Since 1969, when enrollment reached a peak of 149,000, the number of students in Washington's public school system has dropped by nearly 20 percent. The current enrollment of 120,000 is the lowest in the last 20 years. To be sure, the District isn't alone. During the past decade most of the nation's large urban school systems have experienced sharp declines in student population. Nor is the phenomenon a uniquely urban one. Because of the country's lowered birth rate, by 1982 school enrollment nationally is expected to decrease by another 5 million pupils.

For Washington's school system, the decline in student population has been matched by an increasingly stringent operating budget. But, during the last three years, as enrollments have continued to decline, some 20 new schools and school additions (whose construction was planned and paid for years ago) have been built. Thus, the school system now has a great deal more space (some 17,000 extra seats) than students - or money to operate effectively both the new and the old schools. What these facts mean is that some of the District's 182 elementary schools, where the enrollment losses are steepest, must be closed.

School officials are preparing to do that. The District's school board will hold public hearings this spring on School Superintendent Vince Reed's recommendation to close 23 elementary schools st the end of the current school year. Mr. Reed also proposed closing five more elementary and junior high schools by 1980. The list of schools is based on a year-long study of each city public school by groups of school officials, parents and community leaders.

School closings are a deeply emotional issue, in Washington as elsewhere, because schools are neighborhood as well as educational institutions. They not only educate the neighborhood's children; they also contribute to the neighbor's character. Given the declining enrollment, the lean budget and the new schools, it seems likely that some schools now in use should be closed. But we think that it's imcumbent upon schools officials to prove conclusively why a particular school should be closed.

An equally important issue, in our view, is what happens to those school buildings that are closed. Because of the District's tight real-estate market, many of the schools that could be closed this year occupy choice sites. The land being made available for other kinds of development could significantly affect a neighborhood and the city as a whole. LIke its counterparts in the Washington area, the District's school board has three ways to deal with a school building it closes. It can keep the building for future use, board it up and provide the necessary maintenance. It can lease the building to a public agency or a private firm (such as a private school or a daycare center). Or it can give up the buildings to the city government. Without knowing what schools will be closed, one can't say what should be done with the school buildings. But we hope school and city officials keep in mind that closing a public school isn't just an educational issue. It's a matter of neighborhood and city development as well.