c.s.-ccmrb-program-evaluation-2020-2021

Central Colorado Mountains River Basins Weather Modification Program Cloud Seeding Report for the 2020-2021 Winter Season Sponsoring Organizations: Ski Area of Winter Park Front Range Water Council Colorado River Water Conservation District Colorado Water Conservation Board California Six Agency Committee Central Arizona Water Conservation District Southern Nevada Water Authority Metropolitan Water District of Southern California November 8, 2020 – April 19, 2021 *Original State Permit extended through end of April 2021 Program Conducted and Report Prepared by: Mike Hjermstad Eric Hjermstad Larry Hjermstad Alisa Hjermstad WESTERN WEATHER CONSULTANTS, LLC P.O BOX 58 DURANGO, COLORADO 81302 August 2021 PERMIT # 2017-02 CONTRACT # CA20045-A TABLE OF CONTENTS: EXECUTIVE SUMMARY - PAGE 03 INTRODUCTION - PAGE 04 PROJECT INFORMATION - PAGE 06 FORECAST-GUIDED OPERATIONAL PROCEDURES - PAGE 13 OPERATIONAL SUMMARY - PAGE 21 LEASED REMOTE OPERATIONS - PAGE 38 PROCEDURES AND METHODOLOGY FOR ESTIMATING PRECIPITATION INCREASES - PAGE 40 EVALUATION OF SEEDING RESULTS AND EFFECTIVENESS - PAGE 43 RECOMMENDATIONS - PAGE 49 Images: Image Seeding Response Model - PAGE 43 Image Proof of Insurance - PAGE 52 Figures and Charts: Images and Graphs associated with operations - PAGES 14-37 Tables: Table A Table B Table C Table D Table E Generator Locations - PAGE 09 Seeding Criteria- PAGE 10 Summary of Operations - PAGE 23 Estimated Project Increases - PAGE 44 Estimated Runoff Increase by Sub-basin - PAGE 48 Maps: Map CCMRB Program Target Area - PAGE 05 Map Estimate Precipitation Increase - PAGE 47 Appendices: Appendix A: Summary by Seeding Event - PAGE 53 Appendix B: Emergency Management - PAGE 117 Appendix C: 2020-21 Target vs Control Report - PAGE 128 Executive Summary This report summarizes cloud seeding activities undertaken by Western Weather Consultants (WWC) under contract with the Colorado River District-for Water Year 2021 In all, WWC seeded a total of 32 storms over 47 days and 2,500.19 hours of cloud seeding between November 8, 2020, and April 19, 2021 The State granted an extension to seeding operations through the end of April Unfortunately, only one storm on April 19, 2021, was seeded during this extension Available snowpack data was evaluated by WWC to estimate cloud seeding program effectiveness Results suggest the CCMRB Program activities produced an additional 94,413 to 112,652 AF of water within the target area This range is based on 12% less and 5% more than a “best estimate” of 107,288 AF of volumetric snow water equivalent increase This enhancement resulted in an estimated additional to 17 inches of snowfall assuming a 10 to snow to water ratio The estimated increased water yield related to direct cloud seeding expenditures indicates the cost per acre-foot (AF) of water is between $2.54/AF to $3.03/AF, with the “best estimate” cost of $2.67/AF INTRODUCTION This report details the results of the 2020-21 Central Colorado Mountains River Basins Weather Modification Program (CCMRB Program) The first cloud seeding operation was on November 8, 2020, and the last operation was on April 19, 2021 Within this timeframe, there were 32 cloud seeding events which covered 47 days and utilized 2,025.33 hours In addition to the contracted hours there were 252.67 seeding hours provided to the CCMRB Program using two leased DRI remote generators funded by the State and Lower Basin The CCMRB Program uses 17 manually operated cloud nucleating generators and remotely operated generators DRI also operates more remote generators for Winter Park This was the ninth consecutive season for the CCMRB Program The objective of the CCMRB Program is to increase precipitation through the augmentation of natural precipitation