Colorado River Water Research Articles

Hydrogeologic and hydrochemical inputs to emerging wetlands on the shores of the receding Salton Sea, California

AbstractThe Salton Sea has experienced significant recession over the past two decades due to changes in the diversion of Colorado River water to the Salton Trough for agricultural irrigation. As a result, wetlands have emerged in some exposed playa areas along the Salton Sea, primarily in regions with extensive agricultural return flows and agricultural drainage. One notable wetland system, known as the Bombay Beach Wetlands, has formed on the north shore of the Salton Sea, in an area devoid of agriculture. In many other areas with limited or no agriculture, wetlands have failed to develop, leaving exposed playa surfaces as the Salton Sea recedes. These dry playa surfaces pose a significant threat to the health of local residents due to the presence of toxins contained in windblown dust associated with playa deposits. In this study, stable water isotope data, combined with other hydrological information, led to identification of two potential water sources for the Bombay Beach Wetlands. The first possibility proposes that thermal artesian waters alone contribute to the wetlands' water source, while the second hypothesis involves a combination of drainage from Salton Sea bank storage water mixing with the thermal artesian water. The thermal artesian water discharges into drainage channels that flow towards the Bombay Beach Wetlands, initially devoid of possible groundwater baseflow until reaching the wetlands. Studies were subsequently done along the full reach of the drainage channels receiving thermal artesian water. Dissolved solids content, P and N nutrients, arsenic, and stable water isotopes were tested synoptically along the drainage channels. Channel investigations led to the development of a novel model of salinization, which is linked to channel discharge, channel morphometrics, and channel incision.

“Whiskey is for drinking, water is for fighting”. Colorado River water disputes over the Lake Powell Pipeline

“Whiskey is for drinking, water is for fighting”. Colorado River water disputes over the Lake Powell Pipeline

Last Call: The Limitations of New Mexico's Existing Water Management Framework in the Face of Reduced Colorado River Water Deliveries

Last Call: The Limitations of New Mexico's Existing Water Management Framework in the Face of Reduced Colorado River Water Deliveries

Correction to “Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water”

Correction to “Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water”

Water quality mitigation strategy analysis of the Salton Sea, California, using the Delft-3D modeling suite

The Salton Sea is the largest lake in California and is a shallow, hypersaline lake. The endorheic lake has been significantly maintained by agricultural return flows from Imperial Valley farming and two rivers- the New River and Alamo River- which originate in Mexicali, Mexico. The current salinity is at 74 ppt and is expected to increase due to the Quantification Settlement Agreement signed in 2003, stipulating the transfer of nearly 0.616 km3 per year of Colorado River water to urban areas for up to 75 years. This has resulted in inflows reduction, and the dust storms created by the dried-up playa have become a prominent risk to public health in the region. Massive fish and bird kills began in the 1980s and continued to occur periodically. In this study, the Delft3D numerical modeling suite- FLOW, WAVE, and WAQ- was utilized to investigate the transport and cycling of nutrients under the influence of wind-induced sediment resuspension activity. The three-dimensional hydrodynamic and water quality combined model was applied to simulate mitigation scenarios to assess long-term effects on salinity and water quality of (1) emerged islands as a nature-based solution, (2) seawater import/export, and (3) seawater import/export in addition to treating tributary rivers to remove nutrients. Overall, this study supported the findings from previous studies and showed that sediment resuspension is the driving force for nutrients cycling in the water column and that emerged islands have long-term potential to enhance burial activity for pollutants removal in the Salton Sea. Furthermore, the seawater import/export scenario showed promising results of reducing salinity level from 46 ppt to 38–39 ppt in 2 years. The 3D numerical hydrodynamic/water quality model developed in this work is the first and latest integrated modeling approach tailored to the Salton Sea's system and has the capacity to improve understanding of the complicated water quality dynamics changes in various restoration concepts. This study demonstrated that being able to explore the full potentials of restoration designs using a comprehensive 3D water quality modeling framework is critical in achieving wholesome planning that will create environmental, social, and economic benefits in the long term for the Salton Sea.

