“One Water,” Resilience, and Advanced Water Recycling

In a previous blog, we looked at the global “One Water” revolution and outlined how agencies in Metropolitan Los Angeles are adopting this new perspective as a foundational element of their sustainability strategies. One Water, we noted, integrates the many forms of water management (surface water, groundwater, wastewater, stormwater, and drinking water) into a single system instead of the separate silos that typically characterized water management in the past.

A second planning revolution is also occurring in many places in the world, including Metropolitan Los Angeles. Long-range planning always involves forecasting – of demographic and economic trends, and how those trends are expected to be influenced by new investments in infrastructure, housing and the like. Until recently, such forecasting sought to settle on a “most likely” view of the future results of plans and their implementation.

But now we live in a world that is highly uncertain, too uncertain to be confident of a single “most likely” forecast of conditions decades into the future. Rapid climate change in particular is resulting in changes in environmental conditions that are inherently unpredictable, especially because those conditions will depend in large part on policies, plans and projects throughout the entire world, not just in local areas.

In Metropolitan Los Angeles, the principal supplier of water for most of the region is the Metropolitan Water District (MWD). Its newest Integrated Water Resources Plan (“IRP” – adopted in 2020) adopts both of the revolutions described above. It commits to a One Water approach involving enhanced collaboration with other agencies and communities throughout its service area, and also for the first time relies on a dynamic form of scenario planning that considers four plausible views of the region’s water future in 25 years, then endeavors to be resilient and able to respond appropriately to whatever scenario transpires. Here in a simple diagram are the scenarios it addresses:

Reflecting on this diagram, one can begin to imagine how creative partnerships with other agencies and communities throughout the region could help with either lowering the demand for water, or with supplementing the imports that might be (and probably will be) reduced from sources such as the Colorado River. MWD’s 2020 IRP indeed provides examples of needs that can incent such activities, including:

• Improve water storage capacity, especially in ways that can take advantage of wet years for use in dry years
• Make appropriate changes in outdoor water use
• Use indoor water more efficiently
• Cultivate local water supplies that reduce dependence on long distance supplies
• Do a more effective job of monitoring local water supply and demand

MWD garners substantial water supplies for much of Southern California. But how does that water get to end users? The following map of the MWD service area provides an important clue.

This map depicts 26 water agencies in Southern California that purchase water from MWD and then make it available to customers within their service areas. Fourteen of those agencies are cities and an additional twelve are water districts comprised of multiple cities and/or unincorporated areas. While those agencies get much of their water from MWD and its long-distance, imported water supplies (mainly Colorado River and the State Water Project), they also have access to their own local supplies (in the past, mainly groundwater, stormwater, and smaller rivers and creeks). To create the drinking water that comes out of the taps within each agency’s service area, those various sources were then mixed together and cleaned to an acceptable standard for the end users.

In the new age of One Water strategies, a new process is now taking root – advanced “water recycling.” Once derided by the phrase “toilet to tap,” it’s now becoming acceptable to acknowledge that wastewater can be purified to a level that’s completely suitable for drinking. In the old days, treated wastewater throughout Metropolitan Los Angeles was unsuitable for drinking and was typically dumped into the ocean. Or at best it was cleaned to a level that could be used for purposes such as groundwater replenishment or the watering of golf courses, but was not suitable for drinking. But experiences elsewhere in the country, combined with common sense, are resulting in a paradigm shift that makes advanced water recycling effective. I can vouch personally for this approach because I live in Saint Paul, Minnesota which, along with its twin city Minneapolis gets its drinking water from the Mississippi River. The Mississippi River is also where our wastewater ends up, and our wastewater professionals point out that the water they put into the river is much cleaner than the water that is already there. And within the massive Mississippi River watershed we are not alone. There are hundreds of wastewater plants lining the Mississippi River and its tributaries, matched by treatment plants that produce drinking water using the water from that same river system. 

So, how might water recycling be implemented in Metropolitan Los Angeles? It can’t be done by relying solely on MWD and its member water agencies since neither of those entities conduct large-scale wastewater treatment. What’s needed, then, are partnerships between MWD, its member agencies, and wastewater agencies in Metropolitan Los Angeles. There’s an organization that would seem to have access to all the wastewater that the core of the region could provide to MWD and its partner agencies, an agency known as the Los Angeles County Sanitation Districts (LACSD). And as we shall see, that agency is indeed emerging as an important innovator and partner in water recycling. It should be noted, though, that its name is somewhat misleading. As this map demonstrates, it essentially serves only the eastern and southwestern suburbs of Los Angeles along with isolated communities in northern Los Angeles County. It does not include the City of Los Angeles proper, nor the northwestern suburbs of LA.

The City of Los Angeles (with its wastewater agency, the Los Angeles Department of Sanitation and Environment = LASAN) has gradually improved its capacity to ensure that all of its wastewater is recycled, and that much of it will be “potable” (the technical term that means “suitable for drinking”). Most notable is its oldest wastewater plant, the Hyperion Reclamation Plant, initially created in 1894 and now one of the largest in the nation, treating an average of 275 million gallons of wastewater daily. It is implementing a long-term project to ensure 100 percent water recycling by 2035, some of it potable. The City’s newest such plant, the Donald C. Tillman Reclamation Plant, initiated in 1985, is now building a $500 million advanced water purification facility to provide 15 million gallons per day of potable water out of its total 80 million gallons per day of treated wastewater. At present, this facility is on track to be the City’s principal provider of potable recycled water. 

The City of Los Angeles has four wastewater treatment plants, while LACSD members manage eleven such plants. Ten of the eleven LACSD plants already recycle water, mainly for groundwater replenishment. The eleventh such LACSD plant currently produces water too salty to recycle, but now is being reengineered to be a nationally significant provider of potable water instead. That plant, the A.K. Warren Water Resource Facility in the South Bay and Harbor community of Carson, is hosting a new “Pure Water Southern California” program that is being designed to provide drinking water for 1.5 million people. 

In short, even as water supplies from traditional sources such as the Colorado River are diminishing, Metropolitan Los Angeles is becoming a leading-edge innovator in the One Water practice of advanced water recycling, providing potable water on a scale serving millions of customers. This is one of the most important ways that the region is preparing to be resilient and sustainable, even as imports from distant water sources become greatly reduced.