A crop’s water footprint—–all the water needed to grow and process it—–is one way of measuring its water efficiency. But there is more to the picture than just how much water is used to produce every pound of a crop. Comparing the nutritional value of each one, you can see which crops provide the most bang for your buck, or in this case, the most bang for your gallon.

Almonds have a high water footprint. They’re not very efficient when it comes to gallons of water used to produce one pound, but they make up for some of that high water use when you consider gallons per grams of protein and kilocalories (one thousand calories) produced. have a high water footprint. They’re not very efficient when it comes to gallons of water used to produce one pound, but they make up for some of that high water use when you consider gallons per grams of protein and kilocalories (one thousand calories) produced. Cherries have a relatively small water footprint compared with almonds, but nuts are much more nutritionally efficient, producing more protein per gallon of water used. have a relatively small water footprint compared with almonds, but nuts are much more nutritionally efficient, producing more protein per gallon of water used.

Nuts, cherries, and peaches grow in trees and must be watered year-round. They have a large water footprint per unit of edible plant, unlike crops where nearly the whole mass is consumed, such as spinach . Leafy greens, while nutritious, just don’t pack a lot of calories.

Raisins have a much bigger footprint than grapes . They use the same amount of water to grow but result in less product after the drying process. Processed foods like canned tomatoes and fruit cocktails also have larger water footprints than their raw form.

On this scale, rice doesn’t have a glaring inefficiency. But among California’s top export crops, only nuts rank higher. Rice fields are continuously irrigated during their growing season but not year-round.