The Chesapeake Bay faces an uncertain future. Despite considerable effort and millions of public and private dollars, the Bay has seen only incremental improvement during the past decade, and considerable concern remains about emerging trends in water quality.

Fish advisories that set safe consumption levels have called public attention to the almost ubiquitous presence of chemical compounds in our waters, but in terms of the ecosystem as a whole, nutrients and sediments remain the primary threat to the Chesapeake.

Nitrogen, phosphorus and sedimentation all pose systemic problems, affecting not only contaminated backwaters but broad reaches of the Bay itself. The primary drivers behind this are material consumption, population growth and the manner in which we are developing the land.

Projections demonstrate that while inputs of nutrients and sediments from farm fields and forest lands are expected to drop during the next 30 years, inputs from developed land will grow at a rapid rate. Annual loadings of nitrogen from all sources, for example, will increase another 30 million pounds, bringing total inputs to the Bay to about 330 million pounds a year if recent trends continue.

The key word is “if.” Already the Bay jurisdictions have taken ambitious steps toward reducing that flow of nutrients, and if current commitments hold, nitrogen levels could, by the year 2030, drop just below the 40 percent reduction goal set in 1987.

If a range of creative and aggressive measures were taken to limit the impacts of development — especially by curbing harmful sprawl — nitrogen levels could drop as much as 140 million to 150 million pounds per year, with annual loadings closer to 180 million pounds than the roughly 300 million seen in the year 2000 or the 330 million we should expect if recent trends continue.

The point here is that the Chesapeake’s future is not inevitably bleak. There are tools — including progressive policies and creative technologies — that can alter the pattern witnessed the last three decades, shaping a different pattern for the next three decades.

The scenarios painted by the Chesapeake Futures report represent likely outcomes, given three possible ways of moving through the first part of the 21st century.

Researchers and technical experts participating in this project drew upon their own experience and data, much of it contributing to the wealth of knowledge now employed in managing the Bay. The report is a vehicle for the scientific community to synthesize its thinking in a broad and comprehensive way.

The first scenario, which predicts the likely outcome if trends observed in the recent past were to continue, makes clear that increased population and poor land use planning could well result in the loss of almost two-thirds of the nitrogen load reductions achieved between 1985 and 2000. Similarly, phosphorus loads would grow by about 6 percent or more over current levels.

The 2 million acres of farm and forest land projected to be lost in this scenario would virtually all fall to development.

Some might argue that this represents another example of the “tragedy of the commons,” as individuals may benefit greatly from selling farm and forest lands to developers, but in the aggregate, the quality of life in the region, and certainly the water quality of the Chesapeake Bay, will almost certainly deteriorate.

Projections derived from the second scenario, which attempts to account for the gains we should make if we hold to our current commitments, demonstrate the direct benefits of improved planning and more rigorous environmental engineering.

With nitrogen dropping almost 45 million pounds, according to this scenario, the Bay would see considerable improvement. Algal blooms would, on average, likely decline, and severe hypoxia could decrease to levels not seen in 30 years.

This is the future that is very much in our grasp, if we can stay the course, despite budgetary challenges and a barrage of demands on policy makers.

According to projections resulting from this effort, though, even current commitments will not bring us to the levels of the 1950s — to a time when underwater grasses extensively carpeted the Bay, and fish and shellfish were plentiful.

Reaching those levels, these scenarios suggest, will require a more aggressive treatment of wastewater; substantial reduction in smokestack and tailpipe emissions; more widespread implementation of best management practices on farm and forest lands; better handling of stormwater on ever-increasing areas of developed lands; and a more pro-active manipulation of the Bay environment itself, through constructed oyster reefs, reclaimed wetlands, replanted seagrass beds and state-of-the art shoreline protection that goes beyond simple bulkheading and rip-rap.

To sustain the bounty of the past will also require creative fisheries management, so that we do not, in the words of W. K. Brooks at the turn of the last century, “squander our birthright.”

A future where the Bay’s clarity returns at last, and where its legendary productivity is no longer hampered by an overenrichment of nutrients and sediments, is not a pipe dream.

The numbers in the Futures analysis speak volumes about what is possible, if we are able to use the tools at our disposal and to make the hard choices for a better way.