Officials of three government agencies and two private developers are expected to sign an agreemment today to create a residential-office-retail complex and a 20-acre park on the Georetown waterfront. The agreement could end years of acrimonious haggling over the Potomac River shore that has kept the waterfront a shambles of parking lots, gargage trucks, abandoned buildings and a cement plant.

The area is south of K Street, NW, between Key Bridge and Rock Creek. The new park will bridge the only gap in a river front pathway that stretches from Hains Point to Cumberland, Md.

But the park plan probably will not placate militant Georgetown preservationists who have demanded a total ban on commercial development on the waterfront. The plan calls for about half the commercial construction originally planned by Inland Steel Corp. and the Chessie System Inc., owners of much of the property.

Inland has agreed to sell its land to Western Development Corp., which will build the complex as a joint ven-subsidiary of the railroad.

Western development is the Georgetown firm now building the Georgetown Park Complex at the southwest corner of Wisconsin Avenue and M Street, NW, a few blocks from the waterfront.

The waterfront property is valued at about $25 million, but developers have not put a price tag on the total complex.

The plans call for 375 luxury apartments as well as shops and offices - all in a cluster of three-to-six story buildings on a four-acre tract now mostly occupied by the cement plant.

The rest of the Chessie and Inland properties will be given over to the park, under the agreement to be signed today by the developers and the Department of Interior, the District of Columbia government and the National Planning Commission.

The developers would also give to the park a 160-foot swath along the riverbank in front of their complex, creating a continous public pathway along the river.

Details of the complex and the agreement between the government and the developers are expected to be revealed after today's signing.