Lake Powell and Glen Canyon Dam
The construction of Glen Canyon Dam in 1964 created Lake Powell. Both are located in north-central Arizona near the Utah border. Lake Powell acts as a holding tank for outflow from the Colorado River Upper Basin States: Colorado, New Mexico, Utah and Wyoming.
The water stored in Lake Powell is used for recreation, power generation and delivering water to the Lower Basin states of California, Arizona, and New Mexico.
The lake, the nation’s second largest manmade lake, can hold up to 26 million acre-feet of water, or about two years of total average flows for the Colorado River. The reservoir assists the Upper Basin of the Colorado River with its delivery obligations to the Lower Basin [see also Colorado River Water Use 4.4 Plan].
Lake Powell and Glen Canyon Dam Overview
The dam’s construction was controversial and Lake Powell flooded a natural canyon some deemed worthy of national park status.
Since, some have proposed draining Lake Powell. Proponents list restoration of prehistoric American Indian archeological sites, riparian ecosystems and endangered fish species as key reasons to empty the lake. They also site evaporation and sediment build-up as detrimental to the success of Lake Powell and its ecosystem.
Supporters of the reservoir say Lake Powell is needed because it supports the local economy through tourism and recreation, is a major source of hydroelectric power (80 percent of the Colorado River Storage Project’s electrical generation occurs at Glen Canyon Dam) and ensures steady water supplies to the Lower Basin.
There has also been concern from stakeholders in the Upper Basin states (Colorado and New Mexico) that continued demands from the Lower Basin could lower Lake Powell below the minimum level required for hydropower generation.
The Bureau of Reclamation also developed the Glen Canyon Adaptive Management Program in 1997 to better integrate “dam operations, downstream resource protection and management, and monitoring and research information.”
Much of the focus of the AMP has been the experimental high flow releases from Glen Canyon Dam that aim to restore sandy beaches in the Grand Canyon – improving the environment for both rafters and aquatic species. In 1996, 2004 and 2008, the U.S. Geological Survey (USGS) conducted experimental flood releases at Glenn Canyon Dam to redistribute sediment along and within the river channel, scour non-native streamside vegetation, protect cultural resources, restore native fish habitat and provide beaches for Colorado River rafters. An evaluation of the 2008 flows showed that the releases resulted in more sandbars and larger camping areas, and that even with subsequent erosion, sandbars remained more abundant than before the test flows.
Subsequently, federal officials adopted a High Flow Protocol for similar releases from the dam when conditions are favorable for high sediment deposits, usually during early spring or fall, between 2012 and 2020. The first High Flow Protocol releases were made in November 2012. The volume of water released through the river outlet tubes during the five-day release was higher than usual but the total amount of water released from Powell to Mead remained the same for that year and was not altered under the high flow releases.
The adaptive management plan has particularly focused on experimental high flow releases from Glen Canyon Dam that aim to improve the environment and restore sandy beaches in the Grand Canyon.
Lake Powell and Glen Canyon Dam Looking Ahead
Lake Powell and Glen Canyon Dam are currently in the midst of a drought that began in 2000.
A study by the Bureau of Reclamation, Colorado River Basin Water Supply and Demand, could help provide a roadmap for the future. The study’s goal is “to complete a comprehensive review of water supply and current and long-term demands through 2060; to assess options for resolving water supply imbalances; and to develop recommendations for future consideration to address current and projected imbalances.”
The study includes an assessment of potential impacts of climate variability and climate change on water demand, supply and system reliability.