Qualla: Oroville Dam Crisis

Oroville Dam Crisis: Introduction

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit California Department of Water Resources, Public domain. The emergency spillway had never been used since Oroville Dam's construction in 1968. On February 11, 2017, water flowed over it for the first time, and engineers watched in horror as the barren hillside began eroding at a rate no one had predicted. The concrete weir at the top of the spillway threatened to undermine and collapse, which would have sent a 30-foot wall of water crashing into the Feather River and flooding communities downstream. Within two days, 180,000 people fled their homes in the largest evacuation in California history.

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Image: California Department of Water Resources | Public domain

Oroville Dam Crisis: Five Years of Drought, Then the Deluge

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit California Department of Water Resources, Public domain. California had suffered through five consecutive years of drought when the storms arrived in early 2017. The parched ground could not absorb the excess precipitation. Lake Oroville, the second largest reservoir in the state, began rising rapidly. Oroville Dam, an earthen embankme...

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Image: California Department of Water Resources | Public domain

Oroville Dam Crisis: The Spillway Disintegrates

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit California Department of Water Resources, Public domain. Damage to the main spillway first appeared on February 7, 2017. A crater opened in the concrete-lined channel, and as water continued to flow, the hole expanded. By February 10, the gaping wound in the spillway had grown large enough that operators faced an impossible choice: con...

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Image: California Department of Water Resources | Public domain

Oroville Dam Crisis: Headward Erosion

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Florence Low / California Department of Water Resources, Public domain. The hillside below the emergency spillway began eroding far faster than engineers anticipated. Water carved into the slope, working its way uphill toward the concrete weir in a process called headward erosion. If the erosion undermined the weir, the entire structure could collaps...

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Image: Florence Low / California Department of Water Resources | Public domain

Oroville Dam Crisis: The Aftermath Below

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit Kelly M. Grow / California Department of Water Resources, Public domain. The crisis created cascading problems downstream. Approximately 1.7 million cubic yards of erosion debris clogged the Feather River channel below the dam, blocking releases from the hydroelectric plant and reducing the dam's overall discharge capacity. State workers evacuated ove...

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Image: Kelly M. Grow / California Department of Water Resources | Public domain

Oroville Dam Crisis: Lessons Carved in Concrete

Fri, 23 Jan 2026 00:00:00 GMT

Photo credit California Department of Water Resources, Public domain. Investigations by the Federal Energy Regulatory Commission and an Independent Forensic Team produced a nearly 600-page report in January 2018. Public hearings in May 2017 saw the California Department of Water Resources criticized for ignoring warning signs in the spillway's desi...

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Image: California Department of Water Resources | Public domain