Tensions around a wastewater reclamation collaboration in Southern California

There’s some fascinating tension around a proposed wastewater reclamation collaboration in Southern California.

The project, if it goes forward, would provide some 150 million gallons per day (~170,000 acre feet per year) of treated effluent. Water now being discharged into the ocean would instead be available for aquifer recharge within Southern California.

There are a number of technical and environmental questions, most notably the project’s cost effectiveness, to be analyzed before the so-called “Regional Recycled Water Program” goes forward. But there’s a really interesting set of institutional threshold questions to be resolved as well, which are lurking in agenda items at this week’s Metropolitan Water District of Southern California board meeting.

Whose Project Should This Be? Local or Regional?

This is a perfect case study for concepts we’ve been discussing in our crazy Zoom session classes this fall with students in the UNM Water Resources Program. The question – where do you draw the boundary(ies) around a water resources problem, and its potential solution.

The preliminary discussions about this project have drawn the boundaries quite broadly. Pilot-scale work has been done through a partnership between Los Angeles County Sanitation District No. 2 and the Metropolitan Water District. Under this model, should the project go forward, the water produced would become a regional supply, alongside water from the Colorado River Aqueduct and State Water Project, which Met provides as a wholesaler to its 26 member agencies.

That’s an institutional model that draws broad boundaries around the project.

Whether that’s the right model, though, is subject to some debate among Metropolitan’s member agencies. The San Diego County Water Authority, for example, seems to favor a more “local control” sort of model, where individual member agencies build their own projects, using the water themselves, rather than having Met build big regional projects, sharing water (and costs) among all.

Should This Be an Interstate Project?

But there is a proposal on the table that would drawn the boundaries even more broadly. In May, Met and the Southern Nevada Water Authority (Las Vegas, Nevada’s big regional water wholesaler, a sort of Met equivalent there) signed a letter of intent that opened the door to SNWA’s possible participation in the Southern California Project. In return for picking up some of the cost, SNWA would get a share of the water. (You wouldn’t actually pipe the water to Las Vegas, that would be crazy expensive, it’s much easier to just do an accounting swap.)

Readers of my work will know that I love deals like this – water bargaining, or sharing, or whatever you call it, collaboration across boundaries. But according to a letter sent over the weekend, San Diego is not so enamored of the idea: “We oppose potential exchange of Colorado River water with other states,” wrote SDCWA board member Michael Hogan on behalf of the agency’s board.

What Happens Next

This is still early days for this project – more study needed, as we academics like to say. But based on Hogan’s letter, there might be some lively discussion at this week’s MWD board meeting about where the boundaries should be drawn.


  1. With all due respect to my friend Mike Hogan, I would not characterize the SDCWA MWD Delegate letter as an official position of the entire SDCWA Board. The Board does not weigh in on letters like that – at least I know I was never asked for my thoughts on the matter. I will say that the letter correctly highlights the need for careful and accurate future demand projections, something that is lacking in the SDCWA evaluation of a second pipeline to Imperial County.

    With respect to where to draw the boundaries on these sorts of projects, I would draw them as wide as possible. Many rate structures are primarily volumetric based which incentivizes local projects where agencies “roll off” regional demand and their share of regional costs. This leaves agencies without access to alternative supplies paying a much greater share of these regional costs. Spreading the costs and benefits of these projects across regions is a much more equitable way to go. The reason Rainbow MWD is seeking detachment from SDCWA is inherently linked to rising regional costs that will only go up as agencies down south roll off due to local supply projects.

  2. I looked into recharging aquifers a few years ago. My interest was in storing water in a way that would avoid evaporation and sediment problems. A couple of scientists responded that the main problem was possible contamination of the aquifer. And that was from ordinary streams and rivers. The natural process of filtering water though the earth over hundreds of years would be skipped.

    “Treated effluent” would not be “pristine” water. Human and municipal waste water contains a number of things that are not filtered. https://www.scientificamerican.com/article/only-half-of-drugs-removed-by-sewage-treatment/

    If the stored water is used only for agriculture irrigation there is still the chance that these chemicals would be put in our food chains. If the stored water is used for domestic use the chemicals would come directly into humans. That is already the case for water systems that draw from existing waterways that contain the chemicals discharged upstream. The assumption is that anything harmful will be diluted to a safe level. I wonder if this theory has really been adequately examined. Something is causing the average American lifespans to decline.

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