In August, while Palo Alto was urging residents to save water under California's mandated restrictions and to carry buckets of water from our showers to our gardens, we and other neighbors watched numerous construction projects pump 50-100 gallons per minute of groundwater, 24/7, directly into the storm drains. This pumping occurred unabated for months.
Finally we asked, "Why in the fourth year of a severe drought is this groundwater being wasted?" Upon investigation we learned this groundwater was being extracted for construction of residential basements. As concerned residents and neighbors, we joined to form Save Palo Alto's Groundwater. Our goal was to educate residents and City leaders of the value of this discarded groundwater. Now we are working to encourage City leaders to implement policies that protect, preserve and use our groundwater for the benefit of all residents.
In 2015, using a method known as "dewatering," between 100 to 160 million gallons (300-500 acre-feet) of Palo Alto's groundwater was pumped from our shallow aquifer to allow construction of 14 residential basements. This amount of water, if contained on an 8,000 square foot residential lot, would reach a height of almost 2,000 feet and be higher than the World Trade Center. It is also close to the total amount of groundwater Palo Alto's consultants estimated could be sustainably extracted annually for use as an emergency water supply or a significant percentage of the rainwater flowing into our aquifers. It is a lot of water!
The volume of groundwater extracted for residential basement construction has tripled in the last decade. More than 99 percent of the water originates from beneath the surrounding properties. Greater than 98 percent of the extracted groundwater is shunted directly into the Bay; only 1-2 percent is used for any beneficial purpose.
This groundwater extraction and discharge adversely affects our ecosystem. Groundwater provides support and stability for all structures and infrastructures, recharges our aquifers and maintains normal levels of soil moisture. We know groundwater is a valuable, limited resource, essential to all humanity and all ecosystems. We believe Palo Alto's leaders are not managing our groundwater prudently.
Over the years conflicting engineering reports have influenced Palo Alto's groundwater policies and management. The 2004 report by consultants EIP incorrectly states the effects of dewatering extend only "a few tens of feet" from the property, when in fact groundwater is likely significantly lowered up to 1,000 feet away. The report also states our shallow aquifers, from which groundwater is pumped for basement construction, and our deeper aquifers are "hydrologically separated." However, other engineering reports and two groundwater experts have confirmed the shallow aquifer water directly and indirectly replenishes the deeper aquifer's water. The pumped groundwater being dumping into the Bay could be part of our emergency water supply.
Unfortunately the amount of groundwater sustainably available for Palo Alto's use, and details of the flows between the shallow and deeper aquifers, are not precisely known. The 2003 Carollo Engineering Report estimated Palo Alto could safely pump 500 acre-feet yearly from the deep aquifer; additional sustained pumping could lead to repeat subsidence and/or saltwater intrusion. Recently neighboring cities have improved their existing wells or are planning new wells to enhance their water supply resources. How will these changes affect Palo Alto's emergency groundwater supply when so many are planning to extract water from the same aquifer system? Can Palo Alto afford to allow a few to use so much valuable groundwater in a time of drought, climate change and growing population demands? Remember that aquifers don't make water; they are replenished from precipitation and percolation.
Save Palo Alto's Groundwater is asking the City Council to impose an immediate moratorium on the issuing of new dewatering permits for residential basement construction until State and locally mandated drought restrictions are lifted and Palo Alto has developed a Groundwater Management Plan that clearly allocates and monitors this valuable resource for the benefit of all residents. The California Sustainable Groundwater Management Act empowers local agencies to adopt such Groundwater Management Plans. Palo Alto would be wise to formulate a Groundwater Management Plan; this will take time, research and hard work.
Some residents claim that dewatering is not a problem or that Palo Alto has bigger problems to solve. We disagree. Should Palo Alto wait until our water supply from Hetch Hetchy is disrupted or severely limited to discover our emergency water supply is inadequate? That may be too late. Is it not better to use best practices for basement construction that preserve our groundwater?
This need not be a divisive issue; we all want water security. Let us work together and promote methods of basement construction that protect our valuable groundwater for now and future generations. Let us leave a legacy of ample groundwater supplies and stellar management practices.
To quote Dr. Seuss in The Lorax, "Unless someone like you cares a whole awful lot, nothing is going to get better. It's not." We invite all of you to tell Palo Alto's leaders that you care about your groundwater, your emergency water supply and your future.
Make suggestions, write letters to the editor and the City Council and attend City Council meetings. The council's Policy & Services Committee will be addressing dewatering on 12/15; we invite you to become involved. More information is available at http://savepaloaltosgroundwater.org/.