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

The Colorado River water crisis: Its origin and the future

AbstractDuring much of the 21st century, natural runoff in the Colorado River basin has declined, while consumption has remained relatively constant, leading to historically low reservoir storage. Between January 2000 and April 2023, the amount of water stored in Lake Mead and Lake Powell, the two largest reservoirs in the United States, declined by 33.5 million acre feet (41.3 billion cubic meters). As of April 2023, total basin‐wide storage was sufficient to support the 21st century average rate of basin‐wide consumption for only 15 months. Runoff in spring 2023 is predicted to be large, providing a short‐term reprieve. However, it will take four to five additional unusually wet years in succession to refill Lake Powell and Lake Mead if basin‐wide water use remains unchanged. Increasing evapotranspiration and dry soils associated with global climate change makes such a scenario unlikely. To stabilize reservoir storage, basin‐wide use needs to equal modern runoff. To recover reservoir storage, basin‐wide use needs to decline even more. Based on 21st century average runoff, a 13%–20% decline in basin‐wide use would allow for stabilization and some reservoir storage recovery. Future policy debate about reservoir operations will inevitably concern whether most, or all, reservoir storage should be in Lake Mead or in Lake Powell. The choice of one or the other will result in significantly different environmental and recreational outcomes for Glen Canyon and the Grand Canyon.This article is categorized under: Water and Life > Stresses and Pressures on Ecosystems Human Water > Water Governance Science of Water > Water and Environmental Change

Colorado River (Argentina) Water Crisis Scenarios and Influence on Irrigation Water Quality Conditions

The characterization and evaluation of water quality in the Valle Bonaerense del Río Colorado (VBRC), Buenos Aires, Argentina, is necessary, given the immense importance of this region for sustaining the population livelihoods and maintaining the ecological balance, especially in the face of drought and climate change scenarios, and loss of crop production yields. This study evaluated the possible reuse of drainage canals from the perspective of their use for irrigation. Surface water samples were collected at four sampling sites during 2015–2021, one over the Colorado river entering the VBRC, and the remaining three drainage canals flow into the Atlantic Ocean. These physicochemical parameters were performed following the protocols proposed using standard methods: total dissolved solids, pH, electrical conductivity (EC), calcium, magnesium, sodium, potassium, carbonates, bicarbonates, chlorides, sulfates and sodium adsorption ratio were analyzed and classified. The irrigation water quality index (IWQI), principal component analysis, hierarchy of classes analysis and statistical analysis were applied to the dataset. The general hydrochemistry of the VBRC river water indicates a slightly alkaline nature, with a mean pH value of 8.03, and the predominance order of the major ions follows the pattern of Na+ > Ca2+ > Mg2+ > K+, and SO42− > Cl− > HCO3− + CO32− for the anions. For the IWQI, 88.06% of the samples analyzed were classified as safe water for irrigation, and a theoretical yield loss was estimated for crops considering the salinity variable, with vegetables showing the highest losses. The surface water from rivers increases the EC due to the decrease in its discharge because of the water crisis affecting Latin America. Water reuse could be useful for one of the three drainage canals. This study concludes that the reuse of drainage water (S2) has great potential as an adaptation strategy to address the water scarcity and climate change challenges in the Colorado river basin. The research highlights the importance of considering this alternative to achieve sustainable water management in the region. Moreover, the data obtained from the study can be used for making policy and resource management decisions. In view of the possible scenarios of low water flow and increases in the EC values, it is recommended to reorient agricultural production toward crops with higher tolerance to salinity as an alternative, to ensure the sustainability and viability of production in the basin.

Suspended sediment transport in Rio Colorado agricultural basin, Argentina

The nutrient input from inland water discharges is vital for the development of marine aquatic fauna, being significantly sensitive to changes in water quality (WQ). The assessment of the contribution and distribution of some water quality parameters (e.g., nutrients, metals and inland organic compounds) is of vital importance, especially in irrigation basins. The study area is the Bonaerense Valley of the Colorado River (BVCR) and Mar Argentino, near the mouth of the Colorado River (Buenos Aires, Argentina). The study of water quality parameters is performed in an indirect way, by studying the spatiotemporal dynamics of cohesive sediment (CS), this is possible because the CS has a fundamental role in the transport of substances by adsorption/desorption interactions. We used numerical models (MOHID Land and MOHID Water) in a coupled way, evaluating the complex dynamics involved. The evaluated parameters (flow, velocity, cohesive sediment, salinity and temperature) were calibrated and subsequently validated with data from 7 monitoring stations, located along the Colorado River and adjacent water collectors. Calibration and validation values are within an acceptable range for the purposes, with mean values of 0.8 for NSE (Nash-Sutcliffe model efficiency coefficient), 0.9 (Pearson correlation) for calibration and 0.6 (NSE), 0.9 (Pearson) for validation. The irrigation zone (through the collectors) shows a significative contribution of cohesive sediment, on the order of 300 ppm. The river presents approximately 100 ppm and generates a plume along the coast to the northwest.

