Gilbert Wants to Pay You to Remove Your Grass. Here’s What the Science Says About Whether That’s Actually a Good Idea.

Gilbert, Arizona is considering a $250,000 expansion of its Non-Residential Grass Removal Rebate Program, partly funded by a federal WaterSMART grant through the Bureau of Reclamation. Since the program launched in May 2023, fifteen projects have already removed 149,600 square feet of grass across the town. Town staff estimate that every square foot of grass removed saves roughly 50 gallons of water per year. And with about 41% of Gilbert’s water supply coming from the Colorado River — a system that is, in the words of Gilbert’s own water resources manager Lauren Hixson, “overallocated, meaning there’s more demand than there is supply” — the urgency behind this program is real and not something worth dismissing.

Arizona has a water problem. That is not up for debate.

But the way we talk about solving that problem and more importantly, the way we are spending public money to solve it, deserves a closer look. Because there is a growing assumption baked into these rebate programs and into the broader public conversation around Arizona landscaping that goes something like this: grass is bad, removing grass saves water, and whatever replaces the grass is by definition better. That assumption is not entirely wrong. But it is not entirely right either, and the parts where it breaks down matter a lot if you actually live here and care about what your neighborhood looks and feels like twenty years from now.

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The Grass Villain Argument Is Incomplete

Grass has become the villain of Arizona’s water story, and honestly, it earned some of that reputation. Huge ornamental lawns that nobody uses, decorative turf in commercial medians, grass installed in full sun on a south-facing slope with no shade and an irrigation system that runs on a fixed schedule regardless of weather. These are legitimate targets. Removing them makes sense. The water savings are real, and those landscapes are not providing anything meaningful in return for what they consume.

But not all grass is the same, and the public conversation rarely makes that distinction.

A small patch of functional lawn where kids play, where a dog runs, where a family actually spends time outdoors — that is a different conversation than a decorative commercial strip. A living lawn surrounded by mature trees, mulched beds, shrubs, and healthy soil is a different system than a massive exposed lawn baking in direct sun with no shade and daily shallow watering (please stop watering your lawn daily). The science actually supports this distinction quite clearly. A Phoenix-region study that modeled different landscape types found that what researchers called an “oasis” landscape — a design that included a modest turf area alongside shrubs and trees — produced strong daytime cooling while requiring significantly less irrigation than the turf-heavy alternatives. The study specifically concluded that oasis landscapes can provide strong daytime cooling with lower irrigation requirements than mesic, or lawn-dominant, landscapes.

This is an important finding, because it means the conversation should not just be about whether grass is present. It should be about what role the grass is playing, how much of it there is, what surrounds it, and how it is managed. Those details determine whether a landscape is a problem or a functioning system.

“The conversation should not just be about whether grass is present. It should be about what role the grass is playing, how much of it there is, what surrounds it, and how it is managed.”

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Heat Is the Other Half of This Equation

Arizona’s water conversation is almost entirely focused on gallons. How many gallons does grass use? How many gallons does rock use? How many gallons can we save by swapping one for the other? Those are fair questions. But they leave out something that affects every single person who lives here: heat.

Phoenix has one of the largest urban heat island effects in the world. The Arizona State Climate Office documents nighttime temperature differences of 10 to 14°F between Phoenix and the surrounding rural desert on calm, dry summer nights — which is exactly the kind of night we have from June through September. This is not Arizona just being Arizona. It is the accumulated result of what we have built: roads, parking lots, rooftops, concrete, asphalt, artificial turf and increasingly, hardscape yards. These materials absorb solar radiation during the day and release it slowly through the night, which is why stepping outside at 10 p.m. in August can still feel like standing in a convection oven.

The Climate Office offers a local example from Mesa. When the air temperature was 105°F at 3 p.m., asphalt in direct sun measured 155°F and concrete in direct sun measured 140°F. Shaded concrete, measured just a few feet away and within minutes of the same readings, measured 93°F.

That 47-degree difference between a shaded and unshaded surface, taken essentially in the same spot on the same afternoon, tells you almost everything you need to know about how much shade and living cover matter in this climate.

