What If Arizona Implemented Different Water Rights Policies?

The Actual History

Arizona's approach to water rights has been shaped by its arid climate and the scarcity of water resources in the American Southwest. Like most western states, Arizona primarily adopted the doctrine of prior appropriation for surface water rights, often summarized as "first in time, first in right." This system, which emerged during the mining boom of the 19th century, grants senior water rights to those who first put water to "beneficial use," regardless of their proximity to the water source. This stands in stark contrast to the riparian doctrine prevalent in water-abundant eastern states, where water rights are tied to land ownership adjacent to water bodies.

In 1919, Arizona formally codified its surface water rights through the Public Water Code, cementing the prior appropriation system. However, the state took a different approach to groundwater, which remained largely unregulated until the 1980s. This created a dual system that treated surface water and groundwater as legally distinct resources, despite their hydrological connection.

A pivotal moment came in 1980 when, facing severe groundwater depletion and pressure from the federal government regarding the Central Arizona Project, Arizona passed the Groundwater Management Act (GMA). This landmark legislation established Active Management Areas (AMAs) in regions with critical groundwater problems, primarily around urban centers like Phoenix and Tucson. The GMA imposed restrictions on new agricultural irrigation, required developers to demonstrate a 100-year assured water supply, and set conservation requirements for municipal and industrial users.

Meanwhile, Arizona's rights to Colorado River water—crucial for supporting its growing population—were established through interstate compacts and Supreme Court decisions. The 1922 Colorado River Compact allocated 7.5 million acre-feet annually to the Lower Basin states (Arizona, California, and Nevada). After decades of legal battles, Arizona secured 2.8 million acre-feet of this allocation through the Supreme Court's decision in Arizona v. California (1963), though California maintained senior rights.

The completion of the Central Arizona Project (CAP) in the 1990s finally allowed Arizona to fully utilize its Colorado River allocation, transporting water 336 miles from the river to central and southern Arizona. This massive infrastructure project, costing over $4 billion, became the state's lifeline.

In recent decades, Arizona has faced increasing water challenges due to climate change, prolonged drought, and population growth. The Colorado River has experienced significantly reduced flows since 2000, leading to unprecedented cuts in water deliveries under the 2019 Drought Contingency Plan. Arizona, with its junior priority status, has borne the brunt of these reductions. Groundwater remains overexploited in many areas outside the AMAs, where few restrictions exist.

Despite these challenges, Arizona has implemented some innovative approaches, including the Arizona Water Banking Authority (which stores unused Colorado River water underground for future use) and managed aquifer recharge programs. The state has also been a leader in treated wastewater reuse, with cities like Phoenix recycling nearly all of their municipal wastewater.

By 2025, Arizona faces a precarious water future. The reservoirs of Lake Mead and Lake Powell have reached critically low levels, climate models predict continued aridification of the Southwest, and groundwater levels continue to decline in many areas. The state's water management framework, built around prior appropriation, grandfathered rights, and bifurcated regulation of surface and groundwater, struggles to address these 21st-century challenges.

The Point of Divergence

What if Arizona had implemented a different water rights system in its formative legal period? In this alternate timeline, we explore a scenario where Arizona adopted a modified riparian rights system instead of prior appropriation, fundamentally altering how water resources would be allocated, managed, and conserved throughout the state's development.

The point of divergence occurs in the territorial period, specifically in the 1880s. In our timeline, the territorial legislature and courts largely followed California's lead in adopting prior appropriation principles. However, in this alternate history, a different combination of legal precedents, influential settlers, and practical considerations led Arizona down a different path.

Several plausible mechanisms could have caused this divergence:

First, Arizona's territorial courts might have been influenced by judges with eastern backgrounds who brought riparian doctrine thinking with them. If influential early jurists like Judge William H. Barnes (appointed to the Territorial Supreme Court in 1885) had stronger ties to eastern water law traditions, they might have established precedents favoring riparian principles adapted to arid conditions.

Alternatively, the timing of Arizona's settlement and development could have played a crucial role. If agricultural development had preceded mining as the territory's economic driver (rather than the other way around), the legal system might have evolved to protect the interests of farmers with lands adjacent to rivers, rather than distant mining operations.