A Survey of the Bureau of Reclamation’s Decree Accounting Reports in the Lower Colorado River Basin

From the Rocky Mountains in the US to the Sea of Cortez in Mexico, the Colorado River is one of the most managed and monitored rivers in the world. As decreasing river flows from drought and climate change continue to impact the Colorado River Basin, the US federal government, seven US states, and Mexico have signed agreements that would reduce deliveries, including a Drought Contingency Plan (DCP), an agreement among the US states and the Bureau of Reclamation, and Minute 323 (a treaty agreement between the US and Mexico). As part of the DCP, the US Bureau of Reclamation (Reclamation) committed to increasing conservation efforts to augment storage in Lake Mead. This paper presents an analysis of Reclamation’s Decree Accounting Reports that record water deliveries and conservation savings from 1964 to 2019. Overall, this analysis illustrates that (1) the agency has implemented significant conservation actions over the last three decades, (2) the agency has responded to increased accounting needs as dictated by national and international management agreements, (3) some actions have resulted in environmental costs, and (4) future actions could be designed to avoid environmental harms while also augmenting Lake Mead levels. As climate change continues to constrain Colorado River water supply, detailed accounting may help reveal areas for potential efficiencies or demonstrate where the greatest levels of savings have been reached while ensuring that environmental and social benefits are preserved.

Human-Induced Resource Scarcity in the Colorado River Basin and Its Implications for Water Supply and the Environment in the Mexicali Valley Transboundary Aquifer

The Colorado River delta is a sedimentary alluvial formation that embodies the Lower Colorado River transboundary aquifer. The Mexicali Valley overlies the Mexican part of the aquifer, and the Imperial Valley the aquifer’s portion north of the Mexico–U.S. border. Mexico receives an annual water allocation from the Colorado River stipulated by an international treaty between Mexico and the United States. The Colorado River water allocation to Mexico is shared by farmers in the Mexicali Valley and by several border cities, rural communities, and industries in the northern region of the State of Baja California. Farmers withdraw groundwater from the Mexicali Valley’s aquifer to make up for insufficient Colorado River water to grow their crops. Groundwater withdrawal has created overdraft of the Mexicali Valley aquifer with associated adverse impacts: sea water intrusion, declining groundwater levels, upwelling of brackish groundwater, land subsidence, degradation of groundwater-dependent ecosystems, and emigration of displaced farmers. This article reviews the natural and human histories in the Colorado River basin and the Mexicali Valley, and presents a methodology applying remote sensing, geographic information analysis, and hydrologic analysis to calculate the annual water deficit in the Mexicali Valley. Finally, this work evaluates the valley’s annual water deficit in reference to current agricultural and socioeconomic trends observed in the study region. Aquifer and related environmental degradation have adversely affected small-scale farming and exacerbated demographic instability.

Review: The Settler Sea: California’s Salton Sea and the Consequences of Colonialism, by Traci Brynne Voyles

In Traci Brynne Voyles’s new work on the largest body of water in California, paradoxes abound. The Salton Sea, she shows in this profound and compelling book, is a difficult entity to define and narrativize. Is it a man-made entity or part of a centuries-old ecological rhythm? An environmental disaster, or the heart of a thrumming ecosystem? A consequence of settler colonialism’s disastrous designs, or evidence of its pervasive failures? In The Settler Sea, the answer to all of the above, and more, is both.The Settler Sea builds on the familiar narrative of the Salton Sea, a body of water created in 1905 in the middle of the desert when rain-swollen Colorado River water jumped a canal headgate and flowed unimpeded into the below-sea-level basin for two years. This resulted in a highly saline lake that has served as an irrigation runoff catch, a short-lived resort and boating hub, an avian nesting ground along the Pacific flyway, a bomb testing site, a center of massive bird and fish die-offs, and a cause of toxic pollution.Voyles adds to the already well-documented history of the Sea by combining approaches from settler colonial studies and environmental history. This method is particularly potent not only because the Salton Sea is a shared epicenter of white settlers’ totalizing dreams (familiar to all students of settler colonialism) but also because of the manifold unintended consequences of their environmental tinkering (a common theme among environmental historians). Following from these fields, The Settler Sea largely focuses its analysis on the relationship between social inequality and environmental problems. “The functions of social power built into settler colonial processes—racism, sexism, classism, heteropatriarchy, ableism,” Voyles argues, “are themselves environmentally ruinous” (p. 7). In showing how social and environmental issues intertwine in the settler process, the narrative centers the experiences of desert Indigenous groups, especially the Cahuilla and Kumeyaay peoples. It is, however, no mere tale of destruction, but a complex weave of survival, paradox, and change within the wider settler project.Like floodwater carving its way through the sand of the Colorado Desert, Voyles’s narrative is anything but straightforward. The book’s three sections respectively deal with the Salton Sea’s creation, its rise to political, cultural, and economic prominence, and its role in various environmental disasters. But with titles ranging from Birds to Bodies to Bombs, its chapters meander and twist across time, space, and subject, all ultimately returning to the sea at its heart. While this method yields powerful results in tracking the wide scope of histories tied to the Salton Sea, it sometimes obscures the more basic flow of causality and narrative, especially for readers unfamiliar with the history of the region.The Settler Sea is, nonetheless, delightfully written. So often dismissed as a wasteland, the desert blooms under Voyles’s pen. In capturing the many stories of the Salton Sea’s precariousness—“the way it sits uncomfortably between worlds, existing always in the interstices of human and natural influences” (p. 267)—this book is an important new entry, useful to scholars of settler colonialism, environmental history, Indigenous studies, and the American West writ large.

