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 Impacts on Wildlife Direct impacts Marine Invertebrates N/A Fish and Essential Fish Habitat N/A Anadromous Fish N/A Marine Fish N/A Freshwater Fish None Northern Access Alternative (Mat-Su Side) Freshwater Birds There will be a loss of wetland habitat and habitat quality that may lead to changes in the local abundance and distribution of bird species, but will not likely lead to long term adverse effects on any populations of freshwater birds. Terrestrial Birds There will be a loss of habitat, food sources, cover, breeding grounds, and roosting sites. Marine Birds N/A Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) Marine Invertebrates Negligible impacts. Fish and Essential Fish Habitat EFH will be lost due to fill: Subtidal waters: ~8 acres Estuarine shores and mud flats: ~82 acres 33 piers will be placed; tidal channel portion of Sixmile Creek within Knik Arm will be altered. Anadromous Fish Intertidal mud flats and subtidal areas will be filled. Placement of bridge approaches will adversely affect the movement, feeding, and growing of adult and juvenile salmon by creating a movement barrier of high-current speeds. Fill will also displace fish and permanently eliminate foraging habitat Marine Fish Intertidal mud flats and subtidal areas will be filled. Placement of bridge approaches will adversely affect the movement, feeding, and growing of marine fish by creating a movement barrier of high-current speeds. Fill will also displace fish and permanently eliminate a small fraction of benthic habitat in Knik Arm caused by the 90 acres of infill and 33 piers. Freshwater Fish N/A Freshwater Birds N/A Terrestrial Birds N/A Marine Birds Loss of habitat from the placement of piers and from the placement of fill. Disturbance from vehicular traffic. Direct mortality from collisions with vehicles or structures. Loss of intertidal feeding habitat which could change foraging patterns of the bald eagles in the area. Marine Invertebrates N/A Fish and Essential Fish Habitat None Erickson Alternative (Anchorage Side) Anadromous Fish Some contaminants, such as automotive fluids and metals from vehicle brake dust, could reach drainage pathways to Ship Creek (an anadromous fish stream) and Knik Arm. Marine Fish N/A Freshwater Fish None Freshwater Birds None Terrestrial Birds Loss of food sources, cover, breeding grounds, and roosting sites. Small loss of common upland vegetation types east of the POA. Marine Birds N/A Exhibit S-23 Environmental Impacts Associated with Construction and Operation (continued on next page) S-48
Knik Arm Crossing Final EIS Summary Exhibit S-23 Environmental Impacts Associated with Construction and Operation of the Recommended Alternative (continued) Impact category Direct impacts (continued) Construction impacts Northern Access Alternative (Mat-Su Side) Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale N/A Beluga Whales N/A Terrestrial Mammals A large increase in wildlife (mainly moose)-vehicle accidents could result in traffic increases on Port MacKenzie Road since Point MacKenzie Road lies between areas highly utilized by mammal species. During Phase 2, fencing and the 4-lane roadway would create a physical barrier to terrestrial mammal movement and could result in reduced access to habitat, fragmented habitat, and subdivided animal populations. Marine Invertebrates N/A Fish and Essential Fish Habitat None Anadromous Fish None Marine Fish N/A Recommended Alternative Southern Alignment Crossing with 8,200-Foot Bridge and Connecting Roadways on Gravel Fill (The Crossing) Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale None Beluga Whales Bridge approaches extending into Knik Arm could create barriers for beluga whale transit and could change their movement patterns. Placement of the bridge piers could affect whale movement by creating in-water obstacles. Terrestrial Mammals N/A Marine Invertebrates Negligible impacts. Fish and Essential Fish Habitat See impacts on anadromous fish, below Anadromous Fish The 2-year construction period may adversely affect anadromous fish (salmon) resulting in depressed annual returns. Filling in nearshore habitats could kill, injure, or isolate fish. Noise from pile driving would produce underwater noise and vibrations that might displace or harm anadromous fish. Juvenile pink, chum, and sockeye salmon would be the most vulnerable; however, the percentages of fish exposed would be well within the annual variations in adult salmon returns for Knik Arm drainages. Underwater noise and vibrations will risk displacing or harming small or juvenile fish. No adverse impacts from pile driving are expected for adult salmon. Construction activity might lead to excessive energy expenditure and increased stress on rearing fry and smolt. Marine Fish Underwater noise and disturbance of substrate will cause adverse effects. Sound pressure from pile driving might displace or harm marine fish. Mortality of some fish is expected during pile driving. Erickson Alternative (Anchorage Side) Harbor Seals, Steller Sea Lion, Harbor Porpoise, Killer Whale N/A Beluga Whales N/A Terrestrial Mammals Habitat of marginal quality to terrestrial mammals associated with the Government Hill greenbelt wooded areas will be lost. Marine Invertebrates N/A Fish and Essential Fish Habitat None Anadromous 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. Marine Fish N/A (continued on next page) Exhibit S-23 Environmental Impacts Associated with Construction and Operation S-49
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 47: Knik Arm Crossing Final EIS Summary

FEIS Summary - Knik Arm Bridge and Toll Authority

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