The bounty of the Bay is on full display at this time of year. Sailors and seafood lovers, birders and botanists, commercial and recreational fishermen, and those of us who are simply thrilled at the sight of the sun setting behind a still marsh are all reveling in the wonder of summertime in Chesapeake country. It is a feast for the senses.

This is what the Chesapeake Bay Program is all about—restoring and revitalizing the living resources of the Bay. We do our work because this watershed is one of the world’s ecological wonders, home to literally thousands of species.

It is the cultural center of early U.S. history, from Jamestown to Gettysburg.

And, it is the economic engine that drives a vital regional economy.

But most importantly, we work on the restoration because of the exciting pull of a fighting rockfish on the line and the succulent taste of a steaming, softshell crab.

We do it for the thrilling sight of a bald eagle soaring and the fecund smell of moist soil on a forest floor.

And we strive to restore the Bay so that we can stand along the edge of a marsh and listen to the whisper of reeds rattling in a summer breeze.

The natural beauty and pulsing life of the Bay are extraordinary. It is no exaggeration to say that it is a national treasure and an ecological resource of international significance.

But the bounty of the summer can sometimes mask the problems that imperil the Bay.

We spend much of our time here at the Bay Program analyzing the problems facing the Chesapeake and trying to devise effective strategies for dealing with their root causes.

We measure dissolved oxygen levels and nutrient and sediment flow concentrations. We have stream gauges to monitor river flow and air sampling stations to measure nitrate and ammonium deposition.

But our most important measures are of the living resources themselves.

By definition, ecosystems are complex. For resources to survive and thrive, they need a complicated web of physical and biological parameters to be in balance.

When we look at the living resources of the Bay, we see a complicated story about the overall health of the resource and the progress of the restoration effort.

American bald eagles are at their highest levels in decades. Between 1977 and 2003, the number of nesting pairs in the watershed had grown by more than tenfold, to 760.

Waterfowl tell a more equivocal story. We look at 20 important species and find that trends for half of them, including northern pintails and ruddy ducks, are improving while the others, like canvasbacks and tundra swans, are lagging.

The story in the waters of the Bay is more complicated. American shad are making a steady comeback. With focused stocking efforts, the methodical removal of fish blockages on the Bay’s tributaries and a protective harvest moratorium, that trend should continue as these anadromous fish are increasingly able reach their historic spawning grounds.

Rockfish, too, have been a well-documented success story. After the moratorium on commercial harvesting and the institution of conservation harvest limits, these important fish are bouncing back from the low numbers recorded 15 years ago.

But the news about rockfish is not all good. There is growing concern about Mycobacteriosis, a wasting disease that is afflicting increasing numbers of rockfish. Scientists don’t yet know what, if anything, we can do.

In addition, some fisheries experts and watermen are becoming concerned about another important fish. Menhaden play a key role in the complicated ecology of the Bay. They are filter-feeders (influencing water quality), a critical food source for rockfish (influencing the food web), and are an important commercial species in their own right (influencing the local economy).

The lack of an ecosystem-based management plan has some of us worrying about the long-term health of the species.

When we get to the Bay’s bottom, the story, while mixed, is decidedly sobering.

The blue crab, one of the Bay’s signature species, is showing very modest gains from record low numbers in the late 1990s. Even so, harvests are dramatically lower than they were a couple of decades ago.

Oysters, on the other hand, have quite simply crashed. Commercial harvests are less than 1 percent of historic levels.

So what does this mean? Do we look at bald eagles and conclude that the restoration is a success, or do we look at oysters and say it has been a failure? While both indicators are accurate, neither is an especially good indicator of Bay health.

I would argue that bald eagles are a poor overall indicator of Bay health because their decline was the result of a relatively narrow cause—toxic pesticides. The ban on DDT has been the single most important factor in the resurgence of this national symbol.

Oysters, too, are a poor indicator species. They suffer from devastating diseases that are rampant, localized poor water quality, lack of appropriate habitat, and, sadly, continuing harvest pressure. There are so many and varied problems that it’s almost impossible to use them to tell a simple story.

The Bay is a complex ecosystem, so there is no one species that can tell its whole story.

Perhaps the best simple indicator of the overall health of the Chesapeake is the abundance of Bay grasses. They are not subject to harvest pressure, and we can see a powerful correlation between their prevalence and water quality.

Cutting back on nutrient and sediment loads throughout the 1980s and ‘90s resulted in a modest recovery of these important species.

And, when the drought years of 2001-2002 effectively shut off the tap of polluted stormwater runoff throughout the watershed, grasses made dramatic improvements. By 2002, they had increased 250 percent over 1985 levels and were showing healthy improvements annually.

But the record wet weather of 2003 turned on non-point source pollution like a fire hose, washing massive amounts of nutrients and sediments into the Bay and its tributaries. The result was a dramatic decline in Bay grasses giving us a disheartening drop of 30 percent in a single year.

When we look out upon the Bay this summer, we should take time to revel in the wonder of this special place. In the poet Wendell Berry’s words, we need to go “where the wood drake rests in his beauty on the water, and the great heron feeds…and come into the peace of wild things.”

This is what summers are for—to fill us with natural wonder and to let us soak in the magnificent restorative powers of the Bay. Because the Bay grasses are telling us that when summer ends, we’ll still have a lot of work to do.