El Niño Won’t Fill Up California’s Critical Groundwater Reservoirs

, Former climate scientist | January 22, 2016, 6:37 pm EDT
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El Niño is hitting California at last, bringing the pitter-patter of rain, snowy mountains, and more wet weather in the weeks ahead. For me, El Niño’s arrival the last couple of weeks has been an opportunity to introduce my toddler to the joy of splashing in puddles—which have been practically nonexistent since she was born.

And while El Niño-fueled storms are beginning to fill above-ground reservoirs, it is important not to forget one of the major lessons of this drought: the critical importance of California’s groundwater. We recently released a fact sheet that describes the vital role groundwater has been playing in avoiding catastrophe for the Golden State in The Big Water Supply Shift: Groundwater Key to Water Security in California’s Changing Climate.

During the four-year drought, groundwater supplied half of California’s water. Unfortunately, it’s not raining underground. While aquifers can hold up to three times more water than surface reservoirs, they do not fill as quickly. In addition, our groundwater reserves have been depleted much more than those above-ground reservoirs that you are used to seeing pictures of—you know, the ones with the bathtub rings and the dry docks above parched soil that once was a lake bed.

The situation underground is far, far worse.

Groundwater: current problem

Rather than being low, many of California’s groundwater aquifers are completely tapped out and in negative territory. In the Central Valley, we have been withdrawing about 2 million acre-feet of water more than we replace each year for the last decade. Scientists estimate that excessive groundwater pumping over the last century has depleted Central Valley groundwater reserves by a total of 125 million acre-feet. That is about 4.5 times the capacity of Lake Mead, the biggest surface reservoir in the U.S.


Groundwater: future solution

Groundwater is California’s best strategy to buffer the impacts of climate change and to respond to the much more severe droughts we can expect in the future. Sustainable groundwater management can help protect California from both more severe droughts and floods. When it rains, we can slow sink, and capture runoff in the ground to recharge depleted groundwater aquifers by designing storm-water capture and management systems in urban areas and developing aquifer-recharge infrastructure in rural areas above accessible groundwater.

UCS is actively engaged in improving California’s groundwater management – playing an important role in the passage of the Sustainable Groundwater Management Act and currently working to ensure its effective implementation.

One wet season will have very little effect on our groundwater supplies. The only kind of rain that would refill our groundwater aquifers this year is of truly Biblical proportions—or else a steady flow of storms for years to come. So, while it is time to enjoy this rain, don’t be fooled into thinking California’s water problems will go away—they are still right underfoot.

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  • Bullfrog

    The reservoirs will be full again and this author will look like an idiot just like those who said the same about Texas a year or two ago. Now our reservoirs in N Texas are overflowing and have been since last spring.

    Drought, flood. Drought, flood. That’s how weather patterns in CA and TX work according to the almanacs. So just bide your time and wait for the reservoirs to fill back up and the aquifers to recharge.

    Thanks for your patience.

  • CapitalistRoader

    The only kind of rain that would refill our groundwater aquifers this year is of truly Biblical proportions—or else a steady flow of storms for years to come.

    Recent history is informative:

  • dougproctor

    How much has groundwater removal exceeded pre-drought, “normal” acquifer renewal? If the current drought unmanageable because of prior excessive withdrawal from the acquifers?

    Acquifers are like bank accounts. You don’t go penniless in a topsey-turvey economic world if you keep money in reserve for the no-billable-hour years. So how much of the Californian crisis is the result of the last few years low precipitation, and how much of it is about hydraulic spendthrift ways?

  • solodoctor

    Thanks for pointing out how much more there is to do in water management here in Calif. Farmers large and small have been ‘robbing Peter to pay Paul’ via over drafting underground water for years now. I hope the groundwater management system getting set up will include things like incentives and support for transitioning to drip irrigation systems, for changing to crops which are less water intensive, for building recycling water plants, etc. Israel has worked wonders with its water usage in the last 25-30 years. We could learn a lot from them.

    A few years ago I read about a man in the LA area who was trying to build cisterns to catch and store rain runoff from homes, streets, etc. A HUGE amount of water is allowed to run off the the ocean without ever being used for other purposes. Does UCS engage with these kinds of projects?