Federal agency proposes marine mammal permit for Juneau's Seawalk extension

The National Marine Fisheries Service on Friday proposed a permit covering the effects on five marine mammal species of the City and Borough of Juneau's work to extend the downtown Seawalk from the Franklin Dock to the AJ Dock. The species are humpback whales, killer whales, harbor porpoises, Steller sea lions and harbor seals.

The noise comes from pile driving. Crews would pull 80 old piles, 64 timber and 16 steel, and drive 238 permanent steel pipe piles, about 230 of them for the walkway and the rest for a catwalk and a cruise ship mooring dolphin. Work is scheduled to begin in April 2027, with pile driving on about 238 days over a year.

The notice says the noise could change the behavior of all five species. Only Steller sea lions and harbor seals could experience hearing injury. The agency does not expect serious injury or death, and it is beginning an Endangered Species Act consultation for the western stock of Steller sea lions.

The city did not propose bubble curtains, which can muffle underwater pile-driving noise, saying strong tides would limit their effectiveness and the cost would be impractical. It would instead start impact pile driving softly and stop work when animals come within set distances. For harbor seals, that shutdown zone is limited to 25 meters over practicability concerns.

The $28 million extension was planned to run entirely on marine passenger fees, with about $4 million set aside for design. In September, a Juneau Assembly committee directed an unrequested $6 million state grant to the project's first phase, which the city said would let it build without borrowing.

The agency preliminarily found the work would have a negligible impact and qualifies for an exclusion from further National Environmental Policy Act review. Comments are due within 30 days of the notice's Oct. 13 Federal Register publication. Any authorization would last one year.