Dam failure prompts crisis as 150,000 evacuate
The Short Version
California’s Oroville Dam, the highest in the nation, reached its peak yesterday after heavy rains in the area caused water to begin cascading over the top of the 770-foot tall wall. When emergency spillways were opened to relieve the pressure on the dam, a giant sinkhole formed threatening the structure of the entire system. Emergency evacuation orders were issued yesterday afternoon for the nearly 200,000 residents immediately downstream as officials attempt to prevent the damn from breaking.
A Little More Detail
“Get out now!” was the order that came down from Acting Director Department of Water Resources Bill Croyle after engineers warned that the nation’s tallest dam, which creates one of the nation’s largest man-made lakes, could potentially fail at any time without any further warning.
Every nightmare you’ve ever had about being caught in a flood of water stood ready to come true and it caught everyone off guard.
We’ve talked before about how much water Northern California is getting this season. For officials at the Oroville Dam, about 45 minutes North of San Francisco, that difference is very real. Just two years ago, people who had boats on Oroville Lake had to repel down the embankment to get to their vessels. Yesterday, water was slipping across the top of that dam and officials are very frightened that the whole system may fail.
Not that this scenario wasn’t foreseen. Not one, but two emergency spillways were constructed just in case the lake ever became as full as it is now. The emergency spillways would allow for the measured release of water without flooding the cities downstream. Sounds like good, solid planning, right?
It probably was when the whole thing was constructed, but in the nearly 50-year history of the damn, the spillways have never had to actually be used. They’ve just sat there, undergoing routine inspection that, apparently, wasn’t too terribly particular about the decay that was occurring. After all, the spillways have never been needed. It’s never gotten close.
So, when water reached the apex of the damn yesterday and the emergency spillways were opened, a problem developed in the form of a giant sinkhole at the top of the second spillway. Concrete in the first spillway began to fail as well.
This, dear children, is what we adults call an “oh shit” moment.
At first, officials thought they’d be able to use helicopters to drop sandbags and boulders into the sinkhole. However, after looking around for boulders and sandbags and seeing that the choices were less than ideal, that idea was nixed for the time being. The only choice left: get everyone out of the way, just in case.
As one might expect, the folks living downstream were less than happy. This wasn’t supposed to happen. They had been promised that there were safety measures in place to keep it from happening. Now, everything they own is at risk of being swept away should the dam completely fail. People crammed as much as they could inside their vehicles and head toward Chino or someplace else well outside the potential flood zone.
California officials are doing their best to control the situation. Late last night, the water had receded and was no long flowing over the spillway. That will give engineers a chance this morning to take a look at the erosion and develop a plan to repair the damage. However, that does not mean it is safe for residents to return. Water is still pouring through the dam’s gates at the rate of 100,000 cubic feet per second. Do a little math. That’s a LOT of water and the longer it continues the greater the risk of flooding downstream.
Even worse, the continued arrival of more water from upstream sources continues to place an incredible amount of pressure on the dam. While officials insist that the main dam is structurally sound, the spillways obviously are not. Further erosion of the spillways could cause millions of gallons of water to be released without any means of control.
California National Guard has 23,000 soldiers and airmen on call should they be needed and the California Highway Patrol is sending an additional 235 officers to help with the situation.
Here’s hoping that daylight brings sure solutions and that everyone gets back home soon.