Near-term Colorado River Operations Draft Supplemental Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | April 11th, 2023

Reclamation is proposing revising the 2007 Interim Guidelines for the near-term operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year (beginning O

Reclamation is proposing revising the 2007 Interim Guidelines for the near-term operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year (beginning October 1, 2023) to address the potential for continued low-runoff conditions in the Basin.

Near-term Colorado River Operations Revised Draft Supplemental Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | October 26th, 2023

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potent

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potential for continued low-runoff conditions in the Colorado River Basin. The potential impacts of low runoff conditions in the remainder of the interim period (prior to January 1, 2027) pose unacceptable risks to routine operations of Glen Canyon and Hoover Dams; therefore, modified operating guidelines should be expeditiously developed. Due to size, this file has been divided. Part one, Part two.

New water accounting reveals why the Colorado River no longer reaches the sea

Nature Portfolio (Springer Nature) | March 28th, 2024

On the Sources of Water Supply Forecast Error in Western Colorado

American Meteorological Society (AMS) | December 1st, 2023

Orographic amplification of El Niño teleconnections on winter precipitation across the Intermountain West of North America

Nature Portfolio (Springer Nature) | December 4th, 2023

Overview of Management and Restoration Activities in the Salton Sea

Congressional Research Service (CRS) | November 24th, 2013

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provid

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provided baseline data about the Sea, and some restoration plans have been proposed. The State of California, the Salton Sea Authority, and the federal government through the Bureau of Reclamation have devised plans for restoring the Sea. However, none of these plans are being fully implemented. Federal authorities that address restoration of the Salton Sea are generally based on creating and evaluating proposals for restoration, rather than implementing restoration activities in a comprehensive manner similar to other initiatives in the Everglades and Great Lakes. California is pursuing restoration options, but funding for implementing them is lacking. Whether or not to restore the Salton Sea remains controversial. Proponents of restoration contend that the Salton Sea ecosystem is valuable from an ecological standpoint because it is one of the few remaining large-scale wetland habitats in California for migratory birds and fish. Further, some argue that keeping the Salton Sea intact will stimulate economic development, recreation, and tourism in the region. They note that losing the Sea could cause economic and environmental decline, and could lead to air quality problems from exposed seabeds. Others contend that the Sea should not be restored. They argue that the Salton Sea is naturally declining, as it has throughout its geological history. Further, they note that countering this process will be costly and ultimately not worth the expense. They state that limited restoration funds should be used to restore other natural wetlands in California, such as the Sacramento-San Joaquin Bay Delta. The decline of the Salton Sea ecosystem is accelerating due to water transfers from agricultural lands to municipal water districts in San Diego under the terms of the Quantification Settlement Agreement, an agreement on how to share California’s apportionment of Colorado River water. The water transfers have resulted in less water flowing into the Salton Sea and accelerated increases in salinity and shoreline recession. According to some scientists, salinity levels may reach lethal levels for most fish and wildlife as soon as 2018. These predictions, along with the steadily declining ecosystem might provoke Congress to consider a larger role in restoration for the federal government. Congress may decide to address restoration by increasing the federal role in restoration efforts.  This could be done by funding existing federal authorities that address, or could address, restoring the ecosystem; authorizing federal participation and appropriations for implementing existing restoration plans; or authorizing a new comprehensive plan to be created that might involve participation from federal and non-federal stakeholders, similar to other restoration initiatives around the country. Congress might also decide not to address restoration of the Salton Sea ecosystem, or simply maintain the status quo of federal participation.

Pathways and Barriers to Corporate Water Stewardship in the Colorado River Basin

Pacific Institute | October 24th, 2023

The Colorado River is the lifeblood of the American West. It supports 30 Native American tribes and farms, cities, and ecosystems in seven US states—Arizona, California

The Colorado River is the lifeblood of the American West. It supports 30 Native American tribes and farms, cities, and ecosystems in seven US states—Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming—and the Mexican states of Baja California and Sonora. However, the river is in crisis. Twenty-three years of drought, the over-allocation of water, and climate change have exacerbated a structural deficit—where more water leaves the system than enters it—for the tribes, communities, and ecosystems that depend on the Colorado River. To advance water resilience in the Colorado River Basin (Basin), accelerated action and investment are required from all sectors. These efforts must be strategic, coordinated, and amplified to effectively tackle the Basin’s challenges. Corporations can play a key role through their operations and supply chains, and by co-funding innovative projects. While a subset of leading companies is engaging in corporate water stewardship (CWS) in the Basin, more is needed to meet the magnitude of the water crisis at hand. This report outlines barriers and pathways to CWS in the Basin based on 20 interviews with corporate and non-corporate stakeholders from February to April 2022, and interviewee feedback on the results. The report is part of a broader Pacific Institute effort to advance CWS in the Basin. We are using these findings to prioritize CWS projects, initiatives, and approaches to pilot and scale in the Basin. More broadly, the findings are applicable to moving CWS toward building long-term water resilience in the Basin and other water-stressed basins around the world.

