The AP reports on the nation’s largest seawater desalination plant in Carlsbad, Calif., set to open later this year. Supporters consider seawater desalination a partial answer to drought in the U.S. Opponents say high costs and threats to marine life leave better alternatives, like recycling and conservation.

The billion-dollar project is only the nation's second major seawater plant. The first U.S. foray in Tampa Bay is widely considered a flop.

More details here.