Uniting for Water: Regional Groundwater Management for Flagstaff, Arizona and Beyond

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Nestled at the base of the San Francisco Peaks in northern Arizona, Flagstaff is a city renowned for its natural beauty, vibrant community, and unique location along the Colorado Plateau. Beneath this picturesque landscape lies the Coconino Aquifer (C-aquifer), a vast groundwater resource spanning four states and two tribal nations. The aquifer serves as a vital water source for Flagstaff, supporting its 76,000 residents, industries, and growing community. However, the C-aquifer is under increasing pressure. Rising temperatures and prolonged droughts linked to climate change, coupled with overuse from expanding agricultural, industrial, and urban demands, threaten to deplete this critical resource. For Flagstaff, which relies heavily on the C-aquifer to meet its water needs, these challenges raise urgent questions about long-term water security. In this blog, we’ll explore the factors driving these challenges and highlight potential solutions to ensure the sustainable management of Flagstaff’s groundwater.

Figure 1: Flagstaff is located in northern Arizona and consists of two drinking water treatment plants and two water reclamation plants (WRP).

Hydrology and Water Sources

Flagstaff’s hydrology is intricately tied to its high-altitude location and seasonal climate, which define the availability of its water resources. The City experiences distinct wet and dry periods throughout the year, with precipitation concentrated during the monsoon season (July to September) and the colder months (October to March). Monsoons bring two to three inches of rainfall per month, while winter storms deliver abundant snow, contributing to an average annual snowfall of 109 inches.1 Dry spells from April to June see less than an inch of rain monthly, emphasizing the importance of snowmelt and monsoonal rains for the region’s water supply.

Figure 2: Most of Flagstaff’s annual precipitation occurs in its monsoon seasons (July through September) or colder winter months in the form of snowfall (November through March).

Beneath Flagstaff lies the C-aquifer, part of the expansive Colorado Plateau aquifer system, which spans over 100,000 square miles across Arizona, New Mexico, Colorado, and Utah.2 This aquifer is essential for the Southwest U.S., supporting municipal, agricultural, and industrial needs. Flagstaff relies on the C-aquifer for 60 to 70 percent of its drinking water, drawing from municipal wells that tap into its vast reserves.3 The aquifer recharges primarily through snowmelt and precipitation in high-elevation areas, such as the nearby San Francisco Peaks. Surface water, including flows from Upper Lake Mary and smaller streams, also contribute to the City’s water portfolio, though these are highly dependent on variable precipitation.4 To supplement these sources, Flagstaff has also invested in the use of reclaimed water, distributing treated wastewater for irrigation and other non-potable purposes. This diversified approach to water management highlights the City’s innovative efforts to adapt to its semi-arid environment, but it also underscores the importance of protecting the C-aquifer as a lifeline for the region.

Figure 3: The Coconino Aquifer spans four states, as well as two tribal nations. (Source: USGS)
Figure 4: Over 60 percent of Flagstaff’s water supply comes from the Coconino Aquifer and an additional 18 percent from surface water.

Groundwater Challenges

Flagstaff faces a growing set of challenges that threaten its water supply, driven by climate change, population growth, and a lack of comprehensive groundwater regulation. Climate change is altering the City’s seasonal precipitation and temperature patterns, introducing uncertainty into its water systems. Models predict variations in snowpack and precipitation as climate change-driven patterns persist, which affect the timing and availability of water resources. Extended droughts are expected to reduce surface water supplies from sources like Upper Lake Mary and the springs in the Inner Basin of the San Francisco Peaks.5 Additionally, diminished precipitation will slow aquifer recharge, increasing reliance on the C-aquifer. Rising temperatures and longer summers will heighten water demand, amplifying the risk of over-extraction from this vital groundwater source.

Figure 5: A web of water-related challenges that Flagstaff faces, many of which relate to unregulated and unmonitored groundwater.

