The revised trail also will stray farther from the banks of the river than when it was initially planned in 1998.
It will lead people into historic downtowns, through parks and tunnels, and through woods and the margins of rolling farmland.
Yesterday, officials were preparing to post warning signs on the waterway, while mothers kept a careful eye on their children and everyone else sank their teeth into a good mystery.
"It's like the Loch Ness monster," said Maria Maurer, who was visiting Masons Mill Park in Upper Moreland Township with her husband, Herman, and their 3-year-old grandson, Casey. Usually there's hundreds of them," Herman Maurer said, gazing at a creekside pond where a single goose paddled, bravely, across the dark water.
In the process, 10 more miles are being added to the map.
"You want to be more cautious," said Buddy Mullen, the Warminster Township public works director.
"It's like that movie Jaws, when they tell you it's safe to go in the water and then you see that fin." Two alligators have been captured at the creek in the last week.
"When we first started talking about the trail, we didn't anticipate meandering from the Delaware River," said Mary Pat Robbie, director of Burlington County's Resource Conservation Department, which is creating part of the trail on the New Jersey side.
Behind the project are the Delaware Valley Regional Planning Commission, local governments, and nonprofits such as the Delaware River Greenway Partnership.