Those of you outside of California are probably wondering what’s behind our ongoing and ever-changing problems with water.
Believe me, we’re wondering too.
First we don’t have enough. Then we’ve got too much and can’t figure out what to do with it.
The bridges we build over it would be better suited to deserts. We’ve got some of the world’s biggest dams–but apparently we can’t maintain them.
A quick summary of the background: As a result of the unusually heavy rain in January and February, the reservoir behind the Oroville Dam is quite literally full to the brim. With two more months left in the rainy season and higher-than-usual snow melt expected, it’s necessary to release some of the water in a controlled fashion to avoid flooding. Unfortunately, a large chunk of the main spillway collapsed, reducing the amount of water that it can safely carry. A secondary spillway was activated for the first time in the dam’s history, and it quickly eroded to the point where the integrity of the dam itself was threatened.
The collapse of the dam, releasing the entire contents of the second-largest reservoir in the state would be, well, let’s say, not an ideal outcome. An evacuation order has been issued covering some 200,000 people. Engineers are trying to reinforce the secondary spillway, and the main spillway is running at its maximum safe capacity. With luck, the next round of storms, expected to being tomorrow, will hold off long enough for the reservoir to drain enough to hold the inflow.
The question everyone is asking now is “Why is the main spillway disintegrating?” And the answer is “We don’t know yet.”
What we do know is that the Department of Water Resources (DWR) has known about problems in that part of the spillway for nearly a decade. Defects were found in 2009, and repairs were made in 2013, 2014, and 2015–in exactly the area that collapsed last week. The obvious inference is that the repairs didn’t address the underlying cause of the problem; treating the symptoms rather than the disease.
It’s worth emphasizing that this is not the same situation as we’ve been hearing about with the Bay Bridge. No violations of the guidelines for proper construction. Testing is being done and issues are being addressed. The Chron–as usual, my primary source–quotes several engineering experts as saying that the DWR has been doing “everything that normally should be done.”
So the question we should be asking is “What changes in the ‘normal’ processes need to be made to avoid this situation in the future?”
The Federal Energy Regulatory Commission has ordered a forensic analysis to determine the root cause of the spillway failure. Let us hope that the outcome of that analysis is used to update the definition of what normally should be done. At least Caltrans isn’t involved. There’s hope.