Since the advent of irrigation in California with the widespread drilling of wells in the 1930s and the proliferation of orchard crops during the past two decades, total annual water use in many watersheds exceeds supply. Partly as a consequence, California enacted the Sustainable Groundwater Management Act in 2014, which limits withdrawals to replenished levels.

Because irrigated agriculture accounts for nearly 80% of total water use, reductions in irrigation will be required, but preferably without decreasing either productivity or food supply. Furthermore, with some climate change projections  suggesting a potential 20% water loss by the middle of the century, the need for more efficient water use could become acute....