Opponents of the proposed development of the Georgetown waterfront yesterday told the D.C. City Council that the project should be delayed for two years while the possibility of a Potomac River flood in the area is studied. But the developer and top city officials argued that the project should be approved.

The latest potential hitch in the long battle over plans for the $120-million residential and commercial development is that the project would be built on the Potomac River flood plain. Opponents say the project could be inundated if the river floods, which has occurred periodically.

Nine of the 13 council members have cosponsored a bill that would prevent the city from issuing building permits to the developer, Western Development Corp., until a federal study of the flood plain is completed. A spokeman for the Federal Emergency Management Agency, which is conducting the study, said it will take at least two years to complete the report.

The ongoing fight to halt the development is being led by the Georgetown Citizens Association, whose president Donald H. Shannon, said the potentia flood danger is "just another good reason not to go ahead with the project." The neighborhood group has staunchly supported creation of a park on the waterfront tract, now occupied by an unsightly collection of trash, parking lots and a cement plant. The federal Fine Arts Commission also favors creation of a park, although it has approved the basic design of the development.

James O. Gibson, the city's planning director, told the council's Committee on Transportation and Environmental Affairs that Mayor Marion Berry opposes the plan to delay the development.

Like the citizens, Harry would like to see the entire area made into a park, Gibson said. But Berry believes that the idea is impractical and that the current development proposal -- which still must receive final approval from city planers -- should not be impeded.

Representatives of Western Development argued strongly against the proposed delay, citing figures that indicate that the project will eventually provide $8.6 million a year to the District in tax revenues and a total of 1,400 new jobs.

The developers also argued that they had already taken into account the possibility of periodic flooding when they designed the project, and contended that the council bill would be unconstitutional because it would unfairly deprive the company of the use of the property.

The bill, originally introduced by council members Polly Shackleton (D-Ward 3), in whose ward the project would be located, and Jerry A. Moore (R-At-Large), the committee chairman, would deny building permits for the areas from the Potomac to K Street NW between Rock Creek and Key Bridge until the flood plain study is completed. b

Supporters of the moratorium argued that residents of the condominiums in the planned low-lying complex could find themselves stranded on a newly created island in the event of the kind of widespread flooding that was caused by Hurricane Agnes in 1972,

They also argued that the planned development violates an executive order issued by President Carter in 1977 that bans government-supported projects built on lands subject to floods unless there is no feasible alternative.

Opponents of the moratorium contended that no special restrictions have been placed on other projects built on the flood plain, such as the Southwest waterfront, the Watergate apartment complex and the Kennedy Center for the Performing Arts.

They also noted that the development plan already sets aside 15 acres of the total 18.5-acre site for a park.