A third possibility involves the influence of the federal government. If federal policies had more strongly encouraged water conservation in the late 19th century, Arizona might have been pressured to adopt a system that limited water rights to reasonable use by riparian landowners, with stronger public interest provisions.

In this alternate timeline, by 1900, Arizona had established a hybrid "regulated riparian" system with these key features:

Water rights primarily attached to lands adjacent to water sources, but with reasonable use limitations
A public trust doctrine giving state authorities power to allocate water for essential public needs
No legal separation between surface and groundwater rights
Systems for registering and transferring water rights while maintaining watershed protections
Conservation requirements embedded in the fundamental water rights framework

This approach would have set Arizona on a dramatically different trajectory for managing its scarce water resources, with profound implications for the state's development over the following century.

Immediate Aftermath

Early Territorial Impact (1900-1912)

The immediate impact of Arizona's alternative water rights system would have been most visible along the major river systems—the Colorado, Gila, Salt, and Verde rivers. Under this modified riparian system, development patterns would have concentrated more heavily along watercourses, with agricultural settlements forming coherent communities with shared water interests.

In our timeline, mining companies secured distant water rights through prior appropriation claims, often diverting water far from its source. In this alternate reality, mining operations would have needed to negotiate with riparian landowners for water access or develop alternative water supply strategies. This would have significantly altered the economics and geography of Arizona's mining industry, potentially slowing development in some areas while encouraging more water-efficient mining techniques.

The Salt River Project, which began construction in 1903 as one of the nation's first federal reclamation projects, would have evolved differently. Rather than allocating water based on prior appropriation claims, the project would have operated more as a collective management system for riparian users along the Salt River. This might have resulted in a smaller initial project footprint but would have established stronger cooperative water management institutions.

Statehood Era and Early Development (1912-1940)

When Arizona achieved statehood in 1912, its constitution would have codified this modified riparian approach rather than enshrining prior appropriation. This constitutional difference would have shaped all subsequent water development in the state.

During this period, cities like Phoenix and Tucson would have developed in more compact forms along river corridors. Without the ability to claim distant water sources through prior appropriation, urban growth would have been more constrained and water-conscious from an earlier stage. The integrated governance of surface and groundwater would have prevented the legal fiction that treated them as separate resources, likely resulting in more sustainable early groundwater use.

The Roosevelt Dam and subsequent Salt River Valley water projects would have operated under different allocation principles. Rather than distributing water based on temporal priority, the system would have allocated water proportionally among riparian users during shortage periods, creating stronger incentives for collective conservation.

Agricultural development would have been more heavily concentrated along river valleys, with less expansion into areas dependent solely on groundwater. This would have established a more sustainable agricultural footprint from the beginning, though potentially limiting the total agricultural acreage compared to our timeline.

Federal Projects and Interstate Relations (1940-1960)

The most significant divergence would emerge during negotiations over Colorado River water. In our timeline, Arizona fought California in the Supreme Court for decades over prior appropriation rights to the Colorado River. In this alternate history, Arizona's riparian-based system would have provided a different legal foundation for its claims.

Arizona might have argued that as a riparian state to the Colorado River, it deserved a proportional allocation based on its needs and riparian status rather than fighting over temporal priority. This approach could have resulted in a different allocation framework for the Colorado River Compact of 1922, potentially one that was more adaptable to changing conditions and recognized ecological needs.

The planning for the Central Arizona Project would have begun earlier in this timeline, as the legal battles might have been resolved more quickly under different legal principles. However, the project would have been designed differently—perhaps smaller in scale but more integrated with groundwater management from the beginning.

Water Law Revolution (1960-1980)

The 1960s and 1970s would have seen a gradual evolution of Arizona's water regime rather than the stark crisis that led to the 1980 Groundwater Management Act in our timeline. Since groundwater and surface water were already legally connected, the state would have implemented incremental controls on groundwater pumping decades earlier.

The federal government's environmental awakening in the 1970s would have found more fertile ground in Arizona's water rights system. The public trust elements of the state's water law would have made it easier to incorporate environmental flow requirements for rivers and streams, potentially preserving riparian ecosystems that were lost in our timeline.

Municipal water utilities would have developed differently, with more emphasis on local source protection and watershed management rather than distant water importation. Cities like Phoenix might have implemented water conservation measures decades earlier than they did in our timeline, as the legal framework would have emphasized the finite nature of the resource from the beginning.

