Why the Oroville Dam Won’t Fail

February 12th, 2017 by Roy W. Spencer, Ph. D.

While it is said, “never say never”, after researching this issue I’m pretty convinced that it would be nearly impossible for the Oroville Dam to fail.

Even though it is an earthfill embankment dam, which can be destroyed if the dam is topped, the following Metabunk graphic demonstrates why the Oroville design is virtually foolproof:

The emergency spillway (which is now in use) drains excess water along its 1,700 ft length when the lake level exceeds 901 ft. At this writing the lake level is 902.5 ft, which is 1.5 ft. above the lip of the spillway.

The water level would have to rise another 18.5 feet (!) in order to reach the top of the dam itself, which would never happen because the emergency spillway flow (which occurs over a natural ridge made of bedrock) would handle the excess flow long before the lake level ever reached that point.

Now, is there any scenario in which this might happen? I’m not a hydrologist, so I can’t answer that. But if there was a sudden warm spell in the next few weeks with say, 10-20 inches of rain over the watershed melting most of the mountain snowpack, adding tremendously to the inflow into the lake, I’m sure we would see a much greater flow over the emergency spillway. But I suspect it would never reach the top of the dam itself. Nevertheless, there would be a massive flooding event downstream in the Feather and Sacramento Rivers.

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