Friday, April 03, 2015

California Drought—Getting Worse or Getting Better?

News stories about the Governor's actions to deal with the water shortage emphasize how low the snowpack is this year. But while some of the water used in California comes from melting snow, more comes from rain stored in reservoirs, and none of the stories I saw gave figures for either the reservoirs or the total. Being of a suspicious nature, it occurred to me that if snowpack went down and reservoirs went up, people who wanted to make a point of the water shortage would be likely to emphasize the first and ignore the second. That would include both people trying to encourage reductions in consumption in California and people trying to use the California drought to promote concern with climate change more generally.

I have not yet found a figure for the change in the total amount of water in reservoirs—readers who have are welcome to point me at it. But I did find charts showing the individual reservoirs. Lake Shasta, the largest, is up substantially. Of the others, some are up, some down. My guess is that the total is up a little, although probably not by enough to balance the reduction in snow pack, but with only bar charts to go on it's hard to be sure. 

Here are the charts:



12 Comments:

At 8:30 PM, April 03, 2015, Blogger Jonathan Ashley said...

Please post the URL where you generated the charts. Thank you.

 
At 1:01 AM, April 04, 2015, Blogger David Friedman said...

The charts were from:

http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action

Poking around the site, I found what appeared to be a comparison between total water in reservoirs at the end of February this year and last. Assuming I'm not misreading it, The figure for this year is 42,225, for last year 40901.7, which fits my guess that reservoir storage is going up, not down. That's from:
http://cdec.water.ca.gov/cgi-progs/reservoirs/STORAGE

But the table is sufficiently complicated that I'm not sure I am reading it correctly, in particular not sure it includes all reservoir. And I didn't find the figures for the beginning of April.

 
At 6:54 AM, April 04, 2015, Blogger Fred Mangels said...

One reservoir I've never seen mentioned in those charts is Ruth Lake in NW California. That's where the greater part of Humboldt County gets its water. I believe it's at 100%. I forget how low it got last year, but even at it's lowest the Humboldt Bay Municipal Water District said we had enough to last two years at normal consumption rates.

We actually have a surplus, unlike most of the state. Yet local papers recently reported we'll be expected to reduce water use by 25%, or whatever, just like everywhere else in the state. Water not used, of course, will just flow into the ocean.

 
At 12:17 PM, April 04, 2015, Anonymous Dain said...

I just looked at a live webcam for Lake Shasta. It's low but not nearly as low as I expected.

 
At 2:44 PM, April 05, 2015, Anonymous Simon said...

I might be reading the charts wrong, but it looks like the red lines show the average water level in the reservoirs for the date you've searched, based on the historic record. In which case the blue bars show the current levels are significantly down compared to the long-term historical average.

Hard to say from that whether or not the drought is getting better or worse; for that we'd need to look at rates of change. Obviously your comparison between Feb '14 and '15 would certainly suggest that things are getting better. One explanation could be that the reservoirs are lower than the long-term average because there has been a drought, but that they're currently filling back up.

 
At 6:53 AM, April 06, 2015, Blogger Fred Mangels said...

I'm of the impression most reservoirs are a bit better off than they were this time last year. Snowpack, however, is at record lows. That means a lot. Snowpack is the state's longer term water storage and replenishes the rivers, lakes and reservoirs after the rain stops.

We're probably at least a little worse off because of the essentially non- existent snowpack, with the exception of at least northern and central Humboldt County whose reservoir is at 100% and doesn't rely so much on snow.

 
At 12:26 PM, April 06, 2015, Blogger Fred Mangels said...

Oh; and don't forget groundwater depletion which is a serious problem in its own right. I believe most of the communities that literally ran out of water were ones that drew water from wells. Some say there's no way to restore some of them.

 
At 3:32 PM, April 06, 2015, Blogger albert nelmapius said...

Some say that only 30% of runoff from rain is being captured and that environmentalists have countered efforts to build more reservoirs for years

 
At 7:51 PM, April 06, 2015, Blogger James Picone said...

If a bunch of snowpack has melted, the water has to go somewhere - wouldn't be surprised if it ended up in various reservoirs. Not that I know anything about how California gets water or the Californian drought. Still, if snowpack has drastically declined recently, I would expect an uptick in reservoir water, but less water overall.

Albert: Context is kind of important here. There are valid reasons to not capture a lot of runoff, like groundwater recharge, making sure rivers don't dry up/become saline downstream, wanting local flora to have water, etc. Those are all kind of important things.

 
At 11:09 AM, April 07, 2015, Anonymous mobile said...

End-of-February statewide reservoir storage for various years.

http://cdec.water.ca.gov/cgi-progs/reservoirs/STORAGEW

Levels in 2015 slightly higher than in 2014, much lower than in 2013.

 
At 7:01 AM, April 08, 2015, Blogger Fred Mangels said...

"If a bunch of snowpack has melted..."

The big problem was there was no snow to melt this year. They're saying the current snowpack only holds 5% of normal water.

 
At 9:04 AM, April 11, 2015, Anonymous Anonymous said...

Have been linked an fascinating article describing Californian water shortage as a negative outcome of government intervention, sharing it: http://mises.org/blog/american-west-water-political-weapon

 

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