The Fairfax County Board of Supervisors yesterday proposed sweeping cutbacks in Metrobus service, recommendations that would eliminate or change 26 routes and save the county an estimated $1.3 million a year.

County officials say the proposed bus service reductions target routes with the lowest ridership, such as a bus route from Tysons Corner to Ballston that is used by an average of four passengers per trip at midday.

The issue exploded into an emotional debate when other county officials argued that the cutbacks would hurt those riders who most need the service, lower income and handicapped riders.

"How do some of those people get there?" charged Annandale Supervisor Audrey Moore, a Democrat and the only member to oppose the cutbacks in bus service. "They just disappear!"

The cutbacks, if approved by the board after public hearings, would eliminate 16 routes and reduce or reroute 10 others. County officials have proposed that the cuts be implemented in June.

The recommendations reflect a steady decline in Metrobus ridership in many sections of Fairfax, said Shiva K. Pant, county transportation director.

About 43 percent of all evening bus routes are operating at "poor or marginal" service levels, according to county records. Even at peak hours, 36 percent of all bus service is operating at those low levels, he said.

In the past three years, Metrobus ridership in the county's three primary route corridors has plunged by about 25 percent, according to county figures. Throughout the Washington area bus ridership has dropped 7 percent in the same period.

Pant blamed the ridership loss on a combination of factors including an increasing number of county residents working within the county rather than commuting to jobs in the District and the opening of the Huntington Metro station and I-66 inside the Capital Beltway.

"Do we pay hundreds of dollars per rider to provide a 40-foot bus with a driver to reach four or five people?" said Supervisor James M. Scott, a Democrat and member of the Metro board.

Local governments throughout the Washington metropolitan area have been grappling with mounting Metro deficits in recent years. This year Fairfax County is budgeted to contribute $25 million as its share of the system's deficit.

In addition to cutting routes, Fairfax and other jurisdictions are experimenting with operating their own bus systems.

Fairfax County is planning to start a bus system of its own late next spring to serve the area around the Huntington Metro station, a system that officials estimate could save the county about $600,000 a year compared with Metrobus service to the same region.

The issue of cutting and reducing routes is always politically sensitive, with supervisors quick to ask that routes in their districts be spared.

Board Vice Chairman Martha V. Pennino, a Democrat, called a halt to yesterday's attempts to save some routes, declaring: "I have two senior citizens communities in Reston. It's not easy for me to stand in front of a room of 300 senior citizens and say we will have no service for you."

The board also voted yesterday to join a national prison reform group in a suit against the District that criticizes overcrowding at the D.C. Jail.

Board Chairman John F. Herrity said he is concerned that the city could be ordered to use the Lorton prison in southern Fairfax to relieve overcrowding at the jail, which is housing about 2,330 prisoners, almost twice its capacity.

The National Prison Project, acting on behalf of prisoners at the jail, last week asked U.S. District Court Judge William B. Bryant to force city officials to end the overcrowding.

"Without using much imagination, it's my suspicion that Bryant could order these prisoners be shipped to Lorton," said Herrity.

If Bryant allows the county to intervene in the case, Herrity said the county will suggest that the District "ought to ship the inmates to various federal prisons throughout the country."

D.C. Corrections Director James Palmer said yesterday that he has no plans to move prisoners from the jail to Lorton without first consulting with officials in Fairfax.

"If I decide to move people to Fairfax, I will meet with the proper people in Fairfax," Palmer said. "If we have to move anyone, the first people I would get in touch with would be them."

Asked if the city had any imminent plans to move large numbers of inmates from the jail to Lorton, Palmer said: "I can't understand that people don't think I have to ship people down there [from the jail]. That's done every day.