Arizona says Marana has enough water for building boom but critics disagree

Arizona water officials gave the green light to Marana’s growth for another decade by affirming the town has enough water to serve that much more development for 100 years.

The Arizona Department of Water Resources’ draft decision in Marana’s favor will, when finalized, allow for more than doubling of the population living inside the town’s water service area by 2034.

The decision came over written objections of well over 50 people and groups who argued, among many other things, the town was betting too much of its future on pumped groundwater.

ADWR found the objections had no legal basis, and that the town proved its groundwater supply will be “physically, legally, and continuously available for 100 years.” Under state law, new subdivisions built in urban areas such as those of Tucson and Phoenix must have a state-designated, assured 100-year water supply.

In response to one objection, however, ADWR did issue a potential future warning about assured water supplies, to Marana and other cities and towns that take Central Arizona Project water from the Colorado River’s declining flows.

In the future, the “department may consider amending its assured water supply rules for Colorado River and CAP water supplies ... once additional information becomes available on what future Colorado River management might look like,” ADWR said.

Today, ADWR is required by state rules to assume that cities and towns can rely on having 100% of their CAP supplies when the department determines if they have an assured water supply. Marana gets about 15% of its water from CAP, with 72% coming from native groundwater and the rest mainly from treated sewage effluent.

Marana Water Director Jing Luo said the decision will help Marana chart a path to a sustainable water supply and allow it to focus on making more renewable supplies available.

Working with ADWR officials, “together, we have navigated complex data analysis, groundwater modeling, and stakeholder engagement to demonstrate all criteria required for the new (designation) that incorporates all of its existing development plans,” Luo said.

Mark Johnson of the Tortolita Alliance said the decision simply confirms his view that the state’s 44-year-old, nationally heralded groundwater law isn’t consistent with prudent groundwater management.

But, “after considering the application, the objections, and Marana’s response, the department determined that the application satisfies all of the requirements for a designation of assured water supply,” wrote David McKay, manager of ADWR’s Recharge, Assured & Adequate Water Supply Program, in a letter last week to the objectors and to Marana officials.

State requirements for financial capability of delivering the supply, its water quality, and its consistency with the state’s management plan and goals for the Tucson area were also met, McKay wrote.

The agency’s Feb. 26 decision amounts to a modification of its 2018 finding that the town had an assured water supply. It was needed because Marana’s development has outrun the amount of assured water supplies certified by past state decisions.

The 2018 decision re-certified the same amount of assured supply as had been approved in 2007, and “since then, development has boomed in Marana,” Luo said.

“This ... modification is especially meaningful for the fast-growing Marana community, “ Luo said.

As examples of new renewable supplies, she cited a project, expected to start design in early 2025, to double the capacity of Marana’s wastewater treatment plant. She also cited a $3 million state grant — of which the town will match $1 million — to expand an effluent recharge facility at the sewage treatment plant site.

“These initiatives are best management practices, demonstrating our commitment to a sustainable water future,” Luo said.

The Tortolita Alliance, a nonprofit activist group that led the parade of objections, penned ADWR a letter last week saying it won’t appeal the agency’s decision.

“It is clear that any appeal will be denied based on strict legal interpretation of existing statutes,” the alliance wrote.

But Alliance President Johnson notes that some of his group’s objections echo the findings of two reports from Arizona State University researchers that decried the continued use of groundwater to support population growth.

When finalized, this draft decision will allow Marana water service area population to reach about 74,200 in a decade, town officials say.

Marana’s total population was nearly 56,000 in July 2022, said the most recent U.S. census report. But many existing residents live in parts of Marana supplied by the Tucson Water utility rather than by Marana Water.

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Marana has long been one of Arizona’s fastest-growing municipalities. Marana Mayor Ed Honea says the town’s total population could hit 100,000 by the late 2020s. The regional Pima Association of Governments has projected 78,300 people living there by 2035 and 86,000 by 2040.

The alliance had raised 17 concerns about Marana’s application. Many other objectors followed the alliance’s footsteps in their letters.

Johnson is also concerned about officials’ ability to keep recharging Colorado River supplies from the Central Arizona Project into the aquifer due to the likelihood of future river water shortages. His objection letter said Marana’s projected future population and water demands are “unrealistic and unsustainable.”

His objection took particular aim at Marana’s projection that continued pumping there could cause the aquifer in the area to fall to up to 800 feet deep. While a 1,000-foot reduction in groundwater levels is allowable under state law, he said it would still leave the aquifer “severely impacted with significant drawdown” in water levels.

Marana Water has said that projection is unlikely to materialize because it expects the recharge of CAP water into nearby basins will keep the water table from falling that far.

Some specific ADWR responses to objections raised by opponents of Marana’s request:

— Objectors argued for revising downward Marana’s future water demand projections to account for the prospect of less water available due to climate change and future conservation requirements.

ADWR responded, “Neither statute nor rule currently require the Department to consider impacts from climate change or future water conservation in reviewing demand projections or physical availability requirements.”

— Objectors said the Town Council should approve no new subdivisions “until renewable and permanent water supplies are secured to service new growth and ensure long-term safe yield is achieved and maintained.” Safe yield is accomplished when no more groundwater is pumped from an aquifer than what’s replenished naturally or by human efforts.

But not only do state laws and rules prohibit modifying a designation if it has already approved specific development plans and agreements, such plans support the projected demands included in the application by Marana, ADWR said.

— While the state law allows groundwater in urban areas to be pumped up to 1,000 feet deep, opponents said the application shouldn’t be approved until it can be shown via computer modeling that safe yield can be achieved. The town’s current plan is inconsistent with the state’s management plan and management goals for the state-run Tucson Active Management Area for water, the opponents said.

But ADWR said an entity can be consistent with a state management goal of safe yield by joining the three-county Central Arizona Groundwater Replenishment District. The district must replenish enough groundwater to compensate for what’s pumped by Marana’s new development for the next 10 years.

— Objectors said the town’s application should not be approved until additional permanent and renewable sources of supply are secured, citing state law.

But that law not only explicitly authorizes the use of groundwater as part of an assured water supply application, it is the first water supply on the list of acceptable supplies, ADWR said.

The alliance, in its letter saying it won’t appeal, asked ADWR to impose five new conditions on Marana as part of its approval.

The most consequential of those requests is for the state to agree to modify or revoke Marana’s assured supply designation “if CAP supplies are appropriately adjusted downward due to over allocation of the Colorado River.”

Another request is to require Marana Water to post on its website the current population and future population projections for the entire service area and each of five individual water systems for every year until they are completely “built out.”

Opponents also want the town to conduct at least three public workshops concerning the latest ADWR decision and any future modifications of Marana’s assured supply status.

Marana officials do not believe these proposed conditions “are required or appropriate,” Luo told the Star.

“Marana Water will continue to engage in the state and regional-level planning efforts that are necessary to support a reliable water future. Additionally, Marana Water looks forward to sharing more information with the community through websites, social media, and public engagement events in the very near future,” Luo said.