Bay Pollution Progress Overstated

Government Program's Computer Model Proved Too Optimistic

At news conferences, on its Web site and in its regular publications, the government agency leading the cleanup of the Chesapeake Bay has documented more than a decade of steady progress.

The Chesapeake Bay Program has reported that the flow of major pollutants from rivers into North America's largest estuary has declined nearly 40 percent since 1985, bolstering the claims of politicians in Virginia, Maryland, Pennsylvania and the District that they were "saving the bay" and helping the states fend off criticism and lawsuits from environmentalists.

Those reports, however, significantly overstated the environmental achievements.

The estimates of pollution reduction were based on a computer model -- not water samples -- that program officials now say was distorted by overly generous assumptions.

Bay Program officials said there was no deception involved. The magnitude of the gap between the computer estimates and actual water quality is a matter of scientific debate.

But U.S. Geological Survey water monitoring data from the mid-1980s through 2003, requested by The Washington Post, indicate that observed concentrations of the two targeted pollutants, nitrogen and phosphorus, showed no decline in most of the major rivers spilling into the bay.

Several scientists affiliated with the Chesapeake Bay Program said the water monitoring reports offer a more reliable measure of pollution reduction than the computer estimates that the program has used.

"Basically, what we're seeing is that the government has had its thumb on the scale for years," said J. Charles Fox, former secretary of the Maryland Department of Natural Resources. "There's no question now that the government was inflating progress in the Chesapeake Bay."

He attributed the overstatements to "an institutional bias to show progress."

While conceding that the computer model had overestimated progress in reducing pollution, Chesapeake Bay Program officials defended its use to report to the public about the bay cleanup. They have revised the model's assumptions to reflect new scientific findings.

"There was no intention to mislead," said Richard Batiuk, the associate director for science at the Environmental Protection Agency's Chesapeake Bay Program office. "Our models continue to be refined over time."

The Chesapeake Bay Program, an alliance of the federal government and Maryland, Virginia, Pennsylvania and the District, has been under pressure to show progress since 1987, when members signed a landmark agreement to reduce the flow of phosphorus and nitrogen into the bay.

Since then, as the Chesapeake Bay Program reported steady reductions in pollution, the bay suffered precipitous drops in its prized blue crab and oyster harvests, and at times its desolate "dead zone" grew.

The disclosure by the Bay Program this spring that the model had overstated the cleanup underscores the folly of relying on it to measure progress, environmentalists said.