Agricultural Adaptation

Arizona's agricultural sector would have followed a different development path under this water rights regime. Instead of vast irrigation districts spreading across the desert based on prior appropriation claims, farming would have concentrated more intensively along river valleys.

The crops grown would likely have shifted earlier toward higher-value, less water-intensive options. The massive cotton, alfalfa, and cattle feed operations that characterized Arizona agriculture in our timeline would have been more limited in scale, with greater emphasis on specialty crops that could provide more economic value per unit of water.

By the late 1970s, the foundation would have been laid for a fundamentally different water landscape in Arizona—one with more intact river systems, more compact urban development, different agricultural patterns, and more integrated management of all water resources.

Long-term Impact

Urban Development Patterns (1980-2000)

The long-term impacts of Arizona's alternative water rights system would become increasingly apparent as the state faced rapid population growth in the 1980s and 1990s. The Phoenix metropolitan area, which exploded outward in our timeline through massive master-planned communities in the desert, would have developed very differently.

Compact Growth Around Water Resources

Under the modified riparian system, development would have remained more tightly clustered around secure water sources. The Salt River Valley would still be the population center, but growth patterns would resemble more water-conscious Southwestern cities like Santa Fe rather than the sprawling model of our timeline's Phoenix.

Tucson, which sits atop a large aquifer but has limited surface water, would have developed even more water-conservative practices earlier. The city might have become a national model for water-efficient urban planning decades before such approaches became necessary elsewhere.

Water-Oriented Urban Design

Architecture and urban design would reflect this water consciousness. Rather than the lush, irrigated landscape aesthetic that characterized much of Phoenix's development in our timeline (often called "desert denial"), cities would have embraced xeriscaping and desert-adapted design principles much earlier. Public spaces would be oriented around the remaining flowing rivers and riparian corridors, which would have been protected as valuable community assets.

Transportation and Infrastructure

Transportation infrastructure would have evolved differently as well. With more compact development, investments in public transportation would have proven more economical earlier. The light rail system that Phoenix didn't build until the 21st century in our timeline might have been developed in the 1980s or 1990s in this alternate history.

Agricultural Transformation (1980-2010)

Arizona's agricultural sector would have undergone a more dramatic transformation under this different water rights regime.

Crop Shifting and Efficiency Innovation

Without the security of unchangeable prior appropriation rights, farmers would have faced stronger incentives to adopt water-efficient practices decades earlier. Arizona might have become a global leader in precision agriculture, drip irrigation, and drought-resistant crop development in the 1980s rather than the 2010s.

The state's agricultural output would likely be lower in total volume but higher in value per acre and per gallon of water used. The massive alfalfa fields growing cattle feed for export would largely disappear, replaced by high-value fruit, nut, and specialty crop production.

Early Market Mechanisms

Water markets would have developed earlier and more extensively in this timeline. The riparian framework, combined with the public trust elements, would have created a more flexible system for water transfers while protecting environmental values. Farmers might routinely lease water to cities during drought periods, creating economic opportunities while maintaining agricultural land ownership.

Environmental Conditions (1980-2025)

The environmental differences between our timeline and this alternate history would be striking by the 21st century.

River System Preservation

Many of Arizona's river systems that run dry in our timeline—portions of the Santa Cruz, San Pedro, and Gila Rivers—might remain flowing year-round in this alternate reality. The integrated management of surface and groundwater would have prevented the groundwater pumping that dried up many streams.

These intact riparian corridors would support significantly higher biodiversity, creating green ribbons through the desert landscape. Species that have become endangered in our timeline, such as the southwestern willow flycatcher and Gila topminnow, might remain common in this alternate Arizona.

Colorado River Watershed

The Colorado River system, while still heavily utilized, would likely be in better ecological condition. Earlier recognition of the connection between groundwater pumping and river flows would have led to more sustainable management practices throughout the basin. Lake Mead and Lake Powell would still face challenges from climate change but might have maintained higher levels through more adaptive management.

Climate Change Adaptation (2000-2025)

As climate change impacts intensified in the early 21st century, Arizona's different water rights system would prove either a significant advantage or disadvantage, depending on how it evolved.

