Draft Environmental Impact Statement




НазваниеDraft Environmental Impact Statement
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Дата конвертации29.10.2012
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Impacts of No Action 349

Impacts of the Proposed Action – River Erosion Alternative 350

Impacts of the Dredge and Slurry Alternative353

Aesthetics 355

Summary of Regulations and Policies 355

Methodologies for Analyzing Impacts 355

Impacts of No Action 356

Impacts of the Proposed Action – River Erosion Alternative 357

Impacts of the Dredge and Slurry Alternative 363

Required Impact Sections 364

Impacts on Energy Consumption 364

Unavoidable Adverse Impacts 365

Short-term Uses vs. Long-term Productivity 366

Irreversible and Irretrievable Commitments of Resources 367

Consultation and Coordination

History of Public Involvement 369

Scoping Issues 371

Public Comment Period 371

Preparers and Contributors 372

Preparers 372

Contributors 375

Agencies and Organizations That Received Copies of the Draft Implementation Environmental Impact Statement 378

References

Bibliography 383

Glossary and Acronym List 403

Index 409

Appendixes

Appendix 1. Public Law 102-495 - Elwha Restoration Act 413

Appendix 2. Elwha river Fish Restoration Plan 419

Appendix 3. Revegetation Plan 441

Appendix 4. Flooding Impacts Associated With Removal of the Elwha and Glines Canyon Dams 451

Appendix 5. Programmatic Agreement 463

Appendix 6. Requirements for Completing the Proposed Action 475

Tables

Table 1. Summary of Costs for Each Action Alternative 8

Table 2. New Wild Salmonid Production and Recovery Time 13

Table 3. Substantive Issues and Concerns Analyzed in this EIS 32

Table 4. Summary of Features for Existing Projects 42

Table 5. Summary of Mitigation Measures for River Erosion and Dredge and Slurry Alternatives 50

Table 6. Restoration Actions for Elwha River Anadromous Fish Stocks 60

Table 7. Water Quality Mitigation Measures 64

Table 8. Mitigation Measures Required under the Interagency Programmatic Agreement and Section 106 of the National Historic Preservation Act 67

Table 9. Cost Estimates – River Erosion Alternative (Proposed Action) 68

Table 10. Cost Estimates – Dredge and Slurry Alternative 74

Table 11. Summary of Alternatives 76

Table 12. Impact Summary Chart 84

Table 13. Major Elwha River Tributaries 104

Table 14. Estimated Sediment Gradation and Volumes for Lake Mills and Lake Aldwell 106

Table 15. Peak Discharge and Recurrence Intervals for Flooding in the Lower Elwha River 110

Table 16. Discharge Statistics for the Elwha River 113

Table 17. Maximum Daily Water Temperatures for the Elwha River at River Mile 3.3 116

Table 18. Water Quality Statistics for the Elwha River 117

Table 19. In-River Life cycle Stages of Elwha Salmonids 121

Table 20. Vegetation Cover Types in Elwha and Glines Canyon Study Area 128

Table 21. Air Quality Data and Standards for Olympic National Park 144

Table 22. Major Employers in Clallam County 153

Table 23. Comparative Statistics on Economic Status 153

Table 24. Estimated Annual Economic Value of Elwha Salmon and Steelhead 155

Table 25. Existing Summer Peak Hour Level of Service 164

Table 26. Monthly Visitor Use of the Elwha River Valley in Olympic National Park 169

Table 27. Overnight Backcountry Visitor Use Nights in the Elwha River Valley, Olympic National Park 172

Table 28. Range of Final Sediment Release During and Following Dam Removal – River Erosion Alternative (Proposed Action) 195

Table 29. Sediment Before and After Dam Removal – River Erosion (Proposed Action) 196

Table 30. Fine-grained Sediment Behind Dams and Quantities Expected to Enter River upon Dam Removal – River Erosion (Proposed Action) and Dredge and Slurry Alternatives 204

Table 31. Range of Final Sediment Release During and Following Dam Removal – Dredge and Slurry Alternative 205

Table 32. Elwha River Valley Structures and Existing Flood Conditions for the 100-year Frequency Flood Event 209

Table 33. Water Surface Elevations Before and After Dam Removal with the 100-year Frequency Flood Event 210

Table 34. Structural Mitigation for Flooding Impacts 215

Table 35. Elwha River Turbidity Measurements Upstream and Downstream of the Dams 219

Table 36. Water Quality Impact Indicators 220

Table 37. Short-term Water Quality Impact Indicators 222

Table 38. Long-term Water Quality Impact Indicators 223

Table 39. Mitigation Measures Included – River Erosion Alternative (Proposed Action) 224

Table 40. Water Quality Before and Following Proposed Mitigation 225

Table 41. Surface Water Suspended Sediment Concentrations for Sequential Steps in Dam Removal Comparing River Erosion and Dredge and Slurry Alternatives 229

