Glen Canyon Dam: The Controversial Dam Above the Grand Canyon

**Glen Canyon Dam** on the Colorado River near Page, Arizona, is a **216-meter** concrete arch dam completed in 1966. It created **Lake Powell**, the second-largest reservoir in the United States with a capacity of 30 km³, stretching 299 kilometers upstream through the red sandstone canyons of southern Utah and northern Arizona.

Introduction

The dam was built to store water for the Upper Colorado River Basin states and to generate hydroelectric power, but it became one of the most controversial dams in American history. The Sierra Club's David Brower called Glen Canyon "the place no one knew," and the loss of the canyon's extraordinary natural beauty galvanized the modern environmental movement. The reservoir's dramatic decline during the 21st-century megadrought has reignited debate about the dam's future.

Engineering & Structure

• Type: Concrete arch dam
• Height: 216 meters
• Crest Length: 475 meters
• Concrete Volume: 3.75 million m³

Glen Canyon Dam is a thin concrete arch dam, relying on its curved shape to transfer the load of the reservoir into the canyon's Navajo Sandstone walls. At 216 meters, it is the second-tallest dam in the United States after Oroville. The dam contains 3.75 million cubic meters of concrete and was built in a narrow section of Glen Canyon where the red sandstone walls provided excellent abutments.

The dam's eight generators can produce up to 1,320 MW of electricity. However, as with Hoover Dam downstream, declining water levels have significantly reduced power output in recent years. The dam also includes river outlet works that allow controlled releases for environmental management of the Colorado River through the Grand Canyon downstream.

Geographic Setting

• River: Colorado River
• Location: Page, Coconino County, Arizona, United States
• Coordinates: 36.94°N, 111.49°W
• Lake Powell Length: 299 km

Glen Canyon Dam sits at the boundary of the Colorado Plateau, one of the most geologically dramatic landscapes on Earth. The reservoir fills a labyrinth of deep, narrow sandstone canyons carved by the Colorado River and its tributaries over millions of years. The surrounding terrain is a semi-desert of Navajo Sandstone cliffs, mesas, and buttes painted in shades of red, orange, and cream.

Lake Powell's 3,058 kilometers of shoreline (at full pool) exceeds the entire California coast, winding through side canyons that once contained natural bridges, alcoves, petroglyphs, and riparian oases. Many of these features were submerged when the reservoir filled between 1963 and 1980. However, as water levels have fallen, some of these features — including the iconic Cathedral in the Desert — have re-emerged.

Hydroelectric Power

• Installed Capacity: 1,320 MW
• Annual Output: ~3.5-5 TWh (declining with water level)
• Turbines: 8 Francis turbines
• Service Area: Upper Colorado Basin states

Glen Canyon Dam's eight Francis turbines generate electricity for the Western Area Power Administration, serving utilities in Arizona, Colorado, New Mexico, Utah, Wyoming, and Nebraska. At full reservoir, the dam produces roughly 5 terawatt-hours annually, but chronic low water levels have reduced output substantially, dropping below 3.5 TWh in drought years.

The dam's primary purpose is water storage rather than power generation. It holds water for the Upper Basin states (Colorado, Wyoming, Utah, New Mexico) to fulfill their delivery obligations to the Lower Basin states and Mexico under the Colorado River Compact of 1922. The power revenue helps fund the Bureau of Reclamation's operations throughout the Colorado Basin.

Environmental & Social Impact

• Canyon Lost: Hundreds of km of side canyons submerged
• Downstream Ecology: Colorado River through Grand Canyon fundamentally altered
• Cultural Sites: Ancestral Puebloan and Navajo sites inundated

The loss of Glen Canyon is considered one of the greatest conservation failures in American history. The canyon contained hundreds of natural features including natural bridges, alcoves, and pre-Columbian archaeological sites that were documented but not fully cataloged before flooding. Sierra Club executive director David Brower called his failure to prevent the dam's construction the greatest regret of his life.

Downstream, the dam transformed the Colorado River through the Grand Canyon from a warm, sediment-laden, seasonally flooding river into a cold, clear, steadily flowing stream — devastating native fish species adapted to the pre-dam conditions. Four of the Colorado's eight native fish species in the Grand Canyon are now endangered or extinct. Controlled experimental floods released from the dam have attempted to rebuild beaches and restore some natural processes, with mixed results.

Key Facts

• Glen Canyon Dam created Lake Powell, the second-largest US reservoir.
• At 216 meters, it is the second-tallest dam in the United States.
• The reservoir drowned hundreds of kilometers of spectacular sandstone canyons.
• Lake Powell's shoreline at full pool (3,058 km) exceeds California's entire coast.
• The dam's construction galvanized the modern American environmental movement.

Fun Facts

• Cathedral in the Desert, a magnificent natural amphitheater in Clear Creek canyon, has partially re-emerged as Lake Powell has dropped — delighting environmentalists who had mourned its loss for decades.
• The city of Page, Arizona, was built from scratch in 1957 specifically to house dam construction workers.
• Author Edward Abbey's novel "The Monkey Wrench Gang" featured characters plotting to destroy Glen Canyon Dam, inspiring the radical environmental group Earth First!.

Final Thoughts

Glen Canyon Dam sits at the intersection of America's water crisis and its environmental conscience. As Lake Powell shrinks and the canyons slowly re-emerge, the dam's future is increasingly uncertain — a symbol of the 20th-century hubris that the modern West is now being forced to reckon with.