King Ridge Road Bridge Replacement over Austin Creek
What’s Happening?
Sonoma County plans to replace the one-lane bridge over Austin Creek on King Ridge Road.
Location: 21653 King Ridge Rd (Lat/Lon 38.561, −123.102)
The new bridge will be a single-span steel girder with two 10-ft lanes (no piers in the creek). It will be built upstream (east) on a new alignment. The existing bridge will stay open during construction and be removed after the new bridge opens. To reduce construction noise, abutments will use seat-type supports on footings with CIDH piles.
How We Got Here
Inspections identified scour (erosion around foundations) and seismic deficiencies at the current bridge, triggering the need for replacement.
Why It Matters
- Improved safety and earthquake performance
- Year-round reliability with a span that keeps piers out of the creek
- Better access for residents, visitors, and emergency services
- Construction staged to keep traffic moving on the existing bridge
What’s Next
The project is in the NEPA environmental process. After environmental clearances, the team will secure permits, right-of-way, and finalize plans, then bid and build. Construction is planned over two seasons starting in 2027 (subject to change).
Timeline (target, subject to change)
- NEPA clearance: Spring 2025
- CEQA clearance: Fall 2025
- Permitting: 2025–2026
- Right-of-way: 2025–2026
- Construction: 2027 (two seasons)
Learn More
Project goals include:
- Replace the existing bridge to modern design/construction standards
- Reflect local character and the natural environment
- Improve safety and access for drivers, pedestrians, cyclists, and emergency services
Get Involved / Contact
Questions or comments? Contact Chet Jamgochian at chet.jamgochian@sonomacounty.gov
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