Potential Advantages

The integrated, watershed-based approach would provide more tools for adaptive management as precipitation patterns changed. The public trust elements of the water rights system would give state agencies more flexibility to modify allocations as conditions changed, rather than being locked into rigid priority systems.

Water conservation technologies and practices, having been developing for decades longer, would be more advanced. Per capita water use in Arizona cities might be half of what it is in our timeline, creating more buffer against drought conditions.

Potential Vulnerabilities

However, the riparian system might face challenges in allocating increasingly scarce resources. Without the clear prioritization that prior appropriation provides during shortage, conflicts between users might be more difficult to resolve. This could lead to more litigation or require the development of complex shortage-sharing agreements.

Economic Development (2000-2025)

By 2025, Arizona's economy would look substantially different under this alternative water rights regime.

Technology and Innovation

Arizona might have emerged as a global leader in water technology and conservation innovation, attracting significant investment in these sectors. Companies specializing in water-efficient agricultural systems, water reuse technologies, and sophisticated water monitoring tools might form a significant industrial cluster, particularly around Phoenix and Tucson.

Tourism and Recreation

With more intact river systems and riparian areas, Arizona's tourism economy would have a stronger ecological component. River recreation, birdwatching, and riparian hiking would complement the state's traditional desert and Grand Canyon tourism draws.

Manufacturing and Industry

Manufacturing development would be more water-conscious from the beginning. The semiconductor industry, which has a significant presence in Arizona in our timeline, would have developed with much more water-efficient processes. This could position Arizona as a leader in sustainable manufacturing practices.

Current Water Status (2025)

By 2025 in this alternate timeline, Arizona would face many of the same climate challenges as in our reality—reduced Colorado River flows, increased temperatures, and greater evaporation rates. However, the state would approach these challenges from a very different starting position.

Groundwater aquifers would be in significantly better condition, with water tables higher throughout most of the state. Rivers would be more likely to maintain base flows even during drought periods. Per capita water consumption would be much lower, creating more system resilience.

The cultural attitude toward water would also be fundamentally different—rather than seeing water as a commodity to be claimed and used, Arizonans in this timeline would more likely view it as a shared, limited resource to be carefully stewarded. This cultural difference alone might be the most significant long-term impact of the divergent water rights system.

Expert Opinions

Dr. Robert Glennon, Professor of Water Law and Policy at the University of Arizona, offers this perspective: "The riparian doctrine, as traditionally conceived, would have been a poor fit for Arizona's arid landscape. However, this alternate history's modified riparian system—with its reasonable use limitations and integrated groundwater management—addresses many of the fundamental flaws in our actual prior appropriation system. By avoiding the artificial legal separation between surface and groundwater, this alternate Arizona would have prevented much of the environmental degradation we've witnessed. Prior appropriation served its purpose during territorial development, but its rigidity has become a liability in the face of climate change. This alternate legal framework would likely provide more tools for adaptation in our increasingly water-stressed region."

Dr. Sharon Megdal, Director of the Water Resources Research Center, suggests a more nuanced view: "While this alternate water rights system offers compelling advantages for environmental protection and adaptive management, we shouldn't romanticize it. The challenge of allocating scarce water resources fairly would remain. The modified riparian system might have protected rivers but created different equity problems. Riparian landowners would have gained tremendous power over water resources, potentially creating new forms of water inequality. Additionally, the certainty provided by prior appropriation rights—while problematic in many ways—has enabled long-term infrastructure investments that might have been more difficult to finance under a more flexible system. The ideal approach probably incorporates elements of both systems, which is the direction many western states are gradually moving today."

Dr. Margaret Wilder, Professor of Geography and Development, adds a social perspective: "The most fascinating aspect of this alternate timeline is how it might have shaped Arizona's social landscape and power structures. Indigenous water rights, which have been recognized through prior appropriation in our timeline, would need different legal frameworks for protection in this alternate system. Border communities along the Santa Cruz and San Pedro Rivers would have developed differently, perhaps with stronger transboundary watershed governance. The more concentrated development patterns would have created different transportation needs, housing markets, and community structures. While our actual water rights system has many flaws, any alternative would create its own winners and losers. The question isn't whether this alternate system would be perfect—it wouldn't be—but whether it would better serve both human communities and ecological needs in an increasingly water-scarce Southwest."