Green Mountain Reservoir Substitution and Power Interference Agreements Final EA Table of Contents Acronyms...................................................................................................................................... vi 1.0 Purpose and Need .......................................................................................................... 1-1 1.1 Introduction.......................................................................................................... 1-1 1.2 Project Purpose and Need .................................................................................... 1-1 1.3 Study Area........................................................................................................... 1-2 1.4 Background.......................................................................................................... 1-2 1.4.1 Prior Appropriation System .....................................................................1-2 1.4.2 Reclamation and Green Mountain Reservoir...........................................1-2 1.4.3 Western Area Power Administration.......................................................1-4 1.4.4 Springs Utilities’ Collection Systems and Customers .............................1-4 1.4.5 Blue River Decree....................................................................................1-7 1.4.6 Substitution Year Operations...................................................................1-8 1.4.7 Substitution Memorandums of Agreement............................................1-10 1.5 Required Permits and Approvals ....................................................................... 1-11 1.6 Agency and Public Input.................................................................................... 1-11 1.7 Environmental Resources.................................................................................. 1-12 2.0 Alternatives..................................................................................................................... 2-1 2.1 Introduction.......................................................................................................... 2-1 2.2 Alternative Screening Process ............................................................................. 2-1 2.3 No Action Alternative.......................................................................................... 2-2 2.4 Proposed Action................................................................................................... 2-3 3.0 Affected Environment and Environmental Consequences ........................................ 3-1 3.1 Introduction and Methodology ............................................................................ 3-1 3.1.1 Impact Thresholds....................................................................................3-1 3.1.2 Climate Change........................................................................................3-2 3.1.3 Reasonably Foreseeable Water-Based Actions Considered in Cumulative Effects Analysis .......................................................................................3-3 3.2 Issues and Impact Topics Considered but Excluded from Further Evaluation ............................................................................................................ 3-7 3.3 Hydrology .......................................................................................................... 3-10 3.3.1 Affected Environment............................................................................3-10 3.3.2 Environmental Consequences................................................................3-29 3.3.3 Cumulative Impacts ...............................................................................3-58 3.4 Hydroelectric Generation................................................................................... 3-62 3.4.1 Affected Environment............................................................................3-62 3.4.2 Environmental Consequences................................................................3-65 i Green Mountain Reservoir Substitution and Power Interference Agreements Final EA 3.4.3 Cumulative Impacts ...............................................................................3-67 3.5 Water Quality..................................................................................................... 3-67 3.5.1 Affected Environment............................................................................3-69 3.5.2 Environmental Consequences................................................................3-70 3.5.3 Cumulative Impacts ...............................................................................3-70 3.6 Aquatic Resources and Special Status Species.................................................. 3-74 3.6.1 Affected Environment............................................................................3-74 3.6.2 Environmental Consequences................................................................3-79 3.6.3 Cumulative Impacts ...............................................................................3-87 3.7 Wetland and Riparian Resources and Special Status Species ........................... 3-87 3.7.1 Affected Environment............................................................................3-89 3.7.2 Environmental Consequences................................................................3-93 3.7.3 Cumulative Impacts ...............................................................................3-96 3.8 Recreation .......................................................................................................... 3-96 3.8.1 Affected Environment............................................................................3-96 3.8.2 Environmental Consequences................................................................3-98 3.8.3 Cumulative Impacts .............................................................................3-100 3.9 Socioeconomics ............................................................................................... 3-100 3.9.1 Affected Environment..........................................................................3-100 3.9.2 Environmental Consequences..............................................................3-101 3.9.3 Cumulative Impacts .............................................................................3-102 3.10 Summary of Impacts........................................................................................ 3-102 4.0 Consultation and Coordination .................................................................................... 4-1 4.1 Scoping Process................................................................................................... 4-1 4.2 Comments on the Draft EA.................................................................................. 4-2 4.3 Preparers .............................................................................................................. 4-2 5.0 References....................................................................................................................... 5-1 Glossary ..........................................................................................................................................1 List of Tables Table 1-1 Summary of Historical Substitution Year Operations Table 3-1 Springs Utilities Substitution Summary, Modeled Differences between No Action and Proposed Action Alternatives (AF) Table 3-2 Blue River below the Continental-Hoosier System, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) ii Green Mountain Reservoir Substitution and Power Interference Agreements Final EA Table 3-3 Blue River below Dillon Reservoir at USGS Gage 09050700, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-4 Blue River below Green Mountain Reservoir, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-5 Upper Blue River Reservoir, Modeled Differences in Content between No Action and Proposed Action Alternatives (AF) Table 3-6 Dillon Reservoir, Modeled Differences in Content between No Action and Proposed Action Alternatives (AF) Table 3-7 Green Mountain Reservoir, Modeled Differences in Content between No Action and Proposed Action Alternatives (AF) Table 3-8 Williams Fork River below Williams Fork Reservoir, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-9 Williams Fork Reservoir, Modeled Differences in Content between No Action and Proposed Action Alternatives (AF) Table 3-10 Muddy Creek below Wolford Mountain Reservoir, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-11 Wolford Mountain Reservoir, Modeled Differences in Content between No Action and Proposed Action Alternatives (AF) Table 3-12 Colorado River below the Confluence with the Williams Fork River, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-13 Colorado River near Kremmling at USGS Gage 0905800, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-14 Colorado River below the Confluence with the Eagle River, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table 3-15 Homestake Creek below Homestake Project at USGS Gage 09064000, Modeled Differences in Flow between No Action and Proposed Action Alternatives (cfs) Table