Table 42. Water Quality Before and Following Proposed Mitigation – Dredge and Slurry Alternative 230

Table 43. Groundwater Impacts and Mitigation 234

Table 44. New Wild Salmonid Production and Recovery Time 249

Table 45. Restoration Potential of Elwha Salmonids – River Erosion Alternative (Proposed Action) 250

Table 46. Impacts of Suspended Sediments on Adult Anadromous Salmonids – River Erosion Alternative (Proposed Action) 257

Table 47. Summary of Short-Term Impacts on Anadromous Salmonids – River Erosion Alternative (Proposed Action) 260

Table 48. Impacts of Suspended Sediments on Adult Salmonids – Dredge and Slurry 263

Table 49. Summary of Short-Term Impacts on Anadromous Salmonids – Dredge and Slurry Alternative 264

Table 50. Expected Vegetation Types in Recovered Reservoir Areas 268

Table 51. Air Quality Data and Standards for Olympic National Park 293

Table 52. Annual Particulate Matter Emissions Less than 10 Micrometers 293

Table 53. Construction Equipment Noise Levels 296

Table 54. Peak Flat-Weighted Sound Pressure Levels 297

Table 55. Number of Houses at Reference Distances from Damsites 298

Table 56. Typical Sound Levels 299

Table 57. Estimated Decibels for Continuous Construction Noise at Reference Distances under Best and Worst Atmospheric Conditions 299

Table 58. Predicted Flat-Weighted Peak Sound Pressure Levels Under Best and Worst Atmospheric Conditions 300

Table 59. Mitigation Measures Required under the Interagency Programmatic Agreement and Section 106 of the National Historic Preservation Act 306

Table 60. Estimated Annual Net business Benefits from Elwha Fish 313

Table 61. Estimated Annual Real Energy Cost for Replacement Power for Daishowa Mill 315

Table 62. Estimated Annual Net business from Elwha Fish Restoration – After Completion of Fisheries Rebuilding 316

Table 63. Summary of the Net Present Value of Elwha River Restoration Market Benefits over Project Life – at 3% Discount Rate 317

Table 64. Peak Hour Traffic for the Year 2000 Compared to Existing Conditions (1995) for Both Weekday and Weekend Traffic 333

Table 65. Peak Hour Traffic for the Year 2005 Compared to Existing Conditions (1995) for Both Weekday and Weekend Traffic 334

Table 66. Year 2000 Peak Weekday/Weekend LOS Levels with Project Traffic Added 335

Table 67. Year 2005 Peak Weekday/Weekend LOS Levels with Project Traffic Added 336

Figures

Figure 1. Location Map 2

Figure 2. Project area 24

Figure 3. Sequence of Documents and Events Leading to this Environmental Impact Statement 25

Figure 4. Elwha Dam Features 45

Figure 5. Glines Canyon Dam 47

Figure 6. Dredge & Slurry Pipeline Route 72

Figure 7. Elwha River System 102

Figure 8. Elwha River Reaches 103

Figure 9. Floodplain Map 111

Figure 10. Northern Study area 115

Figure 11. Cultural Sites 149

Figure 12. Fault Map 160

Figure 13. Potential Disposal Sites & Routes 165

Figure 14. Recreation Areas 168

Figure 15. Olympic National Park Features 171

Figure 16. Land Ownership 175

Figure 17. General Land Use 177

Figure 18. Zoning 182

Figure 19. Landscape Districts 185

Figure 20. Thalweg and Water Surface Elevations – Short-term Impacts 200

Figure 21. Thalweg and Water Surface Elevations – Long-term Impacts 201

Figure 22. Comparison of Elwha River Anadromous Fish Habitat under Each Alternative 242

Figure 23. Elwha Dam Area – Current Conditions 359

Figure 24. Elwha Dam Area After Dam Removal 359

Figure 25. Lake Aldwell – Current Conditions 360

Figure 26. Lake Aldwell – 20 Years After Dam Removal 360

Figure 27. Glines Canyon Dam – Current Conditions 361

Figure 28. Glines Canyon Dam Area After Dam Removal 361

Figure 29. Lake Mills Looking South – Current Conditions 362

Figure 30. Mills Valley Looking South – 20+ Years After Dam Removal 362

Pg. 12 = pg.1

Summary

Introduction

This document is a draft environmental impact statement (DEIS), prepared to analyze environmental impacts of alternative ways to remove two hydroelectric projects on the Elwha River. This DEIS is the second of two, which in combination study how to fully restore the river’s dam-altered ecosystem and native anadromous fisheries in a safe, environmentally sound and cost-effective manner. The first, “programmatic” EIS (Elwha River Ecosystem Restoration Final Environmental Impact Statement) was finalizes in June, 1995. The programmatic EIS is procedurally connected (tiered) to this document, the Implementation EIS.


