Alexandria's City Council last night approved the start of negotiations to buy millions of dollars' worth of land along the Potomac River in what is expected to be a large-scale -- and costly -- effort to preserve parts of its historic waterfront for public use.

A committee spent the past year looking for spots to preserve as parkland amid rapidly disappearing open space in the city of 16 square miles. The committee targeted seven parcels of land on Old Town's shore as the top priority for preservation. Acquiring the 2.1 acres could cost $10 million to $15 million "or possibly more," city estimates said. Critics of the plan said it will be far more expensive.

Alexandria Mayor William D. Euille (D) said the decision would start development of a recreation plan for the waterfront that the city hopes will be ready by early 2006.

"It could take weeks, months, even a year," Euille said. "The fact is, we're beginning to do something instead of constantly talking about it. . . . The waterfront deserves to have a continuity to it, for walking, biking, leisure activities. We're unique in that we're one of the few cities in America to have an asset like this river."

There have been previous efforts to spruce up Alexandria's historic seaport, including development of the Torpedo Factory Arts Center, the food court and the area around the city docks.

But the waterfront south of King Street remains occupied by a ragtag bunch of warehouses, parking lots, patches of park and a gun store.

The five owners of the properties along Strand, Prince and King streets have shown varying degrees of interest in selling their land, city officials said. The Robinson Terminal Corp., a subsidiary of The Washington Post Co., owns two waterfront newsprint storage and distribution warehouses that are not targeted as priorities for acquisition.

Officials believe one of the biggest problems is that pedestrians and cyclists don't have a clear path along the river. The Mount Vernon trail diverts to Union Street, which in some places is a block from the river, to bypass the industrial sites. The city now hopes to change all that.

A major opponent of the effort has been the Old Dominion Boat Club, which has operated in Alexandria since 1880 and has had its headquarters at the foot of King Street since 1923.

Members said they fear that the city eventually would use eminent domain to take either their clubhouse or its adjacent parking lot and boat launch without offering a viable waterfront site to which they can relocate. The city is considering the parking lot for purchase among the priority sites.

"The city has indicated they want to do some type of purchase," said Marianne McInerney of Alexandria, a former chairman of the club's board. "But a purchase doesn't seem to be a positive resolution. That's land we've been on and own.

"There is an emotional and historic tie to that space. . . . It's hard for us to have been a good friend and neighbor to the city to suddenly become a target."

Euille said staff members had begun talking to the boat club about the lot in hopes of reaching a "positive agreement."

"I don't expect it to be a smooth-sailing process," Euille said.

"It's something we need to undertake, to work with property owners," he said. "As long as there is positive discussion and collaboration, there will be a win-win for the city and property owners."