> California's farmers probably will pump an additional six to seven million acre-feet of water from their wells this year, above what they normally use

Compare that volume to the historic/nominal annual flow of the Colorado River at 16.5 million acre feet (per a 100 year old compact). That would be a big pipeline or canal to build or pump. Electric, heat, and carbon costs for desalinization plants would be equally infeasible.

Yes, price water at market values, drive aquifer mining done to zero, and beyond to replenish, and let the market decide if almonds or pistachios are more valuable than other choices.