Earlier quoted context omitted.
Mandatory aquifer recharging would be a good first step. One of the big problems is that California can't adequately take advantage of these wet winters because the reservoirs can only hold so much and the ground can only absorb water so fast, so a lot of water ends up getting into the rivers and escaping back into the Pacific (or sits in ephemeral lakes/ponds/wetlands until it evaporates). If we helped along the pro…
I think the main reason we don't have desalination plants is because they have to be on or near the ocean, which is the most expensive property in the state. No one wants to ruin their view or have a big industrial machine near their home. Basically, I think NIMBYism keeps us from having Desal.
The main reason we don't have desalination plants is that the water is more expensive than other sources, they're expensive to run, consume a lot of power, and you have to deal with the brine effluent.
Imported water and even purified recycled wastewater(potable reuse) are cheaper. In the case of the desalination plant in Carlsbad, desalinated water is about $2.1-2.4k per acre-foot whereas imported water is ~$1k and potable reuse had an estimate of $1.7-1.9k per acre-foot for the San Diego region(OC's potable reuse is cheaper at ~$800 per acre-foot, but trying to keep similar comparisons).
Power comprises most of the cost of desalination for the high pressures required for the membranes to work. I think it's 5 megawatt hours per acre-foot, but those were somewhat dated figures. While one could deal with blending the brine with wastewater treatment plant effluent or power plant cooling water, the greater reclamation of wastewater and the California Coastal Commission cracking down harder on the discharge of power plant cooling water is complicating things.
Desalination is an expensive commitment that produces at a slower rate than other sources. If you have a wet year, you're still stuck with the production commitment. It's great for water security though.