The Oroville Dam: A cautionary tale from 1969


Curt Gentry was no Nostradamus or Edgar Cayce, but he made a prediction in 1969 that would have done either of them proud — and which for a few hours last Sunday looked like it might come to pass. And it still might.

He predicted the collapse of the Oroville Dam.

Gentry, who died in 2014, was a San Francisco newspaper man turned author. His best-known book was probably the 1974 best seller Helter Skelter, an account of the Charles Manson case, which he wrote with chief Manson prosecutor Vincent Bugliosi.

But in 1969, he wrote a fictional account of the destruction of California by an earthquake and tsunami. That book, The Last Days of the Late, Great State of California, was in the tradition of Edward Bellamy’s novel Looking Backward, in that most of it is devoted to a discussion of California’s post-war cultural and political trends from the perspective of a future historian writing about the lost Golden State.

But the climactic chapter is a rattling, good catastrophe yarn in its own right. And the collapse of the Oroville Dam got a prominent billing in it.

Last week’s news reports of the damage to the Oroville Dam’s main spillway, the narrowly averted collapse of its emergency spillway, the emergency evacuation of 200,000 people living downstream of the dam, and the continuing potential for catastrophe from further storms and Sierra snowmelt, produced a lot of eerie parallels with Gentry’s fiction.

Here are some of the passages regarding the dam from Gentry’s book, starting with his description of conditions at 3:12 p.m. on a Friday in early spring, a minute before the putative quake began:

For more than a week the unseasonably warm rain had been melting snow in the high mountains of Northern California, sending torrents of water downhill into the streams… Behind Oroville, the world’s highest earth-filled dam, swirled nearly 3.5 million acre-feet of water …

3:13 p.m.

At this moment buildings were toppling in Santa Rosa, Petaluma, Napa, and even Sacramento — a full 75 miles east of the San Andreas Fault. At Oroville, 150 miles away, ominous cracks appeared in the dam …

4:25 p.m.

The whole world is watching Oroville. This small Northern California gold rush town, whose usual population is just under 10,000, is almost completely deserted now, and there is an ominous feeling as you drive down the empty streets …

To the south of here, much of the Sacramento Valley is just a few feet above sea level …

Again, here is the list of cities and towns ordered evacuated because of the flood threat …


Here’s the bulletin we’ve all been waiting for. A spokesman for the U.S. Army Corps of Engineers has just told newsmen he believes the danger from the Oroville Dam has now passed. “If it was going to break,” he said, “it would probably have done so before this.” This is especially good news because many of the roads are still jammed and large numbers of people … emergency facilities are being established at …


It’s terrible, oh, it’s terrible. It’s picking up cars as though they were toys. I can see a farmhouse down there, and people on the roof. Oh, God, now both the house and the peope are gone and it’s crashing on — Highway 70 — jammed with stalled traffic. The people see it now. They’re getting out of their cars and starting to run. Oh, my God. Gone, all gone. It must be ten miles wide now and a hundred, no, two or three hundred feet tall. Nothing stops it … I’m going to be sick …

… thought the water would disperse, spreading over a large area, but instead the valley acted as a giant funnel … it shot through the Suisun Straits into San Francisco Bay with the velocity of a hurricane … not a trace of the Golden Gate Bridge remains …

Gentry was talking about the sudden collapse of the entire dam, not just the emergency spillway, which is off to a side on a hill.

Officials have said that if the emergency spillway failed, a mere 30-foot high wall of water would have gone down the Feather River, not a 300-foot one. These are the same “officials” who said the emergency spillway was designed to accommodate a flow of 250,000 cubic feet a second; a flow of 12,500 cubic feet a second for just a few hours caused enough erosion to bring it to the brink of failure and prompt a mandatory evacuation order for 200,000 people.

Not that a 30-foot high wall of water couldn’t do some serious damage. In 1965, a flash flood sent a 6-foot wall of water down Platte River in Denver. It did half a billion dollars in damage ($3.8 billion in today’s dollars).

The California authorities who ordered the evacuation lucked out. Had the emergency spillway failed when they thought it would, about an hour-and-a-half after they ordered the evacuation, the wall of water would have hit thousands of people on the roads, just as Gentry predicted.

There’s a lesson in all this for the City of Boulder and the University of Colorado, which are keen on annexing and developing the land CU owns southwest of U.S. 36 on South Boulder Creek. The property is a mined-out gravel pit situated as much as 35 feet below South Boulder Creek, which is held back by a berm. Upstream is Gross Reservoir, which holds 40,000 acre-feet; the Denver Water Board wants to raise the dam and double its capacity.

The lesson is simple: Don’t build in a flood hazard area. Nature is less than impressed by the predictions of hydrologists and the assurances of civil engineers — and can be infinitely creative in finding unexpected ways to destroy your property and drown your kids.

This opinion column does not necessarily reflect the views of Boulder Weekly.

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