within the project Target Area (Map 1) to improve early season snowpack for ski resort activities and increase the high elevation snowpack which helps replenish the water supply to the Upper Colorado River Basin The operational technology and procedures used in the CCMRB Program are consistent with other permitted snowpack augmentation programs operated in Colorado Specifically, the CCMRB Program is informed and guided by experience gained from managing and operating various cloud seeding programs over the years This includes the Climax and Wolf Creek Colorado State University research programs (Mielke, 1981), and the observations and experiences gained from more than 45 winters of seeding operations in the Central Colorado and San Juan Mountains under the sponsorship of various entities The CCMRB Program “Target Area”, as shown in Map 1, is the Upper Colorado River Basin, generally above 8,500 feet, in Pitkin, Summit, Eagle and Grand Counties, with an exclusion area in the Tenmile Creek basin The Upper Colorado River sub basins that are being seeded are the Fryingpan/Roaring Fork, Eagle, Blue River, Williams Fork and the Fraser River basin The CCMRB Program is designed and carefully operated to only impact the defined and permitted Target Area The following map shows the Target Area along with manual generator locations (Red Stars = CCMRB, Blue Triangles = Vail, Purple Diamonds = Shared Generator Locations, Yellow Flags = SNOTEL sites and Red Pentagons = Desert Research Institute’s (DRI) Remote Generators) Map Target Areas: CCMRB Program = Blue Line Light Blue shading Map Vail & Beaver Creek Program = Red Line within Blue shading Project Information Data Services WWC monitors and evaluates the weather conditions throughout the target area within the contracted operating period for time periods of positive cloud seeding potential The weather data utilized is sourced from the following: The National Weather Service (NWS), University of Wyoming, Pennsylvania and Texas A&M Weather, National Center for Atmospheric Research (NCAR), and National Oceanic and Atmospheric Administration (NOAA) Pivotalweather.com is used for short and long-range model forecasts Information from the Natural Resources Conservation Service (NRCS) website is used to monitor snowpack in the Target Area, as recorded by the network of SNOTELs in Colorado and detailed analyses of snow accumulation are completed using these measurements Additional sources of information were used from the Colorado Department of Transportation (CDOT) to monitor road conditions and concerns, as well as from the Colorado Avalanche Information Center (CAIC) for Weather Research Forecasting (WRF) point forecasts, and to understand the avalanche and potential avalanche conditions in and around the Target Area From the above listed data sites, WWC reviews, and archives, as needed, weather data such as: surface and upper air data, synoptic surface maps, significant level maps, model forecast data, rawinsonde data, satellite and radar data, surface observations, webcam images, and other forecast aids These data assist in selecting favorable storms for modification and compliance with suspension criteria Snowpack Suspension Criteria Pursuant to the State of Colorado issued permit, seeding operations can only occur within the targeted mountain regions under ‘normal’ conditions The comparative normal for these snow observation sites is the last 30-year average updated every 10 years as last published by the NRCS for the 1981 to 2010 time period Historical evaluation of Snow Water Equivalent (SWE) content has indicated that flooding and stream channel capacities can be exceeded when late winter SWE reaches or exceeds 155% of median More substantial flooding problems can be anticipated when