Saving the Chesapeake Bay is turning out to be a lot more complicated than we thought.
In the mid-1980s, it seemed as simple as a second-grade subtraction problem: Just take out the main pollutants -- nitrogen and phosphorus -- and we'd be left with clear water and bountiful seafood harvests.
Now, as the bay's guardians begin refining their long-term plan to restore the bay, they're looking at the first dozen years' worth of results and realizing they don't add up. And new worries are cropping up: toxic Pfiesteria piscicida, rising sea levels, oyster diseases.
Bay restoration is beginning to look less like simple arithmetic and more like a complex equation whose solution is part genius and part luck.
This year, the bay's top scientists and administrators are taking a hard look at bay protection efforts. The Chesapeake Bay Agreement -- the 1987 compact in which Maryland, Virginia, Pennsylvania and the District of Columbia pledged to clean up the Chesapeake -- has a set of goals that expires next year.
Maryland Gov. Parris N. Glendening is leading negotiations to update the agreement, and experts are trying to figure out where the restoration effort stands and what the new goals should be.
"The question is: How much has actually been achieved? Not a lot," says Donald Boesch, president of the University of Maryland's Center for Environmental Science and a longtime bay ecologist. Scientists using computer simulations of the bay can point to some theoretical gains, "but they're dealing with a virtual bay."
In the real world, Boesch says, "even if our management practices have been successful, we don't see much of an impact yet."
Pollution is down, but not as much as had been hoped. The bay's health doesn't seem to be rebounding as fast as expected.
There are successes, but they're mixed: Rockfish are abundant, but they may not have enough food. Bay grasses are spreading, but they're disappearing in prime blue crab havens where they're needed most.
Meantime, new problems are emerging:
Toxic pfiesteria, which seems to feed on polluted runoff in Eastern Shore rivers.
Forests disappearing at the rate of 100 acres a day.
Mysterious declines in such small fish as menhaden and bay anchovies that feed bigger creatures.
Doubts about what might happen to the bay if Earth's climate really is heating up, as most local ecologists now believe it is.
"This is a daunting prospect," says Bill Matuszeski, director of the federal Environmental Protection Agency's Chesapeake Bay Program. "The bay is going to require human beings to play Mother Nature for a while, until it gets back into balance.
"And we're not too good at playing Mother Nature. The bottom line is, we don't know a lot."
Many of the bay agreement's current goals have not been fully met, including the central pledge to reduce nitrogen and phosphorus flowing into the bay by 40 percent by 2000.
Both substances are essential for life. But the bay is getting an overdose from sewage, animal wastes, fertilizers, air pollution and other sources.
Once nitrogen and phosphorus levels went down, experts reasoned, life-choking algae blooms should fade and bay waters should become healthier.
It hasn't worked that way yet. Chesapeake Bay Program computer models show that the goal of cutting phosphorus will be met by 2000, mostly because of a ban on phosphate whiteners in detergents, but the nitrogen cuts have not kept pace.
The bay program's water samples show no downward trend so far in nutrient levels in the open bay, no significant improvement in water clarity and no shrinking of the oxygen-depred dead zones along parts of the bay bottom.
That means in summer, a crucial swath of the bay can't support the array of creatures nature intended.
"It's very hard to see any improvement" in underwater oxygen levels, says senior Chesapeake Bay Program scientist Kent Mountford, "and that initially was one of the main things we were going to manage the bay for."
Why is change so slow to come? Like most questions surrounding the bay, this probably doesn't have a single answer. More likely a half-dozen different problems compound one another.
For example, over the decades nutrients have built up in ground water. The nitrogen and phosphorus now reaching the bay may be old pollution slowly seeping into rivers and streams. It may take as few as five years, or as many as 40, to get rid of it.
The rainy winters and springs of 1994 and 1997 have complicated matters, washing more sediment and nutrients into the bay than you'd expect in a normal year.
And as Earth's climate appears to be changing, predictions call for more storms, and that means "more runoff, more nutrients, more sediment," says Boesch. "The hill's going to get steeper and we're going to have to run harder to get to the top."
Add in population growth, which is literally making the bay dirtier.