Mill Creek culvert replacement and fish passage
The failing culvert under Cedar Street will be replaced with a fish-passable box culvert; Cedar closes for ~6 weeks in August.
What is happening
Public Works is replacing the 1962 culvert that carries Mill Creek under Cedar Street. The old pipe is undersized (it backed up in the 2024 storms) and blocks salmon passage. The replacement is a 12-ft box culvert with a natural streambed. Construction is scheduled August 3 – September 11, closing Cedar Street between 5th and 7th with a signed detour.
Why it might matter
This is the main flood-risk fix for the lower Mill Creek neighborhoods and reopens 2.8 miles of upstream habitat to coho salmon for the first time in 60 years. The closure also cuts off the most direct route to Hazel Elementary two weeks into the school year — the detour adds about 6 minutes.
What is known
- Contract awarded to Cascade Earthworks for $2.34M, 8% under engineer's estimate (council minutes, June 9).
- In-water work must occur within the state Fish & Wildlife window (Aug 1 – Sep 15).
- The detour route (Birch/9th) will get temporary school-zone signage before school starts September 1.
- Design passes a 100-year storm event; the old culvert passed roughly a 10-year event.
Still uncertain
- Weather risk: if in-water work slips past September 15, the project pauses until next summer's window.
- Whether the contractor will get the second crew needed to finish the roadway before school starts (they have said "likely").
Open questions are listed on purpose. Treat certainty claims you see elsewhere against this list.
Who or what may be affected
Lower Mill Creek homeowners
Reduced flood risk once complete; the 2024 backup flooded 11 basements.
Cedar Street commuters and school families
Six-week closure with detour via Birch and 9th; overlaps the start of school.
The creek itself
Restored fish passage; in-water work is limited to the state-permitted August window.
Thoughtful actions available
Neighborhood briefing July 29
Show up · an evening · by Wed, July 29
Public Works walks through the detour, hours, and noise windows. Good place to flag driveway access needs.
Check the detour against your school run
Get oriented · 5 minutes
The closure overlaps the first two school weeks. Look at the detour map now, not on September 1.
Sources
- Staff reportPublic Works project page: Mill Creek culvert (CIP 24-08)
Published Mon, June 15
- MinutesCouncil minutes, June 9 — contract award
Published Fri, June 12
- Permit recordWDFW hydraulic project approval
Published Sat, May 30
Demo sources link to placeholders. Live connectors carry real document links — see the Live data page.