Mid-winter snowpack is more than 175% of median Since the CCMRB Program is designed for reasonable levels of snowpack enhancement and consistent with permit requirements, CCMRB seeding operations will be suspended in seeding areas when one or more of the following SWE conditions are observed: 175% of median on December 1st, 175% of median on January 1st, 165% of median on February 1st, 155% of median average on March 1st and 145% of median on April 1st Additionally, seeding operations may be suspended due to high avalanche hazard levels and as such, seeding must be suspended when avalanche hazard levels are triggered for highway corridors, as determined by the CAIC and the NWS “Hazardous Weather Statements” Specifically, “the permit holder must suspend all weather modification operations whenever one of the following is issued that impacts any part of the Target Area: a An urban or small stream flood advisory b A blizzard warning c A flash flood warning; or d A severe thunderstorm warning Operations may resume after these statements have expired.” WWC corresponds with the county emergency managers within the Target Area counties and adjacent counties prior to the first seeding operation of the seeding season If at any time an emergency manager determines that additional snowfall would hinder any emergency procedure, operations are to be suspended in such areas as needed to avoid impairing emergency operations On October 27th, 2020, emergency managers were informed via email as to the start date of the 2020-21 seeding season in the Central Rocky Mountains This correspondence letter can be viewed in the Emergency Management Coordination section of the report Appendix B Seeding Operations, Equipment and Threshold Criteria WWC enhances the snowpack within the Target Area by producing silver iodide crystals (artificial ice nuclei) from a network of approximately 17 manually operated ground-based generators using a 4% silver iodide and 1.25% sodium iodide solution in acetone Additionally, there are two remote generators and two leased remote generators in the CCMRB, these use a 2% silver iodide solution The solution from both types of generators is vaporized in a propane flame at a rate of to 25 grams per hour into a chosen weather system that has a cloud base temperature ranging from 5°C to -16°C and a cloud base at least 500 feet below the height of the mean mountain crest Separately, there are remotely operated generators used for seeding Winter Park in the CCMRB Program and are operated by Desert Research Institute (DRI) Although, DRI coordinates seeding operations with WWC by sending out seeding updates via email as the remotes are turned on and off, remote operations and associated seasonal results are reported separately from this report Open communication between DRI and WWC are made consistently to address any concerns related to suspensions, operations, or extensions to the Program Table A lists all the generator sites within the CCMRB Program seeding region Table A CCMRB Program Generator Locations 2020-2021 Site ID DBB RSR SZL BC REM CFR CDA BBL RKW JV TLB YMCA-REM NDG NG REM PAC DCW SFD FCC MTA OC-REM JSH DWR USFS PCR GAR Site Name Wolcott Divide Red Sky Ranch Adams Rib Beaver Creek Squaw Creek Brush Creek Lady Bell Castles Meredith Woody Creek YMCA Redcliff Nova Guides Cottonwood McQueary Gulch Aspen Canyon Junction Butte Green MTN Res Otter Creek Big Gulch Denver Water USFS Pebble Creek Silverthorn Program Vail/CCMRB Vail/CCMRB Vail/CCMRB CCMRB-REM3 Vail/CCMRB Vail/CCMRB Vail/CCMRB Vail/CCMRB12 Vail/CCMRB15 CCMRB13 CCMRB-REM5 Vail/CCMRB16 CCMRB-REM4 CCMRB1 CCMRB2 CCMRB3 CCMRB4 CCMRB5 CCMRB-REM6 CCMRB6 CCMRB-REM1 CCMRB-REM2 CCMRB7 CCMRB8 Elevation 8194 7704 6950 9512 7879 7144 7144 7002 8305 7375 9175 8687 9222 7926 