Part 3
Water and Agriculture:
Economic and Ecological Water Incoherence
In an arid or semi-arid region, you can irrigate low-value, thirsty crops such as alfalfa and pasture grass only if you have cheap water – if your fields are riparian, or if your dams and aqueducts were built decades ago, or if your water is subsidized by the taxpayers, as one in every three of the far West’s full-time irrigation farmers does.
Marc Reisner, Cadillac Desert: The American West and its Disappearing Water
Our ability to channel and transport water for irrigation is modern society’s single largest use of water. Global agriculture uses about 70%-80% of all available annual fresh water. Arid regions are home to 2.5 billion people and grow 44% of the world’s food. These regions are historically drought-prone and experience periodic water scarcity. They’re intensely affected by climate change-induced desertification and water-table depletion.
Domestically, California supplies two-thirds of the nation’s fruits and nuts as well as 400 other commercial crops. Farms in arid Southern California use over 2 trillion gallons of water annually from the distant Colorado River to produce the high-water-use crop alfalfa. The amount paid for that water does not cover the cost of water delivery.
Climate change will continue to put stress on water supplies and will push water availability for agriculture to crisis levels. As climate change worsens, dry periods are more frequent and last longer. In 2000 the Western U.S. entered into a megadrought – defined as a drought lasting 2 decades or more – which has been the 2nd worst drought in the region in 1,200 years. California, in particular, has experienced drought 9 out of the last 12 years with 2019-2021 being the driest period in the state’s history. Despite rains in November and December of 2021, most of California remains in some level of drought.
During these drought years, California farmers have periodically experienced 80-100% cutbacks of water allotments from the federal system of dams and canals and from the State Water Project, which delivers water from Northern California rivers to Central Valley farmers and Southern California cities.
To make up for the water shortages from the drought, the state’s agriculture sector has relied on extensive groundwater withdrawals, dangerously drawing down aquifers. California did not track groundwater usage until the 2014 passage of the Sustainable Groundwater Management Act. Overdraft of the aquifers in a number of places in the Central Valley has resulted in land subsidence and, in coastal farming regions, saltwater is seeping into the water table, contaminating drinking water supplies.
Aquifers, Critical Contributors to Water Security, are at Risk
Water intensive farming has almost depleted a three-million-year-old aquifer in the high plains. It could be dry in less than 100 years, and would take 6000 years to replenish.
Aquifers are a key source of freshwater, supplying 30% of the global population’s water needs. According to NASA, most aquifers are being depleted faster than they can recharge, and they can take thousands of years to replenish if they become depleted.
The Ogallala Aquifer, one of the largest aquifers in the world, supplies a portion of the water needs for 8 states from Texas to South Dakota.
The aquifer system is an essential water supply source for several million people in the High Plains but the primary use of the groundwater is for farming, accounting for up to 94% of withdrawals.
As a result of this intensive use, the Ogallala is the world’s fastest disappearing aquifer, being depleted at an annual rate equivalent to the flow of eighteen Colorado Rivers. The misguided federal incentive program for farmers to grow water-intensive corn for ethanol – 1000 gallons of water or more is needed to produce one gallon of ethanol – puts a three-million-year-old asset on course to be depleted in less than 100 years, and it could take 6000 years to replenish.
Industrial Agriculture’s Antagonistic Relationship with Water Quality
The depletion of aquifers is just one of the ways industrial agriculture practices wreak havoc on water supplies and the people and ecosystems that depend on them; pollution is another problem with far-reaching consequences.
The EPA has identified farming as one of the most significant sources of water quality degradation—runoff from farms containing pesticides pollute waterways, and excess nutrients from fertilizers cause eutrophication, an excessive amount of nutrients that cause the dense growth of aquatic plants that use up the oxygen in the water. Insufficient oxygen to support life – referred to as hypoxia – results in the death of marine life. 415 sites around the globe have been identified as having some degree of eutrophication, and 40% of those experience hypoxia.
