Among the many complex arguments over water in California, one particularly heated debate centers on whether the state should seek more drinking water from a plentiful but expensive source: the Pacific Ocean.

The debate has reached a critical stage in Huntington Beach, where Poseidon Water has been trying for more than two decades to build one of the country’s largest desalination plants. The California Coastal Commission is scheduled to vote next month on whether to grant a permit to build the plant.