Cambridge and Boston citizens and civic groups are preparing formal opposition to a plan that would put apartments, research firms or industrial buildings on a 40-acre platform over part of the Charles River Basin.

But at present they are not sure when they will have the opportunity to make their objections heard. A public hearing on the measure, scheduled for Monday morning, was cancelled early this week and no new hearing date has yet been announced.

Proposal in Form of Bill

The proposal is in the form of a House bill before this session of the state legislature. The bill would return to the zoning control of the City of Cambridge a plot of submerged land along the Cambridge short south of the Longfellow bridge (see map).

This land is privately owned, and used to be a part of Cambridge, until, in 1903, the Metropolitan District Commission was authorized to dam up the mouth of the Charles and flood the area now known as the Basin.

Now, John Briston Sullivan, local real estate operator, wants to have the property taken out of MDC control so that he can develop it.

Sullivan feels that he can develop the property so that it will not only bring additional tax revenue to the City but will also enhance the appearance of the waterfront. He also claims support of Cambridge taxpayers.

But he will face opposition of a wide variety of groups and institutions, including M.I.T., various yacht clubs, the Cambridge Civic Association, the Citizens Advisory Committee, and the League of Women Voters, as well as a number of citizens.

They point out that the platform on stilts would virtually destroy the recreational and aesthetic value of the Basin, on which millions of dollars have been spent for development.

Basin Used for Sailing

Several fleets of small boats use the Basin for sailing and Harvard's home crew races are held on a course which starts near the proposed platform site. The esplanade on the Boston side of the area is the scene of summer concerts and has playgrounds and other recreational facilities.

The proposal was reported unfavorably in committee last year after a hearing at which several groups and people objected to it. But opponents this year fear the bill has a better chance of passage because of changes in the composition of the legislature.