Arizona officials voted to advance a $5.5-billion project to build a water desalination plant, 200-mile pipeline and associated infrastructure as part of a plan to address drought-driven water uncertainty in the state. But growing controversy around the plan and the method of implementation threatens to derail the proposal.

IDE says the plant could supply up to 3 million households—more than the 2.6 million households currently in Arizona. The plant would initially supply less water per year, about 300,000 acre-ft, according to the company.