The 'Dynamic Duo' of Charles V. Stern and Pervaze A. Sheikh penned (Updated 6 February) this CRS Report: 'Management of the Colorado River - Water Allocations, Drought, and the Federal Role' .
Download CRS_Report_Mgmt_CR_Water_Allocation_Drought_Fed_Role_6Feb2023
Summary
The Colorado River Basin covers more than 246,000 square miles in seven U.S. states (Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, and California) and Mexico. Pursuant to federal law, the Bureau of Reclamation (part of the Department of the Interior) manages much of the basin’s water supplies. Colorado River water is used primarily for agricultural irrigation and municipal and industrial (M&I) uses; it is also important for hydropower production, fish and wildlife, and recreational uses.
Apportioned Colorado River water is widely acknowledged to be in excess of the river’s natural flows, and consumptive use plus other losses of these waters (i.e., evaporation) typically exceeds natural flows. This causes an imbalance in the basin’s available water supply and demand. Stress on basin water supplies is exacerbated by a long-term drought dating to 2000.
River Management
The foundational document governing basin water management is the Colorado River Compact of 1922. Pursuant to the compact, the basin states established a framework to apportion water supplies between the river’s Upper and Lower Basins, with the dividing line between the two basins located at Lee Ferry, AZ. Each basin was allocated 7.5 million acre-feet (MAF) annually under the compact, and an additional 1.5 MAF in annual flows was made available to Mexico under a 1944 treaty. Further agreements and court decisions addressed other issues, and subsequent federal legislation provided authority and funding for federal facilities that allowed users to develop their allocations. A 1963 Supreme Court ruling confirmed that Congress designated the Secretary of the Interior to manage the delivery of all water below Hoover Dam.
Reclamation and basin stakeholders closely track the status of two large reservoirs—Lake Powell in the Upper Basin and Lake Mead in the Lower Basin—as an indicator of basin storage conditions. Under criteria agreed upon by basin states, water releases from both lakes are tied to specific water storage levels. Since the onset of drought in the early 2000s, storage levels at these reservoirs have been falling. In 2021 and 2022, Reclamation declared the first-ever Tier One and Tier Two Shortages in the Lower Basin, respectively. These designations reduced water deliveries to contractors in Arizona and Nevada, as well as to Mexico. In the Upper Basin, Lake Powell’s storage has continued to drop. This trend could soon jeopardize hydropower generation at Glen Canyon Dam, and has led to operational changes in the Upper Basin.
Efforts to Address Drought
The federal government has led multiple efforts to improve the basin’s water supply outlook, resulting in collaborative agreements in 2003 and 2007 and the 2019 drought contingency plans (DCPs) for the Upper and Lower Colorado River Basins (authorized by Congress in the Colorado River Drought Contingency Plan Authorization Act, P.L. 116-14). The DCPs required new cutbacks to Lower Basin water deliveries based on specified storage levels in Lake Mead, committed Reclamation to supporting water conservation efforts, and put in place plans to coordinate Upper Basin operations to enhance Lake Powell storage levels and prevent the loss of hydropower generation.The hydrologic outlook for the Colorado River Basin has deteriorated further since approval of the DCPs, and there remains widespread concern about the basin’s long-term water supply. On June 14, 2022, Reclamation called on basin states to conserve an additional 2-4 MAF of water in 2023 and 2024. When these commitments failed to materialize, Reclamation initiated a process to revise its current operational guidelines for 2023 and 2024; this process could lead Reclamation to implement additional unilateral delivery curtailments without state input. In addition to these short-term water management decisions, decisionmakers face longer-term questions, such as whether to renew basin water management agreements (including the DCPs) expiring in 2026 and whether major changes to basin water management are warranted.
Congressional Role
Congress plays a multifaceted role in the federal management of the Colorado River Basin. Congress funds and oversees management of basin water and power facilities and has held oversight hearings on drought in the basin. Congress also has enacted legislation involving allocation of Colorado River waters (e.g., authorization of Indian water rights settlements; new water storage facilities) and authorities to mitigate water shortages (e.g., the DCPs and other related efforts). Further, Congress may consider amending, extending, or repealing existing authorities or providing funding to mitigate the effects of the basin’s water shortages. Most recently, in Section 50233 of P.L. 117-169 (popularly known as the Inflation Reduction Act), Congress provided $4.0 billion for drought mitigation in the West, with priority given to Colorado River Basin activities.Introduction
From its headwaters in Colorado and Wyoming to its terminus in the Gulf of California, the Colorado River Basin covers more than 246,000 square miles. The river runs through seven U.S. states (Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, and California) and Mexico. Pursuant to federal law, the Bureau of Reclamation (Reclamation, a bureau in the Department of the Interior [DOI]) plays a prominent role in the management of the basin’s waters. In the Lower Basin (i.e., Arizona, Nevada, and California), Reclamation also serves as water master on behalf of the Secretary of the Interior, a role that elevates the status of the federal government in basin water management. The federal role in managing Colorado River water is magnified by the multiple federally owned and operated water storage and conveyance facilities in the basin, which provide low-cost water and hydropower supplies to water users.
