CARLSBAD (AP) - San Diego's water board has given Poseidon Resources final approval to begin constructing the largest desalination plant in the Western hemisphere.

Vice President Scott Maloni says he's pleased that the permitting process is finally over after six years, 14 public hearings and over 70 hours of public testimony and debate.

Environmental groups have fought the proposal, saying the plant's intake valve would damage marine life, destroying fish, larvae and other sea life.

Construction is expected to begin this year in Carlsbad. Once completed, the plant is expected to produce 50 million gallons of drinking water per day or provide 10 percent of San Diego's County's water supply.

Poseidon Resources said it hopes to complete the more than $300 million project by 2012.

The plant will be located adjacent to the Encina Power Station at Agua Hedionda Lagoon in Carlsbad.

The decision comes one day after a Superior Court judge ruled against two environmental groups who sued the California Coastal Commission in an effort to halt the construction
of the desalination plant.

The Surfrider Foundation and the Planning and Conservation League had argued the commission failed to require the developer to reduce the amount of marine life that would be killed in the desalination process. Superior Court Judge Judith Hayes ruled that the commission's approval of the project in 2007 did not violate the state water code.

Copyright 2009 The Associated Press.