Groundwater management in Arizona compounds these challenges for some regions of the state. While Arizona’s Groundwater Management Act of 1980 regulates pumping in six designated Active Management Areas (AMAs), Flagstaff and much of rural Arizona fall outside these zones.6 In these areas, groundwater use is loosely governed by the Adequate Water Supply Program and the reasonable use doctrine, which allow landowners to withdraw groundwater for beneficial purposes without strict oversight.7 Although Flagstaff has voluntarily demonstrated a 100-year water supply under the Adequate Water Supply Program, there is no mandate for sustainable yield or mechanisms to prevent over-pumping.8 The lack of regulation makes it difficult to monitor groundwater usage and address overuse by agricultural and industrial users, which already places strain on the C-aquifer.

Figure 6: Active Management Areas (AMA) in Arizona only account for a portion of the state’s necessary groundwater management needs. (Source: Inside Climate News)

As Flagstaff’s population grows and climate change intensifies, these overlapping challenges risk depleting the C-aquifer and jeopardizing the City’s future water security. Addressing these issues will require innovative approaches, improved management strategies, and collaboration across local and regional stakeholders.

Figure 7: Upper Lake Mary’s water supply receding during a drought. (Source: AZ Central)

Local Solution: Expanding Use of Reclaimed Water

To address its growing water challenges, Flagstaff can build upon its existing use of reclaimed water, a key component of its diversified water portfolio. The City currently treats wastewater at two advanced reclamation plants: the Wildcat Hill Water Reclamation Plant (WRP) and the Rio de Flag WRP.9 These facilities produce Class A+ reclaimed water, the highest quality of non-potable water in Arizona, which Flagstaff uses for irrigation, industrial processes, and dust suppression. Reclaimed water accounts for 19% of Flagstaff’s current water supply.10

Figure 8: Flagstaff’s largest water reclamation plant (WRP), Wildcat Hill WRP. (Source: City of Flagstaff)

To enhance resilience and reduce dependence on vulnerable potable water sources, Flagstaff could expand its use of reclaimed water, substituting it for potable water in appropriate non-drinking applications. For example, residential water use – currently relying almost entirely on potable water – could shift to include reclaimed water, reducing potable consumption by 25%. Similarly, manufacturing and non-residential landscaping could cut potable water use by 50% in favor of reclaimed water. Such measures would help reduce stress on the C-aquifer and Upper Lake Mary, conserving these critical resources for future drinking water needs.

Figure 9: Example of a potential water portfolio for Flagstaff that would decrease their reliance on the aquifer and increase their reclaimed water supply. (Source: Water Management Summary 2016)

However, implementing this shift comes with challenges. Expanding reclaimed water infrastructure is both time-intensive and costly, requiring significant investment and coordination. Additionally, consumer acceptance of reclaimed water, particularly for residential use, is crucial for the success of this strategy. Public education campaigns and incentives could play a vital role in changing perceptions and promoting the sustainable use of reclaimed water in Flagstaff.

Regional Solution: A Regional Approach to Groundwater Management

In contrast to the localized solution of expanding Flagstaff’s reclaimed water use, a more effective approach addresses the issue at its core: the implementation of a regional strategy for managing the C-aquifer across all geographies that draw from it. The absence of a unified regulatory body and comprehensive monitoring system significantly limits the ability to prepare for future population growth and respond to a changing climate. Currently, the US Geological Survey (USGS) monitors the C-aquifer only in northeast Arizona, leaving much of the aquifer unmonitored in the other three states.11 While Flagstaff can take steps to manage its own water use, the C-aquifer is a shared resource that is impacted by agricultural, industrial, and residential demands from the entire region.

A regional solution requires a coordinated, cross-jurisdictional approach to ensure the long-term sustainability of the aquifer. Flagstaff, as one part of this broader system, needs to work with the region to develop a unified governance structure. A governing body, with representation from all four states and the Navajo and Hopi Tribal Nations, should be established to oversee, regulate, and enforce sustainable management of the C-aquifer. This approach would incorporate a “One Water” philosophy, recognizing the interconnected nature of groundwater and surface water. By managing both systems together on a regional scale, Arizona and its neighboring states can take a proactive, collaborative stance in safeguarding this critical resource for future generations.