The 2,340-mile-long Mississippi River drains all or part of 32 states and 2 Canadian provinces between the Rocky Mountains and the Appalachian Mountains. This vast watershed serving 30 million people is the ill-fated recipient of chemical runoff from Midwestern farms that drains into the Mississippi and down to the Gulf of Mexico, creating a hypoxic “dead zone” roughly the size of the state of New Jersey, disrupting marine food webs and human fisheries. It is irrational that food production on Midwestern farms causes the destruction of a food source in the Gulf of Mexico.
More than 100 different pesticides are used around the world. According to Cornell University Cooperative Extension, “the cleanup of groundwater contaminated by pesticides is usually impossible. The slow movement of groundwater means that it may take decades for the contaminated water to flow beyond the affected wells.”
While some of these issues are deeply entrenched with no easy solutions, a systemic remedy is to steadily transition agricultural practices towards those that develop healthy, carbon-rich soils that increase the water-holding capacity of soil, build fertility, and enable farmers to reduce or eliminate agricultural chemicals. Learn more about these practices via our series on Regenerative Agriculture.
On-Farm Water Conservation
Given the water challenges facing the agricultural sector, especially in arid regions, conservation strategies, new technologies, groundwater recharge, and policies that take a long view of water stewardship are urgently needed. While strategies such as drip irrigation, smart irrigation, retention ponds, dry farming and the use of recycled water for irrigation are slowly being adopted, the pace and scale of implementation needs to be radically increased to avoid a serious disruption of food supply. Transitioning to a new way of thinking about water use and stewardship will be essential to sustain the capacity to grow food.
Organic farmer Tom Wiley suggested at a California Climate and Agriculture Network conference that we should rehydrate the Central Valley by allowing nature to do what it historically did prior to engineering and canalization of the natural water flow.
The pre-agricultural grassland ecosystem of California’s Central Valley was endowed by the generosity of the snowpack from the Sierra Nevada mountains. Annual snowmelt released water slowly to lower elevations and hydrated the landscape creating what Ross Noss, Chief Scientist of the Florida Institute for Conservation Science, called “one of the biologically richest and most glorious grassland regions in North America.”
Wiley’s suggestion to allow seasonal flooding seemed risky to farmers who feared that their perennial crops would be damaged by sitting in water, but since then, winter trials performed in vineyards and nut orchards allowed as much as 2 feet of water onto fields for 2 weeks to percolate into the ground to recharge the water table, and no harm was done to the vines or trees.
Mike Montgomery of Monterey One Water highlights another solution, the use of recycled water: “Agriculture makes up about 92% of all the water that is pumped out of the ground in Monterey County. When seawater intrusion was making its advances down the Salinas Valley, most crops couldn’t tolerate the high levels of salinity in the water.
Now, with recycled water in the mix, water quality has improved, and farmers are able to grow more high-value food crops such as strawberries, lettuce, celery, broccoli, cauliflower, Brussels sprouts, etc. In the county, in most of the areas that directly make use of the recycled water, seawater intrusion has slowed significantly, but in the areas where they’re still pumping a lot of groundwater, it has continued to get worse.”
Over the next twenty years, California’s Central Valley is projected to lose hundreds of thousands of acres of farmland due to the pressures of urbanization, the challenging economics of farming and the multiple stresses of climate change. That loss poses potentially dire consequences for the nation’s food supply. Implementing practices for on-farm water security will be paramount to adapting agriculture to a hotter, drier climate.
DIVE DEEPER
Growing Food in a Hotter Drier Climate
An interview with Gary Paul Nabhan, Ph.D., a world-renowned, Arizona-based Agricultural Ecologist, Ethnobotanist, Ecumenical Franciscan Brother and author whose work has focused primarily on the interaction of biodiversity and cultural diversity in the arid, bi-national Southwest.
NEXT:
Part 4Soil: The Ultimate Defense Against Drought
Ultimately the answer for making farms more drought-resilient lies in the soil.
