An example is almonds. Almonds now use close to 10% of water used in California. One almond takes approximately 1.1 gallons of water to create it.
So: Why, in the midst of drought, are California farmers planting *more* almonds? The answer, paradoxically, is because water has become more expensive. The water projects are not delivering water to California farmers, so California farmers have a choice between a) not growing crops (and thereby losing their farm, since no crops means they can't pay the mortgages they took out on their farm equipment and/or farmland to expand in earlier more optimistic times), or b) drilling wells. Drilling wells that in some cases are a thousand feet or more deep. The water from these wells is ridiculously expensive for two reasons: 1) the simple cost of drilling, and 2) the large amount of electricity needed to haul that water (at 8 pounds per gallon) up that 1,000+ feet of pipe to the surface.
In fact, the water from these wells is so expensive that if the farmers used it to grow a low-water-use crop like wheat they'd lose money. Most low-water-use crops like wheat or corn have a relatively low price on the commodities market, a price that will not pay for the cost of the well and the electricity to pump water out of the well. So, paradoxically, expensive water has caused farmers to instead grow almonds -- one of the only crops that sell for a higher price than the cost of the water needed to grow them, yet also one of the most water-thirsty crops on the planet.
And now you know the side of the story you don't get from the Libertarian free market think tanks and their notion that expensive water would cause water usage by farmers to decline. What matters to farmers is *not* the absolute cost of the water. What matters to the farmers is the *marginal* cost of the water -- the difference between what it costs to obtain the water, and what income they get from using the water. When water was cheap but in limited supply, farmers grew crops that were water-thrifty because the price of those commodities was enough to pay for the water. Now that water is expensive but they can pump as much as they wish from the ground (until the aquifer runs dry, anyhow!), the California farmer's slogan becomes "drill, baybee, drill!" and the almond trees go in.