Environmental Impacts of the Proposed Desalination Plant

By Al Sattler, Group Chair

West Basin Municipal Water District (West Basin) has released the Draft Environmental Impact Report (DEIR) for its proposed Ocean Water Desalination plant http://www.westbasindesal.org/draft-eir.html .

Ocean desalination uses much more electrical energy than water recycling. A desalination plant would harm animals and plants in two ways — killing small marine life by sucking it in, and by pumping concentrated brine back into the ocean. 

Comments may be submitted until Friday, May 25, 2018 at 5:00 p.m. West Basin will be hosting a public meeting Saturday, May 12, 10 am – 1 pm, at the Richmond Street Elementary Auditorium, 615 Richmond St, El Segundo.

The Desalination plant proposed by West Basin would produce 20 Million Gallons per Day (MGD) of treated water, and could be increased to 60 MGD.

This proposed plant would be located at the site of the El Segundo Generating Station, a retired coastal power plant north of Manhattan Beach. It would use the existing intake pipe from this retired power plant to take ocean water into the desalination facility and the existing pipe to discharge concentrated seawater, possibly with chemicals used in the plant, back to the ocean.

Sierra Club policy on Desalination: http://www.sierraclub.org/sites/www.sierraclub.org/files/uploads- wysiwig/desalination-guidelines.pdf


One key point is “Desalination should not be used for water supply needs that can be met by water conservation, water recycling, and other water use efficiency practices.”

Process: For ocean Desalination, like for water recycling, the basic process is to use high-pressure pumps to push the untreated water through pre-filters, then through reverse osmosis filters to produce purified water.

Perhaps the largest environmental impact of ocean desalination is that it uses a significant amount of electrical energy for treatment. Ocean desalination uses much more electrical energy for treatment than water recycling, because wastewater is not concentrated with salt like ocean water. However, West Basin claims that desalination uses less energy than pumping water from the State Water Project over the Tehachapi Mountains.

There are two ways that a desalination plant would harm animals and plants in the ocean. On the inlet side, the plant would be killing small marine life by sucking it in. West Basin has said that it will use wedge wire screens with openings 1 mm (.04 inch) diameter to prevent larger marine life from being sucked in. However, smaller marine life would still be sucked in.

On the outlet side, the plant would be pumping concentrated brine, perhaps twice as concentrated as ocean water, back into the ocean.

The Draft EIR does not even consider increased water recycling as an alternative to this project. The existing water recycling plant operated by West Basin in El Segundo produces 40 MGD water now, taking wastewater from the Hyperion wastewater treatment plant. Water recycling uses much less electricity for treatment, because the water is not concentrated with salt like ocean water, and will not suck marine life through the treatment system. However, recycled water cannot be put directly into drinking water systems, but it could be pumped to the top of existing groundwater basins, allowed to percolate into basins, then pumped out after it has been there for a suitable length of time. This process has been used since the 1960s along the San Gabriel River.

A coalition of environmental organizations, including Los Angeles Waterkeeper, Heal the Bay, Surfrider Foundation and the Desal Response Group, is opposing this project, and has a website https://www.smarterwaterla.org/.


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