The Patriots Point Development Authority was told Tuesday that its waterfront land could hold a value of $180 million -- but only if it chooses to rethink entirely how it uses the site.

John Alschuler, who led the early transformation of Daniel Island, spoke from New York by video conference at the agency's monthly meeting, after board members asked for specific numbers as they move forward with a master plan for the property.

Alschuler advised them that a small fraction of the 367 acres they control along Mount Pleasant's waterfront could be worth $50 million in five years, if developed properly.

But that welcome news came with a caveat: "You need to establish a new identity," he said.

He estimated that 48 acres between the golf course and Charleston Harbor could comprise the first phase of development in a master plan that would transform the financially strained military tourist attraction at Patriots Point into a diverse mixed-use development.

He said that, over the next 15 to 20 years, the entire site could be worth $150 million to $180 million and generate a 10 percent annual return for the authority.

"That's a goal which I believe you should aspire to," he said. The board won't achieve it, he warned, unless it executes the development intelligently but also boldly.

"You need to change the image and character of the site," Alschuler said. He added that "the easiest and least encumbered path is the one that gets you the least value."

The master plan that's under way at the attraction would create a harbor-front trail and parks stretching along three miles. The concept calls for at least 2,000 homes, a hotel with a higher price point than other Mount Pleasant lodging options and a "town center" retail format.

Alschuler said the revenue stream should be $3 million or $4 million annually from that first phase and $15 million to $18 million after the build-out.

Mount Pleasant Mayor Billy Swails, who is on the Patriots Point board, said getting city approval on those homes could prove challenging because of traffic implications, despite planners' intentions to keep cars at a minimum.

Bill Kercher of AECOM, the design firm hired to create the master plan, said the project takes into account those concerns. He described the proposal as "recognizing the economic power of the land" and pointed out that some experts describe the property as the best available site on the East Coast.

"You have to change the idea of y'all being custodians of a historical and cultural resource to being interested in development," Kercher said.

Reach Allyson Bird at 937-5594.