It's the dams that caused the droughts. The central valley had the largest lakes on the west coast and was once a vast marshland, which is why it was such good farmland. But they created canals and dammed the major rivers, which drained the land. Without the evaporation from the large bodies of water, the water table can't replenish itself and it's slowly getting dryer and dryer. And the land is becoming salter and polluted from decades of chemical ferts. Farmers and rancher have to keep digging deeper wells to get at the dwindling ground water, which can't replenish. Not to mention all the fucking fracking and other pollutants the oil companies have generously leached into it. It's not a good situation, but the solution is to restore many of the lakes and rivers that made California fertile to begin with. Look up Lake Tulare and kern Island. There's towns all along the central valley with Port on their name, because they used to be a port for steamboats traveling along rivers and lakes from Delano to Stockton. I could go on, there's so much behind it all.