A longstanding dispute between the Washington Hospital Center and city health planners over construction of a parking garage has ended, and the $4.5 million, 850-space structure is in use. But legal issues remain that may complicate plans for some future construction on the hospital center grounds.

A U.S. District Court judge halted work on the garage in July 1983 when health planners discovered that no one had sought approval for it. District laws require that all expenditures of health care corporations greater than $600,000 be approved by health planners, because of the possible effect on costs to patients.

The hospital argued that the garage was exempt because its year-old parent company, the Washington Health Care Corp., not it, was building the structure. Health planners said this was a technicality and the construction was a legitimate health care expense.

In a court settlement, both sides gave a little. The hospital agreed to file an application to build the half-finished garage and the health planners agreed to let construction resume immediately.

The garage, which serves both the hospital center and the one-third complete 160-bed National Rehabilitation Hospital, was finished in the spring.

But the court did not settle the issue of whether the parent corporation is a health care provider that is bound by health planning laws. This unresolved issue promises to cause trouble again, as the corporation has plans to build other nonpatient structures, such as a hotel and more doctors' offices.

Carl Wilson, director of the D.C. State Health Planning and Development Agency, said his agency will continue to take the position that all expenses related to a hospital's growth should be evaluated by health planners. "It's a question of keeping health care costs down," he said.