The more we try to learn about how the Chesapeake Bay and its rivers work as a system, the more we are awed by the complexity. Admittedly, we are working with one of the most productive and fragile watersheds on Earth -- because of the overall shallowness of the Bay, the extensive land area being drained by the streams and rivers that feed the Bay, and the presence of about 13 million people on that land. Nobody said it would be easy to restore the Chesapeake under these circumstances, and some said it simply couldn't be done.

The latest measures of progress we see here on the Bay confirm the complexity we are dealing with; but they also show that within this immense and unwieldy system, results can be achieved if we are willing to make the commitments.

Take the situation with oxygen levels, which are critical to the vitality of fish, shellfish, grasses and the other living resources of the Bay and its rivers. Spring is a critical season for the Bay, because that is when it receives much of its loadings of nutrients from the rivers, and it is the oversupply of these which lies at the heart of the Bay's oxygen problem. These nutrients overenrich the waters and cause algal blooms which deplete the water of oxygen. While this is to some extent a natural phenomenon, it has been exacerbated by the clearing of forests and the extensive agriculture and development in the watershed.

During the springs of 1993 and 1994, the flow of nutrients was especially high because of extensive snow packs and heavy spring rains. As a result, scientists predicted that the oxygen levels would show higher than normal depletion, which they did. Even though great progress has been made with management practices to reduce nutrient loadings to the rivers and the Bay, when these large-scale natural events occur, they can still overwhelm progress to date.

Well then, what about this year? After all, it was a mild winter with little snow pack in the upper parts of the watershed followed by a dry spring. So shouldn't we expect much improved oxygen levels in the Bay? Well, it turns out it isn't that simple. The middle section of the Bay from the Bay Bridge to the confluence of the Potomac does indeed show higher oxygen levels, but the conditions are actually worse than normal in the upper Bay.

This is attributed to the low flow from the Susquehanna, which failed to move the algal blooms down the Bay and instead allowed their concentration in the north where they depleted the oxygen. So the Bay fooled us once again with its complex responses to natural events.

We are now anxious to see if the same pattern emerges with respect to Bay grasses. The submerged grasses are a good measure of the health of the Chesapeake, because they depend on reduced nutrients and higher water quality to thrive. Grasses reached a low of 34,000 acres on the Bay in 1984, and had doubled by 1993 in response to improved conditions. It was predicted that they would go into decline in response to the spring conditions in 1993 and 1994. But it didnt happen that way. The acreage actually increased by several thousand acres in 1993; then, in some sort of delayed reaction, they dropped 7,000 acres in 1994. The mystery now is what will happen this summer. In the face of low flows and reduced loadings from the rivers, will the grasssbeds recover? Will they again show us a delayed reaction? Or will they duplicate the oxygen results, with different responses in different parts of the Bay? Early readings have been inconclusive.

Now, from all of this it might seem that we not only have a lot to learn about the Bay, but that it's hard to tell if anything we are doing is making much of a difference. While the first is surely true, it is dangerous to conclude the second by focusing on these broad-based phenomenon. Instead, to measure the impacts of the restoration effort, it is necessary to reduce the complexity and isolate the variables. And when we do this, the news is encouraging.

For example, in fisheries management in the Bay, we have seen a remarkable recovery of species when we have been willing to take strong action. The restoration of the striped bass, or rockfish, is attributed to the placement of a moratorium on their harvest until there was assurance that a healthy year-class had survived to breed. And the 1995 reports on the American shad show an almost tripling of the numbers in the Bay to 350,000 from previous years; this has been accomplished as well through moratoria on catch in the Bay, although both Maryland and Virginia continue to allow an ocean intercept fishery, which if terminated would speed the return of the shad to the rivers of the Bay even more.

The other proof that effort can make a difference comes from down in Calvert County, Md., where Bernie Fowler added a full 12 inches this year to the depth he could walk into the Patuxent and still see his white sneakers. Bernie Fowler Day has become an annual June event, when the ex-state senator wades out to see the progress of the last 12 months in returning the clarity of the Patuxent to the 5 feet or so that it was when he was a boy. It so happens that this year marks the first time that all the sewage treatment plants on the Patuxent had operating nitrogen removal processes -- the first river in the Bay system to achieve this -- so the results of investing in better water quality were there for all to see -- to the depth of 40 inches for Bernie.

The point of all this is that we are working with a massive complex of forces that are very much subject to the whims of Mother Nature, so it sometimes seems that we are only playing around the edges as we try to make the Chesapeake a healthier ecosystem. So it is important that we isolate the parts of the system we are working with to understand our impact. When we do this, and when we are willing to make the tough decisions and come up with the needed investments, we can make a difference, and the results can be seen.