The Carlsbad Desalination Plant that began construction last year, and claims to be the largest desalination plant in the western hemisphere, is 65 percent complete, said developer Poseidon Water.

“Our contractors and our host communities of Carlsbad, San Marcos and Vista have set a new standard for cooperation and efficiency, and that has allowed us to make fantastic progress during nearly two years of construction,” said Peter MacLaggan, Poseidon Water vice president.

When all finished in 2015, the $1 billion project will produce 50 million gallons of water daily, generating about 7 percent of the county’s water needs, developers said. The plant is expected to begin delivering water in the fall of next year.

The San Diego County Water Authority signed a 30-year water purchase agreement with Poseidon in 2012 in advance of last year’s construction launch. During the three-year building process, the project is supporting about 2,500 jobs and contributing some $350 million into the local economy, Poseidon said.

The builders are a joint venture of Kiewit Infrastructure West and J.F. Shea Construction Inc. IDE Technologies is the engineering firm, and the plant’s future operator.