7833 8224 7487 8058 8080 8555 8964 9590 9354 9174 These generators produce tiny silver iodide crystals and distribute them over the Target Area using favorable wind flows during selected storms to produce increased precipitation over the target area An analysis of low-level wind fields, cloud characteristics, stability parameters, terrain features, and synoptic meteorological features help determine which network of generators will best seed the cloud system over the project area for each seeding opportunity This analytical technique allows for adjusting the seeding network as new weather information becomes available After the best network of generators is determined to seed a storm, the generator operators are telephoned and instructed to turn on their generators at a specific time, operate at a specific burn rate, and turn the generators off at a specific time These instructions are subject to change by another phone call from the program operators at WWC Continuous monitoring of weather data by of the weather forecasters allows for adjustments related to changing conditions related to criteria of the seeding operation Table B presents the “Seeding Criteria” used by WWC Table B Western Weather Consultants Seeding Criteria for Winter Cloud Systems • • • • • Cloud bases are at least 500 feet below the mean mountain barrier crest of the Target Area and are forecast to move lower in elevation from the onset of seeding and continue throughout the seeding period The weather system has clouds that are forecast to have vertical heights and moisture content capable of producing natural precipitation Temperatures at the height of 500 feet below the mean mountain crest within the Target Area are -5°C (23°F.) or colder and are forecast to become colder if at -5°C Wind directions and speeds from the surface to cloud-base are observed and forecast to favor the movement into the intended Target Area of the silver iodide nuclei being released from the ground-based generator sites There are no stable regions or atmospheric inversions between the surface and cloudbase that would prevent the vertical dispersion of the silver iodide particles from the surface to at least the -5°C (23°F.) level or colder within the cloud system The temperature at approximately 10,000 feet (700 MB) is warmer than -16°C (3°F.) Seeding Potential and Evaluation In addition to the specific meteorological criteria utilized to identify a potentially suitable weather event for seeding over the target area in Table B, WWC evaluates the augmentation potential for each weather event selected for seeding The three equally weighted primary factors are used to evaluate the augmentation potential of a weather event: 1.) the average 24-hour wind direction, 2.) the potential total amount of expected 10 Historical Mean 15.2 16.4 10.6 6.3 12.3 12.3 1.00 0.00 Obs/Pred ratio 1.12 1.04 0.90 0.88 1.02 1.26 1.11 1.02 0.95 1.06 0.99 0.95 Obs minus Predicted 1.24 0.36 -1.09 -0.98 0.27 2.58 1.13 0.33 -0.57 0.77 -0.15 -0.57 1.02 0.28 Seeded Period Water Year 2003 2004 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Ctrl 11.6 10.6 14.6 10.4 19.4 13.3 12.4 17.8 14.6 14.6 16.8 13.8 Ctrl 14.9 14.8 13.4 12.4 20.2 12.9 14.9 18.4 13.1 16.6 20.2 13.9 Ctrl 8.5 10.5 8.8 11.1 8.4 7.5 13.2 14.9 6.4 12.6 9.3 7.4 Ctrl 5.1 4.4 6.8 3.4 6.0 5.2 6.2 9.0 5.0 7.2 8.6 4.5 Target Average 11.2 10.0 9.6 7.5 15.7 12.4 11.8 15.0 9.8 13.1 14.5 9.8 Target Predicted 10.0 9.6 10.7 8.4 15.4 9.8 10.6 14.6 10.3 12.3 14.6 10.4 Mean (03, 04,1221) 14.1 15.5 9.9 6.0 11.7 11.4 Summary Output for Regression Equation (4) Regression Statistics Multiple R 0.92048247 R Square 0.84728798 26 Adjusted R Square Standard Error Observations 0.81135574 1.25872182 22 ANOVA df Regression Residual Total Intercept Ctrl Ctrl Ctrl Ctrl SS MS 