The West Basin Ocean Water Desalination Project

The proposed Ocean Water Desalination Project (Project) would produce between 20 to 60 million gallons per day (MGD) of drinking water from the ocean. The 20 MGD capacity facility (Local Project) would generate approximately 21,500 acre-feet per year of high-quality, drinking water to meet the demands locally. The project also considers a potential expansion of the facility to produce up to 60 MGD of drinking water (Regional Project), to account for future needs in the region. A 20 MGD ocean water desalination facility could add approximately 11% of reliable water to the service area, further diversifying the District’s water supply portfolio.

The proposed Project site would be at an existing 33-acre industrially zoned location within the El Segundo Generating Station (ESGS) at 301 Vista Del Mar in the City of El Segundo, California. The key project components consist of a desalination facility, ocean water intake system, brine discharge system and a drinking water delivery system.


Project Objectives

Ocean water desalination, with over 18,000 facilities in 150 countries, is one component of a water supply reliability solution used around the world. This added drinking or potable supply would enhance regional water reliability, especially during periods of drought and water scarcity (e.g., loss of snowpack in the Sierra Nevada Mountains, catastrophic interruptions of water supply and uncertain impacts of climate change). 

The Project is being explored as one component of the District’s mission to provide safe and reliable water to the communities it serves through the following objectives:

  • Diversify the District’s water supply portfolio to increase reliability in the near and intermediate term (5-15 years) and long term (15-30 years), while reducing reliance on imported water;
  • Improve ability to adapt by developing a water supply that is less vulnerable to climate variations;
  • Improve water security by increasing local control of water supplies and infrastructure;
  • Improve the District’s ability to control water costs and provide long term price stability; and
  • Develop a potable water supply that is cost effective and environmentally responsible.


How Does the Ocean Water Desalination Process Work?

The main ocean water desalination process involves removal of dissolved salts and impurities to produce high-quality clean drinking water. The process involves the following steps: 

  1. Intake: Ocean water passes through screens specifically designed to minimize impact to marine life. The screens will be designed in accordance with the 2015 California Ocean Plan Amendment for desalination.
  2. Media Filtration: Filters remove coarse materials from the water, such as sand and sea shell pieces.
  3. Membrane Filtration: Fine membranes remove the microscopic material in the ocean water, such as bacteria.
  4. Reverse Osmosis: The filtered water is pumped under high pressure through reverse osmosis (RO) membranes to purify it, removing salt, minerals and any remaining viruses. This results in water that meets or surpasses state and federal drinking water requirements. The discarded salt water is referred to as brine.
  5. Post-Treatment: Due to the pure water quality that results from the RO process, the water is remineralized to stabilize it and prevent water pipes from corroding. The water is then disinfected so it is safe for drinking.
  6. Brine Disposal: The brine from the RO process is returned to the ocean where it reaches ambient salinity levels within a 100-meter radius to minimize impacts on marine life. The brine discharge system will be designed in accordance with the 2015 California Ocean Plan Amendment for desalination.