Every weekday a blue van leaves Springfield Hospital Center for Montgomery County, where it deposits about two dozen patients at day programs, social service agencies or their homes.

It is a journey designed to prepare patients, most of whom return to the hospital the same day, to rejoin the community they left.

But every few months, according to Art Namoski, who has driven the van on its 150-mile-a-day round trip since 1981, a terrified patient who has been discharged by Springfield gets on the van with no money, no plans and nowhere to go. "They're geting off and I mean they are lost," said Namoski. "They don't know what's going to happen next."

Some go to shelters. Others return to families who are not expecting them or wander into the county's Mental Health Association in Kensington, the last stop on the route. To Martha Jachowski, director of the association since 1964, they are living symbols of a major problem with deinstitutionalization in Maryland: No one is actually responsible for discharged patients.

"It becomes a we-they type of thing," said Jachowski. "The hospital sees the community as responsible for developing alternatives, and the community sees the hospital as dumping" patients.

In Maryland the job of caring for discharged patients is largely undefined. Although required by law to prepare an individual discharge plan for patients, the hospital is neither obligated nor able to find out what happens to them once they leave. And in Montgomery County, more than seven state and local agencies, each with its own rules and conscious of its turf, provide services to discharged patients.

"Not only is it not clear who's responsible," said James M. Herrell, who resigned last week as director of the county's Mental Health Administration, "it's not even clear what it means to be responsible. Responsible for what? For planning? For funding? For implementation?"

Because the state's data collection system was designed in 1962, before deinstitutionalization was policy, it is not known what happened to the approximately 30,000 people who were once patients in Maryland state mental hospitals.

"It's like the Dark Ages," said Trevor L. Hadley, Maryland's mental health commissioner, who was appointed last summer and has ordered the system overhauled. "It makes decision-making more like tea leaf reading, and it makes it difficult to do good planning."

There are other problems in providing community care. Last winter when the residents of a Gaithersburg subdivision learned that a supervised residence for eight former Springfield patients was planned for their neighborhood, they flexed the kind of civic muscle that has made Montgomery County activists famous.

About 100 residents, some of whom said they were concerned about their safety and their property values, circulated petitions and jammed a public hearing. Many wore buttons patterned after the logo of the hit movie "Ghostbusters" -- a red slash superimposed over a house with eight people hanging out its windows. A final decision about the home is pending before a state hearing examiner.

Although numerous studies have shown that the mentally ill are no more dangerous than the general population, community resistance is a formidable obstacle to deinstitutionalization. It is, hospital and community workers say, a particular problem in Montgomery County.

"Everyone believes in it, but not in their neighborhood," said Jack Hiland, the county's deinstitutionalization coordinator. "How many group homes do we have in Potomac?"

Lack of money is another obstacle. Maryland's top priority continues to be operating its hospitals, where the annual cost per patient ranges from $50,000 to $79,000. The equivalent community services, according to community support director Scott M. Uhl, cost about $27,000. In Wisconsin, a state of similar size that is considered to have a model mental health system, half the state's mental health budget goes to hospitals and half to community programs.

Although hospitalization is considerably more expensive, most insurance companies and federal programs are more willing to pay for it. Most refuse to cover the cost of outpatient services such as halfway houses and day programs.

For reasons that some state officials say partly reflect the power of advocacy groups and differing levels of public sympathy, state programs for the retarded and the mentally ill differ substantially in terms of funding. Maryland pays $1,770 per month for housing for the retarded, an amount in some cases double that paid for care of the chronically mentally ill who may require more expensive services.

Project Home, Maryland's primary housing program for the mentally ill, actually discourages participants from being self-sufficient by subtracting money they earn from their monthly checks.

Placements in most adult foster homes -- a primary means of supportive housing, especially for compliant elderly patients discharged from hospitals in the early days of deinstitutionalization -- are largely unmonitored. Last year police discovered two elderly sisters, former state hospital patients, living in filth in the basement of the house of a Baltimore couple who cashed their benefit checks and had been appointed their legal guardians. Both women were hospitalized, and one died a week later of a cerebral hemorrhage.

"There are probably thousands of people in foster care we don't have a handle on," said Scott M. Uhl, Maryland's deinstitutionalization coordinator.

Montgomery County's problems mirror those of Maryland. "I think we're moving in the right direction, but I think we have a long way to go," said County Executive Charles Gilchrist, who has ordered a consultant's study of the mental health system. "The state needs to do more, especially in terms of money."

According to Maryland's master plan for mental hospitals, Springfield's population is expected to shrink to 505 patients by 1994 as very old patients die and others are transferred or discharged.

That prospect alarms Dr. Rosalie Barr, a psychiatrist with the Montgomery County health department who has worked with Springfield patients since 1961. "There are an awful lot of patients who came out and are very fragile . . . and the sicker the patients are the more individual attention they need.

"We keep putting our thumbs in holes in the dike. No one is looking at the whole picture."