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Strategy 8: Protecting coastal groundwater basins from seawater intrusion
Groundwater basins located along Los Angeles County’s coastline will need continued protection to limit the continued pressure of seawater intrusion from sea level rise that is predicted to result from climate change. Although existing barriers are solely owned and operated by the Los Angeles County Flood Control District, they benefit multiple agencies and stakeholders throughout Los Angeles County. As such, the ability to maintain and possibly further enhance protections and groundwater supply could benefit from regional collaboration.
Actions to support this strategy
8.1
Determine vulnerability of barrier
programs to seawater intrusion as a result of future sea level rise and evaluate opportunities to optimize barrier system operations.
8.2
Explore partnership opportunities to create further investments and increase
recharge potential at barriers to enhance protection and increase groundwater supply
WATER PLAN On Target
Protecting our coastal groundwater basins from future sea water intrusion is critical to meeting the target to optimize production of groundwater by maintaining at least 700,000 AFY baseline groundwater production.
Why this strategy is needed
In coastal aquifers, seawater can move into freshwater aquifers and contaminate potable groundwater supplies if groundwater levels have decreased relative to sea level. Maintaining and optimizing our seawater barriers to prevent seawater intrusion is increasingly important as the sea level rises.
Some coastal groundwater basins in Los Angeles County are protected from seawater intrusion by rows of injection wells that pump freshwater in groundwater basins near the coast to form a barrier that pushes seawater away from the groundwater basin while enhancing groundwater supplies. Without these barriers, saltwater could infiltrate coastal aquifers and contaminate groundwater supplies. In addition to more intense and less frequent storm events and more frequent and more intense droughts, climate change models are also predicting sea level rise. Seawater barrier facilities and operations will need to continue to adapt to meet the challenges of climate change and the need to fully leverage groundwater basin recharge and storage.
