IT'S HARD TO tell which political participants in the building of a new prison in the District of Columbia will have behaved the worst by the time the facility is completed -- but welcome the Reagan administration to the crowd. This time, Mayor Barry (whom we have criticized for taking so long before supporting the new prison) has been negotiating in good faith with the administration; and he is understandably upset by the heavy-handed and patronizing manner in which the Justice Department has responded to his effort to settle on a site.

The negotiations had seemed to be going reasonably on Jan. 16, when the mayor said it was agreed that the federal government would assemble a list of perhaps 10 optional sites from a list the city had made of 257 federally owned and unused or barely used properties of at least five acres. In addition, the city government had assembled a list of more than 10 possible sites.

Now -- in a letter to the mayor that was made available to the press before it was received by Mr. Barry -- Deputy Attorney General D. Lowell Jensen has combined a short list of sites with a long set of orders telling the city government what to do with its prisoners right away and in the future. The letter also announces for the first time that "it is apparent to the Department of Justice that the District of Columbia must add a minimum of 2,000 more beds to its current corrections capacity. Therefore, more than one site may be necessary." This is double the capacity the city and federal governments had been talking about -- and double the number of new prisons.

This goes well beyond constructive federal pressure on the city to get moving on a new prison. It is a disturbing example of the federal government's reassuming tight controls over local criminal justice functions -- just as this administration tried to do when it sought revisions in the home rule charter.

What's the matter with any of the other sites listed by the city?

Each of the three sites listed by the Justice Department presents special difficulties. St. Elizabeths Hospital will become District land anyway and is under legislative consideration for other uses. The old D.C. jail site has been studied as the logical place to add an ambulatory-care wing to D.C. General Hospital, which is already there. The third site, the McMillan Reservoir at 2500 First Street NW, could not be made available until October, according to the Justice Department.

Back to those other sites on the list -- and we have some suggestions: Why not build the prison on the old kilns area on New York Avenue, not far from the Arboretum and not close to residential areas? It is vacant, and it is large enough for whatever facility the District decides to build. If this is historic land or not suitable for heavy construction, how about Bolling Field?

The Justice Department and the mayor's representatives should talk over these sites -- along with any other mutually agreeable possibilities. But wherever the prison goes, it should be with federal cooperation, not unilateral federal directives.