45.2 320.5

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Table B.10. Hydraulic data for the Frazer below Ranch site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4983.56 1.0 0.0 4986.16 33.2 190.0 4983.66 2.0 0.1 4986.26 33.7 207.9 4983.76 2.9 0.3 4986.36 34.3 226.6 4983.86 3.8 0.7 4986.46 34.9 246.1 4983.96 4.8 1.1 4986.56 35.4 265.7 4984.06 6.2 2.9 4986.66 35.9 285.8 4984.16 9.2 5.1 4986.76 36.5 306.7 4984.26 11.6 7.9 4986.86 37.0 328.4 4984.36 13.7 11.3 4986.96 37.5 350.8 4984.46 15.5 15.2 4987.06 38.0 372.4 4984.56 17.2 19.6 4987.16 38.5 394.3 4984.66 18.7 24.5 4987.26 39.0 417.0 4984.76 20.1 30.0 4987.36 39.5 440.5 4984.86 21.4 36.1 4987.46 40.1 464.6 4984.96 22.6 42.7 4987.56 40.6 487.8 4985.06 23.8 49.8 4987.66 41.1 512.1 4985.16 24.9 57.5 4987.76 41.7 537.4 4985.26 26.0 66.4 4987.86 42.2 563.7 4985.36 27.1 76.3 4987.96 42.8 591.0 4985.46 28.0 86.7 4988.06 43.4 619.9 4985.56 28.9 97.7 4988.16 44.0 651.8 4985.66 29.7 109.8 4988.26 44.5 684.8 4985.76 30.5 124.1 4988.36 45.1 718.7 4985.86 31.2 139.2 4988.46 45.7 753.6 4985.96 31.9 155.2 4986.06 32.5 172.3

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Table B.11. Hydraulic data for the Table B.12. Hydraulic data for the Ranch Ranch at Gage site. Angling site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4973.30 1.2 0.0 4996.84 1.3 0.0 4973.40 2.3 0.2 4996.94 3.4 0.2 4973.50 3.5 0.5 4997.04 6.1 0.6 4973.60 4.6 1.1 4997.14 9.2 1.5 4973.70 5.5 2.1 4997.24 11.7 2.9 4973.80 6.2 3.3 4997.34 13.7 5.0 4973.90 6.8 4.7 4997.44 15.1 7.5 4974.00 7.4 6.4 4997.54 16.2 10.3 4974.10 7.9 8.4 4997.64 17.0 13.5 4974.20 8.5 10.6 4997.74 17.7 17.1 4974.30 9.0 13.2 4997.84 18.3 20.9 4974.40 9.5 16.2 4997.94 18.8 25.1 4974.50 9.9 19.7 4998.04 19.2 29.5 4974.60 10.4 23.4 4998.14 19.6 34.1 4974.70 10.8 27.5 4998.24 19.9 38.8 4974.80 11.1 31.8 4998.34 20.3 43.8 4974.90 11.5 36.4 4998.44 20.6 48.9 4975.00 11.8 41.0 4998.54 20.9 54.3 4975.10 12.2 45.8 4998.64 21.2 59.6 4975.20 12.5 51.0 4998.74 21.6 65.3 4975.30 12.9 56.1 4998.84 21.9 71.3 4975.40 13.2 61.5 4998.94 22.2 77.7 4975.50 13.6 67.3 4999.04 22.6 82.2 4975.60 14.0 73.7 4999.14 23.2 79.0 4975.70 14.4 80.6 4999.24 24.1 87.8 4975.80 14.9 88.0 4999.34 25.0 97.1 4975.90 15.3 95.8 4999.44 25.8 107.0

4976.00 15.7 103.9 4976.10 16.1 111.7 4976.20 16.6 120.0 4976.30 17.1 129.0 4976.40 17.6 138.7 4976.50 18.0 150.4 4976.60 18.5 160.5 4976.70 19.1 166.9

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Table B.13. Hydraulic data for the Table B.14. Hydraulic data for the Ranch above Meadow site. Ranch below Meadow site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4995.72 0.7 0.0 4994.00 1.3 0.0 4995.82 1.3 0.1 4994.10 2.4 0.2 4995.92 2.3 0.2 4994.20 3.5 0.5 4996.02 3.5 0.6 4994.30 4.8 1.2 4996.12 5.1 1.4 4994.40 5.9 2.3 4996.22 6.5 2.4 4994.50 7.5 3.6 4996.32 7.8 4.1 4994.60 9.2 6.3 4996.42 8.9 6.2 4994.70 10.7 9.5 4996.52 9.9 8.7 4994.80 11.9 13.3 4996.62 10.8 11.6 4994.90 13.0 17.7 4996.72 11.6 15.1 4995.00 13.9 22.6 4996.82 12.3 19.5 4995.10 14.8 27.6 4996.92 12.9 24.3 4995.20 15.6 33.8 4997.02 13.5 29.8 4995.30 16.3 41.0 4997.12 14.1 35.2 4995.40 17.0 49.3 4997.22 14.7 41.1 4995.50 17.6 58.4 4997.32 15.3 48.8 4995.60 18.2 68.6 4997.42 15.9 57.0 4995.70 18.7 79.6 4997.52 16.4 65.4 4995.80 19.2 91.3 4997.62 16.9 74.3 4995.90 19.7 103.7 4997.72 17.3 83.9 4996.00 20.1 116.8 4997.82 17.8 94.4 4996.10 20.6 130.7 4997.92 18.3 100.5 4996.20 21.0 145.2 4998.02 18.9 112.1 4996.30 21.4 160.4 4998.12 19.4 124.4 4996.40 21.8 175.3 4998.22 19.9 137.4 4996.50 22.2 187.4 4998.32 20.4 151.1 4996.60 22.6 201.0 4998.42 20.9 165.5 4996.70 23.1 216.0 4998.52 21.4 180.6 4996.80 23.5 231.8

4996.90 24.0 248.4 4997.00 24.5 265.7 4997.10 25.0 284.0 4997.20 25.5 303.3 4997.30 26.0 324.1 4997.40 26.5 346.3 4997.50 27.1 369.6 4997.60 27.6 393.9 4997.70 28.1 419.4 4997.80 28.7 446.0 4997.90 29.2 471.9 4998.00 29.8 497.1 4998.10 30.4 523.7

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Table B.15. Hydraulic data for the Table B.16. Hydraulic data for the St. Vasquez site. Louis site.

Water Water Surface Effective Surface Effective Elevation Width Q Elevation Width Q (ft) (ft) (cfs) (ft) (ft) (cfs) 4995.94 5.0 0.2 4999.24 0.7 0.0 4996.04 6.8 0.9 4999.34 1.4 0.2 4996.14 8.2 2.0 4999.44 2.0 0.5 4996.24 9.8 3.8 4999.54 2.6 1.0 4996.34 11.0 6.5 4999.64 3.8 2.2 4996.44 11.9 9.8 4999.74 4.9 3.9 4996.54 12.6 13.7 4999.84 6.5 6.3 4996.64 13.3 18.3 4999.94 8.0 10.2 4996.74 13.8 23.5 5000.04 9.3 14.8 4996.84 14.2 29.2 5000.14 10.7 19.3 4996.94 14.5 35.4 5000.24 12.4 29.7 4997.04 14.9 42.0 5000.34 14.0 40.0 4997.14 15.2 49.1 5000.44 15.5 51.5 4997.24 15.4 56.6 5000.54 16.7 64.1 4997.34 15.7 64.5 5000.64 17.8 77.8 4997.44 15.9 72.3 5000.74 18.8 92.5 4997.54 16.2 80.6 5000.84 19.6 108.2 4997.64 16.4 89.3 5000.94 20.4 123.6 4997.74 16.6 98.3 5001.04 21.2 139.4 4997.84 16.9 107.6 5001.14 21.9 157.6 4997.94 17.2 117.4 5001.24 22.6 175.9 4998.04 17.4 127.7 5001.34 23.3 194.9 4998.14 17.7 138.6 5001.44 23.9 215.0 4998.24 18.0 150.0 5001.54 24.6 237.1 4998.34 18.3 161.6 5001.64 25.3 248.0

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APPENDIX C

GRAIN-SIZE DISTRIBUTION – NO TRUNCATION

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 175 118 68 7 512 1 0.5 99.5 1 0.6 99.4 Tail-out 103 64 31 2 360 4 2.2 97.3 1 0.6 98.9 Average 139 91 50 5 256 10 5.5 91.8 6 3.4 95.5 180 11 6.0 85.8 3 1.7 93.8 128 35 19.1 66.7 31 17.5 76.3 90 16 8.7 57.9 21 11.9 64.4 64 16 8.7 49.2 9 5.1 59.3 45 10 5.5 43.7 15 8.5 50.8 32 13 7.1 36.6 8 4.5 46.3 22.5 10 5.5 31.1 7 4.0 42.4 16 10 5.5 25.7 2 1.1 41.2 11.3 6 3.3 22.4 3 1.7 39.5 8 9 4.9 17.5 8 4.5 35.0 5.6 6 3.3 14.2 13 7.3 27.7 4 7 3.8 10.4 21 11.9 15.8 2 3 1.6 8.7 10 5.6 10.2 1.4 16 8.7 0.0 18 10.2 0.0 Total 183 177

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.1. Grain-size distributions not truncated for the Fraser Highway 40 site.

