If a group of scientists is right, the Chesapeake of the future could have a tinge of nostalgia about it.

A team of leading Bay researchers says the estuary could look much like it did in the 1950s — with clearer water, vast underwater grass beds, and healthier, more plentiful populations of fish and shellfish — if feasible pollution control, land management and habitat restoration efforts are pursued.

The scientists say that emerging technologies — and those expected within the foreseeable future — will make it possible to slash by half the amount of nutrients entering the Bay by 2030.

That’s roughly the same amount of nutrient reductions that recent Bay Program computer models have suggested is needed to meet proposed new Chesapeake Bay water quality standards.

The new report, “Chesapeake Futures,” confirms that such steep levels of nutrient reductions are feasible, although its 2030 time frame is raises questions as to whether they can be accomplished by the Bay Program’s 2010 deadline.

A large chunk of the nutrient reductions envisioned by the scientists, for instance, stems from big cutbacks in air pollution which would not occur until well after 2010 as new technologies become more widespread and tougher air standards take effect.

The report, more than three years in development, was produced by the Bay Program’s Scientific and Technical Advisory Committee. The scientists and other experts participating in the project said their goal was to provide “constructive advice” to policymakers, resource managers and citizens about how decisions made today could affect the Bay of the future.

“The primary question, when considering the Bay’s future, centers on whether or not those who live in the watershed will be able to reverse recent trends — of the past 50 years in particular — or whether growing population, unchecked resource consumption and a casual disregard for the natural environment will overwhelm our attempts to restore the Bay and its fisheries and wildlife,” the report said.

The Bay, after all, is ultimately the downstream recipient of everything that happens on the land. Or, as one scientist stated in the report: “The estuary bats last.”

The scientists acknowledged that trying to forecast 30 years into the future is “risky business” — just three decades ago few could have predicted the impact computers would have on people’s lives today.

Nonetheless, some things are predictable. Sea level rise will continue, and possibly accelerate because of climate change, leading to a loss of tidal wetlands and increased shoreline erosion. Sediment buildup behind Susquehanna River dams will continue until they fill, allowing sediment to pour into the Bay. The basin’s population will grow by about 334 people a day, expanding from 15 million today to 19 million in 2030, consuming more land and producing more nutrients.

Looking to the past, the scientists said the amount of nutrients entering the Bay has roughly doubled in the past five decades, causing massive diebacks of its once-extensive underwater grass beds. Also, phytoplankton production has dramatically expanded, but much of the algae produced now is not the type that fuels the food chain leading to fish and crabs; instead it feeds bacteria that use up the Bay’s oxygen supply.

Large areas of the Bay’s bottom are now anoxic — having no oxygen — every year. As recently as the 1950s, anoxic conditions were rare. Even larger areas are covered by hypoxic waters, which have oxygen, but too little to support most species.

The scientists made their best estimates of how that situation might change, in the face of predictable trends, under three different management scenarios:

o Recent Trends, which extrapolates recent population, land use and nutrient trends into the future.

o Current Objrctives, which outlines what would happen over the next three decades under commitments that have been agreed to by the Bay states. (This does not include nutrient reductions needed to meet proposed new Chesapeake Bay water quality criteria, as those have yet to be agreed upon.)

o Feasible Alternatives, which estimates what would happen if alternative — but feasible — land management and nutrient control technologies were put into place during coming decades.

Under recent trends, scientists said that population growth and development would outstrip existing nutrient reduction efforts, and the Bay would return to its highly degraded conditions of the 1980s by 2030. More than 2 million more acres of forests and agricultural land would be lost as development continues to sprawl across the landscape.

Under “current objectives,” nutrient reductions would drop somewhat from current levels. That would allow underwater grass beds to nearly double their recent acreage, and bottom habitats to expand as dissolved oxygen levels increase in the Bay.

But the report predicted that shoreline erosion would increase, and tidal wetlands would continue to be lost, putting more sun-blocking sediment into the water. The scientists predicted that improvements to the overall health of the Bay would be “modest.” And, abut 800,000 acres of forests and farms would be lost to development.

