I had sort of known that agricultural pot growing would wipe out illegal grows immediately, because it is said to be incredibly easy to grow. But I hadn’t realized how little land it would require. Keith Humpheys at the Reality Based Community says it would only require 10,000 acres of land. (I rounded up.) If it is “thirsty”*, that would be about 40,000af/y. That’s nothing for ag. There are farms on the west side of the valley of more than 50,000 acres. Providing the entire country’s pot cultivation wouldn’t even be their major crop.
It would be so much nicer to have 100 ten-acre farms, although even that would barely support a farm town. They could all be in one water district! Really, this should happen just to get the grow sites out of the mountains.
*I dislike the concept of “thirsty” crops. My first objection is that the difference between thirsty and non-thirsty isn’t that big. Most crops need about 3 to 3.5 af/a-y if you include salt-flushing, which you should. “Thirsty” might be about 4 af/a-y, which is more, but not enough more for me to get riled about. That’s nothing compared to the amount of water that goes into growing food to feed to animals (the losses from going up a trophic level). The increment between “non-thirsty” and “thirsty” is also less than the difference between well-managed irrigation and poorly-managed irrigation.
If the crop is important, I’m not going to object to it because it requires 15 or 20% more water to grow than some other crop. We still have enough water for that. When water is short, however, my choice would be to supply Californians with market crops and then make conscious decisions about growing more stuff vs having nice rivers.