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Run Riffle Tail-out Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 360 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 256 0 0.0 100.0 1 0.6 99.4 1 0.8 99.2 180 5 3.4 96.6 2 1.3 98.1 0 0.0 99.2 128 14 9.4 87.2 14 9.1 89.0 8 6.3 92.9 90 21 14.1 73.2 24 15.6 73.4 16 12.6 80.3 64 27 18.1 55.0 22 14.3 59.1 14 11.0 69.3 45 19 12.8 42.3 14 9.1 50.0 14 11.0 58.3 32 17 11.4 30.9 14 9.1 40.9 15 11.8 46.5 22.5 8 5.4 25.5 12 7.8 33.1 9 7.1 39.4 16 13 8.7 16.8 12 7.8 25.3 5 3.9 35.4 11.3 6 4.0 12.8 10 6.5 18.8 5 3.9 31.5 8 7 4.7 8.1 11 7.1 11.7 8 6.3 25.2 5.6 8 5.4 2.7 8 5.2 6.5 9 7.1 18.1 4 1 0.7 2.0 8 5.2 1.3 6 4.7 13.4 2 2 1.3 0.7 1 0.6 0.6 6 4.7 8.7 1.4 1 0.7 0.0 1 0.6 0.0 11 8.7 0.0 Total 149 154 127

XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Run 115 75 57 15 Riffle 112 72 46 10 Tail-out 100 52 36 4 Average 109 66 46 10

100.0

90.0

80.0

70.0

60.0 Tail-out 50.0 Run 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.2. Grain-size distributions not truncated for the Fraser Robbers site.

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XS Riffle/Tail-out XS Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) Riffle/ (mm) (%) (%) (%) (%) 98 56 38 3.7 512 0 0.0 100.0 0 0.0 100.0 Tail-out 360 0 0.0 100.0 0 0.0 100.0 Riffle/Run 98 69 55 6.8 256 0 0.0 100.0 0 0.0 100.0 Average 98 63 47 5.3 180 5 2.1 97.9 8 3.9 96.1 128 21 8.8 89.1 13 6.4 89.7 90 16 6.7 82.4 17 8.3 81.4 64 30 12.6 69.9 45 22.1 59.3 45 35 14.6 55.2 36 17.6 41.7 32 23 9.6 45.6 11 5.4 36.3 22.5 21 8.8 36.8 17 8.3 27.9 16 8 3.3 33.5 3 1.5 26.5 11.3 7 2.9 30.5 6 2.9 23.5 8 14 5.9 24.7 8 3.9 19.6 5.6 10 4.2 20.5 11 5.4 14.2 4 9 3.8 16.7 5 2.5 11.8 2 23 9.6 7.1 12 5.9 5.9 1.4 17 7.1 0.0 12 5.9 0.0 Total 239 204

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Tail-out

40.0 Riffle/Run

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.3. Grain-size distributions not truncated for the Fraser above Diversion site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 108 68 48 15 512 0 0.0 100.0 0 0.0 100.0 Tail-out 60 38 27 1.9 360 0 0.0 100.0 0 0.0 100.0 Average 84 53 38 8.5 256 0 0.0 100.0 0 0.0 100.0 180 9 5.5 94.5 0 0.0 100.0 128 12 7.3 87.3 2 1.2 98.8 90 17 10.3 77.0 9 5.5 93.3 64 25 15.2 61.8 12 7.3 86.0 45 23 13.9 47.9 20 12.2 73.8 32 26 15.8 32.1 30 18.3 55.5 22.5 16 9.7 22.4 17 10.4 45.1 16 6 3.6 18.8 14 8.5 36.6 11.3 8 4.8 13.9 6 3.7 32.9 8 5 3.0 10.9 5 3.0 29.9 5.6 9 5.5 5.5 4 2.4 27.4 4 7 4.2 1.2 6 3.7 23.8 2 2 1.2 0.0 7 4.3 19.5 1.4 0 0.0 0.0 32 19.5 0.0 Total 165 164

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.4. Grain-size distributions not truncated for the Fraser below Diversion site.

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XS Riffle XS Riffle XS Riffle Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 2 1.3 98.7 360 1 0.7 99.3 4 4.4 95.6 7 4.6 94.1 256 8 5.7 93.6 8 8.9 86.7 5 3.3 90.8 180 18 12.8 80.9 6 6.7 80.0 10 6.6 84.2 128 22 15.6 65.2 11 12.2 67.8 18 11.8 72.4 90 20 14.2 51.1 10 11.1 56.7 11 7.2 65.1 64 21 14.9 36.2 13 14.4 42.2 33 21.7 43.4 45 19 13.5 22.7 13 14.4 27.8 20 13.2 30.3 32 17 12.1 10.6 8 8.9 18.9 14 9.2 21.1 22.5 4 2.8 7.8 3 3.3 15.6 9 5.9 15.1 16 2 1.4 6.4 2 2.2 13.3 10 6.6 8.6 11.3 4 2.8 3.5 2 2.2 11.1 1 0.7 7.9 8 2 1.4 2.1 1 1.1 10.0 2 1.3 6.6 5.6 1 0.7 1.4 5 5.6 4.4 1 0.7 5.9 4 0 0.0 1.4 1 1.1 3.3 0 0.0 5.9 2 0 0.0 1.4 0 0.0 3.3 0 0.0 5.9 1.4 2 1.4 0.0 3 3.3 0.0 9 5.9 0.0 Total 141 90 152

XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Riffle 195 122 88 39 Riffle 220 115 77 27 Riffle 180 88 72 25 Average 198 108 79 30

100.0

90.0

80.0

70.0

60.0 Riffle 50.0 Riffle 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.5a. Pre-runoff grain-size distributions not truncated for the Fraser Winter Park Gage site.

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XS Riffle XS Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 200 134 89 15 512 Riffle 205 152 118 15 360 2 1.5 98.5 3 1.9 98.1 Average 203 143 104 15 256 7 5.3 93.2 5 3.1 95.0 180 19 14.4 78.8 35 21.7 73.3 128 22 16.7 62.1 33 20.5 52.8 90 15 11.4 50.8 14 8.7 44.1 64 14 10.6 40.2 14 8.7 35.4 45 13 9.8 30.3 10 6.2 29.2 32 7 5.3 25.0 8 5.0 24.2 22.5 6 4.5 20.5 7 4.3 19.9 16 5 3.8 16.7 5 3.1 16.8 11.3 6 4.5 12.1 6 3.7 13.0 8 2 1.5 10.6 6 3.7 9.3 5.6 5 3.8 6.8 3 1.9 7.5 4 2 1.5 5.3 7 4.3 3.1 2 5 3.8 1.5 5 3.1 0.0 1.4 2 1.5 0.0 0 0.0 0.0 Total 132 161

XS Riffle 100.0

90.0

80.0

70.0

60.0

50.0 Riffle 40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.5b. Post-runoff grain-size distributions not truncated for the Fraser Winter Park Gage site.

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Run Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Run 205 120 70 2.2 512 2 1.1 98.9 1 0.7 99.3 Riffle 245 160 122 4.1 360 5 2.8 96.0 8 5.6 93.7 Average 225 140 96 3 256 12 6.8 89.3 11 7.7 86.0 180 18 10.2 79.1 26 18.2 67.8 128 23 13.0 66.1 22 15.4 52.4 90 16 9.0 57.1 16 11.2 41.3 64 16 9.0 48.0 11 7.7 33.6 45 7 4.0 44.1 5 3.5 30.1 32 2 1.1 42.9 4 2.8 27.3 22.5 2 1.1 41.8 7 4.9 22.4 16 3 1.7 40.1 3 2.1 20.3 11.3 2 1.1 39.0 2 1.4 18.9 8 4 2.3 36.7 1 0.7 18.2 5.6 2 1.1 35.6 1 0.7 17.5 4 6 3.4 32.2 7 4.9 12.6 2 30 16.9 15.3 9 6.3 6.3 1.4 27 15.3 0.0 9 6.3 0.0 Total 177 143

100.0

90.0

80.0

70.0

60.0

50.0 Run

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.6a. Pre-runoff grain-size distributions not truncated for the Fraser below Vasquez site.

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XS 24 Run XS 25 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) 24 Run 205 110 29 3.6 512 1 0.5 99.5 0 0.0 100.0 25 Riffle 210 118 78 7.5 360 5 2.6 96.9 5 3.2 96.8 Average 208 114 54 5.6 256 15 7.7 89.2 15 9.7 87.1 180 21 10.8 78.5 12 7.7 79.4 128 25 12.8 65.6 22 14.2 65.2 90 7 3.6 62.1 19 12.3 52.9 64 9 4.6 57.4 8 5.2 47.7 45 4 2.1 55.4 8 5.2 42.6 32 7 3.6 51.8 8 5.2 37.4 22.5 14 7.2 44.6 3 1.9 35.5 16 21 10.8 33.8 11 7.1 28.4 11.3 12 6.2 27.7 13 8.4 20.0 8 7 3.6 24.1 5 3.2 16.8 5.6 9 4.6 19.5 8 5.2 11.6 4 11 5.6 13.8 11 7.1 4.5 2 22 11.3 2.6 7 4.5 0.0 1.4 5 2.6 0.0 0 0.0 0.0 Total 195 155

100.0

90.0

80.0

70.0

60.0

50.0 XS 24 Run

40.0 XS 25 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.6b. Post-runoff grain-size distributions not truncated for the Fraser below Vasquez site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 150 63 55 3.5 512 1 0.4 99.6 0 0.0 100.0 Tail-out 130 64 37 3 360 4 1.7 97.9 2 0.8 99.2 Average 140 64 46 3 256 10 4.3 93.6 7 2.9 96.2 180 8 3.4 90.1 6 2.5 93.7 128 28 12.0 78.1 26 10.9 82.8 90 26 11.2 67.0 21 8.8 74.1 64 28 12.0 54.9 24 10.0 64.0 45 24 10.3 44.6 18 7.5 56.5 32 28 12.0 32.6 26 10.9 45.6 22.5 15 6.4 26.2 17 7.1 38.5 16 6 2.6 23.6 10 4.2 34.3 11.3 3 1.3 22.3 11 4.6 29.7 8 2 0.9 21.5 12 5.0 24.7 5.6 5 2.1 19.3 6 2.5 22.2 4 3 1.3 18.0 6 2.5 19.7 2 21 9.0 9.0 22 9.2 10.5 1.4 21 9.0 0.0 25 10.5 0.0 Total 233 239

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.7. Grain-size distributions not truncated for the Fraser Rendezvous site.