When sunlight lands on a living leaf, on mulched soil, on a vegetated surface, some of that energy goes into natural cooling processes — evaporation, transpiration, photosynthesis. When it lands on granite rock, artificial turf, concrete, or asphalt, it gets stored and radiated back out. So if a city removes grass and replaces it with rock or plastic turf, it may reduce one metric — irrigation water use — while making the underlying heat problem worse. That is not a solution. That is a tradeoff that deserves to be named honestly.

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What Living Plants Actually Do (and Why Rock and Plastic Cannot Do It)

The U.S. Environmental Protection Agency explains that trees and vegetation lower surface and air temperatures through two mechanisms: shade and evapotranspiration. Evapotranspiration is the process by which plants take up water through their roots and release moisture through their leaves. The energy required to evaporate that water comes from the surrounding air and surfaces, which has a direct cooling effect on the local environment. This is not a minor effect. The EPA notes that trees and vegetation directly shading buildings can reduce air-conditioning demand, and that urban greenery can reduce nearby building energy demand by around 10%.

This matters in the Phoenix area because cooling loads are enormous. If trees and living landscapes around your home reduce your AC demand, that is a real benefit — one that has an energy cost, an environmental footprint, and a dollar value attached to it. It is not accounted for in a metric that only measures square feet of grass removed.

The EPA also notes that vegetation helps absorb rainfall, reduce runoff, filter pollutants, and create wildlife habitat. Plants are not decoration. They are functioning infrastructure.

When we remove living plants without thinking carefully about what fills the ecological role they are playing, we do not end up with a better landscape. We end up with a different set of problems.

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Artificial Turf Is Not an Upgrade

Artificial turf gets marketed heavily in Arizona as a water-saving, low-maintenance, environmentally responsible option. In this climate, that marketing does not hold up well under scrutiny.

A 2024 systematic review examining synthetic grass surfaces found that they were consistently and significantly hotter than natural grass. Surface temperatures on synthetic turf were measured at 9.4°C to 33.7°C higher than natural grass — and air temperatures directly above synthetic turf were also elevated.

In a climate where excessive heat already kills people, that is not a minor concern.

Beyond heat, there are growing environmental questions that do not yet have clean answers. The Washington State Department of Ecology launched a specific study to evaluate whether artificial turf releases 6PPD-quinone, PFAS compounds, and heavy metals into stormwater runoff. The agency’s own documentation notes that studies have already detected PFAS from artificial turf materials, and the project is designed to characterize the presence and concentrations of these compounds in runoff. This does not mean every artificial turf installation is a contamination event waiting to happen. The science is still developing. But the concern is scientifically credible enough that a state environmental agency decided it warranted dedicated research, and that is worth knowing about before you commit to installing several thousand square feet of it in your yard.

Add in the fact that artificial turf sheds microplastics over time, eventually becomes solid waste in a landfill, and does not biodegrade, and the environmental calculus gets complicated fast. It saves irrigation water. It also adds heat, plastic, unresolved chemical concerns, and long-term disposal costs. That is not a clear win. It is a tradeoff, and homeowners deserve to understand what they are trading.

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Granite Rock Is Not the Same as the Desert

There is a widespread assumption in Arizona landscaping that covering a yard in granite gravel is “desert landscaping.” Let’s discuss why that assumption is wrong.

The Sonoran Desert — the actual, undisturbed Sonoran Desert — is not a flat sheet of decorative granite. It is a layered, living system. There are trees. There are shrubs. There is organic matter, leaf litter, shade pockets created by nurse plants, wildlife moving through, and a complex web of microbial activity in the soil. It is not barren, and it is not hot in the same way a gravel yard is hot, because it has structure and shade and living cover doing thermal work across every layer.

