Analysis and Technical Update to the Colorado Water Plan Technical Memorandum Prepared for: Colorado Water Conservation Board Project Title: Current and 2050 Planning Scenario Water Supply and Gap Results Date: September 18, 2019 Prepared by: Wilson Water Group Reviewed by: Jacobs, Brown & Caldwell Technical Update Water Supply and Gap Results Table of Contents Section 1 : Introduction ................................................................................................................................. 10 Section 2 : Definitions and Terminology ........................................................................................................ 11 Section 3 : SWSI 2010 Water Supply Methodology....................................................................................... 12 Section 4 : Technical Update Water Supply Methodology ............................................................................ 15 4.1 Current/Baseline Water Supply Methodology .......................................................................... 15 4.1.1 CDSS Basin Water Supply Methodology ..................................................................................... 16 4.1.2 Non-CDSS Basin Water Supply Methodology ............................................................................. 19 4.2 Planning Scenario A-E Water Supply Methodology .................................................................. 21 4.2.1 Planning Scenario Water Supply Adjustments ............................................................................ 21 4.2.2 CDSS Basin Planning Scenario Water Supply Methodology ....................................................... 23 4.2.3 Non-CDSS Basin Planning Scenario Water Supply Methodology ............................................... 24 4.3 Explanation of Results ................................................................................................................ 25 Section 5 : Water Supply and Gap - Basin Summary Results ........................................................................ 27 5.1 Arkansas River Basin .................................................................................................................. 27 5.1.1 Arkansas River Basin Agriculture Water Supply and Gap ........................................................... 28 5.1.2 Arkansas River Basin M&SSI Water Supply and Gap .................................................................. 32 5.1.3 Arkansas River Basin Transbasin Export Demand ....................................................................... 35 5.1.4 Arkansas River Basin Summary ................................................................................................... 35 5.2 Colorado River Basin .................................................................................................................. 43 5.2.1 Colorado River Basin Agriculture Water Supply and Gap ........................................................... 45 5.2.2 Colorado River Basin M&SSI Water Supply and Gap .................................................................. 48 5.2.3 Colorado River Basin Transbasin Export Demand ....................................................................... 52 5.2.4 Colorado River Basin Summary ................................................................................................... 53 5.3 Gunnison River Basin ................................................................................................................. 64 5.3.1 Gunnison River Basin Agriculture Water Supply and Gap .......................................................... 66 5.3.2 Gunnison River Basin M&SSI Water Supply and Gap ................................................................. 70 5.3.3 Gunnison River Basin Transbasin Export Demand ...................................................................... 74 5.3.4 Gunnison River Basin Summary .................................................................................................. 74 5.4 North Platte River Basin ............................................................................................................. 81 5.4.1 North Platte River Basin Agriculture Water Supply and Gap ...................................................... 82 5.4.2 North Platte River Basin M&SSI Water Supply and Gap ............................................................. 86 5.4.3 North Platte River Basin Transbasin Export Demand ................................................................. 89 5.4.4 North Platte River Basin Summary .............................................................................................. 89 5.5 Republican River Basin ............................................................................................................... 96 5.5.1 Republican River Basin Agriculture Water Supply and Gap ........................................................ 96 ii Colorado Water Conservation Board Department of Natural Resources Technical Update Water Supply and Gap Results 5.5.2 Republican River Basin M&SSI Water Supply and Gap ............................................................. 100 5.5.3 Republican River Basin Summary .............................................................................................. 103 5.6 Rio Grande Basin ...................................................................................................................... 105 5.6.1 Rio Grande Basin Agriculture Water Supply and Gap ............................................................... 106 5.6.2 Rio Grande Basin M&SSI Water Supply and Gap ...................................................................... 110 5.6.3 Rio Grande Basin Summary ....................................................................................................... 113 5.7 Southwest Basin ....................................................................................................................... 120 5.7.1 Southwest Basin Agriculture Water Supply and Gap ................................................................ 121 5.7.2 Southwest Basin M&SSI Water Supply and Gap ....................................................................... 125 5.7.3 Southwest Basin Transbasin Exports ......................................................................................... 128 5.7.4 Southwest Basin Summary ........................................................................................................ 129 5.8 South Platte River Basin ........................................................................................................... 138 5.8.1 South Platte River Basin Agriculture Water Supply and Gap .................................................... 140 5.8.2 South Platte River Basin M&SSI Water Supply and Gap ........................................................... 144 5.8.3 South Platte River Basin Summary ............................................................................................ 149 5.9 White River Basin ..................................................................................................................... 160 5.9.1 White River Basin Agriculture Water Supply and Gap .............................................................. 161 5.9.2 White River Basin M&SSI Water Supply and Gap ..................................................................... 165 5.9.3 White River Basin Summary ...................................................................................................... 168 5.10 Yampa River Basin .................................................................................................................... 174 5.10.1 Yampa River Basin Agriculture Water Supply and Gap ............................................................. 175 5.10.2 Yampa River Basin M&SSI Water Supply and Gap .................................................................... 179 5.10.3 Yampa River Basin Summary ..................................................................................................... 183 Section 6 : Statewide Water Supply and Gap Results ................................................................................. 189 6.1 Statewide Agricultural Demand and Gap Results .................................................................... 189 6.2 Statewide M&SSI Demand and Gap Results ............................................................................ 192 6.3 Statewide Total Demand and Gap Results .............................................................................. 194 Section 7 : Comments and Concerns ........................................................................................................... 197 Section 8 : References .................................................................................................................................. 200 iii Colorado Water Conservation Board Department of Natural Resources Technical Update Water Supply and Gap Results List of Figures Figure 1: 2050 Planning Scenario Descriptions ............................................................................................. 10 Figure 2: River Basin Boundaries ................................................................................................................... 11 Figure 3: CDSS StateMod Model Availability ................................................................................................. 18 Figure 4: 2050 Planning Scenario Descriptions ............................................................................................