SAN DIEGO -- The developer of a Carlsbad desalination plant capable of producing 50 million gallons of drinking water a day received a permit Tuesday from the California Coastal Commission.

Poseidon Resources said the coastal development permit clears the way to start pre-construction next week.

"With this permit in hand, the project's pre-construction phase formally begins now with the initiation of site demolition and preparation," said Peter MacLaggan, Poseidon Resources' senior vice president.

Construction on the plant, which will be located adjacent to the Encina Power Station in Carlsbad, is proceeding despite pending litigation filed last month by the environmental group San Diego Coastkeeper over changes to the project.

A previous lawsuit seeking to block the plant was rejected.

The desalination plant, the first of its kind in California, is scheduled to be completed by 2012. According to Poseidon, it will be capable of converting enough ocean water into drinking water to meet the needs of 300,000 residents.

The Coastal Commission approved the overall project in November 2007, and the plant's environmental mitigation plan in August of last year.