BALTIMORE, DEC. 15 -- Comparing their meeting to last week's superpower summit, the governors of three states, the mayor of Washington, and a top federal environmental official signed a historic compact today pledging to restore the polluted Chesapeake Bay to its pristine greatness.

The agreement sets, for the first time, specific goals and timetables for the bay's restoration by improving sewage treatment plants, reducing industrial pollution and curbing development. The pact also pledges the top-level signatories to a joint effort they said could cost billions and would be reflected in higher taxes, higher sewer fees and other expenses to be borne by industry and consumers.

In signing, the officials said, they hope to reverse the decline that has imperiled the Chesapeake's status as a major source of jobs, seafood, recreation and regional culture. But the official optimism was tempered by the likelihood of tough legislative battles ahead.

Virginia Gov. Gerald L. Baliles, who headed the interstate summit that seemed today to have won over even some of its most skeptical environmental critics, said, "Both summits followed intense negotiations, clarified the areas of mutual interests, and outlined bold actions for future harmony. Both summits will conclude agreements which will be subject to verification.

"And, it can be said with certainty that the results of this summit, like last week's, will have a lasting effect -- for the better, we hope."

With ceremony and pomp that included a red carpet, music by the Naval Academy Band and a Coast Guard escort, the signers met at the Baltimore Convention Center, including governors Baliles, William Donald Schaefer of Maryland and Robert P. Casey of Pennsylvania, District Mayor Marion Barry, EPA Administrator Lee M. Thomas and Kenneth J. Cole, a Pennsylvania lawmaker who heads the Chesapeake Bay Commission, an advisory group to the state legislatures.

The agreement they signed includes for the first time the ambitious -- and expensive -- target by the year 2000 of improving sewage treatment and reducing runoff from farmland to reduce by 40 percent the nitrogen and phosphorous discharge that kills acquatic life.

The pact pledges the signatories to come up with a plan to replenish oysters, shad and blue crabs. They also agreed to devise and begin implementing in one year a plan to reduce the amount of toxic chemicals dumped by industry into the bay. The goals call for legislation and appropriations for a cleanup so ambitious that, officials said, no price tag can yet be set.

"It will take some equitable distribution of costs, and cooperation, mediation, good will and mutual trust to make the agreement effective," said Casey, whose state encompasses most of the Susquehanna River, the major Chesapeake tributary that accounts for half the bay's fresh water.

The nation's largest estuary -- up to 35 miles wide and once touted as a vast protein factory -- has fallen on hard times: Its oysters, rockfish and shad are in sharp decline. Its waters are polluted by the oxygen-consuming nutrients, industrial toxic chemicals, agricultural pesticides and herbicides and earth washed into the bay from upstream development or shoreline erosion.

The bay's long-term decline threatens the economy of the states, counties and towns that border it and depend on it for jobs and other sustenance. Restaurants, marinas, commercial and sports fisheries are all affected.

Its recreational use is already threatened: fishing for striped bass, or rockfish, is forbidden in Maryland.

And, without a sharp turnaround, officials say, the future looks bleak not only for seafood consumers but for the crab-pickers and oyster shuckers, the colorful watermen crabbing in the summer, oystering in the winter, and also for the marina workers and yacht brokers.

Officials say if the decline is not halted -- the oyster catch, for example, has dropped from 3 million bushels in the 1970s to less than a million bushels this year -- the industry, recreation and culture of the 195-mile-long bay could suffer irreparable harm.

Among the thorniest political problems is how to curb development along the tributaries that drain from five states into the bay, carrying runoff from countless construction sites. Maryland has adopted legislation curbing growth within 1,000 feet of the bay and its tributaries. Virginia, far more conservative in such matters, is only beginning to consider tidewater zoning restrictions.

But with officials and environmentalists agreeing that the hard work lies ahead, even the critics who had complained that the pact was not tough enough hailed the signing.

Will Baker, president of the Chesapeake Bay Foundation, said the document was "light years ahead" of the simple, two-paragraph declaration signed by three governors and Barry in 1983 committing them only to the overall cause of bay cleanup. "We can be proud and pleased. We're happy," he said, adding, "We think more can be done."

Gov. Casey likened the event to "signing a peace treaty."

"In a way we are," said Maryland's Schaefer. "This is one of the most historic events among our jurisdictions in a very long time."

The rare assemblage of high-level officials included United States senators, representatives, county executives and legislators from the three states.

Also present was Charles McC. Mathias Jr., the former Republican senator from Maryland credited with early efforts that led to the pact he termed "one of the most significant dates in the history of man and the bay."

"From now on," said Mathias, "the bay will be viewed as the crabs and fish see it, without political boundaries, without artificial borders."

PACT HIGHLIGHTS

Goals, timetables of regional 1987 Chesapeake Bay Agreement:

Deadline to begin reducing nitrogen, phosphorus: July 1988. Goal by year 2000: 40 percent reduction, with reevaluation by 1991.

Deadline to devise water quality guidelines: January 1988.

Deadline to adopt plan for management of ecologically valuable species: July 1988.

Deadline to begin implementing plans for managing oysters, American shad, blue crab: July 1989.

Deadline to launch plans to control pollutants under guidelines of 1987 Water Quality Act: July 1988.

Deadline to begin reducing toxic chemicals under federal regulation: December 1988.

Target date for EPA to start reducing discharge of pollutants, toxics, nutrients from federal facilities: July 1988.