With “feasible alternatives,” the scientists said it would be possible to turn back the clock and restore the Bay to conditions much like those the 1950s.

Such an effort, the scientists say, could result in underwater grasses covering almost five times as much of the Bay as they do today, helping to clear the water and providing extensive new habitats for blue crabs, juvenile fish and waterfowl.

The size of the low-oxygen dead zone would be dramatically reduced, expanding habitat for bottom-dwelling organisms and the species that feed on them, such as spot, croaker and blue crabs. Anoxic conditions would be rare, and areas of hypoxia sharply reduced.

“The result would not be the Bay at which Captain John Smith marveled, but more akin to the one that Bernie Fowler knew as a young man,” the report said. “The ecosystem would be substantially more diverse and resilient. It would produce less phytoplankton and bacteria but more fish and crabs that depend on bottom habitats.”

Fowler is the former Maryland state senator who leads an annual Patuxent River “wade in.” His goal is for the water to be clear enough that he can stand chest-deep and clearly see his feet, as he could when he was a young man in the 1950s.

But there are two caveats to this “rosy scenario,” the scientists cautioned. The accidental introduction of invasive species could change the Bay in ways no one can predict. Also, human impacts on the top consumers in the Bay food web may also have effects that ripple through the ecosystem. That means careful fishery management must be a part of the recovered Bay — not just reduced nutrients and better management of activities on the land.

The scientists’ conclusions are strikingly similar to those reached independently by the Bay Program.
Both the feasible alternatives scenario and Bay Program estimates for achieving proposed water quality standards would slash the amount of nitrogen entering the Bay to about 160 million pounds a year — or nearly half of what presently washes into the Chesapeake.

Recent projections from the Bay Program also suggest that that level of nutrient reduction would limit anoxic conditions to only a small portion of the deepest areas during typical years. Also, Bay Program officials believe grass coverage could reach around 200,000 acres, or about three times the roughly 70,000 acres that has been present for most of the past decade.

But nutrient reductions will not solve all of the Bay’s ills. Because of disease problems, the scientists doubt that the Bay’s oyster population can recover much beyond 10 percent of its historic levels, although that would still be a tenfold increase over today’s population.

Sea level rise is expected to continue to erode shorelines and wash away valuable tidal marshes at a faster pace than they can be replaced. But with active management envisioned by the “feasible alternatives” scenario — including the placement of thin layers of dredged sediment on tidal wetlands, building offshore oyster reefs to reduce wave action, the construction of new wetlands and the elimination of nutria — the pace of tidal wetland loss could be slowed, though not stopped over the next 30 years.

Also, the scenario calls for actions to remove built-up sediments behind the Susquehanna dams, to keep them from eventually overflowing into the Bay and clouding the water.

Of the three scenarios, the report stated, “only the feasible alternatives scenario appears to offer considerable promise for reversing the negative trends of the post World War II period.”

Achieving it would require aggressive land management controls that focus development around designated growth areas while preserving farms — and especially forests, which leak fewer nutrients than other land uses. Fewer than 400,000 acres of land would be developed, and those areas would have state-of-the art runoff controls that minimize pollution.

The scenario calls for implementing biological nutrient removal technologies at all major wastewater treatment plants in the watershed. Further, it anticipates the widespread use of progressive agricultural practices, such as precision subsurface nutrient application, cover crops and effective buffers, to sharply reduce nutrient runoff.

It also anticipates taking advantage of new technologies, from fuel cells to solar energy, to reduce the use of fossil fuels and the pollution that results. Mass transit would be improved to reduce highway congestion and related pollution.

It predicts that nutrient runoff by farms could be reduced by a third, while air pollution is slashed by 70 percent.

“In conclusion,” the report said, “using a range of innovative and creative techniques is necessary if we are to reach the fundamental goal of restoring the Chesapeake Bay’s clarity and productivity. Anything less will result in incremental improvements that will likely be overwhelmed in the long term by the deleterious effects of unplanned or poorly planned development. The projected outcomes are fairly clear. The choices, while challenging, are ours to make.”