Yesterday it was the Columbia River; today it's my favorite river, the Colorado River. Charles V. Stern and Pervaze A. Sheikh have updated (15 December 2020) this important CRS report: Management of the Colorado River: Water Allocations, Drought, and the Federal Role.
Lots of graphics - click on them to enlarge them or if they are not showing properly.
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Overview
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 also is important for power production, fish and wildlife, and recreational uses.
The water apportioned to states on the Colorado River is widely acknowledged to be in excess of the river’s natural flows. Although a majority of the basin’s precipitation originates in the Upper Basin, the Lower Basin also has been extensively developed by the federal government. Consumptive uses of Colorado River water typically exceed natural flows, causing an imbalance in the basin’s available supplies and demands. These trends are exacerbated by a drought in the basin dating to 2000, which has raised the prospect of water delivery curtailments and decreased hydropower production, among other things. In the future, observers expect that increasing demand for water supplies, coupled with the effects of climate change, will further strain the basin’s limited water supplies.
River Management
The Law of the River is the commonly used shorthand for the multiple laws, court decisions, and other documents governing Colorado River operations. The foundational document of the Law of the River is the Colorado River Compact of 1922. Pursuant to the compact, the basin states established a framework to apportion the water supplies between the Upper and Lower Basins of the Colorado River, with the dividing line between the two basins at Lee Ferry, AZ (near the Utah border). The Upper and Lower Basins each were allocated 7.5 million acre-feet (MAF) annually under the compact (plus the right to an increase of 1 MAF per year in the Lower Basin); an additional 1.5 MAF in annual flows was made available to Mexico under a 1944 treaty. Future agreements and court decisions addressed other issues (including intrastate allocations of flows), and subsequent federal legislation provided authority and funding for federal facilities that allowed users to develop their allocations. A 1963 Supreme Court ruling also confirmed that Congress designated the Secretary of the Interior as the water master for the Lower Basin, a role in which the federal government manages 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 recent criteria, dam releases from these facilities are tied to specific water storage levels. For Lake Mead, the first operational shortage tier (“Tier Zero”) under which Arizona’s and Nevada’s allocations are decreased by specified levels would be triggered if Lake Mead’s January 1 elevation were expected to fall between 1,075 feet and 1,090 feet above mean sea level. This operational tier is currently in effect, and this is expected to remain the case in the near future. As of August 2020, Reclamation projected a 49% chance, depending on the hydrology assumed, for additional curtailments (i.e., a Tier One or greater shortage) at Lake Mead by 2024.
Operational Changes and Drought Contingency Plans
Despite earlier efforts to alleviate future shortages, the basin’s hydrological outlook generally has worsened in recent years. After several years of negotiations, in 2019 Reclamation and the basin states transmitted to Congress plans to further alleviate stress on basin water supplies. Congress authorized these plans, known as the drought contingency plans (DCPs) for the Upper and Lower Basins, in April 2019 in the Colorado River Drought Contingency Plan Authorization Act (P.L. 116-14). Among other things, the DCPs obligate Lower Basin states to additional water delivery reductions at specified storage levels (i.e., reductions beyond previous curtailment plans), commit Reclamation to additional water conservation efforts, and put in place plans to coordinate Upper Basin operations to protect Lake Powell storage levels and hydropower generation. Despite the success of DCP negotiations, many remain concerned about the Colorado River Basin’s long-term water supply outlook, including the potential for a compact call (a “call” on water rights between the Lower Basin and Upper Basin) that might lead to a protracted legal issues. Climate change, tribal water rights settlements, and state and local water supply development in the Upper Basin could further constrain water supplies. A central question facing the basin’s decisionmakers is whether current “interim” guidelines will be renewed prior to their expiration in 2026 and what other changes might be made as a part of those agreements.
Congressional Role
Congress plays a multifaceted role in federal management of the Colorado River Basin. Congress funds and oversees management of basin facilities, including operations and programs to protect and restore endangered species. It has enacted and continues to consider Indian water rights settlements involving Colorado River waters and development of new water storage facilities in the basin. In addition, Congress has approved funding to mitigate water shortages and conserve basin water supplies and has enacted new authorities to combat drought and its effects on basin water users (i.e., the DCPs and other related efforts).
Keep going - lots more to go!
Enjoy!
“A man of the West will fight over water, women, and gold, and generally in that order.” –Sen. Barry Goldwater (1909 - 1998)
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