Environmental clearance gets discussed as a yes-or-no gate. It isn’t. It’s a list of conditions that go straight into the crew loading, and the Duckabush authorization is a good look at what they actually cost.
NOAA Fisheries published a final rule in the Federal Register on Aug. 26 issuing a five-year Letter of Authorization for incidental take of marine mammals during construction of the Duckabush Estuary Restoration Project in Hood Canal, Washington. It runs 2027 through 2032. The applicant is the U.S. Army Corps of Engineers, Seattle District, with the Washington Department of Fish and Wildlife as non-federal sponsor, WSDOT designing the highway bridge, and the Hood Canal Salmon Enhancement Group partnering.
What gets built
US 101 goes up onto a new 1,613-ft bridge sized for future high-tide and flood conditions. The existing north US 101 bridge comes down. So does 1,700 ft of causeway that currently chokes tidal flow through the estuary. With the causeway gone, historical tidal and distributary channels reconnect and about 38 acres of floodplain delta come back. WDFW calls it the largest estuary restoration in Puget Sound.
The conditions are the schedule
The operational terms are where a bidder should spend time:
- Daylight-only work whenever marine mammals can be visually monitored
- Gradually ramped daily work periods, so crews can’t start at full production
- Thirty minutes of pre- and post-activity monitoring around every pile installation or removal
- Protected-species observers running a 300-meter observation zone for all construction
- Hard stops if a seal comes within 10 m of heavy equipment, or a pup under one week old within 20 m
Pile driving inside the wetted channel is limited to a single location, the vibratory removal of the old bridge piers. Everything else is driven on solid ground, at low tide, or isolated behind the existing causeway, cofferdams or aquadams.
The Corps and NMFS calculated attenuation using WSDOT’s 2020 construction-noise model. A 101 dBA vibratory or impact driver falls to the 90 dB harbor-seal threshold at 54 m, and the nearest driving location sits about 265 m from known haulout sites. Only Level B harassment is authorized. No Level A, no injury, no mortality.
Why it’s worth bidding carefully
Daylight-only production, observer-triggered shutdowns, tide-window pile driving and cofferdam isolation are all schedule and crew-loading items. They belong in the bid, not in a change order after mobilization. A contractor who prices this as a conventional marine bridge job and discovers the 300-meter observer zone at week three has already lost the schedule.
The same phasing logic drives large water crossings elsewhere. On the Sagamore Bridge replacement in Massachusetts, the constraint is traffic rather than seals, but the answer is the same: build in phases around something you’re not allowed to interrupt.
Project design ran from late 2019 to late 2025 and construction is roughly a five-year build once federal funding lands. The “$100 million-plus” cost, the largest-in-Puget-Sound framing and the five-year duration are WDFW’s, and the duration is contingent on construction money that hasn’t been appropriated. With the LOA in hand and design complete, this moves toward procurement for a 2027 start.