California’s Drought Extended — by Rain?

A funny thing happened on the way to the (water) forum–the State Water Resources Control Board meeting that is.

Just when the State Board approved the extension of its “Emergency Regulation for Statewide Urban Water Conservation “for a few more months , with opposition from statewide water agency officials, a seeming act of God backed up the decision.  Runoff from wet weather proved to be too much for state’s water system.  Go figure.

Use of Lake Oroville , the keystone storage reservoir of the State Water Project, has been impaired indefinitely due to a dam spillway failure. So, Californians may need to plan to be in a “drought emergency” for the unforeseen future.  Look for the State Board to extend emergency conservation mandates for an indefinite period until the dam is repaired and storage is replenished, especially if the situation worsens.

So, what happened to the spillway of Oroville Dam, the tallest dam in the US?  As water was released down the dam’s spillway during high river flows, a small hole in its concrete became a very big problem.  The force of the cascading water got under the spillway and peeled the concrete from its foundation.

Dam operators shut down the spillway to assess the damage and started preparing for Plan B.  For the first time in the dam’s 50-year  history water would be allowed to overtop the dam through the “emergency spillway.”  As water started to flow over the emergency spillway, it washed away much of the soil in its path, cutting a channel down to bedrock.  The erosion seems to have been a concern for dam operators.

Out of an abundance of caution, officials called for evacuation of nearly 200,000 people downstream of the dam and reopened the main spillway gates to lower the water level in the reservoir below the elevation of the emergency spillway.  The main spillway concrete and soil foundation continues to erode.  The media reported that the water level will continue to be lowered as much as 50 feet from the dam’s crest to relieve pressure on the dam and spillway structures.  With more rain on the way, this episode of California water drama is not likely complete.

oroville-emergency-spillway
The Oroville Dam Emergency Spillway — February 12, 2017 [Source: http://www.kcra.com/article/aerial-view-shows-emergency-spillway-at-lake-oroville/8735835%5D
If the runoff continues and erodes more of the spillways, and for some reason Lake Oroville, which holds about 3.5 million acre-feet, temporarily can’t be used to store water for California’s farms and cities, the State Board may just extend the emergency conservation mandates indefinitely until the dam is fixed.  That could be many months or even years.

We haven’t even discussed how the loss of hydro power generation at the dam will affect electrical energy availability this summer.  Hopefully, the underground turbines at the base of the dam can continue to be used.

As the saying goes, be careful what you wish for, you just might get it.  In this case, “it” is runoff in the Feather River that feeds Lake Oroville.  In the meantime, careful with those sprinklers–we’re still in a drought!

 

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