It’s hard to get one’s head around the magnitude of calamity if the tallest dam in the U.S. were to overtop. But that almost happened to the Oroville Dam in 2017, and this year’s epic storms have engineers on edge that the dam could indeed break.

Most of our discussion of the Oroville Dam — the tallest dam in the country holding back the second-largest reservoir in California, located about 150 miles northeast of San Francisco — is around how Lake Oroville has alarmingly low water levels in drought years, or abundant water levels in years like this when we have healthy winter rains.

But here’s a scary secret about the Oroville Dam that’s hiding in plain sight: were its earth-fill embankment rocks to fail holding the dam together, it would send a 185-foot wave to the surrounding valleys. And this almost happened, though not to such an enormous degree, when the dam was in danger of failure in 2017, and 188,000 people had to be evacuated from nearby areas.

The New York Times looks back on this — and the possibility of a cataclysmic, far worse repeat — in a lengthy but exhaustively researched analysis of whether massive climate change rainstorms like the ones we had this past winter could cause the Oroville Dam to fail. And definitely check out the article’s top image,  a stunning animated video of the majesty, and incredibly deadly power, of the Oroville Dam spillway.

Also, from Getty Images:

In the 2017 incident, a damaged spillway had to be shut off to reduce the giant flash flood risks and an emergency spillway — just a dirt berm — had to be put into use. The dam fortunately remained stable, and the spillway was repaired over the next two years. That billion-dollar repair seems to have the spillway working magnificently after snowmelt from this year’s heavy storms put Lake Oroville at 100% of its capacity this spring. Happy ending to the story, right?

Oh, hell no. The Times quotes a scathing independent forensic report that concluded “The fact that this incident happened to the owner of the tallest dam in the United States, under regulation of a federal agency, with repeated evaluation by reputable outside consultants, in a state with a leading dam-safety regulatory program, is a wake-up call for everyone involved in dam safety.”

Determined to answer that wake-up call, geologists and other experts came up with a hypothetical weather event called “Arkstorm,” which is an absolutely kick-ass name, but outlines how two consecutive years of once-in-a-lifetime type storms could cause incalculable loss of life and damage to the Central Valley.

But the Times describes the response of state officials to these flooding models as “like the mayor in Jaws — unwilling to see a problem they couldn’t fix.”

And there is reason to believe that state officials were encouraging experts to stop talking to the press about it. One hydrologist initially told the Times “I’ll talk your arm off,” but later responded to questions about the models with, “Please. Just lose my email address, OK?”

And to paraphrase Al Gore, these are inconvenient truths to confront as climate change causes more severe problems. As UCLA climate scientist Daniel Swain tells the Times, “All of this infrastructure is designed for a climate that no longer exists.”

Related: Video: New Drone Footage Shows Massive Canyon Created By Oroville Dam Spillway Erosion [SFist]

Top photo: Photo by George Rose/Getty Images