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Why El Niño is No Panacea

photo of pouring rain

By Soquel Creek Water District

Soquel, CA [August 2015] -You might have noticed stories with predictions of a strong El Niño this winter starting to circulate in local media.  This, in turn, has sparked a lot of speculation about how this would affect our local water supplies, which have been impacted by four years of drought conditions.  The short answer here in the District and Mid-County area?  Not much.  Here’s why.

Our water is 100% groundwater from two local aquifers: the Purisima Formation and the Aromas Red Sands Formation.  Both of these aquifers are recharged naturally through rainfall, but recharge is slow, sometimes taking many years to percolate down through the earth to the aquifers below.  Heavy rainfall events, such as the ones typically associated with El Niño years, bring a large amount of rainfall in a short period of time.  It takes time for soil, especially when it has been parched by multiple years of drought, to absorb rainwater.  When more rain falls than can be absorbed by the ground, it runs off into gutters, creeks, streams, rivers, and eventually the Monterey Bay.  The remaining water generally evaporates, is taken up by the roots of plants, or sinks down into the soils below to refill our aquifers.   

The accumulation of water in underground aquifers, however, is a long slow process.  Like a bank account, more water needs to be put into the aquifers than is taken out in order to maintain a healthy and sustainable balance.  When more water is taken out than is naturally replenished, it is referred to as overdrafting.  Since 1980, pumpers in the mid county region (including the District, other local water agencies, and private well owners) have been overdrafting our local aquifers, which has resulted in a significant deficit that many years of good rains would not solve.  This deficit has caused the groundwater level to fall and allowed seawater to begin moving into the aquifers.  This process, referred to as seawater intrusion, is common in many coastal areas; in fact, over 65% of the populated coastal communities around the world are challenged with this problem.  Locally, we are seeing seawater intrusion occurring near Pleasure Point, Aptos, Seascape, and La Selva Beach.  Seawater intrusion is extremely damaging, because once it reaches drinking water wells, they become unusable.  If this occurs, it will impact everyone who relies on our precious groundwater resources, including private well owners and our District customers.

While an El Niño year has the potential to help our neighbors, who receive water from surface water sources such as the San Lorenzo River, the benefits to our groundwater basin are much, much smaller.  Our problem is long-term, and will require ongoing conservation efforts, El Niño or not, until a supplemental water supply can be found.  Currently the District is pursuing three potential options that could provide a supplemental water supply: recycled water, desalination, and river water transfers/purchases.  Please visit the Soquel Creek Water District website for more information.

It is important for our customers and the community to know that, while an El Nino winter will help our thirsty community, it is not the panacea for our water shortage problem.  We need to spread awareness that an El Niño winter will not cure seawater intrusion.

As always, we welcome our community input. Please contact Matt Orbach, Public Outreach Specialist, at 831.475.8501x118 or