More Crop per Drop

By adopting water saving techniques, urban food producers can maximize our region’s increasingly scarce water resources to grow more food.

September 1, 2014

Issue 8: September/October 2014Policy

Holy moly! I got my water bill and saw that my usage went up almost 100 percent last month. It got me thinking. Tucson policy makers are responding to the widespread interest in local food production by revising the zoning rules to support small-scale agricultural activity within city limits. This will likely lead to more households growing food in the near future. But will we have enough water to support small-scale local food production, and if so, at what cost?

No need to mention that we live in a desert where water is scarce and where climate change is expected to make it even scarcer in the future. The western United States is experiencing historic droughts—Baja Arizona is not alone in facing a water crisis.

As a result, changes in water policy are surely on the horizon. Jean McLain, the associate director of the University of Arizona Water Resources Research Center, says that strategies like desalination and direct potable re-use, also known as “toilet to tap,” are currently being considered for stretching scarce water supplies. Brad Lancaster, an expert in the field of water management and co-founder of Desert Harvesters, sees an immediate need for policy change. “We already know the situation will be severe in the future. We need to change now.”

Urban food producers—like those who maintain plots in community gardens—are not large water users. At Pio Decimo Community Garden, a community garden on South Seventh Avenue in Barrio Santa Rosa, 9-year-old Griffin Foster lends a hand fixing an irrigation pipe.

Urban food producers—like those who maintain plots in community gardens—are not large water users. At Pio Decimo Community Garden, a community garden on South Seventh Avenue in Barrio Santa Rosa, 9-year-old Griffin Foster lends a hand fixing an irrigation pipe.

Tucsonans are known for being frugal water users. We use about 102 gallons per capita per day in our homes, compared with 123 in Phoenix and 249 in Scottsdale. According to Tucson Water, we use the same amount of water today as we did 25 years ago even though the population has grown by 40 percent. Nevertheless, the water table is dropping in many areas, requiring deeper and deeper wells. Central Arizona Project (CAP) water from the Colorado River has been used to maintain or even increase water table levels in some areas, but our current water situation is not sustainable, with or without an increase in urban food production.

Surprisingly, urban food producers are not large water users. Tucson Water rates are tiered, so that the price per gallon goes up as your usage increases. An informal survey of backyard gardeners shows that water bills increase about $20 to $50 per month during the seasons when they are growing, and many never exceed the first billing tier. According to Leona Davis at the Community Food Bank, the cost of water for 80 family plots at Las Milpitas, the Food Bank’s urban community farm, is about $6 per month per family.

Local food producers report that they keep their water use low by using alternative water sources such as harvested rainwater and graywater, and by altering their farming practices to maximize “crop per drop.” To produce food without depleting the water supply, gardeners turn to techniques such as dense planting, use of mulch, planting in basins, and infrequent deep soaking, as well as selecting climate-appropriate crops.

Water-Usage

Aquaponics, a new technique that produces both fish and organic vegetables in a dynamic pond-type ecosystem, is another very promising farming adaptation to a low water environment, as it typically uses far less water than irrigated agriculture.

Local policies that promote water conservation have contributed to our relative efficiency in recent years. In 1989, the Tucson Plumbing Code was amended to require water-efficient fixtures in all new residential and commercial construction; in 1991, the City Code was revised to require the use of drought-tolerant plants and limit non-drought-tolerant vegetation to small “oasis” areas in new multifamily, commercial, and industrial developments. Tucson Water offers rebate and incentive programs for water harvesting and graywater installations. Lancaster suggests that other local policies we might consider include expanding the drought-tolerant vegetation requirement to front yards of residential properties, and requiring that we “plant the water,” by installing rainwater harvesting or a graywater system, “before planting the tree.”

Some new local water policies that support urban food production are already underway. Last year the Pima County Regional Wastewater Reclamation Department—the folks who manage our sewer system—made water for food production more affordable by making it possible to remove sewer charges—which account for about half of your water bill—for the water used in community gardens, since that water does not enter the sewer system. In addition, recommendations for a new sustainable zoning code in Tucson relax the rules for the placement of cisterns on residential property, giving residents more options for harvesting rainwater. These are small scale but important efforts that, when combined with efficient water use in the garden, will contribute to the utility and financial viability of local urban food production.

At Pio Decimo Community Garden, 9-year-old Griffin Foster lends a hand fixing an irrigation pipe.

At Pio Decimo Community Garden, 9-year-old Griffin Foster lends a hand fixing an irrigation pipe.

But looking forward, they are not enough. We will need more comprehensive policies that guide how we allocate all of our water resources—groundwater, CAP water, stormwater, graywater, and even blackwater (sewage). And these policies will have to reflect our community values and priorities. According to Tucson Water, 45 percent of the groundwater currently pumped through the municipal water system is used for outdoor irrigation of mostly nonedible plants. Whether we have enough water to support urban agriculture in the future will depend on how much we value food production versus other outdoor uses such as ornamental gardens, lawns, swimming pools, and golf courses.

Water-Usage

According to Tres English, the director of Sustainable Tucson’s Feeding Tucson project and a local food system visionary, about 60 percent of the rainwater that falls on the streets of the Old Pueblo—139,000 acre-feet per year—never makes it to the water table because it is lost to evaporation. That equates to more than 45 million gallons that can be captured and used to grow food without depleting the water table or relying on the Colorado River. English believes that a combination of water harvesting and graywater use, coupled with innovative growing techniques can provide enough water to make Baja Arizona a “food oasis in the desert.” But this will happen only if we face up to the challenges and are willing to create the policies and make the public investments that can make it so.

Turns out my enormous water bill had nothing to do with the garden. I contacted Tucson Water and asked them to check my meter and they sent out an inspector the next day, who determined that the culprit was the innards of my toilet. An easy and inexpensive fix was in order. I wonder how many pounds of vegetables could be produced with the water that is being wasted by toilets in the homes of other unsuspecting residents of Baja Arizona?

Visit TucsonAz.Gov/Water to find out about rebates.
For more resources about wise water use, visit
Watershedmg.org.

Merrill Eisenberg is an applied anthropologist who is retired from the University of Arizona Zuckerman College of Public Health. Her interest in food policy comes from her commitment to community empowerment and participation in policy development.


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