The California State Lands Commission signed off Friday on a plan to construct in Carlsbad a desalination plant capable of producing 50 million gallons of drinking water per day, clearing the way for construction to begin early next year.The commission voted unanimously during a public meeting in Los Angeles to authorize the lease of state lands to build the $300 million seawater desalination plant at the Encina Power Plant."Among the many options to meet the water supply requirements for Southern California is desalination," said Lt. Gov. John Garamendi, who serves on the California State Lands Commission. "The proposed Carlsbad desalination project provides 56,000 acres of new water annually, replacing water now pumped form the Colorado River and Northern California."Requirements of the project are to fully offset greenhouse gas emissions and minimize the impact on marine life," he said. "With those two requirements locked in and the need to develop new water supplies for Southern California, I am comfortable approving the lease of the project."Environmental groups opposed the project over concerns that the facility would increase salinity in the adjacent Aqua Hedionda Lagoon and ocean and kill off fish. They also argued that the facility's emissions would contribute to global warming.The California Coastal Commission gave its final approval of the project at a meeting earlier this month.Poseidon Resources, the project's developer, said the State Lands Commission's vote clears the way for construction to begin."This is a historic day for the state of California," said Peter MacLaggan, Poseidon's senior vice president."As a result of today's State Lands Commission approval, the Pacific Ocean will soon be a critical component of the state's water supply portfolio," he said. "Poseidon will be building one of the most technologically advanced and energy-efficient seawater desalination plants in the world. It will be a model for other desalination projects needed by the state."Construction is slated to begin in the first half of next year, and the plant could begin producing drinking water by 2011, according to Poseidon.Nine public water agencies in San Diego County have signed contracts to receive water from the proposed plant.