The drought has actually done some good: The lack of rain has meant less pollution has washed into the Chesapeake Bay, according to a new report assessing the estuary's health.

Even more important than the reduced runoff has been improvement in the ailing oyster population, more rockfish and more shad--all signaling a slight upgrade in the health of the bay, according to the Chesapeake Bay Foundation. But despite that improvement, the bay remains threatened by pollution and overfishing.

"The Chesapeake Bay is getting better. But the progress is too slow, and the bay is still a system dangerously out of balance," said William C. Baker, foundation president, as he released the organization's annual state of the bay report. He called for more cooperation among Maryland and Virginia officials and federal environmental regulators to combat pollution, restore wildlife habitats and improve fishery management.

The bay is the nation's largest estuary and plays an important role in the region's economy through recreation, commercial fishing and international shipping. Its crabs are famous worldwide. But its pollution problems in recent years have left many fretting about its future.

To assess the bay's health, the foundation, which is the leading independent watchdog on the Chesapeake, has developed a numerical scale rating wetlands, underwater grasses, pollutants and fish to come up with a grade for the bay. The bay now scores a 28 on a scale of 100, with 100 being an estimate of the quality of the waters when they were first explored nearly 400 years ago.

A 28 is one point higher than the score last year, when the foundation began its grading system. Baker acknowledged the rating system was "some art as well as some science." But the environmentalist said the rating provides an easily understood method of evaluating the health of the bay.

Among the criteria are the health of the rockfish, which foundation scientists said had improved. A key sign was an increasing number of older, large fish.

Also evaluated were the numbers of oysters and shad, which, though larger than last year, remain low. Crabs also remain well below the ideal, according to the foundation's report, because of overfishing and the destruction of underwater grasses critical to their replenishment.

Baker said the foundation wants Maryland, Virginia and federal officials to adopt plans that will by 2010 see improved sewage treatment, reduced farming pollution, restoration of wetlands and shoreline forests and expansion of underwater grasses. The plans also should include strategies for restoring populations of rockfish, blue crabs, oysters and shad.

The killing of thousands of fish by the toxic microbe Pfiesteria piscicida two summers ago focused attention on the bay and prompted new regulations on Maryland farmers to prevent runoff that was suspected of spurring the outbreak. Baker said he was concerned that some people may believe that all the problems have been solved.

But he said the bay still has a long way to go. Although the bay will never again be the pristine waterway it was 400 years ago, Baker said, the foundation hopes conditions will improve and eventually earn a score of 70 based on its ratings criteria.

He praised Virginia's efforts to restore oysters but criticized the administration of Gov. James S. Gilmore III for allowing the destruction of more than 2,000 acres of wetlands. "Governor Gilmore has failed to keep even his most basic promise to protect wetlands," Baker said.

A spokesman for Gilmore (R) yesterday referred questions to Virginia Secretary of Natural Resources John Paul Woodley Jr. He did not return a phone call.

Baker said Maryland Gov. Parris N. Glendening (D) has done much for the bay but could do more.

Two years ago, Glendening pushed new limits on farmers' use of fertilizers to help reduce pollution, following the pfiesteria outbreak. He said yesterday that the foundation's report was "a renewed wake-up call that problems that begin on the land quickly show up on the bay."

CAPTION: Chesapeake Bay Foundation President William C. Baker, at a news conference, says the drought has meant less pollution runoff.