A new study suggests it may be impossible to restore Chesapeake Bay unless mid-Atlantic air pollution is sharply curtailed and New York, Delaware and West Virginia can be drawn into the cleanup campaign.
The bay could make at least a partial recovery from decades of pollution if Maryland, Pennsylvania and Virginia stick to their 1987 goal of cleaning up sewage discharges and curbing runoff from farmland and development, the study concludes.
A preliminary draft of the study, compiled by the U.S. Environmental Protection Agency and based on a sophisticated computer "model" of the bay, is to be presented Thursday to a panel of federal and state officials. The panel is re-evaluating the goal of the bay restoration agreement, signed four years ago this month in Baltimore.
But officials and scientists familiar with the study say in interviews that cleanup may be even harder to achieve than they thought in 1987, largely because the agreement does not cover major sources of pollution in the bay's 64,000-square-mile watershed.
State officials have said they see signs of recovering water quality in the Patuxent River and diminishing pollutants flowing into other major tributaries.
But Robert Perciasepe, Maryland's environment secretary and chairman of the panel, acknowledged that the amount of pollution that states had assumed they could control "may not be as much as we thought, and we may have to expand our horizons."
Most officials and scientists agree that the $400 million-a-year restoration effort is on the right track, but debate continues over how "clean" the bay's water must be to replenish underwater grasses, fish and waterfowl.
"That, right now, is unanswerable," said Robert Thomann, professor of environmental engineering and science at Manhattan College in New York. He works with federal and state scientists on the model, which was developed using an Army Corps of Engineers supercomputer in Vicksburg, Miss.
"But if you do nothing," Thomann warned, "the situation will continue to deteriorate."
"The model appears to be showing that while everything we are doing is having an impact, we need to do significantly more if we are to turn around the water quality of Chesapeake Bay," said Ann Pesiri Swanson, executive director of the Chesapeake Bay Commission, a tri-state panel of legislators that is a party to the bay cleanup agreement.
The cornerstone of the original bay agreement was a pledge to reduce nutrients entering the bay by 40 percent by the year 2000.
Nutrients are necessary to sustain life, but the Chesapeake suffers from too much of a good thing.
Nitrogen and phosphorus -- largely from sewage and runoff from farms and developed land -- trigger massive algae "blooms" that block sunlight needed by underwater grasses.
When the algae die and sink, their decay also consumes the dissolved oxygen in the water. As a result, vast portions of the bay's water contains little or no oxygen, making it impossible for fish, crabs and shellfish to breathe.
Scientists told the governors four years ago that computer modeling and studies indicated that a 40 percent reduction in nitrogen and phosphorus would be enough to eliminate these "dead zones."
But the agreement called for a re-evaluation of the 40 percent nutrient reduction goal by the end of this year, so that costly pollution control efforts can be targeted better through the rest of the decade.
The re-evaluation won't be finished until next year, but preliminary computer results suggest it may be impossible to restore life-sustaining oxygen to all the bay's waters, especially the "deep trough" down the center of the Chesapeake.
Part of the problem is that only about three-fourths of the nearly 26 million pounds of phosphorus entering the bay every year is considered "controllable" under the current agreement. And only about half of the bay's annual diet of 340 million pounds of nitrogen is open to reduction, say officials.
As a result, a 40 percent reduction in controllable pollutants will yield only about a 10 percent improvement in the bay's water quality, according to Thomann.
Some officials wonder whether even that is feasible, given the pinch on state budgets due to the recession.
Many of the nutrients are deemed untouchable because they come from natural sources, such as decaying plants, or because they come from man-made sources not covered by the !c agreement.
The largest of these sources is the atmosphere -- mainly smokestack emissions from power plants and vehicle exhaust.
Scientists at the Environmental Defense Fund estimated three years ago that up to 25 percent of the nitrogen entering Chesapeake Bay fell on it in the form of acid rain and microscopic dry "fallout." Subsequent studies by state and federal officials have come up with estimates ranging from 20 to 60 percent.
Congress last year revised the Clean Air Act to attack acid rain and smog with new federal controls on emissions from power plants and motor vehicles.