THE DISTRICT government is in the midst of dealing with very difficult questions on hiring minority workers and trying to figure out if there is some appropriate number of blacks it should have working for it in this 70 percent-black city. Such a number has not been put forward in any formal way, and maybe it never will be. But last week Mayor Barry issued an order to change the entrance exam requirements for police recruits after test results had showed that only 40 percent of those passing the police test were black, while blacks had made up 80 percent of the field of candidates who took the test.

The mayor did not say that 60 percent of the new group of policemen was too many whites for this city to hire, but he did try to change the procedure to get more blacks qualified. Now Anita Shelton, director of the city's Office of Human Rights, has ordered that the fire department hire black people to fill 60 of its 70 current openings. Mrs. Shelton said that the department, now 31 percent black, should be placed under an affirmative action plan until its work force, like the city's population, is 70 percent black.

The Shelton order goes even beyond the mayor's move on the police exam. It ignores the established hiring procedure.It does not favor blacks in hiring standards but simply requires that nearly 90 percent of the people hired be black -- no matter what. Mrs. Shelton and the mayor appear to be turning every which way in a desperate attempt to get more blacks in the city work force, to avoid discrimination suits and yet still to keep some standards for personnel. They are confused and are making bad decisions.

The right decision cannot be to circumvent stringent hiring procedures when the results are not ideal in racial balance terms. The right decision would be to commit the city to keep its hiring policy in place with a tough but non-discriminatory test, and to spend time and money to search out the very best black candidates to take that test. It should be a goal for this city to get more blacks into the police and fire departments. There are certainly too few in the fire department. But to break down the standards of the hiring procedure or to mandate the hiring of a certain number of blacks is to cheapen the reputations of the police and fire departments and undermine their professionalism. It also could create new racial animosities in the departments.

It could also be damaging to the black applicants who are allowed to enter the departments without ever gaining the confidence that comes from qualifying for a job on one's own merit and ability. The idea of finding good black recruits is being put into practice here this week at the annual meeting of the National Black Policemen's Association. The Miami-Dade County police department is on the scene recruiting blacks for its police department from this area. The District should be in that national competition.