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 King Ridge Road Bridge Over Austin Creek Replacement Project
End
Recommended Action:
Recommended action
Adopt a Resolution adopting a Mitigated Negative Declaration and Mitigation Monitoring Program and approving the project to replace the King Ridge Road Bridge over Austin Creek Project (C07001).
end
Executive Summary:
Sonoma County Public Infrastructure (SPI) is requesting adoption of a Resolution to adopt a Mitigated Negative Declaration, adopt a Mitigated Monitoring Program, and approve the King Ridge Road Bridge Over Austin Creek Replacement Project.
Discussion:
The King Ridge Road Bridge replacement project will replace the existing one-lane King Ridge Road Bridge (20C0433), over Austin Creek, with a new two-lane bridge designed to meet current roadway, drainage, and bridge standards. The existing bridge is scour critical due to potential foundation erosion fracture critical, and functionally obsolete. This replacement will also include improvements to the roadway approaches and appurtenant facilities. The new structure will not increase traffic capacity; however, by providing two lanes it will improve vehicular and bicycle safety for the public using this bridge.
A California Environmental Quality Act (CEQA) Initial Study was prepared for the Project and presented to the Environmental Review Committee on November 4, 2025. The Environmental Review Committee reviewed the study and recommended a Mitigated Negative Declaration (MND) be prepared. Notice of a 30-day public review of the MND and Initial Study, from November 18, 2025 through December 18, 2025, was provided in accordance with State and County CEQA guidelines. The MND, including the proposed mitigation measures, was circulated for public and agency review. No comments were received from the public or agencies during the public comment period.
County Public Infrastructure (SPI) will obtain all appropriate permits before constructing the Project.
The Project is receiving federal funds and must satisfy all requirements of the Federal Highway Bridge Program, including approval by Caltrans. This includes performing additional environmental studies, geotechnical investigations, and design work to comply with current state and federal regulations. The Project is currently in the design and right-of-way acquisition phase with 65% PS&E and has completed National Environmental Policy Act (NEPA) review. Construction is anticipated to begin 2028 and last two seasons.
SPI recommends that the Board adopt the attached resolution adopting the Mitigated Negative Declaration and Mitigation Monitoring Program and approve the King Ridge Road Bridge over Austin Creek replacement project. If the Board adopts the Mitigated Negative Declaration and approves this Project, SPI will file a Notice of Determination and proceed with final design, right-of-way acquisition, as well as bidding and award of a construction contract.
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 4: Identify and retrofit bridges in County that are at high risk for damage during earthquakes.
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
December 12, 2023, Item # 25 - Second Amendment to the contract with HDR Engineering, Inc. for the King Ridge Road Bridge Over Austin Creek Replacement Project.
April 25, 2017, Item # 18 - First Amendment to the contract with HDR Engineering, Inc. for the King Ridge Road Bridge Over Austin Creek Replacement Project.
October 21, 2014, Item # 30 - The Board awarded a design engineering Contract to HDR Engineering, Inc. for the King Ridge Road Bridge Over Austin Creek Replacement Project.
Fiscal Summary
Narrative Explanation of Fiscal Impacts:
There is no direct fiscal impact associated with this Board Action. Expenses associated with environmental studies and reports were approved by the Board in previous professional services agreements. Environmental mitigation and monitoring costs associated with the construction phase of the project will be included in contracts to be brought to the Board at a future date. The total project cost is estimated to be $12,400,000. Of this amount, $2,100,000 for the preliminary engineering and right-of-way phases is 100% reimbursable through the Federal Highway Administration (FHWA). The construction phase is estimated at $10,300,000 and is 88.63% reimbursable through FHWA. The remaining 11.37% local match will be funded using allocations from traditional Road funding sources, including the Highway User Tax Account (HUTA) and the Road Maintenance and Rehabilitation Account (SB1).
Narrative Explanation of Staffing Impacts (If Required):
None.
Attachments:
Resolution, Mitigated Negative Declaration, Location Map, Mitigation Monitoring Plan
Related Items “On File” with the Clerk of the Board:
Original Agreement, First Amendment, Second Amendment