Jul. 27--NORTH COUNTY -- The company that has dreamed of building a plant at Carlsbad's Encina power plant to turn seawater into drinking water said Wednesday that news that parts of Encina could be torn down won't affect or change their plans.

But regional water suppliers were less sure.

Officials from the San Diego County Water Authority, whose board members are scheduled to meet today to consider certifying a massive environmental study on the proposed desalination plant, said they "honestly don't know what this means."

NRG Energy Inc., the company that owns the Encina plant surprised many over the weekend by saying they plan within three years to build a power plant on the eastern portion of the 95-acre Encina site. Steve Hoffman, the company's western region president, said the company would eventually demolish, and possibly sell off, portions of the Encina plant site.

Connecticut-based Poseidon Resources Inc. is the company that has been studying the idea of building a plant that would turn 50 million gallons of seawater a day into drinking water at Carlsbad's Encina Power station since 2000.

Poseidon and the Water Authority each said that Encina was the "perfect site" for the seawater desalination project because it could supply power and because it already had regulatory permission to suck water from the sea that could be turned into drinking water.

Poseidon Vice President Peter MacLaggan said Tuesday that the company has "always" known that the Encina plant could be shut down.

He said that the company's proposed desalination plant could find its electricity elsewhere, that any sale of property at the Encina site would not bump Poseidon off the site, and that the company's 60- year lease at the Encina site also protected its access to seawater.

"We've always anticipated that the desalination project was going to outlive the existing power plant," MacLaggan said. "We've prepared for it."

Water Authority officials, however, said Wednesday that they were surprised by NRG's plans and were not sure what effect it might have on the proposed desalination plant.

"For now, we don't know what this means," said spokesman John Liarakos. "We've got to noodle through this. Quite honestly, we were not really expecting (this)."

The news about Encina was just the latest twist in the long- running and already confusing saga of the proposed seawater desalination plant.

Again, Poseidon started studying the idea to build the desalination plant at Encina in 2000.

And the company has been in fruitless negotiations since 2001 with the Water Authority that, as a regional water supplier, has the money and collaborative water demand.

The two sides say they are still negotiating.

Despite that, Poseidon has already reached a deal with the city of Carlsbad to build the same proposed plant, a deal that could apparently be changed if a separate deal was reached with the Water Authority. The Carlsbad deal rests on the idea that Poseidon could reach solid agreements with other agencies to buy the plant's water as well.

Carlsbad city officials certified their own voluminous environmental study in June, and Poseidon officials said Wednesday that they could apply to the California Coastal Commission for a permit as early as the end of the week.

Hoffman of NRG said the company was asking the California Energy Commission for permission to build a power plant because it would crank out more electricity, more cheaply, than the current plant turbines that date to the 1950s.

He said he could not say how the company's plans might affect the desalination project.

"We're not in the desalination business," Hoffman said. "The lease (Poseidon) has with us would give them the right to move the (sea)water themselves."

Hoffman said that while NRG wants to build its power plant within three years, it could take much longer -- a "decade, maybe two" -- to shut down the existing Encina power plant.

Water Authority board members, meanwhile, are scheduled to consider certifying their own environmental impact report -- the second massive report on the proposed desalination plant -- today.

Board members received the 8-inch thick environmental study last month, but put off making a decision to certify it until today, to give themselves more time to review it.

Whichever project would be built -- a Poseidon-Carlsbad or Poseidon-Water Authority -- is expected to face a tough permitting hearing from the California Coastal Commission. The commission has expressed concerns about seawater desalination.

The Water Authority delivers nearly all the water that San Diego County residents use every year, mainly by buying it from the Los Angeles-based Metropolitan Water District, tacking on a surcharge, and selling and delivering it to 23 cities -- including Carlsbad -- and water agencies countywide.

Because of its regional membership, the Water Authority has the financial power to swing deals for large water supplies. And it owns the pipelines that could be used to move the water around the county, to and from cities and water agencies.

A handful of representatives from environmental groups criticized the study and the project at the board's June meeting.

They argued the study had not done a satisfactory job of detailing the harmful effects the project would create, and at looking at alternatives -- such as getting county residents to conserve water -- rather than building the plant.

The Water Authority's proposed plant would use a portion of seawater that is already being sucked into the Encina plant site to cool electricity-generating engines.

It would use three 800-horsepower electrical pumps to force the seawater through a series of filtering tubes filled with state-of- the-art membranes. Half of the water, 50 million gallons a day, would become salt-free drinking water. The other half, now twice as salty, would be sent back out to sea.

The Water Authority's environmental impact report, just like the city of Carlsbad's environmental study, says the project would not harm the sea.