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XS Tail-out XS Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Tail-out 202 132 94 16 512 1 0.6 99.4 0 0.0 100.0 Riffle 205 135 90 23 360 4 2.6 96.8 4 2.7 97.3 Average 204 134 92 20 256 9 5.8 91.0 11 7.5 89.7 180 19 12.2 78.8 16 11.0 78.8 128 25 16.0 62.8 29 19.9 58.9 90 23 14.7 48.1 13 8.9 50.0 64 23 14.7 33.3 18 12.3 37.7 45 8 5.1 28.2 9 6.2 31.5 32 13 8.3 19.9 10 6.8 24.7 22.5 7 4.5 15.4 8 5.5 19.2 16 6 3.8 11.5 3 2.1 17.1 11.3 3 1.9 9.6 14 9.6 7.5 8 4 2.6 7.1 3 2.1 5.5 5.6 4 2.6 4.5 1 0.7 4.8 4 1 0.6 3.8 1 0.7 4.1 2 4 2.6 1.3 1 0.7 3.4 1.4 2 1.3 0.0 5 3.4 0.0 Total 156 146

XS Riffle 100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer thanFiner Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.8. Grain-size distributions not truncated for the Fraser Open Space site.

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XS 16 Run XS 17 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Run 220 120 118 23 512 0 0.0 100.0 0 0.0 100.0 Riffle 184 145 96 6.5 360 6 3.1 96.9 1 0.5 99.5 Average 202 133 107 15 256 19 9.8 87.1 15 6.8 92.8 180 19 9.8 77.3 22 10.0 82.8 128 44 22.7 54.6 39 17.6 65.2 90 27 13.9 40.7 40 18.1 47.1 64 13 6.7 34.0 35 15.8 31.2 45 5 2.6 31.4 16 7.2 24.0 32 3 1.5 29.9 11 5.0 19.0 22.5 4 2.1 27.8 7 3.2 15.8 16 10 5.2 22.7 3 1.4 14.5 11.3 4 2.1 20.6 4 1.8 12.7 8 5 2.6 18.0 5 2.3 10.4 5.6 6 3.1 14.9 6 2.7 7.7 4 8 4.1 10.8 7 3.2 4.5 2 14 7.2 3.6 5 2.3 2.3 1.4 7 3.6 0.0 5 2.3 0.0 Total 194 221

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.9. Grain-size distributions not truncated for the Fraser Angling site.

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XS Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) Riffle/Run 200 75 43 4.6 512 3 1.1 98.9 360 10 3.5 95.4 256 20 7.1 88.3 180 16 5.7 82.6 128 30 10.6 72.0 90 10 3.5 68.4 64 26 9.2 59.2 45 22 7.8 51.4 32 28 9.9 41.5 22.5 24 8.5 33.0 16 13 4.6 28.4 11.3 11 3.9 24.5 8 11 3.9 20.6 5.6 5 1.8 18.8 4 13 4.6 14.2 2 15 5.3 8.9 1.4 25 8.9 0.0 Total 282

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Run 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.10. Grain-size distributions not truncated for the Fraser below Ranch site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 175 110 64 4.8 512 6 2.6 97.4 3 2.8 97.2 Tail-out 185 116 55 3.1 360 3 1.3 96.2 1 0.9 96.3 Average 180 113 60 4 256 11 4.7 91.5 4 3.7 92.6 180 12 5.1 86.3 11 10.2 82.4 128 38 16.2 70.1 16 14.8 67.6 90 30 12.8 57.3 9 8.3 59.3 64 17 7.3 50.0 8 7.4 51.9 45 13 5.6 44.4 4 3.7 48.1 32 5 2.1 42.3 4 3.7 44.4 22.5 11 4.7 37.6 6 5.6 38.9 16 8 3.4 34.2 8 7.4 31.5 11.3 7 3.0 31.2 5 4.6 26.9 8 11 4.7 26.5 3 2.8 24.1 5.6 12 5.1 21.4 3 2.8 21.3 4 22 9.4 12.0 2 1.9 19.4 2 25 10.7 1.3 10 9.3 10.2 1.4 3 1.3 0.0 11 10.2 0.0 Total 234 108

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.11. Grain-size distributions not truncated for Ranch at Gage site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 69 43 31 5.1 512 0 0.0 100.0 0 0.0 100.0 Tail-out 57 30 16 1.7 360 0 0.0 100.0 0 0.0 100.0 Average 63 37 24 3 256 0 0.0 100.0 0 0.0 100.0 180 0 0.0 100.0 0 0.0 100.0 128 3 1.3 98.7 1 0.4 99.6 90 10 4.2 94.5 11 4.1 95.5 64 30 12.7 81.9 21 7.9 87.6 45 36 15.2 66.7 29 10.9 76.7 32 36 15.2 51.5 29 10.9 65.8 22.5 33 13.9 37.6 19 7.1 58.6 16 16 6.8 30.8 18 6.8 51.9 11.3 12 5.1 25.7 25 9.4 42.5 8 8 3.4 22.4 12 4.5 38.0 5.6 11 4.6 17.7 14 5.3 32.7 4 12 5.1 12.7 13 4.9 27.8 2 13 5.5 7.2 10 3.8 24.1 1.4 17 7.2 0.0 64 24.1 0.0 Total 237 266

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.12. Grain-size distributions not truncated for the Ranch Angling site.

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Riffle/Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) Riffle/ (mm) (%) (%) 94 64 46 3 512 0.0 100.0 Tail-out 360 0.0 100.0 256 0.0 100.0 180 1 0.2 99.8 128 25 5.4 94.4 90 55 11.9 82.4 64 85 18.4 64.0 45 68 14.8 49.2 32 39 8.5 40.8 22.5 22 4.8 36.0 16 25 5.4 30.6 11.3 3 0.7 29.9 8 28 6.1 23.9 5.6 15 3.3 20.6 4 5 1.1 19.5 2 43 9.3 10.2 1.4 47 10.2 0.0 Total 461

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Tail-out 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.13a. Pre-runoff grain-size distributions not truncated for the Ranch above Meadow site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Tail-out 88 57 39 5.6 512 0 0.0 100.0 0 0.0 100.0 Riffle 87 58 44 14 360 0 0.0 100.0 1 0.5 99.5 Average 88 58 42 10 256 0 0.0 100.0 0 0.0 99.5 180 2 0.8 99.2 2 1.0 98.4 128 9 3.7 95.5 1 0.5 97.9 90 24 9.9 85.5 24 12.6 85.3 64 42 17.4 68.2 32 16.8 68.6 45 29 12.0 56.2 32 16.8 51.8 32 32 13.2 43.0 21 11.0 40.8 22.5 18 7.4 35.5 30 15.7 25.1 16 14 5.8 29.8 12 6.3 18.8 11.3 10 4.1 25.6 7 3.7 15.2 8 10 4.1 21.5 6 3.1 12.0 5.6 13 5.4 16.1 11 5.8 6.3 4 12 5.0 11.2 6 3.1 3.1 2 8 3.3 7.9 4 2.1 1.0 1.4 19 7.9 0.0 2 1.0 0.0 Total 242 191

100.0

90.0

80.0

70.0

60.0

50.0 Riffle 40.0 Tail-out

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.13b. Post-runoff grain-size distributions not truncated for the Ranch above Meadow site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 127 79 60 15 512 0 0.0 100.0 0 0.0 100.0 Tail-out 115 70 36 7 360 0 0.0 100.0 2 1.2 98.8 Average 121 75 48 11 256 2 1.0 99.0 1 0.6 98.2 180 5 2.6 96.3 8 4.7 93.6 128 22 11.5 84.8 13 7.6 86.0 90 28 14.7 70.2 21 12.3 73.7 64 33 17.3 52.9 21 12.3 61.4 45 27 14.1 38.7 13 7.6 53.8 32 14 7.3 31.4 10 5.8 48.0 22.5 12 6.3 25.1 10 5.8 42.1 16 15 7.9 17.3 14 8.2 33.9 11.3 7 3.7 13.6 13 7.6 26.3 8 11 5.8 7.9 12 7.0 19.3 5.6 6 3.1 4.7 13 7.6 11.7 4 7 3.7 1.0 3 1.8 9.9 2 2 1.0 0.0 7 4.1 5.8 1.4 0 0.0 0.0 10 5.8 0.0 Total 191 171

XS Tailout 100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.14. Grain-size distributions not truncated for the Ranch below Meadow site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 140 92 71 21 360 1 0.5 99.5 Tail-out 135 96 73 16 256 1 0.5 98.9 0 0.0 100.0 Average 138 94 72 19 180 5 2.7 96.2 2 1.2 98.8 128 32 17.6 78.6 30 18.2 80.6 90 28 15.4 63.2 33 20.0 60.6 64 35 19.2 44.0 26 15.8 44.8 45 28 15.4 28.6 13 7.9 37.0 32 12 6.6 22.0 16 9.7 27.3 22.5 6 3.3 18.7 12 7.3 20.0 16 5 2.7 15.9 12 7.3 12.7 11.3 7 3.8 12.1 6 3.6 9.1 8 5 2.7 9.3 8 4.8 4.2 5.6 2 1.1 8.2 1 0.6 3.6 4 5 2.7 5.5 5 3.0 0.6 2 9 4.9 0.5 1 0.6 0.0 1.4 1 0.5 0.0 0 0.0 0.0 Total 182 165

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.15a. Pre-runoff grain-size distributions not truncated for the Vasquez site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 155 112 80 30 360 2 1.2 98.8 0 0.0 100.0 Tail-out 145 108 84 12 256 4 2.5 96.3 4 2.2 97.8 Average 150 110 82 21 180 5 3.1 93.2 5 2.8 95.0 128 34 21.1 72.0 38 21.1 73.9 90 28 17.4 54.7 37 20.6 53.3 64 18 11.2 43.5 28 15.6 37.8 45 11 6.8 36.6 23 12.8 25.0 32 8 5.0 31.7 14 7.8 17.2 22.5 13 8.1 23.6 12 6.7 10.6 16 7 4.3 19.3 5 2.8 7.8 11.3 6 3.7 15.5 4 2.2 5.6 8 3 1.9 13.7 4 2.2 3.3 5.6 4 2.5 11.2 2 1.1 2.2 4 2 1.2 9.9 1 0.6 1.7 2 3 1.9 8.1 1 0.6 1.1 1.4 13 8.1 0.0 2 1.1 0.0 Total 161 180