Professionals in a variety of technical fields from a group of federal agencies and the Lower Elwha Klallam Tribe, as well as consultants and the public helped define project objectives and the range of reasonable alternatives. They also analyzed the impacts of those alternatives to important environmental resources. The National Park Service is the lead agency in the production of this analysis and documentation, and the US Bureau of Reclamation, US Fish and Wildlife Service, US Bureau of Indian Affairs, US Army Corps of Engineers and Lower Elwha Klallam Tribe are cooperating agencies. This team of agency preparers and contributors is referred to throughout this document as the EIS Team.


Purpose and Need

The action proposed and analyzed in this environmental impact statement is the full restoration of the Elwha River ecosystem and native anadromous fisheries through the removal of two hydroelectric dams and implementation of fisheries restoration and revegetation. The dams were installed without fish passage facilities on the Elwha River, on the Olympic Peninsula in Washington State (figure 1). Elwha Dam was built first, 4.9 miles from the mouth of the river. Construction spanned the years 1910-1914. Glines Canyon Dam was completed 8.5 miles further upstream in 1927. Both impound reservoirs: the Elwha Dam forms the Lake Aldwell reservoir, and Glines Canyon Dam forms the Lake Mills reservoir.


Before the dams were built, the Elwha River produced an estimated 380,000 migrating salmon and trout. The construction of Elwha Dam eliminated 93% of Elwha River habitat for these anadromous fish, and began what became a precipitous decline in the native populations of all 10 runs of Elwha salmon and sea-going trout.


Salmon populations in the Elwha River are not the only ones declining, nor are dams the only reason for their decline. Salmonid number in many rivers of the Pacific Northwest are falling for a variety of reasons. Some species are overfished, some are affected on a large scale by fluctuations in the marine environment, and some are affected by conditions in their freshwater habitat. Silt from logging, dredging for gold and from the building and use of roads covers and smothers eggs. Water diversions for industrial, municipal or commercial use, and the addition of pollutants such as pesticides all increase fish disease and mortality.

FIGURE 1. Location Map (SCAN)

Pg. 13 = pg.3

However, dams, even with fish measures installed, are a primary cause of fish mortality. It is estimated the series of dams on the Columbia-Snake river system kill 85 to 95% of migrating smolts on their way to sea, and between 34 and 57% of adults returning to spawn (Sims 1994). This is despite an estimated $1.5 billion spent over the last 13 years to implement fish passage measures on the Columbia and Snake Rivers (Satchell 1994). Degraded freshwater habitat is often expensive and difficult to restore because of developments like dams, roads, agriculture, and water withdrawals for municipal and industrial use. In contrast, the Elwha River remains in pristine condition along most of its length. The single action of removing both dams would restore to pre-dam, high quality condition the vast majority of habitat formerly available to Elwha anadromous fish.


Several specific problems for native anadromous fish and the Elwha River ecosystem are a direct result of the dams. Neither dam has passage measures for fish, and so they obstruct upstream fish migration beyond the first 4.9 miles of the river. The natural transport of coarse sediment downstream has also been halted by the dams and its resulting absence has rendered the river downstream of the dams largely unusable by fish. Salmon and steelhead once filled 70 miles of mainstem and tributary habitat in the Elwha. Their carcasses fed more than 22 species of wildlife and supplied the entire aquatic ecosystem with organic material, phosphorus and nitrogen. Now, populations of primarily hatchery fish return to only the 4.9 miles of river below the Elwha Dam to spawn in crowded, unnatural and poor quality conditions. Both the terrestrial and aquatic ecosystems are less productive and varied as a result.


Humans have occupied the Elwha valley for thousands of years, and have integrated the river and its salmon into much of their daily lives. When the dams separated the fish from their spawning grounds and populations rapidly declined, the Elwha Klallam people were affected culturally, spiritually and economically. Many tribal socioeconomic problems which persist today have had their roots in this decline. The dams are also inconsistent with the federal trust responsibility and treaty rights guaranteed to the Elwha Klallam and three other Indian tribes in the 1855 Treaty of Point No Point and the Treaty with the Makah.


Because the dams and reservoirs on the Elwha River have caused and continue to cause major, adverse impacts to the river’s native anadromous fish populations, wildlife, aquatic ecology and cultural resources, the department of the Interior determined in its programmatic environmental impact statement they would be removed to fully restore the ecosystem and native anadromous fisheries. This EIS examines alternative methods of removing them in a safe, environmentally sound and cost-effective manner and proposes a plan to restore the river’s native anadromous fisheries and ecosystem.

Pg. 14 = pg. 4 & 5

Alternatives

The proposed action (the River Erosion alternative) is to initiate river restoration by removing both dams over a two-year period. Lake Mills would initially be drawn down with Glines Canyon Dam in place to provide flood control water storage until a diversion channel to drain Lake Aldwell is complete. Elwha Dam would be removed by controlled blasting, and Glines Canyon Dam would be removed by a combination of controlled blasting and diamond wire saw cutting of concrete blocks. Sediment would be eroded naturally by the river.
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