To: Board of Supervisors
Department or Agency Name(s): Sonoma County Public Infrastructure
Staff Name and Phone Number: Johannes J. Hoevertsz, 707-565-2550
Vote Requirement: Majority
Supervisorial District(s): Fifth
Title:
Title
Mitigated Negative Declaration for the Mirabel Road Corridor Improvements and West County Trail Project, C24206.
End
Recommended Action:
Recommended action
Adopt a Resolution for a Mitigated Negative Declaration and adoption of a Mitigation Monitoring and Reporting Program, and approving the Mirabel Road Corridor Improvements and West County Trail Project, C24206.
end
Executive Summary:
Sonoma County Public Infrastructure (SPI) is requesting adoption of a Resolution for a Mitigated Negative Declaration and adoption of a Mitigation Monitoring and Reporting Program, and approval of the project that will construct improvements on Mirabel Road from State Route (SR) 116 to River Road in Forestville.
Discussion:
Mirabel Road Corridor Improvements and West County Trail Project (“Project”) includes widening Mirabel Road from State Route (SR) 116 to River Road in Forestville to accommodate Class II bike lanes and northbound and southbound left turn lanes at the intersection of Davis Road and Giusti Road. The Project also includes construction of an 8- to 10-foot-wide Class I bike path (aka West County Trail) along the east side of Mirabel Road from SR 116 to Davis Road. Additional improvements include:
1. Relocation of drainage facilities and utility poles
2. Upgrades to curb ramps and pedestrian landings to meet current Americans with Disabilities Act (ADA) standards, and,
3. Installation of bike lanes consistent with the Sonoma County Bicycle and Pedestrian Plan.
The purpose of this Project is to improve the mobility and safety of the existing roadway for all modes of transportation by constructing left turn lanes at Davis Road and Giusti Road intersection and widening the narrow segments of the Mirabel Road to meet the standards of a Class II bike lane and Class I bike path.
The Project has been analyzed under the California Environmental Quality Act (CEQA) and the CEQA Guidelines, California Code of Regulations. An Initial Study was prepared for the Project, which determined that Project impacts could be mitigated to a less than significant level. Therefore, a Mitigated Negative Declaration (MND) was prepared for the Project. The MND identifies mitigation measures and a Monitoring and Reporting Program for the proposed Project to address potential impacts related to biological resources, cultural resources, and geology and soils. These measures include preconstruction surveys, worker training, construction exclusion fencing, cultural and tribal monitoring, and procedures for the discovery of paleontological resources.
The draft Mitigated Negative Declaration was presented to the Environmental Review Committee on September 2, 2025. The Environmental Review Committee reviewed the study and recommended a Mitigated Negative Declaration be prepared. The Mitigated Negative Declaration, including the proposed mitigation measures, was circulated for public and agency review.
The following dates are the community outreach/engagement meetings that were held:
• 3/27/25 Forestville Town Hall Meeting
• 5/14/25 Forestville Youth Park (On-Site) Meeting
• 5/21/25 Forestville Youth Park Board of Directors Meeting
• 7/10/25 River MAC (Municipal Advisory Council) Meeting
• 2/5/26 Forestville Town Hall Meeting
Notice of a 30-day public review of the Mitigated Negative Declaration and Initial Study were provided in accordance with CEQA and State and County CEQA guidelines; and all comments have been addressed in the MND document. Sonoma County Public Infrastructure (SPI) will obtain all appropriate permits before finalizing the design and constructing the Project.
The project design and mitigation program include measures, as described above, to mitigate any potential environmental impacts. No other environmental impacts have been identified in the Initial Study or through any comments received as part of the environmental review process. There is no substantial evidence before the Board that the proposed project, as mitigated by the mitigation measures described in the Initial Study and to be incorporated in the Project’s MND and Mitigation Monitoring and Reporting Program, may have a significant effect on the environment therefore, adoption of the Mitigated Negative Declaration is appropriate under CEQA and State and County CEQA guidelines.
Currently, the Project is in the design and right-of-way acquisition phases with construction anticipated to begin in the third quarter of 2027. SPI recommends that the Board adopt the attached resolution to adopt the Mitigated Negative Declaration and Mitigated Monitoring and Reporting Program and approve the Project.
If the Project is approved by the Board, Sonoma County Public Infrastructure will proceed with filing a Notice of Determination, right-of-way acquisition, final design, bidding, award, and construction.
Strategic Plan:
This item directly supports the County’s Five-year Strategic Plan and is aligned with the following pillar, goal, and objective.
Pillar: Resilient Infrastructure
Goal: Goal 3: Continue to invest in critical road, bridge, bicycle, and pedestrian infrastructure.
Objective: Objective 1: Continue to maintain road segments, including designated turnouts where feasible, increase efforts on vegetation removal and drainage features, and improve pavement conditions in neighborhoods.
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
None.
Fiscal Summary
Narrative Explanation of Fiscal Impacts:
Since the adoption of the Mitigated Negative Declaration (MND) and Mitigated Monitoring Program (MMP) will not trigger additional tasks or scope to the existing project there is no direct fiscal impact associated with this Board action. The total project cost is estimated to be $10,000,000, of which approximately $1,127,852 has been expended to date. Funding sources currently identified include $3,800,000 from Measure M/Go Sonoma Grants and $3,700,000 from Countywide Development Traffic Impact Fees through the Countywide Mitigation Fund. SPI staff are actively pursuing additional funding sources to cover the remaining $2,500,000. If supplemental funding is not secured, the remaining balance will be funded through traditional Road funding sources, including the Road Maintenance and Rehabilitation Account (SB1).
The total estimated project costs for the West County Trail are $1,205,000 which includes engineering design and construction. The fund sources for the trail development include Go Sonoma ($100,000), Measure M ($500,000), Quarry Impact Fees ($160,000), and Park Mitigation Fees ($445,000).
Narrative Explanation of Staffing Impacts (If Required):
None.
Attachments:
1 - Resolution
2 - Mitigated Negative Declaration
3 - Mitigation Monitoring and Reporting Program
4 - Appendix A _AQ-GHG Energy Report
5 - Appendix B _Biological Resources Report
6 - Appendix C _Delineation of Wetlands
7 - Appendix D_Tree Inventory
Related Items “On File” with the Clerk of the Board:
None.