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.15b. Post-runoff grain-size distributions not truncated for the Vasquez site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Tail-out 170 120 67 1.7 512 1 0.5 99.5 Riffle 205 95 63 1.8 360 3 1.5 97.9 4 2.1 97.9 Average 188 108 65 2 256 7 3.6 94.4 11 5.6 92.3 180 17 8.7 85.6 30 15.4 76.9 128 28 14.4 71.3 22 11.3 65.6 90 18 9.2 62.1 13 6.7 59.0 64 26 13.3 48.7 16 8.2 50.8 45 13 6.7 42.1 14 7.2 43.6 32 18 9.2 32.8 6 3.1 40.5 22.5 6 3.1 29.7 1 0.5 40.0 16 3 1.5 28.2 4 2.1 37.9 11.3 2 1.0 27.2 3 1.5 36.4 8 4 2.1 25.1 4 2.1 34.4 5.6 1 0.5 24.6 8 4.1 30.3 4 1 0.5 24.1 3 1.5 28.7 2 3 1.5 22.6 4 2.1 26.7 44 22.6 0.0 52 26.7 0.0 Total 195 195

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.16a. Pre-runoff grain-size distributions not truncated for the St. Louis site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 155 90 47 5.1 512 1 0.4 99.6 2 1.2 98.8 Tail-out 145 34 14 1.7 360 2 0.8 98.9 5 3.0 95.8 Average 150 62 31 3.4 256 8 3.0 95.8 6 3.6 92.2 180 12 4.5 91.3 8 4.8 87.3 128 41 15.5 75.8 8 4.8 82.5 90 31 11.7 64.2 7 4.2 78.3 64 24 9.1 55.1 9 5.4 72.9 45 15 5.7 49.4 8 4.8 68.1 32 18 6.8 42.6 9 5.4 62.7 22.5 19 7.2 35.5 12 7.2 55.4 16 11 4.2 31.3 6 3.6 51.8 11.3 8 3.0 28.3 6 3.6 48.2 8 13 4.9 23.4 4 2.4 45.8 5.6 14 5.3 18.1 7 4.2 41.6 4 15 5.7 12.5 3 1.8 39.8 2 11 4.2 8.3 4 2.4 37.3 1.4 22 8.3 0.0 62 37.3 0.0 Total 265 166

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure C.16b. Post-runoff grain-size distributions not truncated for the St. Louis site.

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APPENDIX D

GRAIN-SIZE DISTRIBUTIONS – TRUNCATED AT 2 MILLIMETERS

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 180 128 79 14 512 1 0.6 99.4 1 0.6 99.4 Tail-out 108 70 38 3.4 360 4 2.4 97.0 1 0.6 98.7 Average 144 99 59 9 256 10 6.0 91.0 6 3.8 95.0 180 11 6.6 84.4 3 1.9 93.1 128 35 21.0 63.5 31 19.5 73.6 90 16 9.6 53.9 21 13.2 60.4 64 16 9.6 44.3 9 5.7 54.7 45 10 6.0 38.3 15 9.4 45.3 32 13 7.8 30.5 8 5.0 40.3 22.5 10 6.0 24.6 7 4.4 35.8 16 10 6.0 18.6 2 1.3 34.6 11.3 6 3.6 15.0 3 1.9 32.7 8 9 5.4 9.6 8 5.0 27.7 5.6 6 3.6 6.0 13 8.2 19.5 4 7 4.2 1.8 21 13.2 6.3 2 3 1.8 0.0 10 6.3 0.0 Total 167 159

100.0

90.0

80.0

70.0

60.0

50.0 Riffle Tail-out 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.1. Grain-size distributions truncated at 2 mm for the Fraser Highway 40 site.

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Run Riffle Tail-out Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 360 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 256 0 0.0 100.0 1 0.7 99.3 1 0.9 99.1 180 5 3.4 96.6 2 1.3 98.0 0 0.0 99.1 128 14 9.5 87.2 14 9.2 88.9 8 6.9 92.2 90 21 14.2 73.0 24 15.7 73.2 16 13.8 78.4 64 27 18.2 54.7 22 14.4 58.8 14 12.1 66.4 45 19 12.8 41.9 14 9.2 49.7 14 12.1 54.3 32 17 11.5 30.4 14 9.2 40.5 15 12.9 41.4 22.5 8 5.4 25.0 12 7.8 32.7 9 7.8 33.6 16 13 8.8 16.2 12 7.8 24.8 5 4.3 29.3 11.3 6 4.1 12.2 10 6.5 18.3 5 4.3 25.0 8 7 4.7 7.4 11 7.2 11.1 8 6.9 18.1 5.6 8 5.4 2.0 8 5.2 5.9 9 7.8 10.3 4 1 0.7 1.4 8 5.2 0.7 6 5.2 5.2 2 2 1.4 0.0 1 0.7 0.0 6 5.2 0.0 Total 148 153 116

XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Run 118 75 57 16 Riffle 115 72 46 10 Tail-out 103 59 40 7.2 Average 112 69 48 11

100.0

90.0

80.0

70.0

60.0

50.0 Run Tail-out 40.0 Riffle

30.0 Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.2. Grain-size distributions truncated at 2 mm for the Fraser Robbers site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 102 71 58 9 512 0 0.0 100.0 0 0.0 100.0 Tail-out 100 59 43 6.5 360 0 0.0 100.0 0 0.0 100.0 Average 101 65 51 8 256 0 0.0 100.0 0 0.0 100.0 180 5 2.3 97.7 8 4.2 95.8 128 21 9.5 88.3 13 6.8 89.1 90 16 7.2 81.1 17 8.9 80.2 64 30 13.5 67.6 45 23.4 56.8 45 35 15.8 51.8 36 18.8 38.0 32 23 10.4 41.4 11 5.7 32.3 22.5 21 9.5 32.0 17 8.9 23.4 16 8 3.6 28.4 3 1.6 21.9 11.3 7 3.2 25.2 6 3.1 18.8 8 14 6.3 18.9 8 4.2 14.6 5.6 10 4.5 14.4 11 5.7 8.9 4 9 4.1 10.4 5 2.6 6.3 2 23 10.4 0.0 12 6.3 0.0 Total 222 192

100.0

90.0

80.0

70.0

60.0

50.0 Riffle Tail-out

40.0 Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.3. Grain-size distributions truncated at 2 mm for the Fraser above Diversion site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 112 68 48 14 512 0 0.0 100.0 0 0.0 100.0 Tail-out 68 43 35 10 360 0 0.0 100.0 0 0.0 100.0 Average 90 56 42 12 256 0 0.0 100.0 0 0.0 100.0 180 9 5.5 94.5 0 0.0 100.0 128 12 7.3 87.3 2 1.5 98.5 90 17 10.3 77.0 9 6.8 91.7 64 25 15.2 61.8 12 9.1 82.6 45 23 13.9 47.9 20 15.2 67.4 32 26 15.8 32.1 30 22.7 44.7 22.5 16 9.7 22.4 17 12.9 31.8 16 6 3.6 18.8 14 10.6 21.2 11.3 8 4.8 13.9 6 4.5 16.7 8 5 3.0 10.9 5 3.8 12.9 5.6 9 5.5 5.5 4 3.0 9.8 4 7 4.2 1.2 6 4.5 5.3 2 2 1.2 0.0 7 5.3 0.0 Total 165 132

100.0

90.0

80.0

70.0

60.0

50.0 Riffle Tail-out 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.4. Grain-size distributions truncated at 2 mm for the Fraser below Diversion site.

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Riffle Riffle Riffle Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 2 1.4 98.6 360 1 0.7 99.3 4 4.6 95.4 7 4.9 93.7 256 8 5.8 93.5 8 9.2 86.2 5 3.5 90.2 180 18 12.9 80.6 6 6.9 79.3 10 7.0 83.2 128 22 15.8 64.7 11 12.6 66.7 18 12.6 70.6 90 20 14.4 50.4 10 11.5 55.2 11 7.7 62.9 64 21 15.1 35.3 13 14.9 40.2 33 23.1 39.9 45 19 13.7 21.6 13 14.9 25.3 20 14.0 25.9 32 17 12.2 9.4 8 9.2 16.1 14 9.8 16.1 22.5 4 2.9 6.5 3 3.4 12.6 9 6.3 9.8 16 2 1.4 5.0 2 2.3 10.3 10 7.0 2.8 11.3 4 2.9 2.2 2 2.3 8.0 1 0.7 2.1 8 2 1.4 0.7 1 1.1 6.9 2 1.4 0.7 5.6 1 0.7 0.0 5 5.7 1.1 1 0.7 0.0 4 0 0.0 0.0 1 1.1 0.0 0 0.0 0.0 2 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 Total 139 87 143

XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Riffle 198 126 89 40 Riffle 225 120 79 32 Riffle 185 91 74 32 Average 203 112 81 35

100

50 Riffle Riffle 40 Riffle

Percent Finer than Finer Percent 30

0 1000 100 10 1 Particle Diameter (mm)

Figure D.5a. Pre-runoff grain-size distributions truncated at 2 mm for the Fraser Winter Park Gage site.

