Pacific Institute

January 31, 2023January 31, 2023

Managing the Unmeasured – Colorado River

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by Michael Cohen

Key Takeaways

Despite the severity of the current water crisis in the Colorado River and decades of management, research, and litigation, basic facts about the river, such as the exact number of people it supports , remain unknown.
A detailed accounting of where and how we use Colorado River water must be prioritized.

It’s all hands on deck for the Colorado River Basin. Nearing a quarter-century of drought (better described as a continuing shift to an ever-hotter and ever-drier climate), the most famous and important river in the West faces an existential crisis.

Seven months ago, the U.S. Bureau of Reclamation called on Colorado River water users to decrease their use by 15-30% — in one year. Without such extraordinary efforts, the two major Colorado River dams—Hoover and Glen Canyon—could lose their ability to produce hydropower in less than a year and a half. Even more concerning is that the continued decline of storage at Lake Powell could threaten the ability to pass water through Glen Canyon dam, diminishing flows through the iconic Grand Canyon and accelerating the decline of Lake Mead.

In response, farmers offer not to farm, cities pledge to conserve more water, and groundwater recharge operations forsake storing water underground, to compensate for the long-term overuse of supply, exacerbated by continuing decline of that supply. Simply put, every acre-foot of water matters to prevent the system from collapsing.

One might think that because the Colorado River is one of the most tightly managed and scrutinized rivers on the planet, we would have a detailed account of how every acre-foot is used and accounted for, how many people and users rely on the river, and where those uses take place. Yet, despite the severity of the current crisis and decades of management and research and litigation, basic facts about the river and the basin remain unknown, challenging efforts to better manage the system and avert the imminent crisis.

Water Use

Surprisingly, we do not know how much Colorado River water is used each year, especially in the Upper Basin. In the Lower Basin, Reclamation carefully measures releases from Hoover Dam and withdrawals to the Las Vegas metropolitan area – as well as diversion and delivery points downstream – but generally estimates unmeasured return flows [1] “by multiplying a water user’s diversion by an unmeasured return flow factor.” The volume of unmeasured return flows is only about four percent of total Lower Basin consumptive use but exceeds Nevada’s total use. The actual error here is likely very small, but it does suggest that the precision of Lower Basin consumptive use records exceeds their accuracy.

While the annual Lower Basin Decree Accounting reports enjoy broad credibility, Upper Basin water use accounting is much more challenging and less accepted. As Reclamation notes in its periodic Consumptive Uses and Losses report, the reliability of Upper Basin water use and loss estimates “is affected by the availability of data and the current capabilities of data evaluation.” Reclamation also notes that “Quantitative measurements of water use were used wherever available, but the majority of the basin water use was theoretically calculated. In the tributary areas of the basin, records of diversions and return flows are not complete enough to allow direct calculation of consumptive water use.” The Upper Colorado River Commission (UCRC) notes, “Historically, the Upper Division States (UT, CO, WY, and NM) have used multiple methods to estimate water use for irrigation, but these estimates were not consistent at an interstate scale that would be helpful to water managers and decision-makers, nor could the data be generated in a timely manner.” These sentiments reflect long-standing challenges to estimating flows past hundreds of different diversion points, as well as surface and sub-surface return flows. In June, the UCRC adopted a new method to measure agricultural consumptive water use in the Upper Basin.

Uncertainty about actual Upper Basin water use challenges efforts to quantify annual shortages. For example, Upper Basin decision-makers claim to have suffered from almost one million acre-feet (MAF) of shortages in 2021. But determining exactly where those shortages occurred, by how much, and the economic impacts of such shortages, is difficult. For example, the State of Colorado’s Division 5 (the Colorado River headwaters sub-basin) recorded 234 “administrative calls” (curtailments) in 2021, but the records do not include the volumes associated with these calls or whether those curtailed were able to divert their requested water at some later time.

