Southern California’s biggest water supplier has chosen a new general manager — but the selection isn’t yet final, and the fiercely contested vote is exposing deep disagreements within the powerful agency as a severe drought grips the region.

The Metropolitan Water District’s board of directors voted this month to select Adel Hagekhalil to lead the agency, The Times has learned, replacing longtime head honcho Jeff Kightlinger, who is retiring. Hagekhalil runs L.A.’s Bureau of Street Services and was previously second-in-command at the city’s sanitation department.

Metropolitan finds itself at a crossroads after 15 years under Kightlinger’s leadership. The agency delivers huge amounts of water from the Colorado River and Northern California, and has prided itself on hammering out complex deals to protect the region’s water rights and investments. But those far-flung resources are becoming less dependable as the planet heats up.