Gripped by Drought, Marin Considers Desalination, Water Pipeline Over the Richmond Bridge
As the drought deepens across the West, coastal cities are considering whether or not to filter ocean water as a solution to their water woes. In the Bay Area, Marin Water is mulling plans to draw its drinking water from theÂ San Francisco Bay.
Reservoir levels in Marin County are at historic lows this year, and water leaders are calling for a 40% reduction. So far the county has reached a 23% reduction, says Cynthia Koehler, president of the agencyâs board of directors.
âWe need to do more,â she said. âWe’re expecting another relatively low rainfall year. So, we’re preparing not just for right now, but really for 2022.â
The harrowing prospect of another dry winter has the district toying, once again, with the idea of desalination, a process â removing salt and minerals from the sea for clean drinking water â that is simple in principle, maddeningly complicated in practice.
Hereâs how it works: Salty water is pumped in from the ocean, filtered, chemically treated and then forced with high pressure through hole-lined pipes, which are tightly bound by a special polymer membrane â basically a microscopic strainer. Salt, bacteria and viruses canât get through the membrane. Fresh water escapes, brine remains in the tubes.
Marin Water looked at desalination twice in three decades. It shelved a desalination project in 2010 after water use declined, following a couple of dry years. One reason the agency ditched the idea? Cost concerns, which â at the time â could have been as much as $173 million.
âThe cost was disproportionately high,â Koehler said, who joined the district 15 years ago âIt’s not a light switch, you can’t turn it on or off, you’ve got to run it all the time. And so it would have been our most expensive source of supply.â
A shoreline project the district is now considering would cost in the ballpark of $37 million, and could clean enough water to fulfill about a third of the county’s drinking water needs.Â The agency could lease some facilities, keeping the costs down.
Agency staff are considering a floating facility on a barge, too.
They say the boat is likely more expensive and does ânot appear feasible for a number of reasonsâ Koehler said.
The terrestrial plant, while cheaper than the floating barge and âtechnically feasibleâ still has âfairly high costs associated with it,â she noted.
A third option â not desalination, a pipeline over the bridge from Richmond to San Rafael to pump water from the East Bay â is likely to win out, Koehler said.
The agency could buy water from farmers in the Central Valley and elsewhere. Koehler said it is still somewhat up in the air about where the water would come from, but staff is meeting with neighbor agencies like the East Bay Municipal Utility District and others much further away in Amador, Placer and Yuba counties.
But if the drought worsens other areas of the state could be more in need and the water may go to them instead. If the 6-mile pipeline is successful it could provide for all essential homes, businesses, and other indoor water use, and it would cost between $66 million and $88 million â which is more expensive than the desalination option, but would cover a large percentage of the county’s water needs.
âThe preliminary information is that there would be water on the market in California, if we were able to get that infrastructure in place,â she said.
But these options are not quick fixes to the current water shortage and wouldnât be ready until at least June 2022.
A decision could come by the end of the year, but Koehler says the best current option is water conservation.
âWe want a community that is beautiful and that has landscaping, but native landscaping, low-water landscaping, Earthscape, all of these are options that don’t require that level of investment,â she said.
Marin isnât the only Bay Area community considering desalination. The city of Antioch is building a plant to clean brackish water from the Stanislaus River. Itâs supposed to be completed in 2023. When the $100 million project is finished it will allow water to be used from the river year-round instead of purchasing costly water from other agencies.
Environmental factors essentially forced the cityâs hand, says Peter Fiske, director for the National Alliance for Water Innovation at the Lawrence Berkeley National Laboratory.
âBecause of climate change and the drought the salinity of that river is getting worse and worse,â he said âThey got to the point where they were like, âOh, my God, I guess we’re going to have to desalinate.’â
Desalination doesnât make sense for every city, because of the high cost and harm it can cause to marine ecosystems. Fiske says other options should be adopted first, like cleaning wastewater.
âAcross the Bay Area, we generate a lot of wastewater,â he said. âWe are essentially throwing it back into the bay and much of that wastewater could be reprocessed and reused.â
Adrian Covert, senior vice president of public policy at the Bay Area Council, a business and industry group, recently evaluated desalination regionally and found that recycling water could have a large impact.Â
âEvery year, the Bay Area pumps about 500,000 acre feet of highly treated wastewater into the bay,â he said. âIt’s more than enough to meet the Bay Area’s water demand through 2040. And because wastewater is cleaner than ocean water, treating it to potable standards is also about 20% cheaper than desalinating water.â
Agencies like Santa Clara Valley Water, which provides water to 2 million people in the San Jose area, are planning on doubling recycling water efforts. But that still only equals about 10% of their water supply.
Gregory Pierce agrees that recycling water or fixing infrastructure is a faster solution than constructing a desalination plant. In a 2019 study, he examined the impact desalination could have on low-income or marginalized communities as the co-director of the UCLA Luskin Center for Innovation.
Pierce says people need âan even higher ethic of water conservationâ because saving water is about preserving life for all Californians, not just the wealthy, with sprawling green lawns.
âIn California, I think desalination can be part of the answer. But it’s not the best answer right now or in the near term,â he said.
Pierce says desalination can hurt the environment and water agencies often push the high cost onto ratepayers.Â Desalination doesnât encourage people to use less water and could lead to agencies delaying upgrades to aging, leaky water systems.
As a concept, desalination sounds good, he says, but it’s not usually delivered equitably. If water is truly a human right, it should be affordable to everyone.
Andrea LeÃ³n-Grossman, director of climate action for the ocean conservation group Azul, advocates against desalination because the high costs are shouldered by ratepayers.
âProponents claim it will be a few dollars a month,” she said. “For them, it might be a few dollars a month, but for someone who’s struggling to put food on the table that is a struggle.”
She says there are better options for dealing with water shortages, like fixing leaky pipes that waste water.
âIf we were to plug all those pipes and invest in maintaining our infrastructure that could provide a lot more water than building desalination plants,â she said.
Desalination isnât just expensive, itâs hard on ocean life, says Daniel Ellis, a senior scientist with the state water board.
âYou’re not just killing the phytoplankton, you’re also killing the food source for the broader food web,â he said. âThe second part of the environmental impact is you take in ocean water, you take out the freshwater and you’re left with a lot of salt.â
Ellis says the brine byproduct can be twice as salty, and when itâs pumped back into the ocean, can be toxic for some aquatic life.
Even though desalination is theoretically becoming more popular â there are, at least, 11 active seawater desalination plants statewide âÂ he says there are only a few new pending projects in the state, like those in Huntington Beach and Laguna Beach.
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