Water Supply

Many agencies estimate Colorado River flows and total water supply for the system, ranging from short and long-term snowpack and precipitation to “natural flows” and ‘’unregulated inflows.” One federal agency’s unregulated inflow forecasts account for physical factors such as precipitation and soil moisture and reservoir impacts (such as evaporation and change in storage) and measured (but not unmeasured) diversions, while Reclamation’s “unregulated inflows” account for both measured and unmeasured diversions. Reclamation estimates “natural flows” – the conventional measure of Colorado River annual water supply – based on Water Use (see discussion above) and its unregulated inflow forecasts, adding an element of uncertainty. Conventionally, Colorado River flows reflect an annual volume at Lee Ferry – the dividing point between the Upper and Lower basins, more than 765 river miles upstream from where the river used to meet the sea. Between Lee Ferry and Imperial Dam (630 river miles downstream), more than 1.2 MAF of “natural flows” would contribute to the river’s total discharge. That is, discussions about Colorado River supply typically ignore Lower Basin inflows that add another ten percent or so to the Lee Ferry volume – flow that is all consumed before the river reaches the sea.

Tribal Water Rights

The Colorado River basin is home to 30 federally recognized tribes, who have more than 3.2 MAF of recognized water rights. Twelve of the tribes still have unresolved water rights claims within the basin that could increase total settled tribal water rights well beyond 3.6 MAF. Recognition of unresolved water rights is long overdue and challenges efforts to estimate the location of future demands and uses as tribes develop their water rights and/or lease them to other users, again leading to significant uncertainty for Basin decision-makers.

Irrigated Acres

Colorado River basin water irrigates between 5 and 5.7 million acres of farm and ranch land – methods for measuring such acreage vary, and actual irrigated acreage changes year to year based on market conditions and water availability. A little more than half of the irrigated acreage exists within the hydrologic basin (though not within the institutional basin – see Basin Boundaries below). While new methods will improve understanding of both the extent of irrigated acreage and the amount of water used, we still don’t have a credible number for the number of acres irrigated within the basin, acres irrigated with Colorado River water that lie outside the basin, or the acreages of different crops. As we noted in our 2013 report, “the various agencies that report water and land use information for the Colorado River basin use a host of different terms that are often not comparable. The frequency and timing of many of these measurements are rarely synchronized.” It is important to be explicit here—for the sector that uses 70-80% of the Colorado River’s supply, we do not have a detailed understanding of just how many acres of agricultural land are irrigated with that water. As far as we know, no one has attempted another comprehensive accounting of irrigated acreage since our 2013 report, which seems long overdue.

Population

Conventionally, 40 million people use Colorado River water, an estimate from a 2012 report. But a decade later, we’ve learned that nearly seven million people in Southern California thought to use Colorado River water lack any physical connection to the river – the plumbing simply doesn’t exist to deliver water to them. On the other hand, the basin is home to some of the fastest-growing cities in the country – the combined populations of Arizona and the Las Vegas metropolitan area grew by almost 2 million people from 2010 to 2020. The conventional population estimates also mix direct use of Colorado River water (and its tributaries) with groundwater pumped from the basin. How many people actually use Colorado River water (or more accurately, water from the Colorado River basin)? Given the significant growth experienced and projected, we should know this number and we don’t. But it’s much less than 40 million.

Basin Boundaries

Scope – boundaries – matter as we measure and attempt to manage elements such as water use, exports, and water demands. Reclamation’s traditional map of the Colorado River basin excludes a large portion of the river’s former delta and the watershed draining to that delta, because it is a terminal basin that does not return flows to the river, even though the river flowed there repeatedly via gravity over millennia. This means that the basin’s institutional and hydrologic boundaries are not the same and means that millions of acre-feet of water that flow via gravity to the former delta are considered “exports” from the system – and that hundreds of thousands of acres irrigated with this water are deemed outside of the basin.

Boundaries also confound population estimates, because exports to Southern California and Wasatch Front and Front Range water agency service areas have often been counted as contributing to the use of their total service area populations, even if the plumbing doesn’t exist to deliver that water or if only a few molecules of basin water actually enter the service area. (For more discussion on the importance of boundaries see this blog post.)

Operational Neutrality

Reclamation’s August 24-month study “most probable” projection of Lake Mead’s December elevation determines the shortage tier for Lower Basin contractors and for deliveries to Mexico and helps set the operational tier for coordinated reservoir operations for the following calendar year. The 24-month studies show the projected physical elevations at each reservoir. In 2022, the August 24-month study “most probable” projection put Lake Mead’s December elevation at 1040.78’, which would have triggered 0.2 MAF of reductions in California and more than a MAF of total reductions in the Lower Basin and Mexico.