Colorado River water is used primarily for agricultural irrigation and municipal and industrial (M&I) purposes. The river’s flow and stored water also are important for power production, fish and wildlife, and recreation, among other uses. A majority of basin water supplies (70%) are used to irrigate 5.5 million acres of land; basin waters also provide M&I water supplies to nearly 40 million people Much of the area that depends on the river for its water supplies is outside of the drainage area for the Colorado River Basin. Storage and conveyance facilities on the Colorado River provide trans-basin diversions that serve areas such as Cheyenne, WY; multiple cities in Colorado’s Front Range (e.g., Fort Collins, Denver, Boulder, and Colorado Springs, CO); Provo, UT; Albuquerque and Santa Fe, NM; and Los Angeles, San Diego, and the Imperial Valley in Southern California (Figure 1). Colorado River hydropower facilities can provide up to 4,200 megawatts of electrical power per year. The river also provides habitat for a wide range of species, including several federally endangered species. It flows through 7 national wildlife refuges and National Park Service (NPS) units; these and other areas of the river support important recreational opportunities.
Precipitation and runoff in the basin are highly variable. Water conditions on the river depend largely on snowmelt in the basin’s northern areas. Based on observed historical data (1906-2022), natural flows in the Colorado River Basin averaged about 14.6 million acre-feet (MAF) annually. Flows have dippedsignificantly during the current drought, which dates to 2000; annual natural flows from 2000 to 2022 averaged approximately 12.1 MAF per year. Reclamation has noted that the 23-year period from 2000 to 2022 was the driest 23-year period in more than 100 years of record keeping, and among the driest periods in the past 1,200 years. Climate change impacts, including warmer temperatures and altered precipitation patterns, may further increase the likelihood of prolonged drought in the basin.
Pursuant to the multiple compacts, federal laws, court decisions and decrees, contracts, and regulatory guidelines governing Colorado River operations (collectively known as the Law of the River), Congress and the federal government play a prominent role in the management of the Colorado River. Specifically, Congress funds and oversees Reclamation’s management of Colorado River Basin facilities, including facility operations and programs to protect and restore endangered and threatened species. Congress has also approved and continues to consider Indian water rights settlements involving Colorado River waters, and development of new and expanded water storage in the basin. In addition, Congress has approved supplemental funding to mitigate drought and stretch basin water supplies, and new authorities for Reclamation to combat drought and enter into agreements with states and Colorado River contractors. This report provides background on management of the Colorado River, with a focus on recent developments. It also discusses the congressional role in the management of basin watersresulting drawdown of basin storage has left Lakes Mead and Powell at historically low levels that threaten both hydropower production and water deliveries throughout the basin. Water flow projections based on climate change estimate that flows will continue to decrease, whereas new demands and diversions (e.g., development of tribal water rights) suggest that competition for this water will continue to increase.
Despite agreement that some level of water delivery cutbacks will be necessary to protect power generation and reservoir storage, there remain considerable differences of opinion as to what form these actions should take, and whether they should be formulated at the federal or nonfederal (consensus-based) level. The question of which entities will face water delivery cutbacks and of what magnitude, as well as what sort of mitigation might accompany these efforts, take on an added level of urgency due to the river’s economic importance to many areas. The relative importance of established water rights priorities in the basin, compared to priority for health, safety, and other uses, is a central issue currently facing decisionmakers. Other questions, including what changes to infrastructure (e.g., alterations to dam and water delivery infrastructure), accounting (e.g., whether and how to account for evaporation in the Lower Basin), and/or the basis for basin water management (e.g., water allocations based on inflows rather than set amounts) are also likely to figure into future discussions and negotiations.
Cutting to the chase (be sure to read 'The Law of the River' and other material).
Concluding Obervations
There is wide acknowledgement that existing directives for managing Colorado River Basin waters are inadequate and do not account for the basin’s current and projected hydrology. The original basis for the Colorado River Compact assumed more water than turned out to be available for consumptive uses, and a drought dating to 2000 has exacerbated this issue. Although recent agreements have marginally reduced usage, basinwide consumptive use (including evaporation) has continued to exceed natural flows in most years of the past several decades. The resulting drawdown of basin storage has left Lakes Mead and Powell at historically low levels that threaten both hydropower production and water deliveries throughout the basin. Water flow projections based on climate change estimate that flows will continue to decrease, whereas new demands and diversions (e.g., development of tribal water rights) suggest that competition for this water will continue to increase.Despite agreement that some level of water delivery cutbacks will be necessary to protect power generation and reservoir storage, there remain considerable differences of opinion as to what form these actions should take, and whether they should be formulated at the federal or nonfederal (consensus-based) level. The question of which entities will face water delivery cutbacks and of what magnitude, as well as what sort of mitigation might accompany these efforts, take on an added level of urgency due to the river’s economic importance to many areas. The relative importance of established water rights priorities in the basin, compared to priority for health, safety, and other uses, is a central issue currently facing decisionmakers. Other questions, including what changes to infrastructure (e.g., alterations to dam and water delivery infrastructure), accounting (e.g., whether and how to account for evaporation in the Lower Basin), and/or the basis for basin water management (e.g., water allocations based on inflows rather than set amounts) are also likely to figure into future discussions and negotiations.
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