Firefighter spending accounts for $19.4 million annually, or about 19% of all city expenditures.
Staff members are crunching the numbers now, and the City Council is scheduled to review the proposal at a March 8 study session.
"It's going to come down to coverage of the city, the financials, and asking, 'Are there things by going regional that we can do better?'" said Mayor Gary Monahan.
Cities in the authority share 61 stations countywide and a regional operations center in Irvine. Already, the authority serves unincorporated parts of the county, such as the area near the Santa Ana Country Club, and 22 cities, including Tustin and Irvine.
Monahan said the authority may also have newer technology than the city department. For instance, the authority recently implemented a high-tech system that tracks incidents and resources, and recommends coverage.
Both the city and the authority share similar response time goals — responding to 80% of code 3 medical emergencies within five minutes of receiving a call. But the fire authority is slightly more ambitious; it also seeks to respond to code 3 fires within five minutes, while the city's target is five minutes, 45 seconds.
Actual response times were not available Friday evening.
According to the proposal, the fire authority would still be able to meet those response times if it closed one of the city's stations, but continued operations in the other five. The two stations considered for closure are the station at 800 W. Baker St., near Bristol Street and Baker intersection, and 3350 Sakioka Drive, near the Segerstrom Center for the Arts.
All emergency calls would still go to Costa Mesa's communications center first, but then certain calls would be routed to OCFA.
Depending on which of three coverage scenarios it selected, the city would spend between $16.5 million and $18.2 million per year, according to the proposal.
The report also says the city spends about $900,000 each year on fire-related expenses, such as vehicle maintenance and replacement, that would be covered by the Fire Authority. That would bring annual savings to between $2.1 million and $3.8 million.
But the city would incur a one-time cost that could exceed $800,000, in order to start service.
OCFA is a joint-powers authority with a $260-million annual budget. It is governed by a 24-person board of directors, including representatives from the 22 partner cities and two members represent the county unincorporated area.
Costa Mesa, if it chooses to enter into the authority, would agree to 20 years of service, but would have the option to leave after 10 years.