However, because Interior took actions to protect the elevation of Lake Powell and reduced releases from Glen Canyon Dam in 2022 by 0.48 MAF, the projected physical elevation at Lake Mead no longer determines the shortage tier. Instead, Reclamation now uses a separate and unpublished projected elevation, modeling the elevation of Lake Mead “as if” the 0.48 MAF had been delivered (“The reduction of releases from Glen Canyon Dam in water year 2022 (resulting in increased storage in Lake Powell) will not affect future operating determinations and will be accounted for “as if” this volume of water had been delivered to Lake Mead”), to determine shortage tiers and reservoir operations. That is, what is actually measured at Lake Mead is no longer the value that determines actual management and operations. Until the 24-month studies include a new column showing “operationally neutral” elevations, they won’t reflect future shortage triggers for Lake Mead.

Conclusion

What does this all mean? It means that as we respond to the declining reservoirs and risks of falling below power pool in the next year and a half, decision-makers won’t be armed with accurate or precise data on where and how we can reduce demands, especially in the Upper Basin. It may be difficult to identify just how we can get to the 15-30% reduction in uses as demanded by Reclamation if we don’t know exactly how much water we’re using now. Every acre-foot matters. That demands a detailed accounting of where and how we use Colorado River water.

[1] Unmeasured return flows are defined as “Mainstream water that has been diverted and which flows back to the Colorado River or the Colorado River Aquifer as measured or unmeasured flow and is available for use in the United States or in satisfaction of the Mexican Treaty Obligation”.

Guide for Developing Onsite Water Systems to Support Regional Water Resilience

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Overview

Urban communities across the country are facing growing water challenges, including water scarcity, flooding, pollution, aging infrastructure, and more. These challenges present risks, but they also present an opportunity to rethink how we manage water, including adopting circular approaches in new developments that reduce their water footprint and improve urban water resilience. Onsite water systems, for example, collect, treat, and reuse water from onsite sources, such as wastewater, rainwater, and stormwater, for non-potable water uses like toilet flushing, outdoor irrigation, and cooling.

Onsite water systems have the potential to provide multiple benefits for a site, water and wastewater systems, communities, and ecosystems. For private sector developers, onsite systems can help reduce water scarcity risks, provide resilience to water supply disruptions, and support corporate water stewardship goals. For communities, onsite water systems can help enhance water supply reliability, improve water quality, reduce localized flooding, and increase urban green space.

This guide helps site developers consider how water systems can be planned, designed, and operated to provide multiple benefits and promote four desired outcomes: advancing water resilience, supporting equity, supporting the environment, and protecting public health. For each of these outcomes, the guide provides sample questions to consider, stakeholders to engage, resources to examine, and analyses to perform. The guide also offers insights on how the realization and magnitude of benefits can vary with the type of system, scale of adoption, and other context-specific factors.

December 9, 2022December 12, 2022

Water Advances on Global Climate Agenda at COP27

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Water Advances on Global Climate Agenda at COP27
Pacific Institute featured at COP for water resilience thought leadership, innovative tools

Dr. Amanda Bielawski & Jason Morrison

Key takeaways:

For the first time, water was visible in the final UN Climate Summit COP declaration.
Water solutions play a pivotal role in both climate mitigation and adaptation, with attention moving more toward adaptation at COP27.
The transformative change and radical collaboration needed are at the heart of the Pacific Institute’s work advancing water resilience.

As the United Nations Climate Change Conference (COP27) closed in Sharm El-Sheikh, Egypt, the science was grim. At the same time, water management’s role in climate mitigation and adaptation—the heart of the Pacific Institute’s work—was more widely recognized than ever before.

Photo: UN Climate Change Executive Secretary Simon Stiell shared opening remarks at COP27. Photo credit: UN Climate Change (COP27 in Sharm el-Sheikh to Focus on Delivering on the Promises of Paris | UNFCCC)

Climate mitigation progress falls short, placing more emphasis on adaptation

COP27 closed with the stark recognition there may be no feasible path to reach the Paris Agreement’s 1.5-degree goal. New research finds the last eight years are projected to be the warmest eight on record. Climate mitigation efforts have simply not progressed quickly enough—with devastating impacts felt primarily through the water cycle in the form of intensifying flooding and drought.