149.4398 37.359949 17 26.934471 1.5843806 21 176.37427 Coefficients -1.83056385 0.40792321 0.41906185 0.05487288 0.07494782 Standard Error 1.5319122 0.1433774 0.1238599 0.0919299 0.2135834 t Stat -1.1949535 2.84510189 3.38335313 0.59689943 0.35090653 F Significance F 23.580161 9.48068E-07 P-value 0.2485104 0.0111894 0.0035328 0.5584411 0.7299694 Lower 95% -5.06262067 0.105422991 0.157739896 -0.13908243 -0.37567443 27 Upper 95% 1.401492971 0.710423424 0.680383807 0.248828194 0.525570065 Lower 95.0% -5.062620 0.105422 0.157739 -0.139082 -0.375674 Upper 95.0% 1.401492971 0.710423424 0.680383807 0.248828194 0.525570065 Table A-5 Mixed March Snow Evaluation Linear Regression (Equation 5) Historical regression period Water Year 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 Control Average 13.2 16.5 11.2 7.3 9.4 16.2 13.6 11.7 12.7 10.1 7.4 17.0 8.5 7.9 15.3 8.3 11.4 11.9 12.0 14.2 14.1 11.7 10.6 12.6 13.0 10.9 4.2 16.2 14.5 14.8 4.5 12.9 9.2 14.6 11.0 15.0 7.9 12.2 Target Average 16.1 16.2 11.1 8.8 8.0 15.4 14.1 12.6 12.2 11.1 6.3 17.2 8.8 7.1 15.1 7.9 12.1 11.6 11.0 15.1 12.6 11.8 9.2 11.1 12.5 11.2 5.5 15.2 12.9 14.9 5.2 13.9 9.0 15.1 10.0 14.0 10.1 11.0 Target Predicted 13.1 16.2 11.2 7.5 9.5 15.9 13.5 11.7 12.6 10.1 7.6 16.6 8.7 8.0 15.0 8.5 11.3 11.9 12.0 14.0 13.9 11.7 10.6 12.5 12.9 10.9 4.5 15.9 14.3 14.5 4.8 12.7 9.3 14.4 11.0 14.8 8.1 12.2 28 Obs/Pred ratio 1.23 1.00 0.99 1.18 0.85 0.97 1.04 1.08 0.97 1.10 0.84 1.03 1.02 0.88 1.00 0.93 1.06 0.97 0.92 1.07 0.90 1.01 0.86 0.89 0.97 1.02 1.21 0.96 0.91 1.02 1.07 1.09 0.97 1.04 0.91 0.94 1.25 0.91 Obs minus Predicted 3.04 -0.03 -0.16 1.32 -1.44 -0.51 0.58 0.93 -0.32 1.02 -1.25 0.55 0.18 -0.96 0.07 -0.58 0.73 -0.32 -0.95 1.03 -1.34 0.16 -1.46 -1.44 -0.37 0.27 0.96 -0.68 -1.34 0.34 0.34 1.11 -0.27 0.64 -0.96 -0.86 2.04 -1.14 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2006 2007 2008 2009 13.1 9.2 8.4 9.4 13.7 11.0 9.8 15.9 16.2 10.3 11.5 11.5 9.3 8.3 13.1 11.6 13.6 12.9 10.7 8.9 7.8 9.3 12.7 10.4 11.1 16.8 16.3 10.4 11.0 10.2 9.6 8.1 15.4 12.1 15.3 13.0 13.0 9.3 8.5 9.5 13.6 10.9 9.8 15.7 15.9 10.3 11.4 11.5 9.4 8.5 13.0 11.6 13.5 12.8 0.83 0.96 0.92 0.98 0.93 0.95 1.13 1.07 1.03 1.01 0.96 0.89 1.02 0.96 1.19 1.04 1.14 1.02 -2.28 -0.39 -0.68 -0.21 -0.92 -0.56 1.31 1.09 0.42 0.10 -0.40 -1.25 0.15 -0.38 2.42 0.51 1.88 0.24 Historical Mean 11.7 11.6 11.6 1.00 0.00 Water Year 2003 2004 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Control Average 11.1 9.5 9.4 8.0 13.6 10.4 11.0 13.5 8.8 10.9 13.3 8.5 Target Average 10.7 8.6 8.5 6.4 14.7 12.2 10.7 13.9 9.5 12.8 13.6 9.1 Target Predicted 11.1 9.6 9.5 8.2 13.5 10.4 11.0 13.3 8.9 10.9 13.1 8.7 Obs/Pred ratio 0.96 0.90 0.90 0.79 1.09 1.17 0.97 1.04 1.07 1.17 1.03 1.05 Obs minus Predicted -0.44 -0.96 -0.96 -1.75 1.18 1.81 -0.29 0.57 0.59 1.89 0.43 0.39 Mean (03, 04,1221) 10.7 10.9 10.7 1.02 0.21 Seeded Period Summary Output for Regression Equation (5) 29 Regression Statistics Multiple R 0.93451111 R Square 0.873311014 Adjusted R Square 0.870964922 Standard Error 1.068992896 Observations 56 ANOVA Regression Residual Total Intercept X Variable df SS 425.3764831 54 61.70827384 55 487.0847569 Coefficients Standard Error 0.582328362 0.590641467 0.946263745 0.049045626 MS 425.3764831 1.142745812 F 372.2406844 Significance F 6.85456E-26 t Stat 0.985925293 19.29353996 P-value 0.328566888 6.85456E-26 Lower 95% -0.601837509 0.8479331 * 2018 results were adjusted due to a data correction 30 Table A-6 Mixed March Snow Evaluation Multiple Linear Regression (Equation 6) Historical regression period Water Year Lake Irene SN Stillwater Creek SN Burro Mtn sc 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 30.2 31.6 22.0 15.8 15.2 32.3 21.2 22.4 22.7 22.7 15.5 30.9 19.0 15.0 28.5 11.8 21.5 22.6 19.5 26.5 26.3 22.8 5.8 10.4 6.3 