Alexandria city officials have rejected the main points of a citizens group’s proposal to redevelop the waterfront, saying that it would cost taxpayers about twice as much as the city’s plan, that parts are “legally indefensible” and that the group was trying to halt, rather than manage, change along the city’s Potomac riverfront.

Acting City Manager Bruce Johnson said Monday that the proposal by Citizens for an Alternative Alexandria Waterfront Plan (CAAWP) would not only cost between $80 million and $109 million, but would not pay for itself.

“We don’t think that’s financially feasible,” Johnson said at a news conference after releasing an analysis of CAAWP’s proposal. “In each of their [scenarios], we found something deficient or not as effective as they would say it is.”

CAAWP had said the city could pay for the waterfront renovation with a new 10,000-square-foot museum focused on Alexandria’s arts and history. But drawing 500,000 admission-paying crowds each year “is drastically overstated. . . . It would bring in about one-tenth of what they talked about,” Johnson said. “They talked about borrowing money to finance the museum. We are very close to our debt ceiling. They talk about grants, about $5 million . . . that would be very challenging in this economy. They talk about a real estate transfer tax which under Virginia law we are not allowed to increase.”

CAAWP members, who were not at the news conference, later took issue with the city’s analysis, saying that the CAAWP proposal would add value to the historic city.

“Any member of the city council that votes for the city’s plan as currently designed and ignores citizens as they have been doing deserves to be tossed from office in 2012,” said CAAWP co-founder and former city vice-mayor Andrew Macdonald in an e-mail to The Washington Post.

The six-month-long strife over how Alexandria’s waterfront will change has pitted city planners and staff against the citizens’ group that formed in the late spring because some residents thought the city’s two-year process for collecting public input was flawed and that the city plan — which would allow several new hotels, restaurants and residential development — was too commercial.

The city council has set a public hearing on a waterfront plan for Jan. 21 .

CAAWP’s 200-page alternative proposal, released Oct. 30, agrees with much of the city’s plan, but it wants only one small hotel of 60 rooms, and it wants the city to buy the two warehouses that bracket the waterfront. Those warehouses are owned by Robinson Terminal Warehouse, a subsidiary of The Washington Post Co., which also owns the company that publishes The Post newspaper and Web site.

The assumption that the city could buy the warehouses at the assessed value is unlikely, the city said in its report. The city claimed that CAAWP wants to down-zone the land to prevent hotels or townhouses there.

But whether that would really be down-zoning is unclear. Robinson negotiated an agreement with the federal government and others in 1981 to gave it the right to build hotels and townhouses on its land. In 1992, the entire city was rezoned and those development rights were taken away. Robinson sued to return to the more lucrative zoning. After discussions with the city, it dropped its suit.

City Attorney James Banks said that the city’s waterfront plan would return the 1981 zoning to Robinson’s sites. That would mean Robinson could put up hotels or townhouses on its property, something that CAAWP opposes.

“We’re not asking for down-zoning; we’re asking that the zoning not be changed” from 1992, said Boyd Walker, a CAAWP co-founder. The group is not against change, he added. “We just want different change than the city wants.”

CAAWP also suggested trading property or development rights for open space on the riverfront. But the city does not have large enough parcels in the city that could be swapped for waterfront land, Deputy City Manager Mark Jinks said. And Johnson said that offering to transfer development rights from the waterfront to another location is “difficult to implement under Virginia law, but, more importantly, presents issues” of fairness to other areas that would bear the impact of increased density.

Waiting until economic conditions change, or a landowner is willing to take the city’s price, is not feasible, officials said.

“Change is coming,” Johnson said, “and it’s a matter of how we manage it.”