"Spillway Emergency"

Oroville Dam, February 7, 2017. "As water releases from the flood control spillway ramped up to 54,500 CFS (cubic feet per second) in anticipation of inflows expected from rainfall, DWR (Department of Water Resources) employees noticed an unusual flow pattern; the bottom of the spillway appeared to have suffered partial collapse." 

As William Sager and Wayne Wilson note in a chilling, book-length account of what happened next, "the initial discovery of the problem was almost by accident." Two DWR electricians, making a routine check, saw concrete "flying through the air on the spillway," a piece described as "'about the size of a Volkswagen minibus.'"

Five days later, with the main spillway crumbling and water overtopping the dam's emergency spillway for the first time in its history, Butte County Sheriff Kory Honea ordered the evacuation of 180,000 downstream residents. 

The hour-by-hour story, what journalists call a "tick-tock," is told in "Spillway Emergency: The Story Of The Failure Of The Oroville Dam Spillway And The Evacuation Of Oroville" ($20 in paperback, independently published; also for Amazon Kindle). Sager and Wilson, both fire service retirees and Oroville residents, were among those evacuated. 

They conducted interviews and scoured documents and have produced a superb account, fair to all sides, covering "triumphs" as well as "missteps" (especially by DWR). 

The book doesn't assess causes of the main spillway failure; after a survey of flooding incidents in Oroville since 1849, it focuses on how CAL FIRE (which provided emergency response mentoring), DWR (led by Acting DWR Director Bill Croyle), and local law enforcement had to set egos aside and work as a unified team. It did not come easy, but it happened.

February 12. "At 2:00 p.m., the emergency spillway was already eroding at the rate of thirty feet per hour." Structured as a series of connected "monoliths," at 3:15 it appeared monolith 3 might collapse. "At 3:50 p.m., a DWR geologist briefed the unified incident commanders in the DWR boardroom. 'Imminent failure of weir due to head cutting, one hour to go before that happens.'"

One hour before the unthinkable.

In the forward, Honea says the book "chronicles one of the most tense, uncertain, and frightening experiences of my career."