DRAFT Letter Report and Integrated Environmental Assessment Lower Pool 2 Channel Management Study: Boulanger Bend to Lock and Dam No. 2 Upper Mississippi River Dakota and Washington Counties, Minnesota DRAFT June 2017 This page intentionally left blank. Contents EXECUTIVE SUMMARY ................................................................................................ 1 CHAPTER 1. INTRODUCTION ................................................................................. 5 1.1 Authority ................................................................................................. 5 1.2 Project Location and Study Area ............................................................ 5 1.3 Purpose and Need .................................................................................... 6 1.4 Related Studies and Reports .................................................................... 7 CHAPTER 2. AFFECTED ENVIRONMENT ............................................................ 10 2.1 Socioeconomic Conditions .................................................................... 10 2.1.1 Commercial Navigation ....................................................................... 11 2.1.2 Recreation ............................................................................................ 12 2.1.3 Aesthetic Resources ............................................................................. 12 2.2 Natural Resources ................................................................................. 13 2.2.1 Physical Setting .................................................................................... 13 2.2.2 Aquatic Habitat .................................................................................... 20 2.2.3 Fisheries ............................................................................................... 20 2.2.4 Aquatic Invertebrates ........................................................................... 21 2.2.5 Threatened and Endangered Species .................................................... 22 2.2.6 Aquatic Vegetation............................................................................... 25 2.2.7 Birds ..................................................................................................... 26 2.2.8 Water Quality ....................................................................................... 26 2.2.9 Terrestrial Habitat ................................................................................ 27 2.2.10 Air Quality ........................................................................................... 28 2.3 Cultural Resources ................................................................................ 28 2.4 Resource Significance ........................................................................... 30 2.5 Expected Future Without Project Conditions ........................................ 31 2.5.1 Climate Change .................................................................................... 31 CHAPTER 3. PLANNING PROCESS ..................................................................... 33 3.1 Problem and Opportunity Identification ............................................... 33 3.2 Project Goals and Objectives ................................................................ 35 3.3 Planning Constraints and Assumptions ................................................. 36 3.4 Alternative Measures ............................................................................. 36 3.4.1 No Action ............................................................................................. 37 3.4.2 Channel Control Structures .................................................................. 37 3.4.3 Channel Realignment ........................................................................... 37 i 3.4.4 Increased Channel Maintenance .......................................................... 37 CHAPTER 4. ALTERNATIVE PLAN FORMULATION AND EVALUATION ........... 38 4.1 Alternative 1 - No Action Alternative ................................................... 40 4.2 Alternative 2 – Revetments and Wing Dams Channel Control Structures ............................................................................................... 41 4.3 Alternative 3 - Nininger Slough Channel Realignment ........................ 44 4.4 Alternative 4 - Increased Channel Maintenance ................................... 47 4.5 Alternative 5 - Boulanger Slough Channel Realignment ...................... 50 4.6 Alternative 6 - Increased Channel Maintenance with Rock Sill Training Structures ............................................................................................... 54 4.7 Final Array of Alternatives Carried Forward for Further Development 58 CHAPTER 5. ALTERNATIVE PLAN SELECTION .................................................. 61 5.1 Alternative 1 - No Action Alternative ................................................... 61 5.2 Alternative 5 - Boulanger Slough Channel Realignment ...................... 61 5.3 Alternative 6 – Increased Channel Maintenance and Rock Sill Training Structures ............................................................................................... 63 5.4 Comparison of Final Array of Alternatives ........................................... 67 5.5 Plan Selection ........................................................................................ 68 5.5.1 Summary of Accounts for the National Economic Development Plan 69 5.6 Tentatively Selected Plan ...................................................................... 69 5.6.1 Plan Features ........................................................................................ 70 5.6.2 Design Considerations ......................................................................... 70 5.6.3 Environmental Mitigation .................................................................... 71 5.6.4 Construction Considerations ................................................................ 72 5.6.5 Lands, Easements, Rights-of Way, Relocations, and Disposal Site Considerations ...................................................................................... 75 5.6.6 Real Estate Considerations ................................................................... 75 5.6.7 Operation, Maintenance, Repair, Rehabilitation and Replacement ..... 75 5.6.8 Construction Cost Estimate .................................................................. 75 CHAPTER 6. EVALUATION OF ENVIRONMENTAL EFFECTS ........................... 77 6.1 Socioeconomic Effects .......................................................................... 77 6.1.1 Commercial Navigation ....................................................................... 77 6.1.2 Recreation ............................................................................................ 78 6.1.3 Aesthetics ............................................................................................. 78 6.1.4 Noise .................................................................................................... 78 6.1.5 Existing/Potential Land Use ................................................................. 79 6.2 Natural Resource Effects ....................................................................... 80 6.2.1 Physical Setting .................................................................................... 80 6.2.2 Aquatic Habitat .................................................................................... 83 6.2.3 Fisheries ............................................................................................... 84 6.2.4 Aquatic Invertebrates ........................................................................... 85 ii 6.2.5 Threatened and Endangered Species .................................................... 87 6.2.6 Aquatic Vegetation............................................................................... 90 6.2.7 Birds ..................................................................................................... 91 6.2.8 Water Quality ....................................................................................... 91 6.2.9 Terrestrial Habitat ................................................................................ 92 6.2.10 Air Quality ........................................................................................... 92 6.3 Cultural Resource Effects ...................................................................... 94 6.3.1 Wing Dams .......................................................................................... 94 6.3.2 Boulanger Island Remnant ................................................................... 94 6.3.3 Submerged High Probability Landforms ............................................. 95 6.3.4 Proximal Recorded Cultural Resources ............................................... 96 6.3.5 Coordination ......................................................................................... 96 6.4 Cumulative Effects ................................................................................ 97 6.4.1 Scope of Cumulative Effects Analysis ................................................. 97 6.4.2 Actions Identified Within the Project Impact Zone ............................. 97 6.4.3 Environmental Consequences of Cumulative Effects .......................... 99 6.5 Summary of Environmental Effects .................................................... 101 CHAPTER 7. ENVIRONMENTAL COMPLIANCE AND REVIEW