Desalination at Manhattan Beach: One step forward, three steps back. Part 1

Josh Pereira has published an amazing article on Medium. The link is here. The first half is here too.

On the coast of Los Angeles, California lies the small, sunkissed paradise of about 35,000 residents named Manhattan Beach. Here, local surfers dot the waves, taking advantage of some of Los Angeles's most beautiful sandbars, tourism hotspots, and open seas ripe with parasailers and speed-boaters alike. However, against this idyllic background of Californian relaxation and swimming, Manhattan Beach faces a dilemma that could threaten the city's very coastline. Should the region's West Basin Municipal Water District build a desalination plant to supply more potable water to Manhattan Beach? Local "Heal the Bay" water quality scientist Luke Ginger says no, and, like many of the city's residents, he believes that there is no justification for the plant whatsoever. 

"...when it comes to talking about droughts and talking about water availability, we have to keep in mind that those are problems that are human-made...there's only a water availability issue in Southern California because of our mismanagement of water..."

These were the words that Luke Ginger used to describe Los Angeles's water availability issues. But, as droughts in the region become more prominent, is desalination Manhattan Beach's "silver bullet"? Or, are there better options?

The High Price Tag of Desalinated Water.

Right now, in response to the increase in droughts in Southern California, Manhattan Beach imports a lot of its drinking water from exterior sources like the Colorado River and Northern California. However, this expensive process takes a lot of time, energy, and a massive network of pipes and dams to bring the water into the city. In fact, "transporting all that water from Northern California and from the Colorado River is the biggest fossil fuel user in the state," according to Ginger. So, Manhattan Beach's West Basin Municipal Water District needs a solution to its currently expensive, ineffective, and unclean practices. This is where the city's proposed desalination plant comes into play.

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Summer beachgoers at Manhattan Beach's idyllic and threatened "El Porto Beach". Photographed by Joshua Gallego Pereira.

However, there are several caveats to West Basin's solution. Desalination isn't very cost-effective and, counterproductively, can be more expensive than Manhattan Beach's already problematic system of water importation. When water is desalinated, it is pumped out of the ocean, filtered, and then highly pressurized to about 1000 PSI, or about 30 times the pressure that's found inside a standard car tire. This pressure then separates the seawater from the sea salt. Simple, right? Not quite. Pressurizing the thousands of gallons of seawater that would enter the plant each day is incredibly demanding on the city's electrical grid that, as many Angelinos know, is far from being green. The result is a massive, unclean electrical bill for West Basin, which would then drive up the price of the water it supplies to customers. As Ginger put it, "you might be creating this situation where the locally sourced water is more expensive for people than the imported water...[and] that's not really great for the people living in your service area."

So, desalinated water isn't economic. But, the high price tag customers in West Basin's service area would take on doesn't end at the financial level. Ask any water quality scientist and their primary concern when it comes to saltwater desalination is the destructive impact the process has on local marine ecosystems. This is especially relevant in Southern California where the region's coasts tend to be some of the most biologically diverse in the country.

As rich as Southern California's oceans may be, they are not immune to changes in the local environment. After seawater is desalinated, an extremely concentrated brine solution is created. According to the draft environmental impact report of the desalination plant that West Basin submitted to Manhattan Beach in 2018, this brine is set to be pumped back into the ocean right after production. This is a recipe for an environmental disaster. The fish and phytoplankton that thrive in the waters of Southern California depend upon the stability of the ocean's salinity for their survival. If the salt content of the ocean is too high or low, then most marine life will die. By introducing a highly concentrated brine solution to the ocean, the desalination plant would put stress on the local environment by killing many of the fish and phytoplankton that the food chain depends upon. Climate change has already put stress on Southern California's marine life and a desalination plant would do nothing to help the environmental situation. So, desalination is clearly not the city's best option and neither is the city's current water importation system. What now?

-Josh Pereira