After the 2004 oil spill from the tanker, Athos 1, at Paulsboro, officials had to figure out the dollar value of the harm done to more than 100 miles of shoreline, of the lost recreational opportunities, of the harm to fish and birds and other organisms.

They probably could have used a report like the one announced yesterday.

The report, by the University of Delaware, places the economic value of the Delaware River and Bay downstream from Trenton at $10 billion. In addition, more than half a million jobs are associated with waters in the region, the report found.

The new study, "Economic Value of the Delaware Estuary Watershed," is the first of its kind in more than two decades, according to the Partnership for the Delaware Estuary.  "It follows similar reports which catalog the value of other coastal regions, like the Chesapeake Bay, Florida Everglades, and Great Lakes. Those who will use it include economists, environmentalists, legislators, researchers and key decision makers," a Partnership press release said.

"You cannot put a price tag on the value of the Delaware River and Bay to peoples' lives — it's much more than an economic resource. However, we live in a time when major decisions about activities like drilling, dredging and development are made based in part on economics," said Jennifer Adkins, executive director of the Partnership, in the press release.  "This study will help people to consider the economic contributions of our estuary in those types of decisions."

Gerald J. Kauffman, director of the University of Delaware's Water Resources Agency, is the lead author of the study. In addition to using traditional economics, he and his colleagues used a modern technique called "natural capital valuation," the Partnership said. This allowed them to estimate the value of natural goods and services provided by local land and water at over $12 million annually.

The report was announced at a press conference yesterday at the Bridesburg Outboard Club, a private boat launch on the Delaware River.  The organizers said they chose the club because it is next to the former Philadelphia Coke Works, a site many would like to see restored as a park along the East Coast Greenway, a 2,500-mile network of trails and sites.

Patrick Starr, senior vice president of the Pennsylvania Environmental Council, said that restoring the riverfront in Bridesburg should be a top priority.

"Philadelphia is the most populous community in the estuary, yet its residents are sorely deprived of access and enjoyment of the estuary's rich natural resources," said Starr. "Our proposed ecological restoration is intended to provide recreational use as public open space in tandem with new wildlife habitat and environmental quality."