... are the root cause of this long term drought.
We'll pretend this desalinization plant is powered by renewable energy by some unlikely percentage but that's not the reality. California is building more gas plants to meet the increasing demand for electricity.
California's electric mix, day in and day out, is rather like those "Kona Blend" coffees with the small print on the label saying "10% minimum Kona beans. Most of our electricity comes from gas fired power plants.
This particular problem started with the Carmel River, which was overdrawn. New development was killing the river, which is home to several endangered species, so withdraws from the river were limited by the state and federal government. This created water shortages that restricted new development... Everyone knows how that goes.
Even if withdraws hadn't been restricted development would have continued, eventually drying up the river entirely and desalinization would still be a necessity.
This region of California is not hooked into the California State Water Project, which has also been limited by drought.
Eventually California will be forced to quit growing water intensive crops to feed cows and build nuclear powered desalinization plants to keep the water flowing, especially as drought conditions get worse, but most people haven't yet accepted that reality.
Even if we kill all our rivers and capture every last drop of water flowing into the sea we still end up in the same place. Farmers and developers will take all the water they can get. There's no end to it.