Potential impacts of reduced inflows to the Salton Sea: Forecasting non‐market damages

AbstractTerminal lakes throughout the American West provide important amenity and environmental values, but many are shrinking due to reduced inflows and warming temperatures. In California's Imperial Valley, agricultural water use reductions diminish inflows supporting the Salton Sea, a terminal desert lake and important environmental amenity for both the region and the state as a whole. The costs of these reduced inflows are difficult to monetize yet complicate management decisions. We assess the costs of potential future drought‐induced transfers by linking novel hydrologic scenarios to an economic framework for quantifying local and regional damages based on existing estimates of non‐market environmental values from the literature. The costs of lost wetland ecosystems, increases in particulate matter from exposed playa, and other local disamenities are substantial. For the scenarios considered, they range between approximately $500 million and $1 billion in present value (2019 USD). Estimated damages per acre‐foot (or thousand m3) of reallocated water exceed several thousand dollars. The majority arise from loss of wetland habitat; incremental particulate matter damages are relatively modest in our modeling but exacerbate salient air quality issues in the region. Interest in reallocating water from Imperial Valley, the largest user of Colorado River water, to other applications will increase over time. Our work highlights the importance of evaluating the impacts of such efforts.

Featured Collection Introduction: Severe Sustained Drought Revisited: Managing the Colorado River System in Times of Water Shortage 25 Years Later — Part I

Featured Collection Introduction: Severe Sustained Drought Revisited: Managing the Colorado River System in Times of Water Shortage 25 Years Later — Part I

Colorado River Water Use and Climate: Model and Application

ABSTRACTWater availability to meet consumptive use demands over the next century in the Lower Basin of the Colorado River in the southwestern United States is considered under alternative climate and policy scenarios. Modeling reservoir storage and annual releases under scenario alternatives demonstrates that policy can only modestly mitigate losses from potential long run streamflow reductions. The major reservoirs Lake Powell and Lake Mead are treated as composite storage, and Upper Basin depletions are held constant over 97 annual periods beginning with calendar year 2020. Averaged over six climate change scenarios with mean inflow reductions of 22% (reaching 45% by end of century) estimated mean releases fall by 16% to 23% from year 2020 levels depending on decision scenario. Mean releases under the existing Law of the River are 6.1% below the benchmark decision scenario which uses a perfect forecast of future flows. This is largely the result of evaporation losses because reservoir storage across climate scenarios is about double that of the benchmark. In contrast, a decision scenario based on next year and future mean flow expectations shows a release reduction of only 2.6% below the benchmark, and a 2.8% decrease in standard deviation. Across the three decision scenarios, future reservoir storage is well below capacity in almost all years, and under the three higher impact climate scenarios mean storage across the century is only 35% to 40% of capacity.

