VANCOUVER -- Preliminary cost estimates for Site C, a proposed hydroelectric dam on British Columbia's Peace River, show the project could cost between $5-billion and $6.6-billion, doubling previous estimates by the province.

The updated estimates, released yesterday by province-owned B.C. Hydro as part of an updated study of the project, are tentative, as a decision on whether it will be built is still several years away, the report said.

The final costs would be known "only after a competitive procurement process is complete and a final bid is accepted."

A 2005 estimate pegged the cost of the project at $3.2-billion.

But that figure was widely regarded as unrealistic given the size of the project and skyrocketing construction costs in the province.

"Now that we're starting to get into a more realistic [price] range, maybe now the real debate over this project can begin," said Vancouver energy lawyer David Austin.

Site C is a potential third dam and generating station on the Peace River, which is already the site of two large dams that together account for nearly 30 per cent of B.C. Hydro's production.

The project, identified along with other potential dam sites in the 1960s, has been studied several times over the past few decades.

But B.C.'s energy plan, announced last February, puts Site C back on the front burner.

Under that plan, new electricity generation projects must have zero net greenhouse-gas emissions, and clean or renewable electricity must continue to account for more than 90 per cent of total generation in the province.

Site C would flood forests and farms and require moving a highway.

Plans call for a 900-megawatt project that would supply about 8 per cent of the province's current electricity demands.

Yesterday's report completed the first stage of what B.C. Hydro says will be a five-stage evaluation for the project.