Creation of a Joint Powers Authority (JPA)

Our proposed solution is the establishment of a multi-state Joint Powers Authority (JPA) to oversee the management of the C-aquifer. This would serve as a foundational body that could later evolve into an interstate compact agency, granting it broader legal powers. The Coconino Aquifer Authority (CAA) would be responsible for monitoring groundwater resources across portions of Arizona, New Mexico, Colorado, Utah, and the Navajo and Hopi Tribal Nations. This collaborative body could develop a comprehensive strategy for groundwater management, grounded in research and data collection. Once established as an interstate compact agency with enhanced powers, the Coconino Aquifer Commission (CAC) would be able to implement the groundwater management strategy created by CAA. It is critical that this solution be implemented promptly, as any mismanagement of the C-aquifer could have devastating consequences for the millions of people who rely on it. Because obtaining congressional approval for an interstate compact may take several years, forming a JPA initially would allow for immediate action. This would enable progress to begin while awaiting the necessary federal approval for the compact.

Figure 10: The creation of the Coconino Aquifer Authority (CAA) would allow states to better manage and monitor groundwater within the aquifer.

There are several precedents that demonstrate the feasibility of multi-state water management, though they primarily focus on surface water rather than groundwater. The Delaware River Basin Commission (DRBC), established in 1961, provides an example of effective regional water governance. This commission manages the Delaware River system, which spans four states – Delaware, New Jersey, Pennsylvania, and New York. The DRBC has successfully coordinated efforts across state lines, ensuring that the river’s water resources are used sustainably and equitably by all four states.12 Another example is the Great Lakes Commission (GLC), which manages the Great Lakes, one of the largest surface water systems in the world. The GLC is a nonpartisan body composed of government-appointed commissioners representing eight U.S. states and two Canadian provinces.13 This commission has been instrumental in overseeing the management of the Great Lakes, addressing both environmental protection and water usage concerns across a broad, international region.

Figure 11: Both the Delaware River Basin Commission and the Great Lakes Commission span multiple state, and even international, boundaries. (Source: DRBC, GLC)

Closer to home, Arizona, Colorado, Utah, and New Mexico already collaborate through the Western States Water Council (WSWC), which focuses on promoting sustainable water use in the Western U.S. The WSWC brings together water managers, policymakers, and stakeholders from multiple states to address regional water challenges and develop shared solutions.14 However, while all of these examples represent successful regional management of surface water, none address groundwater management. Given the similarities in cross-border water challenges, these precedents offer valuable insights into the potential for creating a multi-state, regional governance structure for the C-aquifer.

To effectively monitor the C-aquifer, CAA could implement a range of advanced and collaborative tactics. A comprehensive monitoring network would include strategically placed wells equipped with real-time sensors to measure groundwater levels, quality, and withdrawal rates.15 Groundwater quality testing would be conducted regularly to detect contaminants, establish baseline conditions, and address pollution sources. Recharge and withdrawal rates could be tracked through tools like flow meters, while water budget analyses compare recharge and extraction to maintain balance.16 Partnerships with agencies like the USGS and local universities could bolster data collection and analysis, supported by centralized platforms for transparent data sharing. Environmental impact studies, including hydrological modeling and ecosystem assessments, would ensure the aquifer’s sustainability under changing conditions, while weather stations could monitor precipitation and drought indicators to evaluate impacts on recharge. Public engagement through community science programs, workshops, and accessible monitoring reports would further enhance understanding and accountability in aquifer management. Together, these strategies provide a robust framework for sustainable groundwater stewardship.

