A carefully orchestrated hoax is being launched at the Old Georgetown Market on M Street in Georgetown. Soon this venerable market house, built in 1865 and occupying the site of Washington's oldest public market, will be decked out with stylized booths and decorative gas lamps. Where the farmer-merchants of the old market once stood, a new breed of hucksters will peddle everything from 'ye ole cracker barrel cheese' to health foods and pots and pans.

In a glowing endorsement of the project in The Post last spring, Sarah Booth Conroy suggested that the spirit of the old market house was about to be rekindled. But a close examination of the plans of the developer, John D. Zimmerman Jr., reveals that it will bear little resemblance to either a public or farmers' market. What it more closely resembles is a cleverly camouflaged shopping center taking up quarters in a public market.

Zimmerman has pledged to spend some $350,000 to rehabilitate the two-story structure. In exchange, the city has generously agreed to cancel his annual rent. This may not exactly be getting something for nothing, but for an enterprise that Zimmerman expects to gross slightly more than $4.5 million a year, it has all the appearances of a good deal.

In fact, a very good deal - for Zimmerman. As soon as his original proposal was approved, he began to shift the expense of rehabilitation to the public. He drew up a proposal to have the U.S. Economic Development Administration pay for restoring the building. The D.C. government has approved this proposal, although Zimmerman's estimate of the rehabilitation cost suddenly doubled to $700,000. The application is now pending before the EDA regional offices in Philadelphia.

As a former manager of a supermarket in California, Zimmerman does not intend to get bogged down with outdated images of a public market: "Some people think that a market has to have little old ladies from Damascus, with bonnets on their heads, selling dirty carrots. I say to them that we can always bring back typhoid, too. We plan quite a different operation."

And indeed he does. The "stalls" will be divided with lacquered floorboards. Shops or stands dispensing crepes, flowers, linens, meat, produce, appliances and pottery will be the prospective tenants. A delicatessen is planned for the mezzanine. In the basement, with its stone walls, and arches, Zimmerman himself plans to set up a wine store.

Where, you might ask, are the farmer-merchants usually associated with a public market? There is to be a "farmers' line" outside the building - but only twice a week. On other days, the farmers will be replaced by antique dealers, flea marketers and other vendors.

The Zimmerman proposal says that he studied the recently restored Quincy Market in Boston, Les Halles in Paris and Covent Garden in London and that his plan "combines the best of all these markets." Whatever one may think of the urban chic of the Quincy Market restoration, the other examples cited were disasters. Les Halles was torn down and scraps of it peddled in the shops of Paris. In Covent Garden the vendors were quite simply removed.

In 1966 an Act of Congress established the Georgetown market as a historic landmark and ordered the city to maintain and preserve it as a "public market." The directive was necessary because the District commissioners, who were in charge at that time, were systematically destroying the city's market system.

Washington once had some of the finest public markets in the nation. They were objects of "considerable interest to strangers," as the author of Illustrated Washington put it in 1890, and a source of pride for the residents of the District. The supermarket and the spread of suburbs into the neighboring counties of Maryland and Virginia have both contributed to erasing all but the memory of the city's rich history of public markets. But the single greatest contributor to the removal of public markets has been the attitude of public officials who saw the markets as obstacles to efficiency and order or simply coveted the land upon which the markets stood.

The great sprawling Center Market at 9th and Pennsylvania Avenue NW, which once attracted hundreds of daily visitors to its 666 stalls, was demolished in 1932 to make way for the National Archives Building. In the 1940s, the District commissioners, finding themselves in apparent agreement with I'Enfant's view of public markets as a nuisance, decided to "get out of the market business." As more and more markets were destroyed, the displaced farmers were moved over to the Northern Liberty Market at Fifth and K Streets NW or to the Western Market at 21st and K Streets NW. These were spacious quarters indeed. The Northern Liberty Market, when it was completed in 1874, had the largest unsupported roof span in the country and room for 284 stalls within its walls. But eventually the vendors had to move again. The Northern Liberty Market was rented to an organization that established a wax museum there and gave the entire building a coat of garish pink paint. Today the building is deserted and chips of pink paint litter the sidewalk around it.

The vendors from the Northern Liberty Market found refuge at the Eastern Market or at the Western Market. But the District Commissioners continued to rid the city of markets. The fish vendors and farmer-merchants at the Southwest Farmers Market had to give way for the Southwest Freeway and other urban-renewal work. In 1966, the District sold the site of the Western Market for $3,020,000. Each time the farmer-merchants were told to move, a number of them just quit.

When the Western Market was closed, nine merchants were operating full-time and about 20 came seasonally. They hoped to be relocated at the Old Georgetown Market, then being rented to an automotive parts firm. But these hopes soon vanished as little was done to bring the vendors in.

The 1966 law directing the District to maintain the Georgetown Market was based upon extensive hearings before the House District Committee, an exhaustive history of the building by the National Park Service and an economic study commissioned by the National Capital Planning Commission, which concluded that the operation of a public market was economically feasible. But the main result of the law was to stop the District commissioners from selling the property, which was deeded to the Corporation of Georgetown in 1802 with the stipulation that it remain a public market "forever."

The lease the District government has recently signed for the market cloaks a private enterprise in public garb.

The irony is not only that the new city government, under home rule, continues the District commissioners' war on public markets. It is also that, at a time when most cities are rediscovering the value and joy of farmers, Washington has chosen to turn its oldest public market into an assembly of boutiques a la Watergate's Les Champs.