Chalk Hill Bridge Replacement

What’s Happening?

Sonoma County is planning to replace the Chalk Hill Road Bridge over Maacama Creek. The current bridge is a one-lane structure built in 1915. While it is a County landmark and eligible for the National Register of Historic Places, it has deteriorated significantly and is no longer safe.

The new bridge will be a two-lane structure designed to modern safety standards, while still reflecting the local character of the Alexander Valley.

How We Got Here

The current bridge is nearly 110 years old. Studies have shown it is unstable in an earthquake and threatened by erosion along the creekbank. To protect public safety and ensure reliable access for residents, visitors, and emergency services, the County began the planning and design process.

Why It Matters

Replacing the bridge will:

• Improve safety for drivers, pedestrians, bicyclists, and emergency vehicles
• Provide reliable access by ensuring the bridge is not at risk of collapse or washout
• Preserve community character by incorporating local design elements into the new bridge
• Meet modern standards for construction, durability, and seismic safety

What’s Next

The Project Team has already:

• Completed technical field investigations
• Held four community outreach meetings (2019 and 2021)
• Selected the new bridge alignment, roadway width, and bridge type based on public feedback

Next steps include:

• Finalizing the bridge design (including concrete color and texture options, as exhibited in September 2021 at Alexander Valley Hall)
• Completing environmental permitting and reviews under NEPA
• Preparing detailed engineering plans and specifications (PS&E)
• Releasing the project for construction bids once approvals are complete

Timeline

• 2019: Technical studies and first community workshops
• 2019–2022: Environmental studies
• 2021: Public input on bridge colors and textures
• 2023: Final design development
• 2024–2026: Construction of the new bridge (anticipated)

Community Outreach

Public input has been central to this project. Community workshops in 2019 and 2021 helped shape the design, including the bridge’s alignment, width, and finishes. More opportunities for community feedback will be shared as design and construction move forward.

Chalk Hill Alignment	Chalk Hill Bridge 30' Width Representation
Elevation Map of Chalk Hill Bridge	Chalk Hill Bridge