Principal Research Analyst
Water Shortage Declared
On August 16, 2021, the U.S. Bureau of Reclamation (Reclamation) declared the first-ever official water shortage on the Colorado River. This declaration triggered significant mandatory water cuts in the Colorado River Basin. While Kansas is not part of the Colorado River Basin, it does have a vested interest in western water issues, as the state relies on Colorado supplying an adequate amount of water each year.
The Colorado River
The Colorado River runs 1,450 miles through seven states (Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming) and Mexico. Water from the Colorado River is used to irrigate 5.5 million acres of agricultural land and to provide municipal and industrial (M&I) water supplies to 40 million people.
Water from the Colorado River is regulated by dams and stored in reservoirs. Two major dams along the Colorado River are the Glen Canyon Dam and the Hoover Dam. Each of these dams has an associated storage reservoir. Lake Powell, associated with the Glen Canyon Dam, has a storage capacity of 26.2 million acre-feet (MAF). Lake Mead, associated with the Hoover Dam, has a storage capacity of 26.1 MAF.
The Law of the River
The laws and agreements governing Colorado River operations are referred to as “The Law of the River,” stemming primarily from the Colorado River Compact of 1922.
This agreement divided the Colorado River Basin into the Upper Basin and the Lower Basin. Each basin region was apportioned 7.5 MAF per year for beneficial consumptive use.
Problems Facing the Colorado River
Supply and Demand Imbalance
When the Colorado River Compact of 1922 was approved, the appropriations of water supply were based on the average flows during the preceding ten-year period, which included several wet years.
The data from this period indicated the average annual flows of the Colorado River totaled 16.4 MAF. But historical data collected by Reclamation from 1906 to 2020 shows that natural flows averaged closer to 14.7 MAF annually.
Thus, water supplies were over-allocated and subject to overuse. Even though this accounting error has been identified, the problem of overuse is likely to persist. By 2050, Reclamation estimates demand for water from the Colorado River will increase to an amount between 18.1 MAF and 20.4 MAF per year, and the number of people who rely on the Colorado River is projected to double by 2060.
In addition to the growing demand for water, a study conducted by the U.S. Geological Survey revealed natural flows from the Colorado River have declined approximately 20.0 percent over the last century. Between 2000 and 2020, flows averaged about 12.4 MAF annually. Reclamation found the current drought (2000 to 2021) has been the driest 22-year period on record, and it has resulted in 8 of the 20 driest years on record.
The drought has negatively affected water storage operations along the Colorado River. In June 2021, modeling completed by Reclamation showed there is a 17.0 percent chance that Lake Powell could sink so low by 2024 that hydroelectric generation at the Glen Canyon Dam would become impossible.
The affected states and Mexico have been working to combat the declining natural flows and elevations of Lake Mead and Lake Powell. Mitigation techniques include using alternative water sources, like aquifers, changing landscaping regulations to incentivize reduced water use, investing in waste water treatment and reuse, and studying the potential of desalination plants to transform saltwater into freshwater.
In August 2022, Reclamation released the Colorado River Basin August 2022 24-Month Study, which determined a Tier 2a shortage level. Lake Powell will operate in the Lower Elevation Balancing Tier, which includes limiting water year 2023 releases to protect Lake Powell from declining below 3,525 feet. Lake Mead will operate in its first-ever Level 2a Shortage Condition in 2023. In this condition, shortage reductions and water savings contributions are required for the Lower Basin States and Mexico, as follows:
- Arizona will experience a 21.0 percent reduction;
- Nevada will experience an 8.0 percent reduction; and
- Mexico will experience a 7.0 percent reduction.
The Future of the Colorado River
Over the next few years, the states, Mexico, Native American Tribes, and the federal government will negotiate a new framework to determine how to distribute water supplies, as the current guidelines expire in 2026.