A St. Elizabeths Hospital staff "dedicated to providing good patient care" is so hindered by poor management that the quality of treatment at the large mental institution varies "from very good to poor," a General Accounting Office inspection team has found.

A draft of the GAO report, obtained by The Washington Post, credits the federally administrated hospital in Anacostia with many improvements over the past few years.

But the report also finds serious management problems at the facility and little cooperation between District of Columbia health authorities and hospital administrators.

The report is the GAO's first major look at the big institution, which currently has 2,300 hospitalized patients and another 3,200 out-patients who go to the hospital for regular attention.

St. Elizabeths administrators have often maintained that their main problem has been lack of funds with which to give better care. The main GAO contention is that the hospital could do far better with the funds it has - now $90 million a year.

Dr. Roger Peele, St. Elizabeth acting administrator, yesterday called the GAO examination "a healthy experience for the hospital" and one that turned up many real problems, although Peele said he disagreed with some of the GAO''s findings.

He promised "a lot of changes in about a year," and said, "We tried unsuccessfully to get the GAO to promise to come back and take another look."

The GAO is the investigating arm of Congress. A body that will be looking at St. Elizabeths again, perhaps by fall, is the Joint Commission on Accerditation of Hospitals, which last September withdrew the hospital's accreditation because of many deficiencies in buildings and programs.

The GAO draft report is still incomplete and unofficial, although GAO staff member Adolf Bruzinsky said the final version "shouldn't be substantially different."

The draft charges that patients suffer from lack of well organized care, that the hospital wastes money by doing surgery at high cost instead of hiring surgeons at community hospitals to do the same operations and that there is no effective system to move less-than-acutely-ill patients to less costly facilities.

The GAO team found that:

Care at "St. Es" is handicapped from the onset by an ill-supervised admitting staff that often admits patients - at a current cost of $97 a day - just because the staff doesn't know enough about alternative forms of treatment and facilities.

A lack of organized, planned treatment for many individuals results in patients not recuperating as quickly as possible "or at all." At the same time, some patients are discharged too soon, so they rapidly return.

Division heads spend so much time on administration - for which, often, they are untrained - that "rarely does anyone oversee" medical programs to determine how effective the programs are.

Inadequate out-patient services inside and outside the hospital also cause many patients to return. Some factors - like inadequate social support services and too few alternative facilities (like nursing homes) in the District - are "beyond the hospital's control." But there is also "no effective system" to get patients out of the hospital, and inadequate planning when a patient is discharged.

In January, 1976, the hospital identified 1,284 of its then 2,678 inpatients as suitable candidates for alternative placement. A year later, 66 per cent of the 1,284 were still at St. Elizabeths at an excess cost to taxpayers of $12.4 million.

The hospital employs four surgeons to do an average of one operation apiece every week at a surgical-care cost of $712 an operation, when the same operations could have been performed by outside surgeons at an average cost of $75.

Most of all, an "ineffective management system" leads to inefficient use of the hospital, so it "lacks effective . . . planning, evaluation, information gathering, budgeting, staffing and training."

Peele - named acting administrator in July, 1975 - said progress has been made in many of these areas, and "we expect to be able to say two years from now that we've improved things another 100 per cent, just as we've done in the past two years."

He said he knows surgery at St. Elizabeths is sometimes costly, but community hospitals cannot always care for disturbed patients who need medical or surgical care. Peele said the hospital already does contract out much of this type of treatment.

Peele said that about half of the St. Elizabeths patients who could be cared for in nursing homes or other facilities have been moved from the hospital.

Those who remain cost the hospital about $40 a day per patient, Peele said - about $5 more a day per patient than it would cost to house each of them in a nursing home and far less than the average $97 a day it costs St. Elizabeths to care for its other patients.

Both defenders and critics of St. Elizabeths agree that it has been handicapped for years by a strong push during the Nixon and Ford administrations to transfer the hospital from federal control (by the National Institute of Mental Health) to the District Department of Human Resources. Most members of Congress have resisted the move, at least until the District runs its own health facilities more efficiently.

The see-sawing over control, it is generally agreed, has weakened both federal and District concern for the sprawling hospital, 85 per cent of whose patients are from the District.