Unlocking Urban Agriculture's Water Problem
A few years ago, if I were asked to imagine a typical farm, I would envision acres of crops, winding along a hilly road bordered with elm trees, leading to a large farm house. There would be a red barn and a green tractor, a farmer in overalls and a checkerboard landscape of harvests and hedgerows spreading out to the horizon.
Perhaps I read Charlotte’s Web a few too many times, but things are certainly changing, and not just due to the rise of industrial agribusiness. If you ask the next generation (the post-post-millennials?) the same question, you might hear them describe skyscrapers and neon lights, living buildings bringing Jack’s beanstalk in the sky to real life. Urban agriculture, a concept that originated in the garden city movement at the end of the 19th century and experienced a renaissance during the 1990s thanks to the pioneering work of the International Development Research Center and Urban Agriculture Network, is indeed growing in popularity and investment. It is estimated that over 800 million people1 practice urban agriculture across the globe today, providing 15% to 20% of the world’s food2. With more than 50% of the world's population now living in urban areas and more on their way3, it is no surprise that the landscape of global agriculture is shifting upwards.
Some assume that modern cities will continue to buy food rather than grow it themselves. Milepost’s work with cities, such as the development of the City of Seattle’s 2014 Environmental Progress Report, Moving the Needle, has led us to view urban and peri-urban agriculture, however, as part and parcel of sustainable urban development. Many national and local authorities have come to appreciate the role urban farming can play in manifold issues affecting urban areas, such as health (food security and nutrition), urban environmental management (urban greening, climate and biodiversity, waste recycling and reducing the ecological footprint), and social development (poverty alleviation and social inclusion). In fact, throughout the United States, many cities are now proudly adopting urban agriculture: San Francisco and Oakland are embracing it as a permanent component of their cities’ General Plan while New York hosts the world’s largest privately-owned and operated rooftop farm.
Farmers also have a lot to gain by producing food near city centers. Strong growth in local food demand, a unique entry point for urban agribusiness, is one of many examples. In terms of sustainability, urban farms mean shorter supply chains, less transport-related CO2 emissions and fewer middlemen. That said, moving urban agriculture from a niche to a food system isn’t easy. Among the challenges urban farmers have to overcome is access to, as well as the availability and high cost of, urban water, making water conservation a critical tool.
During our most recent sustainability assessment for the National Mango Board’s supply chain in Mexico and Brazil, we were reminded of the importance of technologies such as drip or weather-based irrigation that delivers water precisely where and when it’s needed, especially in water scarce areas. Drip irrigation uses a third of the water needed for conventional irrigation methods, can be built from existing local products and allows for the safe use of lower quality water resources.
Using recycled wastewater to sustain crops, a growing practice worldwide, is another effective way of conserving freshwater. In the United States, for example, the California Water Recycling Criteria allows for 43 specified uses of recycled water—including irrigation of all types of food crops. Although some have raised concerns regarding the health risks of using wastewater for irrigation, crop contamination in cities with proper wastewater treatment plants is low4. A 2012 report from the National Water Research Institute’s (NWRI) Independent Advisory Panel states that “current agricultural practices that are consistent with the [Water Recycling Criteria] do not measurably increase public health risk, and that modifying the standards to make them more restrictive will not measurably improve public health”5. In fact, when drip irrigation is used in combination with recycled wastewater, “it offers the added benefit of minimizing the contact of the wastewater and the crop, decreasing the likelihood of contamination” (FAO, 2009). Additional advantages from using wastewater for irrigation include energy savings, a shorter journey from tap to farm, and a new pool of customers for wastewater treatment plants. The latter represents a significant benefit as the cost of treatment and distribution typically outweighs the revenue, but a sizeable new customer base with lower water recycling criteria could result in lower rates for all customers as margins increase.
Urban agriculture opportunities and challenges are of high interest for us at Milepost as they combine many of our areas of expertise: agriculture, municipalities, water and energy efficiency. We would love to learn more about your current experience as urban farmers, particularly the tools you are using overcome the challenges related to the access, availability and high cost of urban water. Comment on the blog and let the learning commence!