4.0 5.1 10.4 8.5 6.3 7.0 5.7 3.8 9.0 5.8 4.5 10.5 6.3 8.3 6.0 8.3 9.3 8.1 8.5 13.5 20.5 12.5 11.5 12.1 18.2 18.0 19.3 17.9 13.0 10.9 22.7 7.8 9.8 19.0 13.3 14.6 15.1 16.1 15.3 17.9 13.0 Gore Pass sc Deer Ridge sc Yampa View sc Target Average 7.9 11.2 8.9 4.0 9.5 13.2 11.8 8.2 8.6 5.5 3.9 14.3 5.2 5.8 13.5 5.2 8.3 8.7 9.9 10.5 12.0 9.6 7.4 6.6 4.2 1.0 2.4 6.9 5.6 1.8 5.9 2.3 2.0 7.9 4.3 2.2 5.0 3.4 3.3 3.6 3.1 8.2 3.4 3.7 31 14.4 18.8 13.5 7.3 12.1 16.3 16.7 12.4 13.8 11.1 8.3 17.0 9.1 9.9 15.2 10.0 12.2 15.6 15.3 15.5 16.7 12.7 16.1 16.2 11.1 8.8 8.0 15.4 14.1 12.6 12.2 11.1 6.3 17.2 8.8 7.1 15.1 7.9 12.1 11.6 11.0 15.1 12.6 11.8 Target Predicted 13.5 16.6 11.3 7.5 9.2 15.9 13.3 11.7 12.5 10.5 7.7 16.3 8.8 8.0 14.8 8.3 11.4 12.1 12.0 14.1 13.9 11.6 Obs/ Obs minus Pred Predicted ratio 1.19 2.60 0.98 -0.39 0.98 -0.24 1.17 1.28 0.88 -1.13 0.97 -0.46 1.06 0.80 1.08 0.93 0.98 -0.28 1.06 0.64 0.82 -1.36 1.06 0.90 1.00 0.02 0.88 -0.98 1.02 0.35 0.95 -0.44 1.06 0.71 0.95 -0.59 0.92 -0.93 1.07 1.01 0.90 -1.38 1.02 0.19 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 17.8 22.6 20.6 20.5 7.1 30.7 25.6 27.6 9.4 24.1 17.5 24.3 19.1 30.7 15.3 23.3 27.0 15.7 11.7 16.2 23.3 20.1 17.3 27.1 26.0 17.3 21.9 19.7 17.4 5.3 8.7 7.5 7.7 3.0 9.1 10.1 8.7 2.9 5.8 4.9 9.5 7.5 10.5 4.0 6.3 6.7 5.4 5.5 4.8 10.2 6.6 6.3 9.8 11.0 6.0 6.6 8.5 6.3 15.1 14.3 18.6 13.8 5.0 19.5 16.8 15.4 6.1 15.4 14.5 18.5 15.6 17.7 10.9 15.1 16.1 9.8 13.0 14.3 16.8 12.6 12.7 18.9 20.4 13.7 13.0 11.9 11.6 7.8 8.2 10.8 9.3 3.2 13.0 12.4 10.6 2.6 10.9 6.4 10.3 8.5 11.7 5.1 9.4 10.1 6.5 8.1 6.7 11.6 8.5 7.9 13.2 12.5 9.0 8.9 8.2 7.0 5.7 4.8 4.3 3.0 0.3 7.8 5.9 9.5 0.2 4.1 0.3 7.2 3.1 6.0 4.4 5.9 5.8 4.0 1.0 2.6 6.5 5.9 1.6 5.6 6.4 4.1 4.1 4.8 1.0 32 12.1 17.1 16.1 11.2 6.3 16.9 15.9 16.7 5.8 16.8 11.4 18.0 12.1 13.6 7.9 13.4 13.1 13.7 10.8 12.0 13.9 12.0 12.7 21.0 20.7 11.7 14.2 16.0 12.6 9.2 11.1 12.5 11.2 5.5 15.2 12.9 14.9 5.2 13.9 9.0 15.1 10.0 14.0 10.1 11.0 10.7 8.9 7.8 9.3 12.7 10.4 11.1 16.8 16.3 10.4 11.0 10.2 9.6 10.4 13.0 12.7 10.7 4.4 15.8 14.1 14.6 4.8 12.9 9.4 14.6 10.8 14.7 7.9 12.1 12.9 9.5 8.1 9.5 13.2 10.8 9.9 15.9 16.0 10.0 11.5 11.8 9.6 0.88 0.85 0.98 1.05 1.24 0.96 0.92 1.02 1.07 1.08 0.96 1.03 0.92 0.95 1.28 0.91 0.83 0.93 0.96 0.98 0.96 0.96 1.13 1.06 1.02 1.04 0.95 0.87 0.99 -1.25 -1.90 -0.23 0.48 1.05 -0.57 -1.18 0.25 0.34 0.99 -0.40 0.50 -0.82 -0.75 2.23 -1.06 -2.20 -0.62 -0.33 -0.21 -0.56 -0.41 1.26 0.89 0.26 0.41 -0.53 -1.56 -0.06 2002 2006 2007 2008 2009 13.8 21.1 19.6 20.2 21.6 4.6 9.8 8.3 9.5 8.9 12.5 15.8 13.7 17.5 15.8 6.1 11.6 7.4 11.8 12.1 1.2 2.1 6.3 6.0 3.6 11.9 18.1 14.4 16.6 15.4 8.1 15.4 12.1 15.3 13.0 8.6 13.1 11.7 13.2 12.6 0.95 1.17 1.03 1.16 1.04 -0.46 2.28 0.35 2.14 0.46 Historical Mean 21.2 7.2 14.7 9.0 4.3 13.7 11.6 11.6 1.00 0.00 Seeded Period Water Year Lake Irene SN Stillwater Creek SN Burro Mtn sc 2003 2004 2012 2013 2014 2015 2016 2017 2018* 2019 2020 2021 19.1 13.3 14.1 11.9 25.7 18.0 15.9 24.0 15.9 18.5 21.5 15.8 8.7 6.1 5.7 4.4 10.2 6.8 7.7 11.1 6.4 6.7 9.3 4.0 14.4 14.4 10.0 10.2 12.1 10.7 12.5 12.1 8.1 13.5 11.6 9.7 8.4 6.7 9.6 8.2 11.6 8.2 10.3 11.8 9.4 10.9 14.1 8.4 2.2 3.2 6.8 0.8 9.2 8.6 5.2 8.5 3.6 3.2 7.4 3.1 13.8 13.2 10.2 12.5 13.0 9.9 14.5 13.2 9.6 12.8 15.7 10.2 10.7 8.6 8.5 6.4 14.7 12.2 10.7 13.9 9.5 12.8 13.6 9.1 11.2 9.5 8.8 8.0 13.2 10.0 10.7 12.9 8.5 10.6 12.7 8.4 Obs/ Obs minus Pred Predicted ratio 0.95 -0.54 0.90 -0.94 0.97 -0.31 0.80 -1.62 1.11 1.51 1.23 2.24 1.00 -0.02 1.07 0.93 1.12 1.02 1.21 2.25 1.07 0.92 1.08 0.69 Mean (03, 04,12-21) 17.8 7.3 11.6 9.8 5.2 12.4 10.9 10.4 1.05 Gore Pass sc Deer Ridge sc Yampa View sc Target Average 33 Target Predicted 0.51 Summary Output for Regression Equation (6) Multiple R 0.93701 R Square 0.87800 Adjusted R 0.86306 Square Standard Error 1.10123 Observations 