Groundwater Rise: An International Problem that California Must Solve

The devastating effects of climate change are numerous, diverse, and often disrupt our best-laid plans.  One novel issue which is only now starting to get attention is groundwater rise.  When we think of sea-level rise, we often think about the ocean encroaching our coastal shores and flooding our beaches – but we forget about the waterways in the ground beneath our feet. Groundwater fills the holes and fractures in underground materials like water fills a sponge. It can be deep in the earth, or shallow and near the surface.  Along coasts, underground saltwater floats directly beneath the freshwater.  When underground saltwater rises with the rising seas, it is expected to push the groundwater up and sometimes even out of the ground.  In addition to flooding basements and impacting plumbing, this rise can also crumble roads and create extended earthquake liquefaction zones. In 2012, Hawaiian scientists discovered the earliest first-hand evidence of the phenomena already in action.

Global climate change is expected to cause at least an average one foot rise in sea levels by the end of the century, with a three foot rise in California, but it may end up being much more. A survey in one Bay Area city found local groundwater to currently be an average of six feet below the surface near the Bay edge, and often as close to the surface as only one to two feet below. Even a small rise in sea levels can have devastating effects with already shallow groundwater. The effects become even more problematic if the groundwater is contaminated by chemicals.  For those who live or work near the shore and in polluted areas, sleeping monsters are about to awake.

Potential Impacts of Sea-Level Rise (SLR) and Flooding in the San Francisco Bay Area: https://lao.ca.gov/reports/2019/4121/Fig2.png
California LAO: Preparing for Rising Seas: How the State Can Help Support Local Coastal Adaptation Efforts

When chemicals pollute soil and groundwater, the contamination may be mitigated by procedures to contain the toxins and reduce the risk to humans nearby. However, these containment procedures generally factor in the current depth of the groundwater at that time and there is usually no follow up later to assess if the mitigation is still sufficient (such as if physical circumstances changed in the area).  More than 945 EPA Superfund sites are at risk due to global climate change generally, and 330 EPA Superfund sites were found to be at risk of flooding due to only five feet of sea level rise. The California LAO recently stated, “floodwaters could penetrate both surface-level and underground tanks and force out toxic liquids, or liberate waste from pits or piles.” Though, this analysis does not even consider vapor intrusion risks as the groundwater rises closer the surface.

The issue of contaminated groundwater rise has been overlooked by city planners and decision-makers for decades, but we cannot wait any longer.  Many coastal cities across the world will be impacted by this issue.  California has an impressive history of environmental innovation and pioneering novel solutions to address global climate change. This issue should be no different — not only because the world needs a solution, but because this issue will be disastrous for Californians if we cannot get ahead of it at home.

– Ashley Gjovik

Ashley is an advocate for human rights, including healthy environments. She is currently a law student at Santa Clara University studying international public interest law and policy. 

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