In America’s fruit and nut basket, water is now the most precious crop of all.

It explains why, amid a historic drought parching much of the American West, a grower of premium sushi rice has concluded that it makes better business sense to sell the water he would have used to grow rice than to actually grow rice. Or why a melon farmer has left a third of his fields fallow. Or why a large landholder farther south is thinking of planting a solar array on his fields rather than the thirsty almonds that delivered steady profit for years.