Qualla: Oroville Dam

Oroville Dam: Introduction

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Martin Alfaro (talk · contribs), CC BY 3.0. On February 12, 2017, emergency sirens wailed across Butte County as 188,000 people scrambled to evacuate their homes. The unthinkable was happening: Oroville Dam, the tallest in the United States, was failing. Water had begun pouring over the emergency spillway for the first time since the dam's completion in 1968, and erosion was threatening to undermine the entire structure. If the spillway collapsed, a wall of water would surge down the Feather River Canyon toward Sacramento. What followed was a desperate race against physics, with engineers gambling that increasing flow down the damaged main spillway could lower the reservoir fast enough to save the emergency spillway from complete failure.

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Image: Martin Alfaro (talk · contribs) | CC BY 3.0

Oroville Dam: Built from Gold Rush Debris

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Mchavez at English Wikipedia, Public domain. The dam that would become America's tallest began as a political compromise. Major flooding in the 1950s convinced California to build a dam at Oroville regardless of whether it would join the State Water Project. Construction began in 1961, and workers discovered an unusual sour...

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Image: Mchavez at English Wikipedia | Public domain

Oroville Dam: Lifeline to Twenty-Five Million

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Quintin Soloviev, CC BY 4.0. Oroville Dam does far more than prevent floods. Buried beneath the structure lies the Edward Hyatt Power Plant, once the nation's largest underground power station. Six turbines can generate electricity during peak demand, then pump water back uphill when surplus power is availab...

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Image: Quintin Soloviev | CC BY 4.0

Oroville Dam: Warnings Ignored

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Miles530 (talk), Public domain. In October 2005, three environmental groups petitioned federal regulators to require concrete armoring of the emergency spillway. They warned that in extreme conditions, water flowing over the earthen hillside could cause catastrophic erosion. The Federal Energy Regulatory Commis...

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Image: Miles530 (talk) | Public domain

Oroville Dam: The Crisis Unfolds

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Podruznik (talk · contribs), Public domain. Dam operators faced an impossible choice. The crater in the main spillway kept growing with each release, but stopping the flow meant the reservoir would overtop the emergency spillway, which had never been used. They continued releasing water through the damaged spillway while t...

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Image: Podruznik (talk · contribs) | Public domain

Oroville Dam: Lessons in Concrete

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Frank Schulenburg, CC BY-SA 4.0. The spillway reconstruction became one of the most expensive dam repairs in American history, totaling $1.1 billion. An independent forensics team identified 24 possible causes for the failure, including faulty drainage, variations in concrete thickness, and corroded rebar. Worke...

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Image: Frank Schulenburg | CC BY-SA 4.0