A front yard covered in several inches of crushed granite, no shade trees, and a few stressed plants poking through is not nature. It is a heat-storing surface that happens to be beige. In full sun, rock mulch absorbs heat during the day and radiates it into the space around plant roots, trunks, walls, sidewalks, and windows. The EPA notes that impervious and hard surfaces reduce infiltration, increase runoff, and alter how water and pollutants move through urban systems. Rock is not as impervious as concrete, but it can still create harsh growing conditions and contribute to heat storage, especially when it covers the majority of a landscape with no vegetated cover overhead.

Rock has a place in desert landscaping. But when it becomes the dominant design feature — when the goal is just to cover the ground with something that does not need water — it works against the natural cooling and water-infiltration functions that a landscape can provide. Nature covers soil because bare, exposed soil degrades and overheats. It covers it with plants, with shade, with organic matter, with living roots. A well-designed low-water landscape does the same thing. A yard full of rocks and a few ornamental boulders is not quite the same thing.

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Nobody Is Talking About the Soil, and That Is a Problem

Here is something that almost never comes up in Arizona’s water and landscaping conversation: soil.

Not plant selection. Not square footage. Not rebate amounts. The actual biological condition of the soil underneath whatever landscape you are building or removing.

Increasing soil organic matter directly increases a landscape’s water-holding capacity and makes it more resilient under drought stress. The USDA’s Natural Resources Conservation Service identifies four core principles of soil health: keep the soil covered, maintain plant diversity, keep living roots in the ground as long as possible, and minimize soil disturbance. Those principles are not just good farming philosophy — they describe exactly what a well-designed landscape should be doing.

Healthy soil absorbs water and holds it. Compacted, biologically depleted soil sheds water and dries out quickly. Healthy soil supports deeper root development, which means plants are accessing moisture from further down in the soil and need less frequent irrigation. Dead, compacted soil forces shallow roots and creates plants that are more stressed, more vulnerable, and — ironically — more water-dependent.

This is why a poorly designed xeriscape can still waste water. Compacted soil with no mulch, no organic matter, too much exposed rock, and stressed plants baking in reflected heat is not a water-efficient landscape just because it has no grass. The irrigation system still has to compensate for all the things the soil is not doing. Conversely, a small lawn in genuinely healthy soil, shaded by mature trees and watered correctly (deeply and infrequently) may be far more reasonable than the current narrative allows for.

Water policy that rewards removing grass without asking what replaces it, what condition the soil is in, or how the irrigation system is designed, is only looking at part of the picture.

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The Research on Mixed Landscapes Is Worth Reading

The Phoenix-region study on landscape types mentioned earlier is worth returning to in more detail, because its findings are specific and useful.

The study modeled three landscape categories. Mesic landscapes were lawn-dominant. Xeric landscapes used low-water plant species but with sparse leaf coverage. Oasis landscapes included a modest area of turfgrass alongside shrubs and trees — a layered, mixed approach. The results showed that xeric landscapes required the least irrigation, but they also produced the weakest outdoor cooling and the least thermal comfort for people actually spending time outside. The oasis landscape produced strong daytime cooling with lower irrigation requirements than the mesic landscape.

This is not an argument for large lawns. It is an argument for nuance. A landscape can include some grass and still use dramatically less water than a conventional yard, as long as the design is right — the grass is functional and appropriately sized, the trees are providing shade, the soil is healthy, and the irrigation is efficient. The issue was never really grass versus no grass. It was always about design quality, and that distinction matters.

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Outdoor Water Use Is Real, But Removal Is Not the Only Answer

To be clear about the scale of the issue: outdoor water use in Arizona is substantial. The Arizona Department of Water Resources has documented that landscaping is the largest single use of potable water in the state, and that as much as 70% of residential water use occurs outdoors. That is a significant target for conservation, and it is reasonable for municipalities to take it seriously.

But ADWR does not say removal is the only path forward. The agency explicitly identifies efficient design, appropriate plant selection, and improved irrigation practices as the core levers for reducing landscape water use. Those are not the same thing as just removing the grass and calling it done.

Fixing broken irrigation heads, stopping shallow daily watering cycles, grouping plants with similar water needs, adding organic mulch to reduce surface evaporation, and watering deeply and infrequently — these practices move the needle on water consumption without necessarily requiring removal of any living material.

