THE COURT DECISION in the Georgetown-water-front-rezoning case last week was a welcome boost to the effort to revive that run-down area and bolster the city's tax base and revenues. Superior Court Judge Sylvia Bacon's ruling has legal significance as well. Essentially, she concluded that the home-rule charter does allow the city government to make zoning decisions without reference to the comprehensive plan approved by the National Capital Planning Commission in 1968. This reading of the law is, we think, correct. And the waterfront-redevelopment policy favored by the city is also reasonable, in our view - although there is a lot more work to do before the waterfront can be a real community asset again.

The big losers, of course, were the Georgetown Citizens Association and allied groups, who have been fighting so tenaciously to curb commercial development and stamp the special character of low-rise, high-priced residential Georgetwon on the dilapidated, largely industrial waterfront. Indeed, thanks to Judge Bacon's leisurely handling of the case, the citizens' groups were losing ground to various projects even before they lost their case. That does not trouble us. The 1974 zoning, after all, will not turn the slope from M Street to the river into a Rosslyn-like mass of big glass boxes. What it does allow - and what is even now being built - is an assortment of commercial and residential projects, no more than 90 feet high and in most cases less than that. If the Fine Arts Commission pays proper attention to aesthetics and amenities such as trees, the results could be quite pleasant - and very much in keeping with the historical liveliness and diversity of the port area.

Two big problems remain, and these are what the city and citizens should concentrate on now. The first and biggest is traffic. Something must be done to get parking under control, get commuter cars off M Street, and eventually get the Whitehurst Freeway off the waterfront. While the Three Sisters Bridge was still alive, there was much talk of putting the freeway in a tunnel or on a K Street shelf, but the money and rationale for such solutions may have perished with the bridge. The subject should get top priority, because simply wringing one's hands - which, we admit, we're doing at the moment - won't solve anything at all.

The second lingering question is the riverfront itself. If everyone agrees on anything, it is that the riverfront ought to be a park. Back in the freeway-planning days, the District acquired most of the land between K Street and the river. The National Park Service has designs on the whole stretch, and the city would be glad to transfer its acreage eventually.

So why not now? The hitch, ironically enough, is caused by one city program that Georgetown residents really appreciate. It seems tat the crackdown on Georgetown parking has created the need for a handy place to put impounded cars. And, yes, the city wants to store them on the waterfront - just temporarily. But that is no progress at all. If the city is really committed to reviving the waterfront, it ought to start by turning its own property from parking lots into a park.