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Riffle XS Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 205 152 118 15 512 Riffle 202 135 90 17 360 2 1.5 98.5 3 1.9 98.1 Average 204 144 104 16 256 7 5.4 93.1 5 3.1 95.0 180 19 14.6 78.5 35 21.7 73.3 128 22 16.9 61.5 33 20.5 52.8 90 15 11.5 50.0 14 8.7 44.1 64 14 10.8 39.2 14 8.7 35.4 45 13 10.0 29.2 10 6.2 29.2 32 7 5.4 23.8 8 5.0 24.2 22.5 6 4.6 19.2 7 4.3 19.9 16 5 3.8 15.4 5 3.1 16.8 11.3 6 4.6 10.8 6 3.7 13.0 8 2 1.5 9.2 6 3.7 9.3 5.6 5 3.8 5.4 3 1.9 7.5 4 2 1.5 3.8 7 4.3 3.1 2 5 3.8 0.0 5 3.1 0.0 Total 130 161

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1

Particle Diameter (mm) Figure D.5b. Post-runoff grain-size distributions truncated at 2 mm for the Fraser Winter Park Gage site.

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Run Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Run 230 136 92 3.5 512 2 1.3 98.7 1 0.7 99.3 Riffle 250 177 140 20 360 5 3.3 95.3 8 6.0 93.3 Average 240 157 116 12 256 12 8.0 87.3 11 8.2 85.1 180 18 12.0 75.3 26 19.4 65.7 128 23 15.3 60.0 22 16.4 49.3 90 16 10.7 49.3 16 11.9 37.3 64 16 10.7 38.7 11 8.2 29.1 45 7 4.7 34.0 5 3.7 25.4 32 2 1.3 32.7 4 3.0 22.4 22.5 2 1.3 31.3 7 5.2 17.2 16 3 2.0 29.3 3 2.2 14.9 11.3 2 1.3 28.0 2 1.5 13.4 8 4 2.7 25.3 1 0.7 12.7 5.6 2 1.3 24.0 1 0.7 11.9 4 6 4.0 20.0 7 5.2 6.7 2 30 20.0 0.0 9 6.7 0.0 Total 150 134

100.0

90.0

80.0

70.0

60.0

50.0 Run Riffle

40.0 Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.6a. Pre-runoff grain-size distributions truncated at 2 mm for the Fraser below Vasquez site.

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Run XS 25 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 220 124 78 7.1 512 1 0.5 99.5 0 0.0 100.0 Tail-out 215 126 31 5.1 360 5 2.6 96.8 5 3.2 96.8 Average 218 125 55 6 256 15 7.9 88.9 15 9.7 87.1 180 21 11.1 77.9 12 7.7 79.4 128 25 13.2 64.7 22 14.2 65.2 90 7 3.7 61.1 19 12.3 52.9 64 9 4.7 56.3 8 5.2 47.7 45 4 2.1 54.2 8 5.2 42.6 32 7 3.7 50.5 8 5.2 37.4 22.5 14 7.4 43.2 3 1.9 35.5 16 21 11.1 32.1 11 7.1 28.4 11.3 12 6.3 25.8 13 8.4 20.0 8 7 3.7 22.1 5 3.2 16.8 5.6 9 4.7 17.4 8 5.2 11.6 4 11 5.8 11.6 11 7.1 4.5 2 22 11.6 0.0 7 4.5 0.0 Total 190 155

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Run

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.6b. Post-runoff grain-size distributions truncated at 2 mm for the Fraser below Vasquez site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Diameter Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) Riffle 150 90 63 16 512 1 0.5 99.5 0 0.0 100.0 Tail-out 140 72 43 8 360 4 1.9 97.6 2 0.9 99.1 Average 145 81 53 12 256 10 4.7 92.9 7 3.3 95.8 180 8 3.8 89.2 6 2.8 93.0 128 28 13.2 75.9 26 12.1 80.8 90 26 12.3 63.7 21 9.8 71.0 64 28 13.2 50.5 24 11.2 59.8 45 24 11.3 39.2 18 8.4 51.4 32 28 13.2 25.9 26 12.1 39.3 22.5 15 7.1 18.9 17 7.9 31.3 16 6 2.8 16.0 10 4.7 26.6 11.3 3 1.4 14.6 11 5.1 21.5 8 2 0.9 13.7 12 5.6 15.9 5.6 5 2.4 11.3 6 2.8 13.1 4 3 1.4 9.9 6 2.8 10.3 2 21 9.9 0.0 22 10.3 0.0 Total 212 214

100.0

90.0

80.0

70.0

60.0

50.0 Riffle 40.0 Tail-out

30.0 Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.7. Grain-size distributions truncated at 2 mm for the Fraser Rendezvous site.

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XS Tail-out XS Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 210 140 96 22 512 1 0.6 99.4 0 0.0 100.0 Tail-out 210 132 96 27 360 4 2.6 96.8 4 2.8 97.2 Average 210 136 96 25 256 9 5.8 90.9 11 7.8 89.4 180 19 12.3 78.6 16 11.3 78.0 128 25 16.2 62.3 29 20.6 57.4 90 23 14.9 47.4 13 9.2 48.2 64 23 14.9 32.5 18 12.8 35.5 45 8 5.2 27.3 9 6.4 29.1 32 13 8.4 18.8 10 7.1 22.0 22.5 7 4.5 14.3 8 5.7 16.3 16 6 3.9 10.4 3 2.1 14.2 11.3 3 1.9 8.4 14 9.9 4.3 8 4 2.6 5.8 3 2.1 2.1 5.6 4 2.6 3.2 1 0.7 1.4 4 1 0.6 2.6 1 0.7 0.7 2 4 2.6 0.0 1 0.7 0.0 Total 154 141

100.0

90.0

80.0

70.0

60.0

50.0 Riffle Tail-out 40.0

30.0 Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm) Figure D.8. Grain-size distributions truncated at 2 mm for the Fraser Open Space site.

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XS 16 Run XS 17 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Run 225 152 125 9.2 512 0 0.0 100.0 0 0.0 100.0 Riffle 190 127 98 29 360 6 3.2 96.8 1 0.5 99.5 Average 208 140 112 19 256 19 10.2 86.6 15 6.9 92.6 180 19 10.2 76.5 22 10.2 82.4 128 44 23.5 52.9 39 18.1 64.4 90 27 14.4 38.5 40 18.5 45.8 64 13 7.0 31.6 35 16.2 29.6 45 5 2.7 28.9 16 7.4 22.2 32 3 1.6 27.3 11 5.1 17.1 22.5 4 2.1 25.1 7 3.2 13.9 16 10 5.3 19.8 3 1.4 12.5 11.3 4 2.1 17.6 4 1.9 10.6 8 5 2.7 15.0 5 2.3 8.3 5.6 6 3.2 11.8 6 2.8 5.6 4 8 4.3 7.5 7 3.2 2.3 2 14 7.5 0.0 5 2.3 0.0 Total 187 216

100.0

90.0

80.0

70.0

60.0

50.0 Run 40.0 Riffle

30.0

Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.9. Grain-size distributions truncated at 2 mm for the Fraser Angling site.

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XS Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) Riffle/Tail-out 208 87 52 10 512 3 1.2 98.8 360 10 3.9 94.9 256 20 7.8 87.2 180 16 6.2 80.9 128 30 11.7 69.3 90 10 3.9 65.4 64 26 10.1 55.3 45 22 8.6 46.7 32 28 10.9 35.8 22.5 24 9.3 26.5 16 13 5.1 21.4 11.3 11 4.3 17.1 8 11 4.3 12.8 5.6 5 1.9 10.9 4 13 5.1 5.8 2 15 5.8 0.0 Total 257

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Run 40.0

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1

Particle Diameter (mm) Figure D.10. Grain-size distributions truncated at 2 mm for the Fraser below Ranch site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 200 128 76 8.8 512 6 2.6 97.4 3 3.1 96.9 Tail-out 170 113 66 4.8 360 3 1.3 96.1 1 1.0 95.9 Average 185 121 71 7 256 11 4.8 91.3 4 4.1 91.8 180 12 5.2 86.1 11 11.3 80.4 128 38 16.5 69.7 16 16.5 63.9 90 30 13.0 56.7 9 9.3 54.6 64 17 7.4 49.4 8 8.2 46.4 45 13 5.6 43.7 4 4.1 42.3 32 5 2.2 41.6 4 4.1 38.1 22.5 11 4.8 36.8 6 6.2 32.0 16 8 3.5 33.3 8 8.2 23.7 11.3 7 3.0 30.3 5 5.2 18.6 8 11 4.8 25.5 3 3.1 15.5 5.6 12 5.2 20.3 3 3.1 12.4 4 22 9.5 10.8 2 2.1 10.3 2 25 10.8 0.0 10 10.3 0.0 Total 231 97

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

30.0

Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm) Figure D.11. Grain-size distributions truncated at 2 mm for Ranch at Gage site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 70 45 34 7.8 512 0 0.0 100.0 0 0.0 100.0 Tail-out 65 40 27 7 360 0 0.0 100.0 0 0.0 100.0 Average 68 43 31 7 256 0 0.0 100.0 0 0.0 100.0 180 0 0.0 100.0 0 0.0 100.0 128 3 1.4 98.6 1 0.5 99.5 90 10 4.5 94.1 11 5.4 94.1 64 30 13.6 80.5 21 10.4 83.7 45 36 16.4 64.1 29 14.4 69.3 32 36 16.4 47.7 29 14.4 55.0 22.5 33 15.0 32.7 19 9.4 45.5 16 16 7.3 25.5 18 8.9 36.6 11.3 12 5.5 20.0 25 12.4 24.3 8 8 3.6 16.4 12 5.9 18.3 5.6 11 5.0 11.4 14 6.9 11.4 4 12 5.5 5.9 13 6.4 5.0 2 13 5.9 0.0 10 5.0 0.0 Total 220 202

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.12. Grain-size distributions truncated at 2 mm for the Ranch Angling site.

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Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) Riffle/Run 98 69 53 9 512 0 0.0 100.0 360 0 0.0 100.0 256 0 0.0 100.0 180 1 0.2 99.8 128 25 6.0 93.7 90 55 13.3 80.4 64 85 20.5 59.9 45 68 16.4 43.5 32 39 9.4 34.1 22.5 22 5.3 28.7 16 25 6.0 22.7 11.3 3 0.7 22.0 8 28 6.8 15.2 5.6 15 3.6 11.6 4 5 1.2 10.4 2 43 10.4 0.0 Total 414

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Run 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.13a. Pre-runoff grain-size distributions truncated at 2 mm for the Ranch above Meadow site.