The Three Colorado Rivers: Hydrologic, Infrastructural, and Economic Flows of Water in a Shared River Basin

AbstractThe Colorado River Basin is a hydrologic river network that directs runoff from rain and snow falling on mountains, primarily in Colorado and Wyoming, to the Colorado River Delta in Mexico. Over the last century, in response to basin‐wide water shortages, legal agreements between stakeholders in seven U.S. states and Mexico, hydrologic flows from users on the main stem of the river have been reallocated to junior water rights holders. Municipalities, businesses, farmers, and households utilize the Colorado River water to produce and trade valuable, water‐derived goods and services, which effectively reallocates water through a continually adapting, boundary‐free economic river network providing indirect access to "virtual" Colorado River water. We conceptualize the Colorado River Basin as a multiplex network comprised of interdependent natural flow networks, direct (infrastructural) flow networks, and indirect (virtual) flow networks. Using this reframing, we quantify the total hydrosocial impact of the Drought Contingency Plan (DCP) on Lower Basin states. For each Mm3 of water reduced through the DCP, Arizona, Nevada, and California lose an additional 0.42–0.43 Mm3, 0.33–0.51 Mm3, and 1.06–1.10 Mm3 of virtual water flow, respectively. Hence, the DCP will require Arizona, Nevada, and Southern California to restructure how they use water, relying less on direct and indirect consumption of the Colorado River water and finding more indirect water sources outside that basin.

Effects of Reservoir Levels on Arizona National Recreation Area Visitation, Visitor Spending, and Local Economies

AbstractThis study estimates the effects of reservoir levels on demand for recreation visits to Lake Powell (Glen Canyon National Recreation Area [NRA]) and Lake Mead NRA, correlating reservoir levels with overnight and total recreation visits. We also consider the effects of closures of recreation access points (such as launch ramps or marinas) when lake levels fall below critical thresholds. Our overall results are similar to past studies, but find that the access point closures are a more robust predictor of visits than simple elevation measures. Policies that manage the Colorado River, including those that seek to maintain reservoir levels above critical levels with the primary goal of preventing water delivery cutbacks, also affect recreation demand and the economies of nearby communities. Our analysis maps changes in visits (from changing elevations) to changes in visitor spending, recreationist user benefits, and regional economic indicators such as value added and employment. Such indicators could be used in future benefit‐cost or economic impact analyses of Colorado River water management policies.

Toward usable predictive climate information at decadal timescales

Toward usable predictive climate information at decadal timescales

Groundwater Origin and Dynamics on the Eastern Flank of the Colorado River Delta, Mexico

Isotope data and major ion chemistry were used to identify aquifer recharge mechanisms and geochemical evolution of groundwaters along the US–Mexico border. Local recharge originates as precipitation and occurs during winter through preferential infiltration pathways along the base of the Gila Range. This groundwater is dominated by Na–Cl of meteoric origin and is highly concentrated due to the dissolution of soluble salts accumulated in the near-surface. The hydrochemical evolution of waters in the irrigated floodplain is controlled by Ca–Mg–Cl/Na–Cl-type Colorado River water. However, salinity is increased through evapotranspiration, precipitation of calcite, dissolution of accumulated soil salts, de-dolomitization, and exchange of aqueous Ca2+ for adsorbed Na+. The Na–Cl-dominated local recharge flows southwest from the Gila Range and mixes with the Ca–Mg–Cl/Na–Cl-dominated floodplain waters beneath the Yuma and San Luis Mesas. Low 3H suggests that recharge within the Yuma and San Luis Mesas occurred at least before the 1950s, and 14C data are consistent with bulk residence times up to 11,500 uncorrected 14C years before present. Either the flow system is not actively recharged, or recharge occurs at a significantly lower rate than what is being withdrawn, leading to aquifer overdraft and deterioration.

Groundwater Recharge for Water Security

The Arizona Water Banking Authority (AWBA) was established in 1996 to make full use of Arizona’s Colorado River entitlement. It aims to address groundwater depletion in central Arizona and to protect Colorado River water users against future shortages due to interannual variability in water availability. Each year, the AWBA pays the costs to deliver any of the state’s unused entitlement to Colorado River water into central and southern Arizona and to store that water underground. The AWBA stores water on behalf of Central Arizona Project municipal subcontractors, other mainstream municipal Colorado River water rights holders, and tribal entities. Through its interstate banking agreements, the AWBA can also store water on behalf of the states of Nevada and California. Water stored by the AWBA is accounted for using Arizona’s statutorily created system of long-term storage credits (LTSCs), which allow future pumping of stored water within the same hydrologic basin. During shortage conditions in the Lower Basin of the Colorado River, the AWBA will distribute the LTSCs, enabling recipients to pump groundwater that otherwise would not be permitted. In this way, the AWBA serves as a unique insurance mechanism against shortages for users of Colorado River water in Arizona and the Lower Basin. To date, the AWBA’s focus has been on storage, yet in the coming years, its activities will shift to recovery, and it will need to confront additional challenges associated with matching supplies with demands and limitations on water available for recharge.