A rebate program that only measures square feet of grass removed is rewarding one action without caring whether the outcome is actually better. Replacing a water-thirsty lawn with a heat-radiating gravel yard and plastic turf is not obviously better for the neighborhood, even if the irrigation meter reads lower next month.

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Let’s Also Be Honest About the Scale of the Problem

One more thing worth saying: the residential and commercial lawn is not the primary reason Arizona has a water problem.

This does not mean homeowners should waste water. It means the framing of the public conversation should be honest about where the bulk of the consumption is happening. When the dominant narrative is that Phoenix’s water future hinges on whether your front yard has grass in it, and meanwhile large agricultural operations have historically operated with little accountability for groundwater use, residents are not wrong to notice the imbalance.

A 2024 Arizona Auditor General report found that Arizona State Land Department agricultural leases, including the widely covered Fondomonte leases involving Saudi Arabia’s Almarai company, did not require payment for water use and did not include provisions to protect basin water levels. The report found the department did not require agricultural lessees to report groundwater use at all. Governor Hobbs announced in March 2024 that Fondomonte was no longer pumping Arizona groundwater in the Butler Valley basin after the state terminated those leases. That history is part of the context.

Individual conservation matters. Residential water use is real and worth reducing. But the conversation should be proportionate, and the policy should be serious enough to address the problem at its actual scale.

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What a Better Landscape Actually Looks Like

None of this is a defense of the large, water-wasting, ornamental lawn. That landscape does not make sense in the desert, and it never really did. But the alternative is not a yard full of plastic grass, granite gravel, and the occasional stressed desert plant. The science points clearly toward something in between.

Shade trees are the most important investment a Phoenix-area homeowner can make in the long-term livability of their property. The EPA documents that trees and vegetation directly shading buildings reduce air-conditioning demand, and that urban green infrastructure can reduce nearby building energy demand by around 10%. In a Phoenix summer, that is a meaningful and measurable benefit. Trees also absorb rainfall, reduce stormwater runoff, filter pollutants, and create the kind of microclimate that makes outdoor spaces actually usable. A tree is not decoration. In this climate, it is infrastructure.

Organic mulch — not granite, not plastic, but actual wood chip or decomposing organic material — covers the soil, reduces surface temperature, slows evaporation, feeds soil biology, and gradually builds the organic matter that helps the soil hold water. It mimics what the natural desert does: covers and protects the soil surface with material that is part of a living system.

Efficient irrigation means drip emitters placed correctly, smart controllers that respond to weather data, and watering schedules built around deep, infrequent cycles that encourage roots to go down instead of staying shallow. It means auditing the system annually to find and fix leaks and broken heads. It means not running the system on the same schedule in October that you ran in July.

And grass, where it exists, should be functional, appropriately sized, surrounded by shade, and watered correctly. A small patch of Bermuda or a drought-tolerant grass variety in a shaded, well-designed yard, watered on a deep and infrequent schedule, is a very different thing from a large exposed lawn running on a fixed-clock system. The design determines whether it is a problem or a feature.

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Sources

• ABC15 — Gilbert considers $250,000 plan to expand grass removal rebate program
• Gilbert, AZ — Water Conservation Rebates
• Arizona State Climate Office — Urban Heat Islands
• U.S. EPA — Using Trees and Vegetation to Reduce Heat Islands
• USDA Natural Resources Conservation Service — Soil Health
• Arizona Department of Water Resources — Landscape Water Use
• EPA WaterSense — Irrigation Controllers
• 2024 systematic review — synthetic turf surface temperatures vs. natural grass
• Washington State Department of Ecology — Artificial Turf Runoff Study
• NASA / ADWR — Arizona water use by sector (irrigated agriculture, municipal, industrial)
• 2024 Arizona Auditor General Report — State Land Department agricultural leases and groundwater reporting
• Phoenix-region landscape modeling study — mesic, oasis, and xeric landscape irrigation and cooling outcomes