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XS 13 Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 90 64 43 9 512 0 0.0 100.0 0 0.0 100.0 Tail-out 88 58 44 15 360 0 0.0 100.0 1 0.5 99.5 Average 89 61 44 12 256 0 0.0 100.0 0 0.0 99.5 180 2 0.9 99.1 2 1.1 98.4 128 9 4.0 95.1 1 0.5 97.9 90 24 10.8 84.3 24 12.7 85.2 64 42 18.8 65.5 32 16.9 68.3 45 29 13.0 52.5 32 16.9 51.3 32 32 14.3 38.1 21 11.1 40.2 22.5 18 8.1 30.0 30 15.9 24.3 16 14 6.3 23.8 12 6.3 18.0 11.3 10 4.5 19.3 7 3.7 14.3 8 10 4.5 14.8 6 3.2 11.1 5.6 13 5.8 9.0 11 5.8 5.3 4 12 5.4 3.6 6 3.2 2.1 2 8 3.6 0.0 4 2.1 0.0 Total 223 189

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.13b. Post-runoff grain-size distributions truncated at 2 mm for the Ranch above Meadow site.

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XS Riffle XS Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 125 80 60 15 512 0 0.0 100.0 0 0.0 100.0 Tail-out 124 72 42 8.8 360 0 0.0 100.0 2 1.2 98.8 Average 125 76 51 12 256 2 1.0 99.0 1 0.6 98.1 180 5 2.6 96.3 8 5.0 93.2 128 22 11.5 84.8 13 8.1 85.1 90 28 14.7 70.2 21 13.0 72.0 64 33 17.3 52.9 21 13.0 59.0 45 27 14.1 38.7 13 8.1 50.9 32 14 7.3 31.4 10 6.2 44.7 22.5 12 6.3 25.1 10 6.2 38.5 16 15 7.9 17.3 14 8.7 29.8 11.3 7 3.7 13.6 13 8.1 21.7 8 11 5.8 7.9 12 7.5 14.3 5.6 6 3.1 4.7 13 8.1 6.2 4 7 3.7 1.0 3 1.9 4.3 2 2 1.0 0.0 7 4.3 0.0 Total 191 161

100.0

90.0

80.0 70.0

60.0

50.0 Riffle

40.0 Tail-out

30.0

20.0 Percent Finer than Finer Percent 10.0

0.0 1000 100 10 1 Particle Diameter (mm) Figure D.14. Grain-size distributions truncated at 2 mm for the Ranch below Meadow site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 140 92 72 19 360 1 0.6 99.4 Tail-out 135 95 73 17 256 1 0.6 98.9 0 0.0 100.0 Average 138 94 73 18 180 5 2.8 96.1 2 1.2 98.8 128 32 17.7 78.5 30 18.2 80.6 90 28 15.5 63.0 33 20.0 60.6 64 35 19.3 43.6 26 15.8 44.8 45 28 15.5 28.2 13 7.9 37.0 32 12 6.6 21.5 16 9.7 27.3 22.5 6 3.3 18.2 12 7.3 20.0 16 5 2.8 15.5 12 7.3 12.7 11.3 7 3.9 11.6 6 3.6 9.1 8 5 2.8 8.8 8 4.8 4.2 5.6 2 1.1 7.7 1 0.6 3.6 4 5 2.8 5.0 5 3.0 0.6 2 9 5.0 0.0 1 0.6 0.0 Total 181 165

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.15a. Pre-runoff grain-size distributions truncated at 2 mm for the Vasquez site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 150 120 89 22 360 2 1.4 98.6 0 0.0 100.0 Tail-out 148 120 85 31 256 4 2.7 95.9 4 2.2 97.8 Average 149 120 87 27 180 5 3.4 92.6 5 2.8 94.9 128 34 23.0 69.6 38 21.3 73.6 90 28 18.9 50.7 37 20.8 52.8 64 18 12.2 38.5 28 15.7 37.1 45 11 7.4 31.1 23 12.9 24.2 32 8 5.4 25.7 14 7.9 16.3 22.5 13 8.8 16.9 12 6.7 9.6 16 7 4.7 12.2 5 2.8 6.7 11.3 6 4.1 8.1 4 2.2 4.5 8 3 2.0 6.1 4 2.2 2.2 5.6 4 2.7 3.4 2 1.1 1.1 4 2 1.4 2.0 1 0.6 0.6 2 3 2.0 0.0 1 0.6 0.0 Total 148 178

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure D.15b. Post-runoff grain-size distributions truncated at 2 mm for the Vasquez site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 225 165 118 36 512 1 0.7 99.3 Tail-out 195 132 88 18

360 3 2.0 97.4 4 2.8 97.2 Average 210 149 103 27 256 7 4.6 92.7 11 7.7 89.5 180 17 11.3 81.5 30 21.0 68.5 128 28 18.5 62.9 22 15.4 53.1 90 18 11.9 51.0 13 9.1 44.1 64 26 17.2 33.8 16 11.2 32.9 45 13 8.6 25.2 14 9.8 23.1 32 18 11.9 13.2 6 4.2 18.9 22.5 6 4.0 9.3 1 0.7 18.2 16 3 2.0 7.3 4 2.8 15.4 11.3 2 1.3 6.0 3 2.1 13.3 8 4 2.6 3.3 4 2.8 10.5 5.6 1 0.7 2.6 8 5.6 4.9 4 1 0.7 2.0 3 2.1 2.8 2 3 2.0 0.0 4 2.8 0.0 Total 151 143

100.0

90.0

80.0

70.0

60.0

50.0 Riffle Tail-out 40.0

30.0 Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm) Figure D.16a. Pre-runoff grain-size distributions truncated at 2 mm for the St. Louis site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 160 98 61 7.9 512 1 0.4 99.6 2 1.9 98.1 Tail-out 210 83 47 9.2 360 2 0.8 98.8 5 4.8 93.3 Average 185 91 54 9 256 8 3.3 95.5 6 5.8 87.5 180 12 4.9 90.5 8 7.7 79.8 128 41 16.9 73.7 8 7.7 72.1 90 31 12.8 60.9 7 6.7 65.4 64 24 9.9 51.0 9 8.7 56.7 45 15 6.2 44.9 8 7.7 49.0 32 18 7.4 37.4 9 8.7 40.4 22.5 19 7.8 29.6 12 11.5 28.8 16 11 4.5 25.1 6 5.8 23.1 11.3 8 3.3 21.8 6 5.8 17.3 8 13 5.3 16.5 4 3.8 13.5 5.6 14 5.8 10.7 7 6.7 6.7 4 15 6.2 4.5 3 2.9 3.8 2 11 4.5 0.0 4 3.8 0.0 Total 243 104

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

30.0 Percent Finer than Finer Percent 20.0

10.0

0.0 1000 100 10 1

Particle Diameter (mm) Figure D.16b. Post-runoff grain-size distributions truncated at 2 mm for the St. Louis site.

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APPENDIX E

GRAIN-SIZE DISTRIBUTIONS – TRUNCATED AT 8 MILLIMETERS

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 192 140 104 28 512 1 0.7 99.3 1 0.9 99.1 Tail-out 115 94 77 28 360 4 2.8 96.5 1 0.9 98.1 Average 154 117 91 28 256 10 7.0 89.4 6 5.6 92.5 180 11 7.7 81.7 3 2.8 89.7 128 35 24.6 57.0 31 29.0 60.7 90 16 11.3 45.8 21 19.6 41.1 64 16 11.3 34.5 9 8.4 32.7 45 10 7.0 27.5 15 14.0 18.7 32 13 9.2 18.3 8 7.5 11.2 22.5 10 7.0 11.3 7 6.5 4.7 16 10 7.0 4.2 2 1.9 2.8 11.3 6 4.2 0.0 3 2.8 0.0 Total 142 107

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.1. Grain-size distributions truncated at 8 mm for the Fraser Highway 40 site.

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Run Riffle Tail-out Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 360 0 0.0 100.0 0 0.0 100.0 0 0.0 100.0 256 0 0.0 100.0 1 0.8 99.2 1 1.1 98.9 180 5 3.8 96.2 2 1.6 97.6 0 0.0 98.9 128 14 10.8 85.4 14 11.2 86.4 8 9.2 89.7 90 21 16.2 69.2 24 19.2 67.2 16 18.4 71.3 64 27 20.8 48.5 22 17.6 49.6 14 16.1 55.2 45 19 14.6 33.8 14 11.2 38.4 14 16.1 39.1 32 17 13.1 20.8 14 11.2 27.2 15 17.2 21.8 22.5 8 6.2 14.6 12 9.6 17.6 9 10.3 11.5 16 13 10.0 4.6 12 9.6 8.0 5 5.7 5.7 11.3 6 4.6 0.0 10 8.0 0.0 5 5.7 0.0 Total 130 125 87

XS d84 d65 d50 d16 (mm) (mm) (mm) (mm) Run 125 83 67 25 Riffle 120 85 65 22 Tail-out 110 78 58 27 Average 118 82 63 25

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out Riffle 40.0 Run

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.2. Grain-size distributions truncated at 8 mm for the Fraser Robbers site.