Pilot Projects to Increase Colorado River System Water in Lake Powell and Lake Mead

U.S. Bureau of Reclamation (USBR) | January 14th, 2022

From calendar year 2015 through 2018, 64 projects were implemented in the Upper Basin resulting in an estimated 47,280 acre-feet of Colorado River System water conserved

From calendar year 2015 through 2018, 64 projects were implemented in the Upper Basin resulting in an estimated 47,280 acre-feet of Colorado River System water conserved in the Upper Basin at a cost of $8.5 million or $180.23 per acre-foot on average. From January 2015 through December 31, 2019 in the Lower Basin, 16 projects were implemented which will result in 175,347 acre-feet of Colorado River System water in Lake Mead by 2035, at a cost of approximately $29.8 million or $170.14 per acre-foot on average. The Pilot Program successfully demonstrated that voluntary, compensated water conservation projects can conserve water for Colorado River System storage to help mitigate the impacts of drought.

Projections of declining surface-water availability for the southwestern United States

Nature Portfolio (Springer Nature) | December 23rd, 2012

Global warming driven by rising greenhouse-gas concentrations is expected to cause wet regions of the tropics and mid to high latitudes to get wetter and subtropi

Global warming driven by rising greenhouse-gas concentrations is expected to cause wet regions of the tropics and mid to high latitudes to get wetter and subtropical dry regions to get drier and expand polewards. Over southwest North America, models project a steady drop in precipitation minus evapotranspiration, P−E, the net flux of water at the land surface, leading to, for example, a decline in Colorado River flow. This would cause widespread and important social and ecological consequences. Here, using new simulations from the Coupled Model Intercomparison Project Five, to be assessed in Intergovernmental Panel on Climate Change Assessment Report Five, we extend previous work by examining changes in P, E, runoff and soil moisture by season and for three different water resource regions. Focusing on the near future, 2021–2040, the new simulations project declines in surface-water availability across the southwest that translate into reduced soil moisture and runoff in California and Nevada, the Colorado River headwaters and Texas.

Punctuated Sediment Discharge during Early Pliocene Birth of the Colorado River: Evidence from Regional Stratigraphy, Sedimentology, and Paleontology

Sedimentary Geology (Elsevier) | January 1st, 2018

The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits th

The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits that formed prior to and during river initiation are well exposed in the lower river valley and nearby basinal sink. This paper presents a synthesis of regional stratigraphy, sedimentology, and micropaleontology from the southern Bouse Formation and similar-age deposits in the western Salton Trough, which we use to interpret processes that controlled the birth and early evolution of the Colorado River. The southern Bouse Formation is divided into three laterally persistent members: basal carbonate, siliciclastic, and upper bioclastic members. Basal carbonate accumulated in a tide-dominated marine embayment during a rise of relative sea level between ~ 6.3 and 5.4 Ma, prior to arrival of the Colorado River. The transition to green claystone records initial rapid influx of river water and its distal clay wash load into the subtidal marine embayment at ~ 5.4–5.3 Ma. This was followed by rapid southward progradation of the Colorado River delta, establishment of the earliest through-flowing river, and deposition of river-derived turbidites in the western Salton Trough (Wind Caves paleocanyon) between ~ 5.3 and 5.1 Ma. Early delta progradation was followed by regional shut-down of river sand output between ~ 5.1 and 4.8 Ma that resulted in deposition of marine clay in the Salton Trough, retreat of the delta, and re-flooding of the lower river valley by shallow marine water that deposited the Bouse upper bioclastic member. Resumption of sediment discharge at ~ 4.8 Ma drove massive progradation of fluvial-deltaic deposits back down the river valley into the northern Gulf and Salton Trough. These results provide evidence for a discontinuous, start-stop-start history of sand output during initiation of the Colorado River that is not predicted by existing models for this system. The underlying controls on punctuated sediment discharge are assessed by comparing the depositional chronology to the record of global sea-level change. The lower Colorado River Valley and Salton Trough experienced marine transgression during a gradual fall in global sea level between ~ 6.3 and 5.5 Ma, implicating tectonic subsidence as the main driver of latest Miocene relative sea-level rise. A major fall of global sea level at 5.3 Ma outpaced subsidence and drove regional delta progradation, earliest flushing of Colorado River sand into the northern Gulf of California, and erosion of Bouse basal carbonate and siliciclastic members. The lower Colorado River valley was re-flooded by shallow marine waters during smaller changes in global sea level ~ 5.1–4.8 Ma, after the river first ran through it, which requires a mechanism to stop delivery of sand to the lower river valley. We propose that tectonically controlled subsidence along the lower Colorado River, upstream of the southern Bouse study area, temporarily trapped sediment and stopped delivery of sand to the lower river valley and northern Gulf of California for ~ 200–300 kyr. Massive progradation of the fluvial-deltaic system back down the river valley into the Salton Trough starting ~ 4.8–4.5 Ma apparently was driven by a huge increase in sediment discharge that overwhelmed the sediment-storage capacity of sub-basins along the lower river corridor and established the fully integrated river channel network.