Water is essential for growing food. To water their crops, most farmers around the world use recycled water or rainfall, but a significant proportion of farms also use water from lakes, rivers, reservoirs, and groundwater. Globally, agriculture accounts for 85% of all water use, which puts a strain on our planet’s limited supply of fresh and groundwater.
Groundwater: water held in the soil or under rocks in reservoirs
Surface water: water from rain, lakes, rivers, and streams
Nuts Versus Seeds
If you are ever choosing between nuts and seeds for a boost of protein, you’re making a choice about water, not just choosing between two plant-based foods.
Tree nuts like almonds, pistachios, walnuts, and cashews are actually some of the most water-intensive crops grown today. Seeds, though usually grouped together with nuts in dietary recommendations, have a much lower water footprint and impact on our environment.
One study that averaged the global water use of various crops found that pumpkins, squash, and watermelons require roughly 20 to 90 times less water to grow than tree nuts (excluding rainwater). The water used to grow squash and melons produces both edible flesh and edible seeds. It’s a two-for-one deal. For tree nuts, the water is only used to grow the nuts.
Peanuts are more similar to potatoes than they are to tree nuts because they grow below the ground, making them far more water efficient than other nuts. On average, peanuts use just slightly more water than sunflower seeds. But pumpkin and watermelon seeds still come out on top.
Location, Location, Location
The high water footprint of tree nuts might not seem like an issue in places with a plentiful water supply, but the tree nuts in the U.S. are grown in an area with limited surface and groundwater. This is why location matters. In the U.S., California is the largest producer of nuts, among many other foods. California has also been repeatedly stricken with severe drought in recent years. A regular and dependable supply of water increases how much food we can grow, making repeated droughts in our nation’s “breadbasket” especially alarming. Water-stressed California produces 82% of the world’s almonds, 98% of the U.S.’s pistachios, and 99% of the U.S.’s walnuts -- the three most water-intensive nuts on the market.
Why Water Matters
When used in high quantities, like for growing tree nuts, water is often diverted from natural ecosystems that house salmon populations, among many other plant and animal species. Salmon populations affected by water diversion have experienced more disease and produced fewer offspring. This kind of water diversion threatens not just wild salmon’s survival, but the greater ecosystem as well. For food grown in places like California, every drop of water being used to grow that food has an impact on the surrounding ecosystem.
But that’s just surface water.
While many farmers have a legal right to use surface water near their land, like rivers or streams, groundwater is technically a shared resource and is far more easily depleted. With wells on multiple farms all tapping into the same supply, and with little regulation on groundwater extraction, the supply of groundwater is being used faster than it can be replenished.
Legal rights to water in California are also complicated, with few incentives for farmers to conserve water right now and no easy solution yet in sight. Tree nut production in California presents the constant tug-of-war between environmental sustainability and economic vitality: with so many other farmers growing food throughout California, it can be difficult to justify the high water footprint of tree nuts, aside from their revenue generating power for farmers.
What We Can Do
We have an impact on the environment in one way or another every time we buy, eat, or throw away food.
Both nuts and seeds provide nutrition with a lower impact on the environment than meat and other animal products. However, nuts and seeds are far from equal in terms of water use and environmental impact.
To help reduce water depletion and alleviate water stress in areas of drought, choose seeds over tree nuts for plant-based nutrition and satisfying snacking.