THE D.C. Council has the authority to block Mayor Barry's shameful last-minute salting of the government with patronage appointees and his lavish disbursing of contracts. So far, it has failed to do so, even though the mayor's frantic dispensation of goodies will only have the effect of blocking the next government's freedom of action and discretion. Mr. Barry recently vetoed council legislation that would have prevented him from awarding large contracts without its consent. That bill would have given the council temporary authority over about $250 million the city has budgeted for contracting and over about $40 million allocated for the buying or leasing of property.

Even though that bill had passed without dissent and only a two-thirds council majority is required to override, there has been no formal talk of an override effort.

Council members also backed away from a bill that would have restricted the mayor's ability to promote or boost the salaries of loyal city employees under his authority, with the lame claim that they might later nullify such personnel moves if the city auditor determined that they were politically motivated.

So Mr. Barry just keeps stacking the deck against his successor, filling as many of some 900 positions on city boards, commissions and committees as possible before the end of his term. The fact that Mr. Barry, facing a six-month jail term for cocaine possession, this week filled 43 slots on such important bodies as the mayor's advisory committees on drug abuse and alcoholism, appointing people for terms that will run all the way into 1993, is almost beyond belief. A strong D.C. Council would already have forced the mayor's hand in these matters. It still can, but only if it summons the nerve to act. The government-to-be deserves a free hand in restoring the city's fiscal and moral credibility, and that freedom should be preserved.