The transit agency plans to cut $925,533 from its budget; $552,470 from its operations and $322,860 from fuel expenses.
The budget reductions would mean a 15 percent decrease in fixed-route service hours, from 107,000 hours annually to 90,950 hours in fiscal year 2010, transit officials said.
Sonoma County Transit relies on Transportation Development Act and State Transit Assistance funding.
The STA funds, allocated at the discretion of Gov. Arnold Schwarzenegger, were 17.75 percent of Sonoma County Transit's fixed-route and paratransit operating budget in fiscal year 2009.
The STA and TDA funds together comprise 63 percent of Sonoma County Transit's operating budget in 2010.
In February, Schwarzenegger eliminated all new STA funding for five years starting in 2010, transit officials said.
Fixed-route operating revenues will decrease by 20 percent, or $2.75 million, because of a 9.76 percent reduction in TDA funds for 2010 and the elimination of STA funding, transit officials said.
Some of the lost revenue will be made up for by $1.35 million in federal American Recovery and Reinvestment Act funding, leaving a $925,533 deficit, according to Sonoma County Transit.
The proposed cuts to bus service have been chosen based on current ridership, duplication of services and existing service alternatives.
The service changes will be reviewed and modified once Sonoma County Transit receives feedback from passengers after Tuesday's public hearing, transit officials said.
The hearing is scheduled for 2:10 p.m. Tuesday, Board of Supervisors chambers, Sonoma County Administration Building, 575 Administration Drive, Santa Rosa.