A Senate subcommittee yesterday authorized $5 million to help implement an antipollution management plan for the Chesapeake Bay being developed by officials in Maryland, Virginia and Pennsylvania.

The funds would be used to build new sewage treatment plants or improve existing ones in the three states, as recommended last year in a special report on Chesapeake Bay pollution.

Lee Zeni, director of the Tidewater administration for Maryland's Department of Natural Resources, said the money is about half of what antipollution authorities had sought, but that its appropriation "does demonstrate a congressional intent under the Clean Water Act to maintain the bay as a national treasure."

The funds were authorized by the Senate Appropriations Committee's subcommittee on HUD and independent agencies.

The panel also authorized an additional $250,000 to help the states establish a Chesapeake Bay liaison office under the Environmental Protection Administration. Zeni said the office would be used to set up a data management center for the bay, monitor water quality and habitat and report to Congress on antipollution efforts.

Zeni said the funds for sewage treatment projects would be divided after officials from the states decide who needs the money the most to combat specific pollution problems.