The Metropolitan Aqueduct: Colorado River Water for Cities in the Metropolitan Water District

Metropolitan Water District of Southern California (MWD) | March 12th, 1931

The Metropolitan Water District of Southern California History and First Annual Report for the Period Ending June 30, 1938

Metropolitan Water District of Southern California (MWD) | January 20th, 1939

The New Inland Sea

Scientific American | April 13th, 1907

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached

The deep channel in the Alamo River, which passed Holtville in August, was gradually approaching Sharp's Heading, and it was recognized that when this cataract reached the heading it would be very difficult and expensive, and perhaps impossible, to maintain that heading. This, however, was not the only peril to the water supply of the valley. The channel of New River had eroded to such an extent that where the two streams separated it was estimated that four-fifths of the water was running down New River and only one fifth down the Alamo. While this proportion was favorable to the regimen of the Alamo and the safety of Sharp's Heading, it was very threatening in an other respect. It accelerated the cutting of the New River channel, in which was a great cataract four or five miles below the separation of the two streams, and this was, of course, advancing upstream. It was well recognized that when this cataract reached the Alamo the channel would be so deep that all of the water would run down New River and leave Sharp's Heading on dry land, without any water for the irrigation of the Imperial Valley. Threatened first with inundation, and next with the destruction of their entire water supply, the inhabitants of the Imperial Valley have naturally been almost in a state of panic for several months.

The Newest Plan of Los Angeles Engineers to Provide More Water for that Enterprising Metropolis

Scientific American | February 1st, 1925

The Press and Pulse of Climate Change: Extreme Events in the Colorado River Basin

American Water Resources Association (AWRA) | June 21st, 2022

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health, vulnerable infrastructure, and threatened ecosystems and species. Often, the steady and progressive trends (or presses) of rising global temperature are the central focus in how climate impacts are described. However, observations of extreme weather events (or pulses) increasingly show that the intensity, duration and/or frequency of acute events are also changing, resulting in greater impacts on communities and the environment. Describing how the influence of extreme events may shape water management in the Colorado River Basin in clear terms is critical to sound future planning and efforts to manage risk. Three scenario planning workshops in 2019 and 2020 were held as part of a Colorado River Conversations series, identifying potential impacts from multiple intersecting extreme events. Water managers identified climate-related events of concern in the Colorado River Basin that necessitate greater attention and adaptive responses. To support efforts to include consideration of climate-change-driven extremes in water management and planning, we explore the current state of knowledge at the confluence of long-term climate shifts and extreme weather in the Colorado River Basin related to the events of concern that were identified by scenario planning participants.

The Salton Sea: A Status Update

Legislative Analyst's Office (LAO) | August 29th, 2018

The seven Colorado River Basin states letter to the U.S. Bureau of Reclamation, 5/22/23

U.S. Bureau of Reclamation (USBR) | May 22nd, 2023

The Status of Tribal Water Rights in the Colorado River Basin

Water and Tribes Initiative | April 9th, 2021

There are 30 federally recognized tribes in the Colorado River Basin. Twenty two of these tribes have recognized rights to use 3.2 million-acre feet (maf) of Colorado Riv

There are 30 federally recognized tribes in the Colorado River Basin. Twenty two of these tribes have recognized rights to use 3.2 million-acre feet (maf) of Colorado River system water annually, or approximately 22 to 26 percent of the Basin’s average annual water supply. In addition, 12 of the tribes have unresolved water rights claims, which will likely increase the overall volume of tribal water rights in the Basin. Under the Upper Colorado River Basin Compact and the U.S. Supreme Court’s decree in Arizona v. California, all tribal water uses are counted against the apportionments made to the states. Tribes’ rights are generally senior to state law-based water rights.

The twenty-first century Colorado River hot drought and implications for the future

American Geophysical Union (AGU) | February 17th, 2017

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. At least one-sixth to one-half (averag

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15-year drought on record. At least one-sixth to one-half (average at one-third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model-based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model-based temperature projections indicate that continued business-as-usual warming will drive temperature-induced declines in river flow, conservatively −20% by midcentury and −35% by end-century, with support for losses exceeding −30% at midcentury and −55% at end-century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.

The twenty‐first century Colorado River hot drought and implications for the future

American Geophysical Union (AGU) | February 17th, 2017

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (

Between 2000 and 2014, annual Colorado River flows averaged 19% below the 1906–1999 average, the worst 15‐year drought on record. At least one‐sixth to one‐half (average at one‐third) of this loss is due to unprecedented temperatures (0.9°C above the 1906–1999 average), confirming model‐based analysis that continued warming will likely further reduce flows. Whereas it is virtually certain that warming will continue with additional emissions of greenhouse gases to the atmosphere, there has been no observed trend toward greater precipitation in the Colorado Basin, nor are climate models in agreement that there should be a trend. Moreover, there is a significant risk of decadal and multidecadal drought in the coming century, indicating that any increase in mean precipitation will likely be offset during periods of prolonged drought. Recently published estimates of Colorado River flow sensitivity to temperature combined with a large number of recent climate model‐based temperature projections indicate that continued business‐as‐usual warming will drive temperature‐induced declines in river flow, conservatively −20% by midcentury and −35% by end‐century, with support for losses exceeding −30% at midcentury and −55% at end‐century. Precipitation increases may moderate these declines somewhat, but to date no such increases are evident and there is no model agreement on future precipitation changes. These results, combined with the increasing likelihood of prolonged drought in the river basin, suggest that future climate change impacts on the Colorado River flows will be much more serious than currently assumed, especially if substantial reductions in greenhouse gas emissions do not occur.