C150307 Final Supplimental Impact Statement

• Contract/PO #: C150307
• Contractor Name: Animas La Plata
• Contract Type: Loan
• Loan Projects - Doc Type: Report

TABLE OF CONTENTS(continued)
Chapter Pane No.
3 AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES 3-1
3.1 INTRODUCTION 3-1
3.1.1 Structural Components 3-1
3.1.2 Non-Structural Component 3-2
3.1.3 Non-Binding End Uses 3-2
3.1.4 Structure of Sections • 3-3
3.2 WATER RESOURCES/HYDROLOGY 3-4
3.2.1 Introduction 3-4
3.2.2 Evaluation Methodology 3-4
3.2.2.1 Methodology 3.4
3.2.2.1.1 Configuration for Future Conditions Without the
Project 3-5
3.2.2.1.2 Configuration for the Refined Alternative 4 3-5
3.2.2.1.3 Configuration for Refined Alternative 6 3-12
3.2.2.2 Significance Criteria 3-14
3.2.3 Affected Environment 3-17
3.2.3.1 Refined Alternative 4 Structural Component 3-17
3.2.3.1.1 Animas River 3-17
3.2.3.1.2 La Plata River 3-18
3.2.3.1.3 Mancos River 3-18
3.2.3.1.4 San Juan River 3-18
3.2.3.1.5 Navajo Reservoir 3-19
3.2.3.2 Refined Alternative 4 Non-Structural Component 3-19
3.2.3.2.1 Pine River 3-19
3.2.3.2.2 Florida River 3-19
3.2.3.3 Refined Alternative 6 3-19
3.2.3.3.1 Dolores River 3-19
3.2.3.3.2 McElmo Creek 3-20
3.2.4 Environmental Consequences and Mitigation 3-20
3.2.4.1 Refined Alternative 4 3-20
3.2.4.1.1 Operation of Structural Components and Delivery
to Non-Binding Uses 3-20
3.2.4.1.2 Water Conveyance Impacts for Non-Binding Uses 3-28
3.2.4.2 Refined Alternative 6 3-28
3.2.4.3 No Action Alternative 3-33
3.3 WATER QUALITY 3-34
3.3.1 Introduction 3-34
3.3.2 Evaluation Methodology 3-34
3.3.2.1 Methodology 3-34
3.32.1.1 Approach 3-34
3.3.2.1.2 Standards by State 3-35
3.3.2.1.3 Sites with Water Quality Measurements 3-37
3.32.1.4 Historic Streamflow Data
3-37
3.3.2.1.5 Streamflow Data from the San Juan River
Hydrology Model 3-37
3.322 Significance Criteria 3-39
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