FEIS Summary - Knik Arm Bridge and Toll Authority

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Knik Arm Crossing Final EIS Summary Exhibit S-23 Environmental Impacts Associated with Construction and Operation of the Recommended Alternative (continued) Impact category Construction impacts (continued) Indirect impacts Freshwater Fish Negligible impacts Freshwater Birds Negligible impacts Northern Access Alternative (Mat-Su Side) Terrestrial Birds Breeding birds will be displaced. Clearing of vegetation and nest abandonment will result in mortality to eggs and nestlings of breeding birds. Marine Birds N/A Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale N/A Beluga Whales N/A Terrestrial Mammals There will be temporary or permanent displacement of mammals due to increased noise levels during construction. Mortality could result from construction activities. Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) Freshwater Fish N/A Freshwater Birds N/A Terrestrial Birds N/A Marine Birds Construction activities, such as pile driving, placement of fill, and marine vessel traffic related to the project, may result in short-term displacement of marine birds in both open water and on tidal flats. Visual and auditory disturbances from construction and operations could affect the bald eagle nesting near Cairn Point. Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale None Beluga Whales Adverse effects of construction activities could include avoidance, changes in resting or feeding cycles, displacement from habitat, alertness, masking of sounds and changes in vocal behavior, changes in swimming or diving behavior, altered direction of movement, and physical injury. Terrestrial Mammals N/A Erickson Alternative (Anchorage Side) Freshwater Fish Equipment movement and noise will cause temporary impacts to both upand down-stream migration of Pacific salmon. Turbidity increases could occur in Ship Creek due to construction of the clearspan bridge (short-term) in Phase 2; Ingra-Gambell Viaduct. Freshwater Birds None Terrestrial Birds Breeding birds will be displaced. Clearing of vegetation and nest abandonment will result in mortality to eggs and nestlings of breeding birds. Marine Birds N/A Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale N/A Beluga Whales N/A Marine Invertebrates Fillets (sediment accumulation) on either side of nearshore fills projecting from the shoreline could provide habitat for enhanced production of organic matter and invertebrates. Fish and Essential Fish Habitat See section on anadromous fish below. Anadromous Fish Future construction and development activities could result in filling of EFH, increased water turbidity, and localized disturbance of aquatic habitat. Increase in the Mat-Su population could increase recreational activities in fish streams increasing the risk of direct disturbance to adult and juvenile salmon, pollutant spills, and boat wake impacts on shorelines. Anadromous Fish Fillets (sediment accumulation) along bridge approaches may result in less deep-water habitat. Fillets may provide more habitat and create more primary productivity due to a greater abundance of food sources. Increased port vessel traffic will increase the effects on fish through the release of toxic chemicals. Terrestrial Mammals Increased noise levels may result in temporary or permanent displacement of mammals. Anadromous Fish None Exhibit S-23 Environmental Impacts Associated with Construction and Operation (continued on next page) S-50
Knik Arm Crossing Final EIS Summary Exhibit S-23 Environmental Impacts Associated with Construction and Operation of the Recommended Alternative (continued) Impact category Indirect impacts (continued) Cumulative impacts Northern Access Alternative (Mat-Su Side) Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) Erickson Alternative (Anchorage Side) Marine Fish Fillets (sediment accumulation) creation would replace rearing and foraging habitats impacting long-term effects on some fish species (such as saffron cod and longfin smelt) that depend on the middle- to upper intertidal and subtidal zones for rearing. Freshwater Fish Impacts would be the same as those described above for anadromous fish. Increase in Mat-Su population will decrease the pressure on sport fisheries in the Anchorage area. Freshwater and Terrestrial Birds Resident bird populations could be fragmented into smaller subpopulations, causing increased demographic fluctuation, inbreeding, and loss of genetic variability. In addition, habitat fragmentation could lead to an increase in predation at the perimeter of habitat patches. Marine Birds Loss of nesting and perching habitat of bald eagles due to development. Intertidal foraging areas for bald eagles could be adversely affected. Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale None Beluga Whales Increased boat and personal watercraft use due to increase in population could increase accidental or intentional harassment of marine mammals. Additional marine vessel traffic could cause accidental fuel spills and increased noise from operations. Terrestrial Mammals 27,543 acres of moose habitat in the Mat-Su could be affected by development. Large increase in wildlife-vehicle accidents could result from traffic increases on the Point MacKenzie and Knik Goose Bay Roads. Enhanced access in the Mat-Su, combined with an increase in the number of hunters, will result in a decrease in game populations. Habitat will be lost in the Mat-Su because of habitat fragmentation and reduced effectiveness. Increase in wildlife-human conflicts will result in some wildlife mortality incidents. Reduced development pressure on the remaining tracts of wildlife habitat in Anchorage. Marine Invertebrates Negligible impact Fish and Essential Fish Habitat Negligible adverse cumulative impacts. Resuspension and redisposition of sediments disturbed by human activity Freshwater Birds Negligible adverse cumulative impacts; could cause a decline in local abundance of a given species Terrestrial Birds Negligible adverse cumulative impacts; could cause a decline in local abundance of a given species Marine Birds Negligible cumulative effects on population of marine bird species in the project area (continued on next page) Exhibit S-23 Environmental Impacts Associated with Construction and Operation S-51
Page 1 and 2: Knik Arm Crossing Final Environment
Page 3 and 4: Exhibit S‐1. Final EIS Document O
Page 5 and 6: Knik Arm Crossing Final EIS Summary
Page 15 and 16: Exhibit S‐22. Reasons for Preferr
Page 17 and 18: Findings, Compliance, and Permits E
Page 25 and 26: ! ! ! ! ! ! ! ! ! ! ! ! Knik Arm Cr
Page 33 and 34: The preliminary design includes pla
Page 35 and 36: Summary Initial Construction (Phase
Page 49: Knik Arm Crossing Final EIS Summary

FEIS Summary - Knik Arm Bridge and Toll Authority

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