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Riffle/Tail-out Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) Riffle/ (mm) (%) (%) (%) (%) 125 73 58 28 512 0 0.0 100.0 0 0.0 100.0 Tail-out Riffle/ 360 0 0.0 100.0 0 0.0 100.0 118 78 67 31 Run 256 0 0.0 100.0 0 0.0 100.0 Average 122 76 63 30 180 5 3.0 97.0 8 5.1 94.9 128 21 12.7 84.3 13 8.3 86.5 90 16 9.6 74.7 17 10.9 75.6 64 30 18.1 56.6 45 28.8 46.8 45 35 21.1 35.5 36 23.1 23.7 32 23 13.9 21.7 11 7.1 16.7 22.5 21 12.7 9.0 17 10.9 5.8 16 8 4.8 4.2 3 1.9 3.8 11.3 7 4.2 0.0 6 3.8 0.0 Total 166 156

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Tail-out 40.0 Riffle/Run

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.3. Grain-size distributions truncated at 8 mm for the Fraser above Diversion site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 120 75 57 28 512 0 0.0 100.0 0 0.0 100.0 Tail-out 75 47 39 22 360 0 0.0 100.0 0 0.0 100.0 Average 98 61 48 25 256 0 0.0 100.0 0 0.0 100.0 180 9 6.3 93.7 0 0.0 100.0 128 12 8.5 85.2 2 1.8 98.2 90 17 12.0 73.2 9 8.2 90.0 64 25 17.6 55.6 12 10.9 79.1 45 23 16.2 39.4 20 18.2 60.9 32 26 18.3 21.1 30 27.3 33.6 22.5 16 11.3 9.9 17 15.5 18.2 16 6 4.2 5.6 14 12.7 5.5 11.3 8 5.6 0.0 6 5.5 0.0 Total 142 110

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.4. Grain-size distributions truncated at 8 mm for the Fraser below Diversion site.

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Riffle Riffle Riffle Diameter Count Retained Passing Count Retained Passing Count Retained Passing (mm) (%) (%) (%) (%) (%) (%) 512 2 1.4 98.6 360 1 0.7 99.3 4 5.0 95.0 7 5.0 93.6 256 8 5.9 93.4 8 10.0 85.0 5 3.6 90.0 180 18 13.2 80.1 6 7.5 77.5 10 7.1 82.9 128 22 16.2 64.0 11 13.8 63.8 18 12.9 70.0 90 20 14.7 49.3 10 12.5 51.3 11 7.9 62.1 64 21 15.4 33.8 13 16.3 35.0 33 23.6 38.6 45 19 14.0 19.9 13 16.3 18.8 20 14.3 24.3 32 17 12.5 7.4 8 10.0 8.8 14 10.0 14.3 22.5 4 2.9 4.4 3 3.8 5.0 9 6.4 7.9 16 2 1.5 2.9 2 2.5 2.5 10 7.1 0.7 11.3 4 2.9 0.0 2 2.5 0.0 1 0.7 0.0 Total 136 80 140

XS d d d d 84 65 50 16 (mm) (mm) (mm) (mm) Riffle 200 128 91 43

Riffle 250 128 87 43 Riffle 190 95 76 35 Average 213 117 85 40

100

50 Riffle Riffle 40 Riffle

Percent Finer than Finer Percent 30

0 1000 100 10 1 Particle Diameter (mm)

Figure E.5a. Pre-runoff grain-size distributions truncated at 8 mm for the Fraser Winter Park Gage site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Tail-out 210 138 105 36 512 Riffle 215 170 140 40 360 2 1.7 98.3 3 2.1 97.9 Average 213 154 123 38 256 7 6.0 92.2 5 3.6 94.3 180 19 16.4 75.9 35 25.0 69.3 128 22 19.0 56.9 33 23.6 45.7 90 15 12.9 44.0 14 10.0 35.7 64 14 12.1 31.9 14 10.0 25.7 45 13 11.2 20.7 10 7.1 18.6 32 7 6.0 14.7 8 5.7 12.9 22.5 6 5.2 9.5 7 5.0 7.9 16 5 4.3 5.2 5 3.6 4.3 11.3 6 5.2 0.0 6 4.3 0.0 Total 116 140

100.0

90.0

80.0

70.0

60.0

50.0 Riffle

40.0 Tail-out

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.5b. Post-runoff grain-size distributions truncated at 8 mm for the Fraser Winter Park Gage site.

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Riffle Run XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 262 177 140 50 512 2 1.9 98.1 1 0.9 99.1 Run 260 194 150 67 360 5 4.6 93.5 8 6.9 92.2 Average 261 186 145 59 256 12 11.1 82.4 11 9.5 82.8 180 18 16.7 65.7 26 22.4 60.3 128 23 21.3 44.4 22 19.0 41.4 90 16 14.8 29.6 16 13.8 27.6 64 16 14.8 14.8 11 9.5 18.1 45 7 6.5 8.3 5 4.3 13.8 32 2 1.9 6.5 4 3.4 10.3 22.5 2 1.9 4.6 7 6.0 4.3 16 3 2.8 1.9 3 2.6 1.7 11.3 2 1.9 0.0 2 1.7 0.0 Total 108 116

100.0

90.0

80.0

70.0

60.0

50.0 Upstream 40.0 Downstream

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.6a. Pre-runoff grain-size distributions truncated at 8 mm for the Fraser below Vasquez site.

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XS 24 Run XS 25 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) XS 24 (mm) (%) (%) (%) (%) 250 170 112 19 512 1 0.7 99.3 0 0.0 100.0 Run XS 25 360 5 3.5 95.7 5 4.0 96.0 256 150 110 19 Riffle 256 15 10.6 85.1 15 12.1 83.9 Average 253 160 111 19 180 21 14.9 70.2 12 9.7 74.2 128 25 17.7 52.5 22 17.7 56.5 90 7 5.0 47.5 19 15.3 41.1 64 9 6.4 41.1 8 6.5 34.7 45 4 2.8 38.3 8 6.5 28.2 32 7 5.0 33.3 8 6.5 21.8 22.5 14 9.9 23.4 3 2.4 19.4 16 21 14.9 8.5 11 8.9 10.5 11.3 12 8.5 0.0 13 10.5 0.0 Total 141 124

100.0

90.0

80.0

70.0

60.0

50.0 XS 24 Run 40.0 XS 25 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.6b. Post-runoff grain-size distributions truncated at 8 mm for the Fraser below Vasquez site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 167 106 77 35 512 1 0.6 99.4 0 0.0 100.0 Tail-out 150 92 66 27 360 4 2.2 97.2 2 1.2 98.8 Average 159 99 72 31 256 10 5.5 91.7 7 4.2 94.6 180 8 4.4 87.3 6 3.6 91.1 128 28 15.5 71.8 26 15.5 75.6 90 26 14.4 57.5 21 12.5 63.1 64 28 15.5 42.0 24 14.3 48.8 45 24 13.3 28.7 18 10.7 38.1 32 28 15.5 13.3 26 15.5 22.6 22.5 15 8.3 5.0 17 10.1 12.5 16 6 3.3 1.7 10 6.0 6.5 11.3 3 1.7 0.0 11 6.5 0.0 Total 181 168

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.7. Grain-size distributions truncated at 8 mm for the Fraser Rendezvous site.

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Tail-out Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Tail-out 208 138 103 38 512 1 0.7 99.3 0 0.0 100.0 Riffle 210 145 105 27 360 4 2.8 96.5 4 3.0 97.0 Average 209 142 104 33 256 9 6.4 90.1 11 8.1 88.9 180 19 13.5 76.6 16 11.9 77.0 128 25 17.7 58.9 29 21.5 55.6 90 23 16.3 42.6 13 9.6 45.9 64 23 16.3 26.2 18 13.3 32.6 45 8 5.7 20.6 9 6.7 25.9 32 13 9.2 11.3 10 7.4 18.5 22.5 7 5.0 6.4 8 5.9 12.6 16 6 4.3 2.1 3 2.2 10.4 11.3 3 2.1 0.0 14 10.4 0.0 Total 141 135

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.8. Grain-size distributions truncated at 8 mm for the Fraser Open Space site.

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XS 16 Run XS 17 Riffle XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) XS 16 (mm) (%) (%) (%) (%) 257 165 138 60 512 0 0.0 100.0 0 0.0 100.0 Run XS 17 360 6 3.9 96.1 1 0.5 99.5 200 138 107 54 Riffle 256 19 12.3 83.8 15 7.8 91.7 Average 229 152 123 57 180 19 12.3 71.4 22 11.4 80.3 128 44 28.6 42.9 39 20.2 60.1 90 27 17.5 25.3 40 20.7 39.4 64 13 8.4 16.9 35 18.1 21.2 45 5 3.2 13.6 16 8.3 13.0 32 3 1.9 11.7 11 5.7 7.3 22.5 4 2.6 9.1 7 3.6 3.6 16 10 6.5 2.6 3 1.6 2.1 11.3 4 2.6 0.0 4 2.1 0.0 Total 154 193

100.0

90.0

80.0

70.0

60.0

50.0 XS 17 Riffle 40.0 XS 16 Run

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.9. Grain-size distributions truncated at 8 mm for the Fraser Angling site.

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Riffle/Run XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) Riffle/Run 250 133 71 27 512 3 1.4 98.6 360 10 4.7 93.9 256 20 9.4 84.5 180 16 7.5 77.0 128 30 14.1 62.9 90 10 4.7 58.2 64 26 12.2 46.0 45 22 10.3 35.7 32 28 13.1 22.5 22.5 24 11.3 11.3 16 13 6.1 5.2 11.3 11 5.2 0.0 Total 213

100.0

90.0

80.0

70.0

60.0

50.0 Riffle/Run 40.0

Percent Finer thanFiner Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.10. Grain-size distributions truncated at 8 mm for the Fraser below Ranch site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 200 140 113 32 512 6 3.7 96.3 3 3.8 96.2 Tail-out 210 150 109 22 360 3 1.9 94.4 1 1.3 94.9 Average 205 145 111 27 256 11 6.8 87.6 4 5.1 89.9 180 12 7.5 80.1 11 13.9 75.9 128 38 23.6 56.5 16 20.3 55.7 90 30 18.6 37.9 9 11.4 44.3 64 17 10.6 27.3 8 10.1 34.2 45 13 8.1 19.3 4 5.1 29.1 32 5 3.1 16.1 4 5.1 24.1 22.5 11 6.8 9.3 6 7.6 16.5 16 8 5.0 4.3 8 10.1 6.3 11.3 7 4.3 0.0 5 6.3 0.0 Total 161 79

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.11. Grain-size distributions truncated at 8 mm for Ranch at Gage site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 76 53 42 23 512 0 0.0 100.0 0 0.0 100.0 Tail-out 72 49 38 16 360 0 0.0 100.0 0 0.0 100.0 Average 74 51 40 20 256 0 0.0 100.0 0 0.0 100.0 180 0 0.0 100.0 0 0.0 100.0 128 3 1.7 98.3 1 0.7 99.3 90 10 5.7 92.6 11 7.2 92.2 64 30 17.0 75.6 21 13.7 78.4 45 36 20.5 55.1 29 19.0 59.5 32 36 20.5 34.7 29 19.0 40.5 22.5 33 18.8 15.9 19 12.4 28.1 16 16 9.1 6.8 18 11.8 16.3 11.3 12 6.8 0.0 25 16.3 0.0 Total 176 153

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.12. Grain-size distributions truncated at 8 mm for the Ranch Angling site.

