Making the Most of the Water
Water conservation sounds like a great idea, in principle, doesn’t it? There is only so much to go around in semiarid regions. But who are we conserving the water for? For the developers who wish to build yet another subdivision on Sonoran desert land? For the corporations who want yet another water-consuming factory? I highly doubt it is for the riparian trees who drink from the groundwater or for the wetland plants who dip their roots into the stream. If we want to conserve water for the plants who live in or along the river- the aquatic and riparian- we need to focus on securing environmental flows for them.
An alternative approach is to consider this question: “How many ecosystem services can we accrue from each drop of irrigation water we apply to the land Matt and I use a fair amount of irrigation water on our acreage. Our place is not bare rock and drought-tolerant shrubs. But the benefits are many. The water we divert from the Salt River sustains diverse and productive riparian forests and desert shrublands that multitask with the best of them:
1) they produces food for us (as well as for the birds and bees), reducing our reliance on external subsidies;
2) they produce shade which lowers our energy usage and makes the summers more bearable (there are known trade-offs between energy use and water use; and
3) they sequester sufficient carbon to allow for a carbon-neutral lifestyle. And, there is more! These habitats provide ecotherapy and year-round engagement for us- as I type, hooded orioles and verdins are keeping me amused by their antics at the water drip- reducing my need to expend resources to recreate elsewhere.
Much of the irrigated acreage in the Valley of the Sun has a single purpose, as in growing a single crop or sustaining a single recreational game such as golf. We have boundless opportunities to get more ‘bang for our buck’ from the water we reroute from the rivers who sustain us, while leaving more water in them for the wild aquatic and riparian residents.
Here is another piece that reflects on water use in the desert, excerpted from Bringing Home the Wild: A Riparian Garden in a Southwest City:
THE SOURCE RIVERS
KUI: JUSTIFYING THE WATER
“What an extravagant waste of water!” admonished a colleague, after hearing about our lifestyle. “As an ecologist in a dryland region, how do you justify its expense?” A fair question. During my early years in Phoenix, as I lectured about water conservation and tended my xeriscaped yard, I might have said the same. Yes, I agree, we should not be wasting water. We live in a desert. Water is a limiting resource. There are too many of us living here, and more arrive daily. The Salt River is impounded in multiple places, as is the Verde River. At Salt River Project’s Granite Reef diversion dam the pooled water flows out of the streambed into canals tracing those built by Hohokam people a millennium ago. As riparian advocates in favor of in-stream flows, how do Matt and I justify our out-of-channel use? How can we flagrantly irrigate a multiacre garden during a drought? Why do we feel so entitled?
Because this was a riparian zone, once. Our patch of land was not quite in the floodplain—we are three miles from the channel of the constrained and channelized Salt River. But the pre-dam riparian zone wasn’t that far away. The Salt River’s floodplain was miles wide, Will Graf ’s studies show, and her channel moved wildly and extravagantly about, carving new pathways, before she was tamed. The land now known as Phoenix was vegetated by forests of Fremont cottonwood and Goodding’s willow and by woodlands of velvet mesquite, known as kui to the Akimel O’odham—the River People. “When Phoenix was laid out, there was an average of six huge mesquite trees to each city lot,” proclaimed an article in 1938, with the vegetation in places being “too thick to be conquered.” Shrublands of desert saltbush (Atriplex polycarpa) and creosote (Larrea tridentata) were abundant, too, according to vegetation maps from the mid-1800s.
Those acres of riparian vegetation are long gone. They were cleared to make way for farms and orchards and then houses and highways. The forests and shrublands sustained by the Salt River became carpets of edible plants from the Old World and New, and then expanses of Eurasian grasses dotted by trees shading houses. Many of the bosques that lined other regional rivers are gone too, having been cut for firewood, cleared for farmland, or deprived of the water that sustains them. Matt and I are giving homes to the riparian birds and plants who lived here before. We are restoring a piece of the riparian past, and that requires water.
The Salt and Verde Rivers drain large watersheds. Snow and rain that fall on the White Mountains, Mazatzal Mountains, Sierra Ancha, and Mogollon Rim and spring flow that discharges from aquifers in the Chino Basin provide water for many out-of-channel users. Matt and I settled on agricultural land with attached water rights. If we opt not to use those rights, there is no guarantee the water will stay in the channel to feed the riparian plants.
Is any one use more justifiable than others? How much does one “get” for each drop? In plant physiological ecology, there is a concept called water use efficiency. It refers to the amount of biomass a green plant produces per unit of water taken in. This concept could be applied at the ecosystem scale, to refer to the “amount” of ecosystem goods and services a unit of vegetated land generates per unit of water applied.
In the lexicon of Salt River Project, a unit of water is the acre-foot: the volume of water that would cover an acre of land twelve inches deep. The industrial-scale farmers who remain in the Phoenix area are using their acre-feet to grow cotton (Gossypium), alfalfa (Medicago sativa), or sorghum to feed cows and the beefeaters among us. The Phoenix Parks and Recreation Department uses some of their water to grow shade trees to buffer the climate and provide relief from the heat, with an ambitious goal of covering 25 percent of the city with canopy. Pollinator gardeners are using their water to generate, ahem, pollinators. A declining but still large share of Phoenicians use their allotment to grow fairways of Bermuda grass (Cynodon dactylon) and greens of rye grass (Festuca perennis) so that wealthy men can relax and stay physically fit. An acre-foot of water, at our place, provides all those functions and more: food, climate buffering, habitat support, mental and physical wellbeing, and education. Our (cocreated) oasis serves as example.
To that colleague who remarked on my lifestyle and asked me that question, I would say this: I appreciate your perspective, but there is a salient distinction to be made. We are using the Salt River’s water, certainly. But we are not wasting it. We are putting it to good and beneficial use. If a research team, somewhere, feels up to calculating the ecosystem services derived per unit of irrigation water applied, I would be glad to offer up our parcel of land for comparison. It hosts an extravaganza of life.