56 Coefficien Standard Error ts Intercept 0.18193 0.766203 Lake Irene SN 0.19624 0.053067 Stillwater Cr 0.16662 0.147180 SN Burro Mtn sc 0.13098 0.085561 Gore Pass sc 0.02984 0.137576 Deer Ridge sc 0.11787 0.105025 Yampa View sc 0.24764 0.091095 t Stat P-value Lower 95% 0.2374 3.6979 0.813300 0.000549 -1.35781 0.089598 1.721674572 -1.357810358 1.72167457 0.302885377 0.089598314 0.30288537 1.1321 0.263096 -0.12914 0.462396418 -0.129145587 0.46239641 1.5309 0.2169 1.1222 2.7185 0.132219 0.829158 0.267206 0.009042 -0.04095 -0.24662 -0.09318 0.06458 0.302931381 -0.040954298 0.30293138 0.306316188 -0.246625344 0.30631618 0.3289275 -0.093187433 0.3289275 0.430709907 0.064582109 0.43070990 34 Upper 95% Lower 95.0% Upper 95.0% Table A-7 Snowcourse-Only March Evaluation Linear Regression (Equation 7) Historical regression period Control Target Water Year Average Average 1957 12.3 11.5 1958 9.4 10.9 1959 10.6 10.2 1960 7.9 8.5 1961 5.9 4.7 1962 14.7 13.7 1963 6.4 6.9 1964 6.6 5.9 1965 12.7 12.7 1966 7.6 6.1 1967 9.6 10.0 1968 9.8 9.5 1969 10.8 8.8 1970 11.8 13.5 1971 12.1 10.3 1972 9.4 10.1 1973 9.7 7.7 1974 10.6 9.9 1975 11.5 10.4 1976 9.0 8.8 1977 3.5 4.0 1978 13.0 12.8 1979 12.0 10.5 1980 12.1 12.8 1981 3.6 3.7 1982 11.1 11.2 1983 7.8 7.9 1984 12.6 13.1 1985 9.4 8.5 1986 12.5 11.4 1987 6.7 7.5 1988 10.2 9.4 1989 10.6 9.3 1990 8.1 7.6 1991 7.7 6.3 1992 8.4 8.0 1993 11.8 10.3 1994 9.5 7.9 Target Predicted Obs/Pred ratio 11.9 0.97 9.0 1.20 10.2 1.00 7.6 1.12 5.7 0.82 14.2 0.96 6.2 1.11 6.3 0.93 12.2 1.03 7.3 0.83 9.2 1.09 9.5 1.00 10.4 0.84 11.4 1.19 11.7 0.88 9.0 1.12 9.3 0.83 10.2 0.97 11.1 0.94 8.7 1.01 3.3 1.22 12.6 1.02 11.6 0.90 11.7 1.09 3.4 1.08 10.7 1.05 7.5 1.05 12.2 1.07 9.0 0.94 12.1 0.94 6.5 1.16 9.8 0.96 10.2 0.91 7.8 0.97 7.4 0.85 8.1 0.99 11.4 0.91 9.2 0.86 35 Obs minus Predicted -0.41 1.84 0.01 0.92 -1.02 -0.50 0.69 -0.44 0.42 -1.22 0.79 -0.01 -1.65 2.13 -1.41 1.06 -1.61 -0.36 -0.69 0.09 0.71 0.23 -1.15 1.03 0.27 0.51 0.40 0.91 -0.52 -0.72 1.03 -0.37 -0.94 -0.20 -1.12 -0.10 -1.03 -1.25 1995 1996 1997 1998 1999 2000 2001 2002 2006 2007 2008 2009 8.0 14.0 14.4 9.3 9.4 9.8 7.7 7.3 10.8 9.9 12.2 10.9 8.5 14.7 13.9 8.8 8.7 8.9 7.6 6.2 13.2 10.0 12.3 10.2 7.7 13.5 13.9 8.9 9.1 9.5 7.4 7.1 10.4 9.6 11.7 10.5 1.09 1.09 1.00 0.98 0.96 0.93 1.03 0.88 1.27 1.05 1.05 0.97 0.71 1.24 0.00 -0.14 -0.40 -0.62 0.23 -0.85 2.82 0.46 0.56 -0.34 Historical Mean 9.5 9.5 9.5 1.00 0.00 Water Year 2003 2004 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Control Average 9.0 8.8 8.4 7.5 10.9 8.6 10.1 11.3 7.2 9.2 11.2 7.5 Target Average 8.7 6.9 6.8 4.9 12.7 10.3 8.8 12.0 7.9 10.5 11.7 7.6 Mean (03, 04,12-21) 9.1 9.0 Seeded Period Summary Output for Regression Equation (7) Regression Statistics Multiple R 0.929261447 R Square 0.863526837 Adjusted R Square 0.860683646 Standard Error 0.970824397 Observations 50 df SS Regression 286.2537495 Target Predicted Obs/Pred ratio 8.7 1.00 8.5 0.81 8.1 0.83 7.2 0.68 10.5 1.21 8.3 1.24 9.7 0.90 10.9 1.10 6.9 1.14 8.9 1.18 10.8 1.08 7.2 1.05 8.8 MS 286.2537495 36 1.03 F 303.7175029 Obs minus Predicted -0.02 -1.64 -1.34 -2.33 2.20 1.97 -0.97 1.06 1.00 1.64 0.84 0.38 0.23 Significance F 2.14137E-22 Residual Total Intercept X Variable 48 45.24000048 49 331.49375 0.94250001 Coefficients Standard Error -0.07531856 0.566053365 0.971677793 0.055755455 t Stat -0.133059122 17.42749273 37 P-value 0.894702893 2.14137E-22 Lower 95% -1.213444467 0.859574002 Water Year 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 Table A-8 Snowcourse-Only March Evaluation Multiple Linear Regression (Equation 8) Historical regression period Gore Pass Deer Burro Mtn Park View Yampa View Target Ridge Average 11.8 5.6 18.0 9.3 16.7 11.5 8.2 1.8 19.3 5.2 12.4 10.9 8.6 5.9 17.9 6.6 13.8 10.2 5.5 2.3 13.0 7.5 11.1 8.5 3.9 2.0 10.9 4.6 