University of Maryland officials unanimously approved yesterday the sale of $49 million in revenue bonds to finance dormitory renovations at the College Park campus and other projects.

The university's Board of Regents, its governing body, also unanimously approved plans to construct a Waterfowl Research and Development Center at the Horn Point Environmental Laboratory in Cambridge, part of the university's Center for Environmental and Estuarine Studies.

The bonds approved by the board are expected to go on sale early next year.

About $21.5 million of the revenue will pay for phases four and five of the seven-phase dormitory renovation plan.

Phase four, which started in August, includes renovations to Allegheny, Baltimore, Frederick, Howard and Washington halls and is expected to be finished by next August. Phase five includes Charles, Montgomery and St. Mary's Halls and is scheduled to begin in May 1986 and be completed by January 1988.

About $4.3 million of the bond revenues will be used for renovating campus graduate housing.

Under that plan, all apartment fixtures and utility lines would be modernized in the Lord Calvert Apartments on Rowalt Drive, which were built in 1949, and in the University Hills Apartments on Adelphi Road, built in 1951. The 17 buildings would be renovated, one at a time, from next April to September 1987.

The decision to borrow money to complete the renovation of 24 residence halls -- many of them built before World War II -- was virtually the only option left for the regents, university officials said.

Annual dormitory fees at College Park, which at $1,842 rank near the highest of any public university, already include a $400 surcharge to finance the renovations.

University officials said construction of the waterfowl center will focus on reversing the downward trend of the non-mallard, wild duck populations in Maryland, as part of the state's commitment to revitalize the Chesapeake Bay.

Plans for the center include a hatchery, a visitor-education center, aquatic grasses research pond and a flooded crop experimental area.

The 1984 session of the Maryland General Assembly appropriated funds, about $500,000, for the construction of the hatchery.

"We at the university put more emphasis on environmental problems than any other university around," university President John S. Toll said, adding that final construction costs and dates have not yet been calculated.