The Smithsonian Institution plans to improve the management of animal wastes at the National Zoo. The National Park Service is using less fertilizer and pesticides on its property in the District of Columbia. And the U.S. Postal Service has converted 120 vehicles to run on natural gas, thereby reducing air emissions.

Those are just some of the activities under way or planned as part of a special tributary strategy for the 40 percent of land in the District of Columbia that is federally owned. The strategy was signed March 25 by more than 20 federal agencies.

"With the strategy we are announcing today, we are committing the federal government to do our part," said EPA Administrator Carol Browner, who is also chairman of the Chesapeake Executive Council, the policy-making body that guides the Bay restoration effort.

The Executive Council - which also includes the governors of Maryland, Pennsylvania and Virginia; the mayor of the District of Columbia; and the chairman of the Chesapeake Bay Commission, a panel representing the legislatures of the three states - in 1987 set a goal of reducing the amount of nutrients entering the Bay 40 percent by the turn of the century.

To do that, the council also directed that the states and the district develop specific strategies for each major Bay tributary detailing how those reductions would be achieved.

The district completed its strategy in 1995, but that document could not address the huge amount of federal land not under its control, leading to the development of the special federal strategy. In all, the federal government owns 15,700 acres in the district, including almost all the shorelines of the Potomac River, Anacostia River and Rock Creek.

"I think what we're saying, fundamentally, is that if we can't get the federal government to clean up our own backyard, how can we expect our partners in the Bay Program to do the same?" said Mike McCabe, administrator for EPA Region III, which includes all the Bay states.

A major part of the strategy is a commitment to improve stormwater management on federal lands in the district. An estimated 300 million gallons of stormwater runs off federal lands each year into the district's sewer system. During heavy storms, that runoff helps to overwhelm the city's combined sewer overflow system - where sanitary and storm drains are mixed - allowing raw sewage and other pollutants to bypass wastewater treatment facilities and flow directly into rivers and streams.

Agencies that signed the agreement will also take actions to reduce the use of fertilizers, pesticides and other chemicals that pollute water. They also plan workshops to assist agencies with improving nutrient management and stormwater controls in urban areas.

The strategy was signed at a ceremony at the National Arboretum, operated by the Agricultural Research Service of the U.S. Department of Agriculture. Arboretum Director Thomas Elias noted that many efforts were already under way to reduce pollution.

For example, he said, the 444-acre arboretum has reduced its use of pesticides 75 percent in the past 2 1/2 years by using integrated pest management, a set of practices that emphasizes alternatives to pesticide use when practical.

The arboretum has also cleared 1,500 tons of debris from an old gravel pit and is restoring the site as a beech-maple forest.

It has moved a composting stockpile, which includes bedding and manure from the National Zoo, away from a site adjacent to the Anacostia River to an abandoned brickyard.

Arboretum staff members have also removed more than 25 tons of trash from two creeks that flow through the property.

"We hope that we can serve as a model for other urban and suburban lands," Elias said.