About the river

Overview

The Colorado River is a vital source of water, hydropower, recreation, ecosystem services, and other amenities for people in the seven basin states (Colorado, Wyoming, Utah, New Mexico, Arizona, Nevada, and California), over two dozen federally recognized tribes, and the Republic of Mexico. Over 40 million people rely on the Colorado River and its tributaries in part or in full for their municipal water supply, while 5.5 million acres of irrigated crops and pasture depend on this water too. The hydropower facilities at major dams collectively generate over 9,000 megawatt-hours annually, though this has declined in recent years with lower reservoir levels. A 2014 study estimated the total economic activity across the seven basin states supported by Colorado River water to be $1.4 trillion annually.

Two huge reservoirs, Lake Powell and Lake Mead, are the linchpins of an elaborate system of reservoirs, canals, and tunnels (see map below) that distribute water and generate hydropower. In total, these facilities can store about four years of average flow. The U.S. Bureau of Reclamation operates the major reservoirs, with many state and local entities contributing to the overall operation of the system.

In their natural state, the Colorado River and its tributaries constituted a network of lifelines through a mainly arid region, distributing valuable water, nutrients, and millions of tons of sediment downstream and ultimately to the Gulf of California, creating an extensive and rich delta ecosystem. Along the way, it supported many endemic species of fish. Starting with the first small transbasin diversions in headwaters in the late 1800s through the

The current situation

The enormous storage capacity of the system’s reservoirs (about 60 million acre-feet), mostly held in Lake Powell and Lake Mead, buffered most of water users from the large variability in the river's flow even as overall basin water use increased by over 50% between 1960 and 2000. But starting in 2000, an extended dry period along with warming temperatures led to average annual streamflows about 20% lower than the long-term average. During this period of low inflows, full water deliveries to the Lower Basin states (California, Arizona, Nevada) and Mexico continued under the Law of the River, while Upper Basin water use stayed relatively constant as well.

As a result of this chronic imbalance between supply and demand, system storage has declined to levels never seen before, except in modeled future scenarios. Lake Powell, as of October 2022, is at 25% of capacity and is uncomfortably close to the minimum level for producing hydropower--and possibly for reliably delivering any water downstream. Lake Mead is at 28% of capacity, also close to its minimum power pool, and closer to dead pool (i.e., unable to deliver any water downstream) than to half-full.

Under agreements made in 2007 and 2019 to forestall severe system impacts, mandatory ("Tier 1") curtailments of Lower Basin and Mexico water use were first triggered in August 2021, with larger "Tier 2" curtailments, totaling 0.7 million acre-feet per year, triggered in August 2022. Even so, the increasingly tenuous state of the system led the Commissioner of Reclamation to demand, in June 2022, that the seven basin states collectively reduce their annual water uses by an additional 2 to 4 million acre-feet in 2023 to ensure there would be no near-term (1-4 years) complete loss of hydropower or water releases from Powell and Mead. As of October 2022, there has been limited progress by the states in committing to specific additional reductions or taking measures that would plausibly lead to reductions.

This short-term water and power crisis has come to the forefront just as Reclamation, the basin states, tribes, Mexico, and other stakeholders started to revisit the 2007 Interim Guidelines for operating Powell and Mead and addressing basin water shortages, in preparation for developing new long-term guidelines by 2026. The new guidelines will need to incorporate lessons from the post-2000 period, and accommodate the increasing influence of climate change on basin hydrology. Other complex challenges in the basin await further amelioration efforts if not durable solutions, such as unresolved tribal water allocations and infrastructure needs, endangered fish and other species, altered streamflow and sediment regimes below dams, and the shrinking Salton Sea.

Additional resources

Reclamation Colorado River Basin homepage

Includes links to recent Reclamation news releases, 1- to 5-year projections of system conditions

CBRFC Upper Colorado Situational Awareness

Dashboard shows late-fall soil moisture (map) and current snowpack (map); current water-year and month-to-date precipitation (maps); most recent forecasts of April-July and water-year inflows to Lake Powell; observed inflows to Lake Powell.

CBRFC Lower Colorado Situational Awareness

Dashboard shows current soil moisture (map) and current snowpack (map); current water-year and month-to-date precipitation (maps).