“United Nations Secretary-General António Guterres opened COP27 by acknowledging the world is approaching a tipping point—and urging a focus on rapid implementation of solutions: “The good news is that we know what to do and we have the financial and technological tools to get the job done . . . We need all hands on deck for faster, bolder climate action.”  

Photo: Secretary-General António Guterres addresses the opening of the Climate Implementation Summit at COP27 in Sharm el-Sheikh, Egypt. UNFCCC/Kiara Worth

Water breaks new COP barriers

While the water agenda rose in prominence during COP26 last year in Glasgow, it broke through new barriers this year at COP27. Visible in both the Blue Zone and Green Zone, water was recognized during negotiations as a powerful solution to address climate change both through mitigation and adaptation.

Notably, this is the first time the final COP declaration directly acknowledged the critical role of water and its many co-benefits:

“. . . Recognizing the critical role of protecting, conserving and restoring water systems and water-related ecosystems in delivering climate adaptation benefits and co-benefits, while ensuring social and environmental safeguards . . .”

The final declaration also urged Parties to include water in adaptation plans:

“. . . Emphasizes the importance of protecting, conserving and restoring water and water related ecosystems, including river basins, aquifers and lakes, and urges Parties to further integrate water into adaptation efforts . . .”

Now in its second year, the Water and Climate Pavilion united more than 40 international organizations, as well as Indigenous leaders, youth, and academics—to advance water on the climate agenda.

The Pacific Institute played a key role. Across more than a dozen sessions, many of them attended remotely, Pacific Institute colleagues shared water resilience thought leadership and innovative tools to build water resilience.

Photo: Jason Morrison, Pacific Institute President and Head of the CEO Water Mandate, (left) pictured with Vania Paccagnan of CDP (right), discusses the role of corporate action to build water resilience at COP27.

If climate is the shark, water is the teeth

To many, COP27 may feel like a far-off meeting. But, for millions of people around the world, decisions made during COP27—and decisions made by the public and private sector leaders every day of the year—will directly impact their personal lives and livelihoods. This is especially true through human interactions with water. As has been stated, “If climate is the shark, water is the teeth.”

A growing swell of research—some of it conducted over the past 30-plus years by the Pacific Institute—is unpacking the specific relationships between climate change and the water cycle. The science is clear. Climate change is intensifying water-related disasters, such as floods and droughts, which have affected millions and cost billions this year alone.

Photo 1: Aerial view of summer 2022 floods in the provinces of Sindh and Balochistan in Pakistan. Photo credit: UN Photo/Eskinder Debebe. Photo 2: Lake Powel on August 16, 2017, (left) and on August 6, 2022 (right). Photo credit: NASA. Photo 3: © UNICEF/Kate Holt; Somali women and children stand outside temporary tents in the Dagahaley refugee camp near the Kenya-Somalia border. 

The evidence is visible before us:

- Record-setting flooding in Pakistan earlier this year left one-third of the country submerged. An estimated 7.9 million people were displaced, while 1,700 died.
- On the other end of the water extreme, in the US West, the current 22-year megadrought is projected to be the driest period in 1,200 years. Lake Powell, the second-largest water-storage reservoir in the United States and a major source of water for millions, was photographed by NASA in August at its lowest level since the mid-1960s.
- Meanwhile, Oxfam warned in October that historic drought in East Africa is likely to kill one person every 36 seconds through the end of 2022.

Climate change is projected to increase the severity and frequency of these sorts of droughts and floods even further into the future, compounding an already concerning water crisis.

Transformation to water resilience—the heart of the Pacific Institute’s work

During the run-up to COP27, Christiana Figueres, who led the UN Framework Convention on Climate Change (UNFCCC) when the 2015 Paris Agreement was adopted at COP21, called for a new mindset and radical collaboration across sectors. Figueres wrote: “One company or one government alone cannot make the kind of difference we need; the transformations must be systemic and exponential, and delivered with justice in mind.”

This type of transformative change and radical collaboration are at the heart of the Pacific Institute’s work.

In 2019, the Pacific Institute announced an organizational goal to “catalyze the transformation to water resilience in the face of climate change” by 2030. This forward-looking goal builds on more than 30 years of thought leadership on climate-water connections. Long before this connection was recognized in mainstream policy discussions, the Pacific Institute conducted early research, made early warnings, and proposed some of the earliest solutions.

