Talking Drought

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The bone dry Nacimiento River

Rain. For the first time in a long time it actually rained a little last night. Little being the operative word as, on the Monterey Peninsula, it amounted to only a couple hundredths of an inch. But that’s OK. We’ll take what we can get.

We have six months (November through April) in which we can reasonably hope to receive significant rain. Three of those months are now gone and we have only about an inch of rain to show for it. That means we’ll need more than double normal rainfall over the next few months to bring this rainy season up to something approaching average. Long range forecasts, which call for drier than normal conditions, suggest this is unlikely.

Just how bad is this drought? The figures from the National Weather Service’s Monterey Climate Station tell the story.

Precipitation at the Monterey Station averages 19.50 inches per year. If we look at the past four years we see that 2010, with 25.70 inches, was a wet year. 2011, with 20.49 inches, was better than average, as was 2012, with 20.60 inches.

Interestingly, almost half of the 2012 total fell in the final two months, as powerful storms at the end of November and beginning of December dropped enough rain to raise the Big Sur River all the way from a summer trickle to an above-flood-stage torrent.

It’s barely rained since. Not one month in 2013 produced even a single inch of rain at the Monterey Station, and the grand total for the year amounted to only 4.13 inches: less than half the previous record for dryness of 8.95 inches, set in 1953. Even if we get more showers tonight and tomorrow, this month will still go into the books as one of the driest Januarys on record. We’re unlikely to even match last January’s sorry total of .87 inches.

So if it’s only been dry for thirteen months, why do people keep referring to this as a two or three-year drought?

Because they’re looking at water years, or rainy seasons, instead of calendar years. If we look at the past four water years, which begin on October 1 to capture rainy seasons as a whole, we see that the 2009/2010 and 2010/2011 water years were above normal, but that the 2011/2012 water year totaled only 14.46 inches and the 2012/2013 water year totaled an even lower 13.09 inches. So if, as seems extremely likely, the 2013/2014 season remains below normal, it will be the third straight below-average rainy season.

The 2011/2012 water year can be below average even though both the 2011 and 2012 calendar years were above average because most of 2011’s rain came in the spring (in the 2010/2011 water year). 2011’s relatively dry fall offset the healthy spring 2012 rains, just as the above average rain in fall 2012 was offset by the almost total lack of rain in the spring of 2013.

So does this mean that we’re headed into a 50 or 100-year drought?

Tree ring studies show that long-duration droughts have happened in California’s past and it’s certainly reasonable to expect them to happen again. Especially since climate change is probably making all kinds of severe weather, including severe droughts, more likely.

Yet, jumping from these facts to the conclusion that the current dry spell is the start of a 100-year drought is quite a leap. California also has plenty of short-term droughts and there’s really no way to tell in advance how long any particular drought is going to last. If El Niño conditions develop next summer, as some models are suggesting, our next rainy season could be pretty wet.

So what does this mean for the Monterey Peninsula’s water supply?

In spite of the dry river, Cal-Am’s Carmel Valley wells, which provide most of the Peninsula’s water, aren’t likely to run dry this summer (at least we hope not). The more immediate problem is keeping the pumping within the limits set for the 2013/2014 water year by the State Water Resources Control Board’s Cease and Desist order. The drought makes this more difficult because it leads to more landscape watering. Thanks to increased lawn watering, etc., rationing may well be necessary this year to avoid exceeding the pumping cap.

And what about the environment?

Damaged ecosystems are obviously less capable of coping with drought. A missed spawning season or two wouldn’t be a big deal to a healthy steelhead population, for example, but it’s a heavy blow to the struggling remnant population in the Carmel River. And the same goes for who knows how many other weakened strands in the local web of life.

Click here for an excellent discussion of the “Ridiculously Resilient Ridge” responsible for the dry conditions of the past thirteen months.

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One Response to Talking Drought

  1. Ken Ekelund says:

    XT, The Monterey County Water Resources Agency’s Reservoir Operations Committee will discuss cloud seeding at their 6 February meeting which starts at 1:30. Address is 893 Blanco Circle.

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