Supertankers typically draw 50 to 60 feet of water when they leave oil fields in the North Sea, Persian Gulf, West Africa and South America. Under those conditions, they are unable to enter the Delaware's 40-foot channel.

But an anchorage formed by glaciers at the entrance to Delaware Bay is up to 100 feet deep. There, supertankers pump some of their load into barges, a process called lightering. Then they continue upstream to refineries, including the Coastal Eagle Point facility in West Deptford; Valero on the Paulsboro-Greenwich border; Motiva at Delaware City in Delaware; Tosco Corp. and Sunoco, both in Marcus Hook, Pa.; and Sunoco's largest facility in Philadelphia.

Because of its depth and proximity to the sea, Big Stone Beach Anchorage, located between Cape May and the Delaware beaches, has been described as an ideal spot in which to build a modern, state-of-the-art oil island for all the companies. But cost and other environmental considerations have prevented it from becoming more than a bright idea.

While waves of heavy industry have left the region in the last three decades, oil has endured, primarily because the Delaware Valley is a major population center with one-day access to 18 million people and because oil has no place to go.

The last refinery built in the United States was in Belle Chase, La., 26 years ago. The newest one on the Delaware is the former Getty facility, now Motiva, in Delaware City.

Unless someone invents a superior energy source, oil refining is a growth industry because of population increases.

"Getting permits to build a refinery today would be next to impossible," says James Benton, of the New Jersey Petroleum Council. "The petroleum industry is committed to the Delaware Valley and it's a given that refining will take place here indefinitely. We are not an industry that can pick up and move easily.

"On the other hand, if the river is not dredged and therefore becomes a less competitive place to do business, then the industry could wind up importing more processed oil, which would raise prices."

East Coast oil refineries are able to meet about 33 percent of the demand in the region. Another 57 percent comes from the Gulf Coast either via pipeline or tanker. Only 10 percent of processed oil comes from foreign sources.

-- EILEEN STILWELL