8.3 4.7 14.3 7.9 22.7 11.7 17.0 13.7 5.2 4.3 7.8 5.8 9.1 6.9 5.8 2.2 9.8 5.2 9.9 5.9 13.5 5.0 19.0 10.6 15.2 12.7 5.2 3.4 13.3 6.3 10.0 6.1 8.3 3.3 14.6 9.4 12.2 10.0 8.7 3.6 15.1 6.2 15.6 9.5 9.9 3.1 16.1 9.5 15.3 8.8 10.5 8.2 15.3 9.5 15.5 13.5 12.0 3.4 17.9 10.4 16.7 10.3 9.6 3.7 13.0 7.8 12.7 10.1 7.8 5.7 15.1 7.7 12.1 7.7 8.2 4.8 14.3 8.5 17.1 9.9 10.8 4.3 18.6 7.5 16.1 10.4 9.3 3.0 13.8 7.8 11.2 8.8 3.2 0.3 5.0 2.5 6.3 4.0 13.0 7.8 19.5 8.0 16.9 12.8 12.4 5.9 16.8 9.2 15.9 10.5 10.6 9.5 15.4 8.5 16.7 12.8 2.6 0.2 6.1 3.2 5.8 3.7 10.9 4.1 15.4 8.2 16.8 11.2 6.4 0.3 14.5 6.5 11.4 7.9 10.3 7.2 18.5 9.1 18.0 13.1 38 Target Predicted 11.9 9.1 10.4 7.2 5.6 13.8 6.1 6.4 11.9 7.1 8.6 10.0 10.2 11.4 11.4 8.9 9.1 10.4 11.3 8.4 3.5 13.0 11.7 12.1 3.3 11.0 7.3 12.4 Obs/Pred ratio 0.96 1.19 0.99 1.18 0.84 0.99 1.12 0.92 1.07 0.86 1.16 0.95 0.86 1.19 0.90 1.13 0.85 0.94 0.92 1.05 1.15 0.99 0.90 1.05 1.11 1.02 1.09 1.06 Obs minus Predicted -0.47 1.74 -0.15 1.32 -0.89 -0.11 0.75 -0.49 0.80 -0.96 1.36 -0.49 -1.42 2.13 -1.19 1.13 -1.41 -0.59 -0.94 0.40 0.53 -0.18 -1.21 0.64 0.35 0.21 0.64 0.68 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2006 2007 2008 2009 8.5 11.7 5.1 9.4 10.1 6.5 8.1 6.7 11.6 8.5 7.9 13.2 12.5 9.0 8.9 8.2 7.0 6.1 11.6 7.4 11.8 12.1 3.1 6.0 4.4 5.9 5.8 4.0 1.0 2.6 6.5 5.9 1.6 5.6 6.4 4.1 4.1 4.8 1.0 1.2 2.1 6.3 6.0 3.6 15.6 17.7 10.9 15.1 16.1 9.8 13.0 14.3 16.8 12.6 12.7 18.9 20.4 13.7 13.0 11.9 11.6 12.5 15.8 13.7 17.5 15.8 7.5 13.6 5.4 7.0 8.0 6.4 5.4 6.2 10.0 8.6 5.3 11.1 11.8 7.9 7.0 8.2 6.1 5.0 6.2 7.8 8.9 7.7 12.1 13.6 7.9 13.4 13.1 13.7 10.8 12.0 13.9 12.0 12.7 21.0 20.7 11.7 14.2 16.0 12.6 11.9 18.1 14.4 16.6 15.4 8.5 11.4 7.5 9.4 9.3 7.6 6.3 8.0 10.3 7.9 8.5 14.7 13.9 8.8 8.7 8.9 7.6 6.2 13.2 10.0 12.3 10.2 8.8 10.9 6.3 10.0 10.2 8.1 7.4 8.0 11.0 8.9 8.1 13.7 13.9 8.7 9.3 9.7 7.5 7.3 11.2 9.7 11.9 10.8 0.97 1.04 1.20 0.95 0.92 0.93 0.84 0.99 0.94 0.89 1.05 1.07 1.00 1.01 0.93 0.91 1.01 0.85 1.18 1.04 1.03 0.95 -0.29 0.45 1.25 -0.53 -0.85 -0.53 -1.17 -0.09 -0.68 -0.97 0.40 1.02 0.01 0.10 -0.65 -0.87 0.11 -1.06 2.01 0.36 0.40 -0.59 Historical Mean 9.0 4.2 14.7 7.7 13.7 9.5 9.5 1.000 0.00 Water Year Gore Pass Burro Mtn Park View 2003 2004 2012 2013 2014 8.4 6.7 9.6 8.2 11.6 Deer Ridge 2.2 3.2 6.8 0.8 9.2 14.4 14.4 10.0 10.2 12.1 6.2 6.6 5.4 5.9 8.5 Target Average 8.7 6.9 6.8 4.9 12.7 Target Predicted 8.9 8.6 8.4 7.5 10.6 Obs/Pred ratio 0.97 0.80 0.80 0.66 1.20 Obs minus Predicted -0.26 -1.70 -1.66 -2.57 2.11 Seeded Period Yampa View 13.8 13.2 10.2 12.5 13.0 39 2015 2016 2017 2018 2019 2020 2021 8.2 10.3 11.8 9.4 10.9 14.1 8.4 8.6 5.2 8.5 3.6 3.2 7.4 3.1 10.7 12.5 12.1 8.1 13.5 11.6 9.7 5.7 7.9 11.1 5.2 5.6 7.2 5.9 9.9 14.5 13.2 9.6 12.8 15.7 10.2 10.3 8.8 12.0 7.9 10.5 11.7 7.6 8.5 9.9 10.5 7.1 9.3 11.5 7.2 1.21 0.88 1.14 1.11 1.13 1.01 1.04 1.77 -1.17 1.49 0.75 1.23 0.12 0.31 Mean (03, 04,12-21) 9.8 5.2 11.6 6.8 12.4 9.0 9.0 1.00 0.03 Lower 95% Upper 95% Lower 95.0% Upper 95.0% Summary Output for Regression Equation (8) Regression Statistics Multiple R 0.9373969 R Square 0.8787130 Adjusted R 0.8649304 Square Standard Error 0.9559131 Observations 50 Coefficients Intercept Gore Pass Deer Ridge Burro Mtn Park View Yampa View -0.07875172 0.23132813 0.225558945 0.160897624 -0.01000731 0.311306915 Standard Error 0.70056861 0.12680365 0.08692337 0.07768114 0.11485827 0.07951141 t Stat -0.112411 1.8243018 2.5949171 2.0712572 -0.087128 3.9152483 P-value 0.911008706 -1.490654934 1.333151493 -1.490654934 1.333151493 0.074901793 -0.024227834 0.486884094 -0.024227834 0.486884094 0.01280686 0.050376405 0.400741486 0.050376405 0.400741486 0.044230516 0.004341573 0.317453675 0.004341573 0.317453675 0.930965475 -0.241488947 0.221474317 -0.241488947 0.221474317 0.000310292 0.151062204 0.471551627 0.151062204 0.471551627 40