Water-Neutral Development as a Key Component in Arizona’s Water Security Strategy

By Benjamin A. Longbottom.


Western water insecurity. Ninety percent of the Western United States is experiencing severe drought. Lake Mead is at its lowest level since the Hoover Dam was built in the 1930s. The recent declaration of a shortage on the Colorado River has heightened concerns about water security and drought resilience in the West. Climate change is exacerbating fundamental sustainability problems like population growth and water insecurity. The United Nations defines water security as “[t]he capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development . . . .”

Drought, along with legal and socioeconomic factors, is making Arizona an increasingly water-insecure state. For example, some farmers in Arizona’s Pinal County, hit hardest by the Colorado River shortage, are unable to sustain their livelihoods because of the lack of water. “We’re not sure how long we can hang on,” said one farmer. For now, municipal water supplies are safe, and residents are unlikely to feel the impact of the drought at the tap. But without rapid, comprehensive, and aggressive changes to the ways Arizona—and other western states—handle water, water insecurity will only worsen. This requires changes to water law and policy, and changes to the ways we think about water.

Arizona water policy. Arizona’s Groundwater Management Act (GMA) requires all new development within “Active Management Areas” (AMAs), roughly corresponding to the major urban areas in Arizona, to prove that it has at least 100 years’ worth of legally, physically, and continuously available water. Otherwise, the development will not be permitted, and construction cannot occur. AMAs also mandate compliance with conservation-focused “Management Goals,” which can involve installation of water-efficient appliances and membership in organizations that recharge groundwater aquifers.

The GMA is a good example of connecting land use and development with water, but it is not doing enough. While the GMA controls urban development and prevents development from occurring without sufficient water, it fails to adequately curb water demand. If a developer can prove that water is “available,” they can build. Just because water is available, however, does not necessarily mean we should use it without considering the impact of that use on water security. Even the AMA Management Goals fall short of capping water demand, which could be increasingly important to reduce the burden of future shortages on farmers and cities.

Water-neutral development 

What is it and how does it work? Water-neutral development is a legal requirement that new and existing developments that cause an increase in water demand must offset that demand, either through conservation or augmenting new supplies. The idea is to ensure that new developments are “neutral” to the water supply system.

Water-neutral programs generally provide new development (and existing development that gets remodeled or otherwise somehow increases its expected water demand) two steps to comply: first, developments can minimize their expected demand with on-site water saving choices such as water-efficient appliances or drip landscape irrigation; then, the development must completely offset whatever new demand is leftover after the initial reductions. Developers complete this second step by facilitating, either directly or through funding, off-site actions that increase water supply or reduce existing water demand in the area, typically at a city or regional level.

In other words, if I am a real estate developer seeking to build a new office park on suburban land, to get the necessary permitting I would need to take two steps. First, I need to reduce the expected demand of my new development by installing low-flush toilets, automatic shut-off faucets, and similar water efficient appliances. Second, I need to offset whatever water demand my development will have after those measures by funding demand-reducing actions in other places. If I have another office building nearby, I can upgrade its appliances and fix leaks. Or I could provide funding for a local farmer to convert from flood irrigation to drip irrigation. Once I have offset my demand (usually on a 1:1 basis), I can complete my new development.

This is similar to the way the Arizona Groundwater Management Act operates, in that new developers sometimes need to purchase recharge credits from other users in order to comply with requirements of “safe yield” (a balance between groundwater withdrawals and recharge). But water-neutral development goes further, firmly capping water demand at its present level.

California cities and water districts as a model. Several cities in California, including Napa, have implemented water-neutral development with great success. Most of the California programs focus on retrofitting as the primary option available to developers seeking to offset their demand. This means that most developers pay for other developments to remove water-using appliances (usually toilets) and reinstall newer, more water-efficient versions. One problem with this strategy is called “retrofit saturation,” which means that the reductions in water demand associated with retrofitting decline the more it is done. Other California programs have more offset options available to combat this problem.

California cities draw legal support for their water-neutral programs from Article X, section 2 of the California Constitution which requires “reasonable” use of water. This generally only requires “reasonable efficiency,” which could limit the offset requirements of a water-neutral program. For example, maybe a 1:1 offset requirement is “reasonable” but a 2:1 requirement is not, though difficulties accurately predicting and measuring demand make higher offset ratios more effective. California’s Water Code also explicitly authorizes water suppliers to adopt water conservation programs and condition new service on customers taking water-saving actions. Arizona’s constitution similarly requires only “reasonable efficiency,” which is unlikely to be a barrier to implementation of water-neutral development policies, but could impact its efficacy.

Challenges. Water-neutral development provides a way to limit the growth in water demand because of continuing population growth and urban expansion. However, it is by no means a cure-all. Water-neutral development policies could easily drive up housing prices by introducing a new cost for residential developers that they could pass on to residents. Water-neutral policies also do little to control the largest water users in the West—farmers. Agriculture consumes nearly seventy-five percent of all the water used in Arizona, whereas domestic and public uses account for around twenty percent. Nonetheless, that twenty percent is crucial and can be significantly reduced by imposing offset requirements and capping demand. Though replacing agricultural land with urban land generally decreases water demand, urban sprawl carries its own host of problems that Arizona should avoid.

Nicole Horseherder, a member of the Navajo Nation, directs an advocacy organization called Tó Nizhóní Ání (“sacred water speaks”). Reacting to the Colorado River shortage, she told Time Magazine, “It’s critical that the rivers continue to flow.” She went on to describe the role of water in Navajo culture: “Everywhere you go, you always greet water as your mother. If there’s a flowing river, that’s your mother flowing, and her body is long, and her body can wind, and her body is pure, and it glistens in the sunlight. And so, you speak to her because she’s powerful.” Arizona’s water is speaking to us, demanding a comprehensive legal, social, and economic paradigm shift, and we have an incredible opportunity to answer her call. Improving water security in Arizona and the West will improve social and environmental justice and eliminate uncertainty that depresses sustainable economic development. Water neutral-development policies, including enforceable mandatory demand offsets, should be an important part of this process and will help us to better internalize the water costs of land use and development.


Water-neutral development could help Arizona get a handle on its urban and suburban water demand as well as slow unsustainable growth. Ultimately, water-neutral development will force developers to internalize the water costs of their actions, thereby reducing demand and freeing up water for the environment, for farmers, and for use in future drought emergencies which are all but certain to be worse than what we have seen so far.

"Blue Water" by fox_kiyo is licensed under CC BY-SA 2.0