Funding Sources

Investing in Sonoma County’s Infrastructure

The Sonoma County Department of Public Infrastructure relies on a variety of funding sources to plan, build, and maintain critical public infrastructure. These sources include local Measure M transportation sales tax revenues, state gas tax, state and federal grants, road and bridge funds, and general funds. By leveraging multiple financial resources, the department ensures the delivery of safe, sustainable, and cost-effective infrastructure projects that enhance the quality of life for all residents.

Gas Tax Revenue: A Changing Landscape

When the state gas tax began in 1923, it fully funded road maintenance and repaving. Today, due to more fuel-efficient vehicles and stagnant tax rates, gas tax revenue in Sonoma County only covers a portion of basic repairs—like pothole patching—and no longer supports larger repaving projects.

State Funding: Senate Bill 1 (SB1)

Enacted in 2017, SB1—California’s Road Repair and Accountability Act—provides about $5.4 billion annually for transportation statewide. Half of that goes to local roads and infrastructure.

While SB1 helps address historic underfunding, Sonoma County receives less per mile than many Bay Area counties because funding is based on both road mileage and registered vehicles—of which the county has fewer.

Local Sales Tax: Measure M

Passed by voters in 2004, Measure M is a ¼-cent sales tax that funds a wide range of transportation improvements in Sonoma County, including:

• Fixing potholes and maintaining local streets
• Expanding Highway 101 with HOV lanes
• Improving traffic flow on local roads
• Enhancing bus and rail transit
• Building safe bike and pedestrian routes

Learn more about Measure M

Federal Funding

Sonoma County receives some support from the Federal Highway Trust Fund, which is funded by federal gas taxes. These funds are typically used on major roads and highways—not local or residential streets. The two key components are:

• Highway Account: for road construction
• Mass Transit Account: for public transportation support

Local Discretionary Funding

Sonoma County maintains nearly 1,370 miles of roads in unincorporated areas. In 2024–2025, over 43 miles of road improvements will be completed, funded by $46 million in new resources approved by the Board of Supervisors. Projects are selected based on traffic, transit routes, and emergency access.

Since launching the Pavement Preservation Program in 2012, the County has repaved 529 miles of roads with $226 million in funding. Sonoma County ranks among the top in California for dedicating discretionary General Fund dollars to road preservation.

Traffic Mitigation Impact Fees

The County’s Countywide Traffic Mitigation Development Fees (Sonoma County Code section 26-98-600 et seq.) and Sonoma Valley Traffic Mitigation Development Fees (Sonoma County Code section 26-98-010 et seq.) are subject to mandatory annual adjustment as set forth in the respective fee adoption ordinances and the Sonoma County Code, as follows:
On January 1st of each year, the development fees . . . shall be adjusted… by a percentage amount equivalent to the percentage change in the Engineering News Record Construction Cost Index for the preceding twelve (12)-month period…

Applying this statutory formula, the following calculations and adjustments are provided:

CALCULATION OF THE INCREASE IN CONSTRUCTION COSTS - YEAR 2026

Construction Cost Index December 21, 2025 =    14,118.46                 14,118.46 - 13,731.60 / 13,731.60        =        2.8%

Construction Cost Index December 30, 2024 =    13,731.60                    

FEE ADJUSTMENTS

*Due to the small sample size in the 12th edition manual, high-rise multi-family housing fees match the mid-rise trip rates until the 12th edition has enough data to support a new trip rate.

**ADU calculation not available in manual, calculation based on half of the SFD trip rate

*** Based on weekday average

 All amounts are rounded to the nearest whole dollar. The new fees shall be effective as of January 1, 2026.