During the early 1990s, climate-water assessments were conducted both domestically and internationally—from the Bay Area of California to the Nile River Basin in Africa. In 1990, the Pacific Institute conducted one of the earliest assessments of sea-level rise impacts for the San Francisco Bay Area. In 2009, this analysis was expanded to cover the entire California coast, becoming a significant lever for policy change.

Photo: Area of San Francisco Bay Threatened by a 1-meter Sea-Level Rise: Southern Portion. From 1990 Pacific Institute report.

In advance of COP26 in Glasgow, the Pacific Institute launched its Water Resilience Issue Brief, calling on decisionmakers across the private and public sectors to rapidly scale solutions. Many solutions stem from what our colleague, Dr. Peter Gleick, Senior Fellow and Co-Founder of the Pacific Institute, describes as the “soft path” for water. This more-sustainable framework calls for decentralized infrastructure, innovative and efficient use of technology, the protection of ecosystems, and reversing the policy inertia historically focused on endlessly increasing water supplies. Some of the specific solutions include integrating nature-based solutions (NBS), which offer multiple co-benefits, as well as increasing inclusion of water efficiency and reuse approaches. Recent Pacific Institute research found water efficiency measures could reduce urban water use in California by up to 48 percent, while also playing a critical role in reducing greenhouse gas (GHG) emissions.

Building an equitable movement powered by collective action

At COP27 and beyond, the Pacific Institute is convening and equipping decisionmakers, including utilities, corporations, and public policymakers, to serve as key levers of change. In all cases, we call for equitable approaches that prioritize the most impacted stakeholders, especially frontline communities often disproportionately impacted by climate change, as well as the natural environment.

During COP27, the Pacific Institute advanced this work during a wide range of sessions. Our colleague Dr. Peter Gleick provided an assessment of the integrated nature of water, climate, and food challenges for the Science, Technology, and Society session organized by the Japanese government.

Many sessions also focused on the pivotal role the corporate sector must play by reducing water impacts of their operations and value chains—and by uniting through collective action. The Pacific Institute is proud to partner with the United Nations Global Compact in leading the CEO Water Mandate, which unites more than 200 companies to build water resilience. This work was front and center at COP27:

- The CEO Water Mandate launched the new Water Action Hub 4.0, a global online platform that highlights more than 1,600 projects and 1,000 organizations to build water resilience. The 4.0 version adds the new Corporate Water Benchmark Tool for companies to gauge their water practices and performance against industry peers.
- The CEO Water Mandate’s water, sanitation, and hygiene (WASH)-focused program, WASH4Work, also launched a new Corporate Declaration for Climate-Resilient WASH, establishing a framework for business WASH action across supply chains and in communities.
- Along with the Alliance for Global Water Adaptation, International Water Management Institute, and World Resources Institute, the Pacific Institute and the CEO Water Mandate also launched the Corporate Guidance for the Water Resilience Assessment Framework to measure and enhance resilience across a range of industries.
- The Pacific Institute and the CEO Water Mandate launched a new Stakeholder Engagement Guide for Nature-Based Solutions for inclusive, culturally appropriate engagement with diverse stakeholders.
- At the Climate Ambition Hub, we premiered the “Ripples of Water Resilience; Stories of Global Impact and Collective Action” campaign highlighting the collective action work of the Water Resilience Coalition.

All hands on deck

As United Nations Secretary-General António Guterres said in his COP27 opening remarks, “The good news is that we know what to do and we have the [tools] to get the job done.”

As we see the water-related impacts of climate change ravage communities around the world—from Pakistan to the US West—one thing is clear. The risks of not acting quickly enough are simply unacceptable.

Indeed, we have the tools. Through transformative change and radical collaboration, now is the time to rapidly accelerate one thing: action.

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Contributions made to the Pacific Institute by December 31 will be matched dollar for dollar up to $100,000.

Guide for Developing Onsite Water Systems to Support Regional Water Resilience

Stakeholder Engagement Guide For Nature-Based Solutions

Advancing Affordability through Water Efficiency

Left Out in Drought: California Fish

Pacific Institute 2021 Annual Review

New Pacific Institute Guide on Onsite Water Reuse Systems

COP27 in Egypt

Water Resilience