In a move that could impact the amount -- and quality -- of water flowing into the Chesapeake, Congress has vowed to halt funding for the interstate commissions responsible for managing the Potomac and Susquehanna rivers, the Bay's two largest tributaries.

Although Congress agreed to fund the commissions this year -- the House had earlier voted to kill federal support -- the House-Senate conference committee that produced the final bill said this would be the last money appropriated for the Susquehanna River Basin Commission and the Interstate Commission on the Potomac River Basin, both of which are key players in the Bay Program.

The conference committee report said 1996 funding was provided to "facilitate an orderly transition to financial self-sufficiency of the compact states." The committee made the same decision for the Delaware River Basin Commission.

Supporters say the action jeopardizes the survival of the commissions. The commissions work with a variety of state and federal agencies to develop watershed- wide management strategies that directly affect the water entering the Chesapeake.

For example, the Susquehanna commission works with federal and state agencies to regulate water "withdrawals" in the basin. This ensures that an adequate amount of fresh water reaches the Bay; less fresh water would mean saltwater portions of the Chesapeake would move farther north.

To help make sure there is enough flow during droughts to avoid major changes in the Bay ecosystem, the commission purchases water from federal reservoirs and sells it to utilities to help offset the huge amounts they need to run their power plants -- the federal government is not allowed to directly sell water to a business.

"You need an agency like the commissions to coordinate everything that is going on," said Richard Cairo, a spokesman for the Susquehanna commission. "The heart and soul of these agencies is the participation of the federal government."

But an aide to the House Energy and Water Appropriations Subcommittee, which handles funding for the commissions, said river watershed management did not require a federal role.

"There are other watersheds managed on a multistate basis without federal participation in a river basin commission," the aide said. "I think that all added up to an inclination that this was a good place to start terminating some federal programs."

Other regional activities under the subcommittee's jurisdiction, including the Tennessee Valley Authority and the Appalachian Regional Authority, also took "extraordinary reductions" in federal funding, the aide said.

"The feeling is that the federal government has just grown out of control and it's time to start trimming back," the aide said, "and anything that is even arguably discretionary bears special scrutiny in these incredibly constrained budget times."

Nonetheless, 11 senators -- including all six from the Bay states -- signed a Dec. 22 letter to Office of Management and Budget Director Alice Rivlin asking that the Clinton administration continue to fight for funding for the commissions.

"The compacts are not limited to an agreement between states; central to their functioning has been the commitment and involvement of the federal government," the senators wrote. "Eliminating federal funding for the commissions should not be done without an exhaustive analysis. In the absence of such a finding, the federal government should not walk hastily away from its obligations."

This year's bill, which has been signed into law, provides the Potomac commission with $511,000, the same amount as 1995, while the Susquehanna commission got $250,000, a $38,000 cut.

Federal funding makes up about 25 percent of the Potomac commission's budget, and about 15 percent of the Susquehanna commission's funding. But that accounts for nearly half of the "hard" money -- funds that do not come from grants -- for the Potomac, and about a third of the Susquehanna's hard money. With state and federal cutbacks, officials believe that grant money, which funds specific projects, will also decline.

Other hard money comes from dues paid by the states within each river's watershed, each of which participate on the commissions. But most believe state budgets are probably too tight to make up the shortfall.

"I think the likelihood that that is going to happen is probably slim to none, said Keith Gentzler, of the Pennsylvania Department of Environmental Protection's Office of Water Management, who is currently chairman of the Potomac commission. "What would be more likely to happen would be a downsizing of both agencies, which of course means they would be doing less."

Some fear a pullout of federal money could lead some states to do the same. For example, New York -- the furthest upstream member of the Susquehanna commission -- has never paid its full portion of membership dues. "To tell them their share went up, I just don't see that happening," Gentzler said.

Without a federal commitment, Gentzler said, "the partnership is certainly significantly weakened because federal agencies continue to have an important role in water management. I suppose they could come to the table and participate in some way without contributing money, but a partnership where you don't share the costs seems to be a weaker partnership."

Many federal agencies -- including the Army Corps of Engineers, the U.S. Geological Survey, the U.S. Fish and Wildlife Service, the EPA and others -- make decisions that impact water management. By working with those agencies, each of which has specific responsibilities, and the states, which are bound by political boundaries, the commissions work to coordinate activities throughout the watershed, such as flood control, water supply management and water quality monitoring.

"We fill that gap," said Herbert Sachs, executive director of the Potomac commission. "We do things that nobody else can do."

The Potomac commission was created in 1940 as a non-regulatory agency to address water-related issues through the basin. It is heavily involved in water supply management issues, water quality restoration issues, and planning projects throughout the watershed. The commission has been involved in coordinating the Bay Program nutrient reduction tributary strategies for the Potomac being developed by Virginia, Maryland, Pennsylvania and the District of Columbia. Its modeling work has been used in the development of tributary strategies throughout the Bay.

The commission is writing the Bay Program's Regional Action Plan to control toxic pollution on one of the Potomac's tributaries, the Anacostia River. It has been involved in fish stocking, the construction of fish passages and habitat restoration in the watershed.

The commission also engages in research activities. For example, it is helping to establish a plankton database for the Potomac and other parts of the Bay watershed. When complete, the database will allow scientists to use these tiny organisms as measures of the Bay's health.

The Susquehanna commission was formed by an interstate-federal compact in 1971. It has the authority to regulate water use in the watershed to ensure the supply is adequate for all users. In the face of increasing growth, the commission has recently been studying how much fresh water flow is required throughout the basin to protect critical habitats in the rivers and to supply the Chesapeake Bay. The Susquehanna is the source of half the fresh water entering the Bay.

The Susquehanna commission has had a major involvement in Bay Program activities. Its monitoring programs track nutrients, sediments and toxics in the basin. The commission is also studying management options for the huge amount of nutrients and sediments that have been trapped behind the large hydroelectric dams on the rivers -- if the reservoirs reach their capacity, which is expected shortly after the turn of the century, the material now trapped behind the dams will be flushed straight into the Bay.

The commission has also conducted numerous research projects relating to Bay issues, including the use of constructed wetlands to reduce nutrient runoff from agricultural lands.

Paul Swartz, executive director of the Susquehanna commission, has noted that it pays the federal government more money than all three river commissions in the region -- the Susquehanna, Potomac, and Delaware River Basin Commission -- get from the federal government. This is the result of water management activities, in which utilities in the 1970s agreed to pay the commission to purchase water storage for them from the federal Cowanesque Reservoir in the northern part of the basin. During periods of low flow, that water is released to help offset the water being used by the utilities. Each year, the commission pays the government nearly $3 million for the water.

"It is very vexing when you give the government $2.8 million and they want to cut you off for $360,000," Cairo said.