With federally granted powers, CAC could manage the C-aquifer regionally through regulation, enforcement, and implementation of sustainable practices. The Commission would establish consistent, region-wide rules, including groundwater permitting, zoning restrictions for critical recharge areas, and safe yield standards to balance withdrawals with recharge.17 During droughts, it could enforce contingency plans to restrict usage and protect the aquifer. With federal backing, CAC would ensure compliance through regular monitoring, audits, and penalties for violations, while also serving as an arbiter for interstate disputes and conflicts among stakeholders. Active management initiatives could include implementing managed aquifer recharge projects, promoting water-efficient technologies, and coordinating regional infrastructure investments, such as pipelines and storage facilities.18 Using data from comprehensive monitoring programs, the Commission would adapt its policies to address emerging challenges and ensure equitable resource allocation. By collaborating with tribal nations, federal agencies, and local governments, CAC could align regional goals, leverage resources, and sustain the aquifer for future generations.

To establish CAA, a review of state statutes is necessary to ensure that interstate agreements are permissible. If such agreements are not allowed under current statutes, amendments must be made.19 Following this, cooperation between governors and tribal leadership is necessary to identify the relevant agencies that can participate in forming the JPA. Once the stakeholders are identified, a Joint Powers Agreement will be drafted, outlining the authority’s purpose, governance structure, and funding mechanisms. The final step involves each state and tribal nation approving the JPA through their respective legislative bodies or by governor approval. Creating an interstate compact is more complex than establishing a JPA. First, a draft compact based on the Joint Powers Agreement must be created. All participating states and nations must approve the compact, after which it will be submitted to Congress for review. The compact must then receive approval from both Congress and the President before it can take effect.20

Figure 12: The process of creating a Joint Powers Authority.

Coconino Aquifer Authority

CAA will be structured with a clear hierarchy to ensure effective governance and coordination among all stakeholders. The State and Federal Council, which will consist of the governors of the four states, as well as the leaders of the Navajo and Hopi Tribal Nations and one representative from the USGS, will facilitate coordination. Each state leader will appoint up to two additional representatives to ensure comprehensive representation. This council will ensure that the diverse interests and priorities of each region are considered in decision-making. Supporting the State and Federal Council will be a State Agencies Committee, composed of appointed representatives from state agencies that play a role in water management. For example, in Arizona, the Department of Agriculture, Department of Environmental Quality, and Department of Water Resources will provide input based on the specific needs and challenges of their state. This committee will ensure that all relevant state-level concerns, such as agriculture, environmental protection, and water regulation, are properly addressed.

Figure 13: The JPA will consist of representation from all states and tribal nations across multiple political levels, including state, county, and local representatives.

County Representatives from those that rely on the C-aquifer for a majority of their water supply will act as liaisons between CAA and local interests. Every two to three years, county representation will be reassessed based on groundwater usage to ensure that any new counties relying on the aquifer are included in the management hierarchy. CAA will also include an Interest Groups and Industries Committee, which will represent key sectors with high water consumption, such as agriculture and industry. This committee will balance the economic needs of these groups with the goals of sustainable water management, ensuring that these stakeholders have a voice in the decision-making process while still adhering to environmental and resource management goals. To ensure transparency and public engagement, the general public will be involved through public meetings and participation in committees. This engagement will allow for equitable representation of community concerns and foster broader public understanding of the challenges and solutions related to the aquifer. Finally, CAA’s staff will handle the day-to-day operations and implementation of the Commission’s directives. This staff will include a Director and Deputy Director, as well as experts in policy, law, groundwater science, environmental studies, engineering, and planning. These professionals will ensure that the JPA’s objectives are met through careful planning, research, and coordination among all parties involved.

