On Tuesday, the governors of Maryland, Pennsylvania and Virginia, the mayor of the District of Columbia, and representatives from the federal government and the Chesapeake Bay Commission will meet in Baltimore to sign a far-reaching and historic agreement to save the Chesapeake Bay.

The bay is dying. It has been choked by decades of neglect and abuse. But the time to point fingers and assess blame is over.

The 1987 Bay Agreement outlines a plan to manage the Chesapeake. It lists specific goals, including a commitment to reduce the amount of nitrogen and phosphorus entering the main body of the bay by at least 40 percent over the next 12 years.

It is not going to be easy to accomplish all that this agreement promises. It will not be cheap, either in terms of funding or in the allocation of staff.

Our experience in Maryland has already shown us how hard the job will be. We have already had to face many tough decisions in our efforts to reclaim the bay. Three years ago, we banned phosphates in Maryland. In 1984, we adopted a law establishing criteria for development around the shore of the bay. We have had to ask sportsmen and watermen to make sacrifices. In 1980, we placed a moratorium on the harvest of shad. Four years later, we banned fishing for rockfish. And this is only the beginning. We must continue to make hard choices if we are really serious about the bay.

One of the most significant aspects of the 1987 Bay Agreement is its cooperative approach. For years, the various jurisdictions have made decisions based on what is best for their citizens, or for their state, or for their special interests. This new agreement gives us a common standard: what is best for the bay.

There are many people who already are saying, "It's not my problem. I don't have a boat. I don't live on the water. I haven't done anything to hurt the bay."

Let me bring it home to you in Montgomery County or Falls Church. Approximately 95 percent of the land in the state of Maryland drains into the bay. Roughly 50 percent of the land in Virginia, 50 percent in Pennsylvania and 100 percent in the District of Columbia drains into the Chesapeake.

Whether it's farmland outside of Frederick or Culpepper, the heart of Baltimore or Washington, Crisfield or Norfolk, the old axiom that water flows downhill is still true. Rainwater washing across fertilized fields, waste water from leaking septic tanks, trash collected in city drains or spillover from treatment plants -- one way or another, they all find their final resting place in the Chesapeake. Even the fumes from our cars, industries and power plants are collected by rain and deposited in the streams feeding the bay, making them too acidic for spawning fish.

Public education is a major focus of the bay agreement. It mandates that each signatory work to inform citizens and communities about their effect on the bay. It sets out a joint review process that forces us to involve all citizens as we make decisions about the bay and about the success of our efforts. It is a public review process rarely found in government.

The agreement makes it very clear that every citizen, every level of government and every private organization or special interest group has a role to play in our campaign to protect the Chesapeake.

During the years ahead, each of us will need to think about many of the habits and activities we take for granted. We are going to have to change everything we do that harms the bay. That sounds very radical, and, in some cases, it may be. It may be as simple as adding water-saving showerheads to a bathroom or disposing of unused chemicals or used oil at a recycling center. But it could involve major commitments for homeowners and recreational boaters. During the next year, we are going to make a lot of suggestions on ways individuals can help.

But this agreement is not a commitment for people alone. Government also has its responsibilities. We need better waste-water treatment facilities. We need many more recycling centers. We need fish passages. We need new regulations for toxic waste.

The standards and deadlines we have set are reasonable. More to the point, they are necessary. But they will demand difficult decisions on money, staff, people, equipment and commitment. I see very few choices here. There is no doubt we can save the bay. But we must now provide the necessary resources to do so.

The Chesapeake will live forever with our help. It will once again become that precious spot in the world described by Captain John Smith, the first European to sail the bay. On entering the bay, he wrote, "Heaven and earth never agreed better to frame a place for man's habitation. . . . Here are mountains, hills, plains, valleys, rivers, and brooks all running most pleasantly into a fair bay compassed but for the mouth with fruitful and delightful land."

Imagine John Smith sailing up the bay today. Can't you see him standing on the quarterdeck, a tear in the eye, a look of disbelief on his face: "What have they done to you!"

William Donald Schaefer is the governor of Maryland.