The Manhattan area has the most urban estuary on the planet. So imagine it with oyster reefs, shoreline wetlands in Harlem, public waterfront for small boats, bird-nesting islands and thriving populations of striped bass and flounder.

After all, the New York Harbor is now clean enough.

"The New York Harbor is no longer inhospitable to aquatic life as it was 10 or 15 years ago," says Mark Bain, director of Cornell's Center for the Environment. "And now Congress has charged the U.S. Army Corps of Engineers to make the waterways of New York and New Jersey an even better environment, but they need a plan."

To give them one, Bain and his colleagues at Cornell and the Hudson River Foundation have been awarded a one-year, $300,000 grant from the Port Authority of New York and New Jersey and the U.S. Army Corps of Engineers to detail just how to go about improving the bottom topography, shorelines and adjacent wetlands of the Hudson-Raritan Estuary. The estuary is the system of bays and tidal rivers that surrounds New York City and embraces northern New Jersey's shoreline and where the Hudson, Hackensack, Passaic and Raritan rivers meet the ocean.

"Designing a future harbor and estuary ecosystem is very challenging because scientists aren't used to designing environments of the future -- we haven't studied them in detail," said Bain. "But someone's got to do it."

Bain and his colleagues have coined a new term to describe features desired in the future: target ecosystem characteristics (TECs). TECs give public agencies and other stakeholders detailed specifications on what is needed to make a better and more sustainable environment.

For example, to create oyster reefs, Bain and his colleagues will provide such details as how many reefs are needed to sustain a population, how big they should be, where they should be placed and how deep the water should be.

Last October they sponsored an interdisciplinary science workshop with national experts and representatives from federal, regional and city agencies to develop a priority list of about two dozen ecosystem targets, including restoring key bird and fish habitats, wetlands and public shoreline areas.

"Now our small group of scientists is undertaking much more intensive and rigorous work to evaluate, refine and justify a final set of ecosystem targets to guide the formulation of a comprehensive restoration plan," Bain said.

If all goes according to plan, New Yorkers will be able to go to a public waterfront to launch small boats, bird watch in the Harlem freshwater wetlands (where dumped shopping carts and refrigerators now abound) and salt marshes or near the harbor's mini-islands created especially for birds, or fish for winter flounder, striped bass and other food fish in the not-so-distant future.