CAA and Interstate Compact Agency Funding

The primary funding source for CAA will come from state governments. States will contribute based on the percentage of their population that relies on the C-aquifer.21 Additionally, federal funding could be accessed through grants or loans. For example, the USGS’s Groundwater Resources Program provides funding for projects that improve the understanding of groundwater systems, including groundwater modeling, monitoring, and data analysis, all of which support aquifer management and protection.22 Also, the Bureau of Reclamation’s WaterSMART program also offers financial assistance for water management improvements, the development of collaborative watershed groups, and projects that contribute to sustainability in the Western U.S.23 Once CAC is established, it will be able to access federal funding. For example, the Delaware River Basin Compact receives 20% of its financing from the federal government, demonstrating the potential for federal support in similar interstate compact projects.24

Figure 14: Potential funding breakdowns for states and tribal nations. Current percentages are estimates based on population densities within the aquifer and reported usage.

Benefits and Limitations

A JPA offers several advantages for the management of the C-aquifer. One key benefit is the faster implementation relative to an interstate compact. While compacts often require a lengthy and complex approval process, particularly at the federal level, a JPA can be established faster. This allows for more immediate responses to the pressing water issues in the region. Additionally, a JPA provides a long-term solution for sustainable groundwater management. By bringing together representatives from multiple states, tribal nations, and key stakeholders, a JPA can create an adaptable governance framework that works toward the preservation and equitable management of groundwater resources. This makes it a robust solution capable of addressing evolving water challenges as the climate shifts and population grows. Unlike physical infrastructure projects that require significant labor and material costs, a JPA primarily functions as a governance structure, which can be implemented and maintained with relatively low overhead. Moreover, a JPA has the potential to evolve into a compact as the need for more formal legal authority arises.

Figure 15: Benefits and limitations to the creation of a JPA to monitor the C-Aquifer.

However, there are limitations to consider. For instance, Arizona still needs its own groundwater management strategy to complement the JPA’s regional work. While the JPA would address broader, multi-state challenges, it cannot replace the need for more localized, state-specific solutions to groundwater use and regulation. Additionally, while a JPA can address many aspects of groundwater management, it is not a comprehensive strategy to solve all of Flagstaff’s water challenges. The City faces broader water issues beyond just groundwater depletion, such as stormwater management, surface water usage, and wildfires, which would need separate and complementary solutions. Regulation and enforcement also pose significant challenges for a JPA. Since multi-state water management is still relatively rare, balancing the legal systems of multiple states and tribal nations will require extensive cooperation and careful navigation of different water laws. This can complicate enforcement efforts and hinder the full effectiveness of the JPA’s mandates. As a more localized governance framework, a JPA has limited access to federal resources, which typically require formal agreements like compacts or other federally recognized entities. However, the implementation of a compact after the JPA would unlock federal funding and grant the entity the regulatory authority it needs to enforce its management strategies across the region.

Conclusion

Currently, the lack of regional monitoring significantly impacts Flagstaff’s ability to accurately estimate groundwater usage. Establishing a Joint Powers Authority would provide the data and resources necessary for Flagstaff to better understand and define sustainable groundwater yield. Since Flagstaff’s primary water source is the C-aquifer, improving the resilience of this resource is essential to ensuring a reliable water supply for the City’s future. On a regional scale, such an organization would help all states contribute their fair share to the sustainable management of the C-aquifer. This would include both monitoring and managing groundwater to ensure that all partners are held accountable for their usage that inevitably affects all others that are dependent. With these measures in place, the C-aquifer could provide a stable and sustainable water supply, benefitting all dependent parties through responsible use and recharge. The establishment of the Coconino Aquifer Authority, and subsequent Coconino Aquifer Commission, could serve as a model for regional groundwater management nationwide. While there are existing interstate compacts, these agencies only manage surface water. No current framework addresses groundwater on a similar scale, nor do independent groundwater-specific compacts exist. On a national level, it is critical to collectively manage groundwater resources, as aquifers do not adhere to municipal or state boundaries. Implementing regional approaches to groundwater management could set an important precedent for addressing water challenges across the country.

Figure 16: Flagstaff, Arizona relies on the secure water supply of the Coconino Aquifer to remain beautiful. (Source: Flagstaff)

Sources

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