ALL TOO HARD on the heels of the summer vacation season comes a day of considerable reckoning for District of Columbia voters, with only the final whirlwind hours of campaigning left before the polls open Tuesday. At stake are six seats on the 13-member D.C. Council -- enough either to preserve or to alter significantly the manner in which this important local legislature functions. Though each election is up to its own particular set of voters -- and subject to another round of voting in November -- the aggregate outcome of the Democratic, Republican and Statehood party primaries could set the stage for a dangerous return to the petty politics and personal friction that made a circus of the early elected school boards here.

To the extent that you can compare the unique responsibilities of the D.C. Council with those of other somewhat similar urban local legislatures, the current membership here looks quite good: holders of more educational degrees than most other bodies, these representatives of different constituencies manage to work together well and to steer away from grandstanding and embarrassing legislative hijinks.

But high on the list of challengers in Tuesday's contests are some candidates who participated in different ways in the tumult of the school board during its worst days. If that gives voters pause, it should. In Ward 4, for instance, incumbent Charlene Drew Jarvis has earned the chance for reelection. In contrast, her best-known challenger, Barbara Lett Simmons, has a record of contentious service on the school board that should not be given the chance to infect the council. Mrs. Jarvis continues to draw on experience and an ability to negotiate that has served her constituents well and helped the council to mature in recent years.

Similarly, in Ward 8, incumbent Wilhelmina Rolark has represented her constituents with exceptional energy and understanding that has made her a familiar name in even the most isolated corner of the ward. We have had our differences with Mrs. Rolark on some substantive issues -- no-fault insurance, cable television -- but her best-known challenger, Calvin Lockridge, like Mrs. Simmons in Ward 4, has been a leader of those who used the school board as a platform for divisive, petty politicking that hindered progress in the school system for an unconscionable number of years. So in this case, too, the choice is clear. Council members Jarvis and Rolark strongly deserve reelection.

Voters registered for the Republican primary can take heart from the fact that two of the candidates vying for the GOP nomination for an at-large seat are knowledgeable and familiar figures on the political scene. Incumbent Jerry A. Moore Jr. points with pride to 15 years' service on the council and with the local Republican Party. The challenge presented by opponent Carol Schwartz has raised a question about Mr. Moore's energy, independence from the Democratic majority and ability to bring fresh thinking to nagging municipal problems. If GOP voters prefer to take new chances on a high-profile activist, their candidate should be Mrs. Schwartz. But if the confidence shown in Mr. Moore by various regional leaders, Republican committee members and others is a factor with voters, they should offer him the opportunity for another term.

In Ward 7, incumbent H. R. Crawford has proved to be a polished politician with an understanding of a part of the city whose concerns are well matched to the kind of professional constituent service and hard-nosed negotiating that Mr. Crawford offers.

In at least one contest the result seems to have been reached already; incumbent Ward 2 Democrat John A. Wilson has no official opposition. Similarly, at-large Democrat John Ray is expected to prevail handily over a lone opponent whose experience in active local politics has been limited. In the Statehood Party primary, Josephine Butler is unopposed for the at-large council nomination.