I consider most of the risks that the media focus on heavily overhyped if not utterly fabricated – I am talking about things like "climate change" or "the risks of nuclear energy" – but yes, when it comes to the worries about the Oroville dam, it seems that the media and the viewers are less agitated in average than I am.
A random good video was embedded to describe some technicalities. Don't get me wrong: I still think it's very likely that things will be fine. But the risk that they won't is nonzero and the consequences would be regionally dramatic.
Roy Spencer is convinced that the dam won't fail and he tells us why.
Note that the Oroville Dam was being built between 1961 and 1968. Its height 230 meters makes it the highest dam in the U.S. Lake Oroville was created in this way whose area 65 squared kilometers holds some 4 cubic kilometers of water.
For the first time after half a century, the amount of water is sufficient so that the emergency spillway is used to get rid of some water. It's ironic – all the "climate change experts" have been feeding the Californians with the "insight" that California had entered the era of "neverending drought" and the "snows are a thing of the past". You know, the snow was sufficient to reach a level unseen in 50 years.
And there are some integrity violations in the emergency spillway and probably other spillways and maybe the bulk of the dam itself – which is 600 meters long. Erosion may be taking place although I haven't seen clear evidence that the reasons to worry about the big barrier have become much more urgent than they should have been in the past. It's plausible that too much motion through some holes would quickly erode them and make them bigger.
Evacuation of 188,000 people was ordered and that's a number that made me feel quite some empathy because this is about the population of Pilsen in the 1980s when the maximum number of adjacent villages was formally incorporated as parts of Pilsen. Since that time, some bureaucratic changes in the opposite direction have taken place and Pilsen is back to some 170,000 people now. At any rate, the populations are comparable. (Well, Oroville itself only has some 18,000 people but many surrounding towns were ordered to be evacuated so that they combine to the equivalent of Pilsen.)
Pilsen is sitting at the confluence of four rivers – a rather extraordinarily high number – namely Drizzle, Lovefaggot, Byhead, and Byfame (I won't torture your brain with the Czech names Mže, Radbuza, Úhlava, and Úslava). And it's the Drizzle River where the main dam "potentially threatening" Pilsen was built, the Peahulls Dam (Hracholusky), built between 1959 and 1964. In Latin, the Drizzle River was known as Misa and Germans have called the river similarly, Mies, a name that coincides with their name for a town on the river which the Czechs call very differently, however, namely Silver (Stříbro) after a historically important product.
OK, the volume of Lake Peahulls is only 0.06 cubic kilometers at the maximum (sitting under the area of 5 squared kilometers or so) but even this amount of water was often said to be enough to flush Pilsen down the toilet. Well, that's one of the "facts" that we would hear as kids in the 1980s. At that time, I was probably not able to do any order-of-magnitude calculations to verify whether these comments may be right – and my teachers and others who have "taught" me such things were probably incapable of verifying even basic things like that, ever. I think that I am able to do them now, sort of, but they're still hard so I haven't really done a meaningful simulation of the "Lake Peahulls water in Pilsen". So I don't know whether a broken Peahulls Dam would be a fatal problem for Pilsen. At any rate, if Pilsen were supposed to be flushed down the toilet, it would be a war-like situation.
The sheer amount of water in Lake Oroville places the potential Californian problem into a higher league. Four cubic kilometers of speedy water that suddenly emerges somewhere could cause some serious problems. Even if all the lives were saved, one could estimate that the destruction would eliminate the assets of $50,000 per capita, mostly buildings and something inside them. Multiply it by 200,000 and you get some $10 billion. That's far higher than the total budget of the construction which was $439 million (and 34 construction workers died).
I wonder whether all these long-term risks of the dams – and perhaps similar projects – are properly taken into account. An engineers' page answers the question Are dams forever? by telling us that it was always expected that the dams would only last for 50-100 years. They may last longer but at some moment, cracks in the concrete have to appear. Do they really know how to safely fix the dams if the problems appear deeply in the water? It's not a trivial thing to quickly yet safely relocate 4 cubic kilometers of water, I guess, and my solution would probably be "run baby run". Do the engineers really have a better scenario? Did they care about these problems given the fact that they would almost certainly not be employed anymore when these problems with the concrete may become relevant?
Nuclear power plants may look "creepy" to the laymen because we don't see the radioactivity with our naked eyes. And green activists often talk about the safe storage of nuclear waste etc. But I believe that this tendency of ours to be afraid "especially of the things that we don't see" is ultimately irrational. At the end, I think it's far more likely that we may be killed by things that we see very well, like the water in the Oroville Dam. Let's hope that this example will remain an academic one.