Tails of California’s Drought

plot_esi-4by Jay Lund

Storms are filling reservoirs, building snowpack, and flooding in ways not seen since the most recent California drought began in 2012.  The state’s reservoirs today contain 1.2 million acre-ft more water than the long-term average for this time of year (the first time above average in 6 years).  Two years ago reservoir storage was 8 million acre-ft below average.  Most of the state’s precipitation and snowpack are far above average, boding well for this water year.

In terms of surface water, most of California is no longer in drought.  The accumulated reservoir and soil moisture deficits of the last 5 years have been filled in most of the state.  Only Santa Barbara, supplied by Lake Cachuma (currently 11% of average storage), faces major urban drought.  Most water shortages last year, from inability to move water across the Delta to the southern Central Valley, seem to be overcome this year.   Today, San Luis Reservoir contains 93% of its long-term average storage for this time of year. Unless the remainder of the year is incredibly dry and warm, 2017 will not be a drought for surface water, with perhaps a few local exceptions.

For groundwater, aquifers in northern California should be doing quite well.  They were not terribly depleted during the drought and have wetter conditions to more readily refill them.  For the southern Central Valley and southern California, wetter conditions will reduce pumping and increase recharge.  But these regions have less surface water to recharge aquifers, and the southern Central Valley typically has net aquifer overdraft in all but the wettest years. Some southern Central Valley aquifers might never recover to pre-drought levels.

Droughts often have long tails, especially for extended droughts over such a large state.  Groundwater in the southern Central Valley might rise some, but will remain low, keeping some wells stranded and increasing pumping costs for years and perhaps decades.  Drought damage to California’s forests could require decades to recover, or, if higher temperatures persist, the ecology of many forests might shift to new normal conditions.  Native fish also will likely need years to recover – with impediments from already depleted numbers and highly disrupted and altered ecosystems.

Droughts usually bring water shortages, but not all water shortages are from drought.  Some speak of drought as permanent for California.  But, it is better to think of California being a dry place with permanent water shortages (except in unusual wet years), which is also prone to drier than average years, which are droughts.  California must reconcile itself to being a dry place and some long-term water shortages.  It must also prepare for periods of drier than average conditions with greater shortages and costs, which are droughts.

For policy-makers the distinction is important. If every year is labeled a drought crisis or emergency, then “drought” loses important meaning and urgency needed to motivate and conserve to higher levels in drier conditions.  In addition to managing during drought, we must manage other years for normally dry conditions, which will often include deliveries less than desires and storing water and suppressing some demands in preparation for still-drier drought conditions.

As this drought goes out the door, it will say, in the words of our former Governor, “I’ll be back.”

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.

Some further reading

You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management

Improving mandatory State cutbacks of urban water use for a 5th year of drought

The banality of California’s ‘1,200-year’ drought

Why utilities shy from mandatory water saving during a drought

Is shorting fish of water during drought good for water users?

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11 Responses to Tails of California’s Drought

  1. David McCabe says:

    Just how, short of direct injection of surface water, do you expect recharge to occur. Virtually all production wells for the last several decades have been completed through impermeable clay layers.

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  2. Jai Rho says:

    “California must reconcile itself to being a dry place and some long-term water shortages.” No. Israel faced similar fatalistic predictions but has fully satisfied its freshwater needs through desalination. Other countries throughout the Middle East, Northern Africa and Asia are utilizing desalination as well, and many of them will be converting dry or desert environments into farmland and wetlands. California has more options than reconciling itself to being “a dry place.”

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    • jaylund says:

      Desalination will work for the very rich, as it does in oil-rich parts of the Middle East. Israel does some good work with desalination for cities, with agriculture using urban wastewater. But this could not support the much larger agriculture in California, which fortunately has much more water than Israel.

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  3. Jeff Camp says:

    At our cabin in Camp Nelso, CA I recently dug down a foot or so and was surprised to find the soil bone dry beneath the surface layer. Is this normal?

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  9. Saxon Holt says:

    Jay – Nice to come across your blog. Thank you. I try to use the term “summer-dry” to describe our climate. “Dry” is inadequate in a climate where a dry summer is not drought it is normal. Of course recent drier than normal winters led to the water shortages and forest issues, but the biggest contributor to continued water shortage as far a humans are concerned is agriculture not population (directly). We can store plenty of water for most uses and need to expect our agriculture industry to adjust to a new normal that does not depend on groundwater.

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