The intersection of State Route 121 and 8th Street East is a key regional corridor that experiences heavy commuter traffic and limited left-turn facilities, leading to congestion and operational challenges. To address these issues, the Sonoma County Transportation and Climate Authorities (SCTCA), in partnership with Caltrans District 4, Sonoma County, the Sonoma County Regional Parks District, SMART, and GHD, is advancing a project to improve safety, traffic flow, and multimodal access at this location.
A public meeting to discuss project options is scheduled for February 5, 2026 at 6:00 – 7:30 pm (Drop by anytime) at
Sonoma Valley High School Library, 20000 Broadway, Sonoma, CA
SCTCA is considering a modern roundabout alterative at the intersection. This alternative would replace the existing intersection of Route 121 and 8th Street East with a modern single-lane roundabout. It would ease traffic congestion by introducing traffic-calming and improving vehicle safety, and pedestrian and bicycle safety within and adjacent to the intersection.
SCTCA is also considering a signal alternative at the intersection. This alternative would convert the existing intersection of Route 121 and 8th Street East to a signalized intersection with curb, gutter, sidewalk, and pedestrian and bicycle improvements. Due to the need to accommodate turn lanes and acceleration/deceleration lanes, the project foot spans several hundred feet to the east and west of the intersection. Therefore, this alternative would also require the replacement of the Bridge over Schell Creek.
The Environmental Document will be an Initial Study/Mitigated Negative Declaration (IS/MND) in conformance with the California Environmental Quality Act (CEQA) and a Categorical Exclusion (CE) in conformance with the National Environmental Policy Act (NEPA).
With both alternatives there will be impacts to some rights of way, wetlands, and will result in tree removals.
Due to the larger footprint of the signal, that alternative includes additional impacts to wetlands, additional right of way needs, more tree removals including established oak trees, impacts to Schell Creek and the potential impact to culturally sensitive areas.
Right‑of‑Way and Property Discussions During Environmental Review
As part of the environmental review process required under the California Environmental Quality Act (CEQA) and the National Environmental Policy Act (NEPA), the project team is currently evaluating potential environmental impacts and developing alternatives.
During this phase, agencies are not permitted to engage in specific discussions regarding potential right‑of‑way needs, property acquisitions, or parcel‑level impacts. This restriction is intended to ensure that the environmental process remains objective, unbiased, and free from any perception of pre‑determination.
Any property boundaries, staging areas, or potential impact zones shown in project materials are conceptual and subject to change as the environmental studies continue.
Once the environmental document is completed and a preferred alternative is selected, the project will move into the next phase, during which:
- Right‑of‑way needs will be finalized, and
- Direct outreach to affected property owners will occur in accordance with state and federal requirements.
To read the full report, CLICK HERE
ROUND ABOUT IS BEST
99% of the traffic is on the highway.
A roundabout make zero sense here.
How about fix the flooding issues and make a stop light.
As someone who lives off of 121 and goes through this intersection at 8th St East daily, I have first hand experience with the left turning dangers here. There’s no easy answer…(1) 121 was created a very long time ago as a two lane road when this was a rural area, now it’s a primary commuter corridor for people trying to get to & from the 101 freeway. (2) Roundabout would be less expensive and help with east/west flow BUT it worsens the time, difficulty, and safety of local residents trying to get out of our neighborhoods to the east (Think Lou’s Luncheonette area). (3) a signal would help create traffic breaks so neighbors could safely get out of their neighborhoods, but we are being told Caltrans is requiring this huge infrastructure change that would impede on the homes at the 121/8th St intersection. A better solution would be to copy the perfectly functional signal light layout at 121/Broadway and sync these two lights so that flow east/west is smooth, and the rural neighborhoods along 121 could still access it safely. Just my opinion.