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Upstream XS d84 d65 d50 d16 Diameter Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) Upstream 107 78 66 33 512 0 0.0 100.0 360 0 0.0 100.0 256 0 0.0 100.0 180 1 0.3 99.7 128 25 7.7 92.0 90 55 17.0 74.9 64 85 26.3 48.6 45 68 21.1 27.6 32 39 12.1 15.5 22.5 22 6.8 8.7 16 25 7.7 0.9 11.3 3 0.9 0.0 Total 323

100.0

90.0

80.0

70.0

60.0

50.0 Upstream 40.0

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.13a. Pre-runoff grain-size distributions truncated at 8 mm for the Ranch above Meadow site.

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XS 13 Riffle XS 14 Run XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) XS 13 (mm) (%) (%) (%) (%) 100 72 56 26 512 0 0.0 100.0 0 0.0 100.0 Riffle XS 14 360 0 0.0 100.0 1 0.6 99.4 92 65 51 25 Run 256 0 0.0 100.0 0 0.0 99.4 Average 96 69 54 26 180 2 1.1 98.9 2 1.2 98.1 128 9 5.0 93.9 1 0.6 97.5 90 24 13.3 80.6 24 14.8 82.7 64 42 23.3 57.2 32 19.8 63.0 45 29 16.1 41.1 32 19.8 43.2 32 32 17.8 23.3 21 13.0 30.2 22.5 18 10.0 13.3 30 18.5 11.7 16 14 7.8 5.6 12 7.4 4.3 11.3 10 5.6 0.0 7 4.3 0.0 Total 180 162

100.0

90.0

80.0

70.0

60.0

50.0 XS 13 Riffle 40.0 XS 14 Run

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.13b. Post-runoff grain-size distributions truncated at 8 mm for the Ranch above Meadow site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 135 88 69 26 512 0 0.0 100.0 0 0.0 100.0 Tail-out 140 90 68 19 360 0 0.0 100.0 2 1.6 98.4 Average 138 89 69 23 256 2 1.2 98.8 1 0.8 97.6 180 5 3.0 95.8 8 6.3 91.3 128 22 13.3 82.4 13 10.3 81.0 90 28 17.0 65.5 21 16.7 64.3 64 33 20.0 45.5 21 16.7 47.6 45 27 16.4 29.1 13 10.3 37.3 32 14 8.5 20.6 10 7.9 29.4 22.5 12 7.3 13.3 10 7.9 21.4 16 15 9.1 4.2 14 11.1 10.3 11.3 7 4.2 0.0 13 10.3 0.0 Total 165 126

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.14. Grain-size distributions truncated at 8 mm for the Ranch below Meadow site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 145 105 79 43 512 Tail-out 140 101 80 27 360 1 0.6 99.4 Average 143 103 80 35 256 1 0.6 98.8 0 0.0 100.0 180 5 3.1 95.6 2 1.3 98.7 128 32 20.0 75.6 30 20.0 78.7 90 28 17.5 58.1 33 22.0 56.7 64 35 21.9 36.3 26 17.3 39.3 45 28 17.5 18.8 13 8.7 30.7 32 12 7.5 11.3 16 10.7 20.0 22.5 6 3.8 7.5 12 8.0 12.0 16 5 3.1 4.4 12 8.0 4.0 11.3 7 4.4 0.0 6 4.0 0.0 Total 160 150

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.15a. Pre-runoff grain-size distributions truncated at 8 mm for the Vasquez site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 160 125 97 29 512 Tail-out 150 115 89 38 360 2 1.5 98.5 0 0.0 100.0 Average 155 120 93 34 256 4 2.9 95.6 4 2.4 97.6 180 5 3.7 91.9 5 2.9 94.7 128 34 25.0 66.9 38 22.4 72.4 90 28 20.6 46.3 37 21.8 50.6 64 18 13.2 33.1 28 16.5 34.1 45 11 8.1 25.0 23 13.5 20.6 32 8 5.9 19.1 14 8.2 12.4 22.5 13 9.6 9.6 12 7.1 5.3 16 7 5.1 4.4 5 2.9 2.4 11.3 6 4.4 0.0 4 2.4 0.0 Total 136 170

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.15b. Post-runoff grain-size distributions truncated at 8 mm for the Vasquez site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 199 135 94 40 512 1 0.7 99.3 Tail-out 230 181 140 53 360 3 2.1 97.2 4 3.2 96.8 Average 215 158 117 47 256 7 4.9 92.3 11 8.9 87.9 180 17 12.0 80.3 30 24.2 63.7 128 28 19.7 60.6 22 17.7 46.0 90 18 12.7 47.9 13 10.5 35.5 64 26 18.3 29.6 16 12.9 22.6 45 13 9.2 20.4 14 11.3 11.3 32 18 12.7 7.7 6 4.8 6.5 22.5 6 4.2 3.5 1 0.8 5.6 16 3 2.1 1.4 4 3.2 2.4 11.3 2 1.4 0.0 3 2.4 0.0 Total 142 124

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out 40.0 Riffle

30.0 Percent Finer than Finer Percent

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.16a. Pre-runoff grain-size distributions truncated at 8 mm for the St. Louis site.

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Riffle Tail-out XS d84 d65 d50 d16 Diameter Count Retained Passing Count Retained Passing (mm) (mm) (mm) (mm) (mm) (%) (%) (%) (%) Riffle 170 124 90 28 512 1 0.5 99.5 2 2.3 97.7 Tail-out 245 126 69 25 360 2 1.1 98.4 5 5.8 91.9 Average 208 125 80 27 256 8 4.2 94.2 6 7.0 84.9 180 12 6.3 87.9 8 9.3 75.6 128 41 21.6 66.3 8 9.3 66.3 90 31 16.3 50.0 7 8.1 58.1 64 24 12.6 37.4 9 10.5 47.7 45 15 7.9 29.5 8 9.3 38.4 32 18 9.5 20.0 9 10.5 27.9 22.5 19 10.0 10.0 12 14.0 14.0 16 11 5.8 4.2 6 7.0 7.0 11.3 8 4.2 0.0 6 7.0 0.0 Total 190 86

100.0

90.0

80.0

70.0

60.0

50.0 Tail-out

40.0 Riffle

Percent Finer than Finer Percent 30.0

20.0

10.0

0.0 1000 100 10 1 Particle Diameter (mm)

Figure E.16b. Post-runoff grain-size distributions truncated at 8 mm for the St. Louis site.

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APPENDIX F

PROBABILITY DISTRIBUTIONS OF FLUSHING FLOW ESTIMATES

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Table F.1. Sample output table from a Monte Carlo critical discharge simulation (first 24 rows of 10,000 rows).

 *c n Log d50 d50 Sf Qc Qc (cms) (cfs) 0.045 0.055601986 6.71677597 105.1843291 0.016556269 3.307173623 116.7917343 0.045 0.048409623 6.850909745 115.4328267 0.017566906 4.593176895 162.2065112 0.045 0.049924937 6.810115248 112.2144961 0.016826253 4.410661133 155.7610279 0.045 0.054032494 6.861617586 116.2927692 0.018419052 3.672533376 129.6942922 0.045 0.05992171 6.382565628 83.43412262 0.01672181 1.655761053 58.47264974 0.045 0.050164649 6.845873569 115.030575 0.017187098 4.487292104 158.4672251 0.045 0.055937713 6.594063153 96.60749084 0.017303556 2.470227245 87.23525187 0.045 0.057860145 6.583040567 95.87219558 0.017746438 2.210068754 78.04784147 0.045 0.059040151 7.139980895 141.0419871 0.016400634 6.297809178 222.4050322 0.045 0.052918863 7.110763157 138.2143076 0.017068008 6.572613671 232.1096613 0.045 0.056371095 7.349176398 163.0506518 0.015278506 10.83557779 382.6548185 0.045 0.051206455 6.443749206 87.04860096 0.017670114 2.103593706 74.28771065 0.045 0.053390208 6.362282327 82.26930364 0.016759837 1.887117059 66.64290999 0.045 0.061150713 7.026230801 130.3485569 0.016800167 4.736331079 167.2619535 0.045 0.052051218 6.50147102 90.60200174 0.017300898 2.347597384 82.90461919 0.045 0.056684138 6.655913318 100.8392385 0.016639669 2.875838735 101.5592865 0.045 0.052321951 6.537017456 92.86206486 0.017168395 2.506916799 88.53093125 0.045 0.058944728 6.678890885 102.4581463 0.016488694 2.867735025 101.2731067 0.045 0.053336909 6.638327131 99.61748829 0.018120715 2.638119991 93.16432825 0.045 0.054459083 6.765122929 108.7689475 0.015965453 3.936721759 139.0240169 0.045 0.059092026 6.801720925 111.5634717 0.017778702 3.092432146 109.2082106 0.045 0.059139168 6.721780754 105.5498526 0.016859433 2.954308299 104.330413 0.045 0.055103325 6.701230222 104.0570009 0.016925657 3.143377574 111.0073314 0.045 0.053159125 6.651829207 100.5541774 0.015725696 3.455405051 122.0264778

Where: d50 = median diameter of bed material; n = Manning roughness coefficient; Sf = friction slope; Qc = critical discharge; and = critical dimensionless shear stress (Shields parameter).

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