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Delta Flows: April 22, 2016

by Tim Stroshane

I recently read an ostensibly scientific paper with the impressive title, “Economic and Water Supply Effects of Ending Groundwater Overdraft in California’s Central Valley” by several researchers led by Jay Lund, professor of civil and environmental engineering at the University of California, Davis, and a researcher with the Public Policy Institute of California.

The study was disappointing, and short on good science. Sadly, the Lund team’s results are often more “truthy” than complete.

In 2014, the “Sustainable Groundwater Management Act” became law in California. This bill requires every groundwater basin in the state to get on a path toward sustainable groundwater management and usage by 2040, and to have a plan in place by 2020 or 2022, depending on where you are. According to Lund’s research team, the Central Valley’s groundwater overdraft stands at about 1.2 million acre-feet per year. That’s about 391 billion gallons of water withdrawn every year from underground, without getting replaced.

Their study was about how to eventually eliminate that 1.2 million acre-feet of overdraft.

The bottom line for the Lund team is that 23 percent of the eliminated overdraft will come from “lost groundwater pumping and reduced agricultural water use” (that is from actual hardship by, mainly, San Joaquin Valley farmers), while the other 77 percent of the ended overdraft will be made up via “increased recharge” and “decreased Delta outflow” comprised of “increased Delta exports and upstream diversions.”

This means that other regions of California like the Delta and the Sacramento Valley would “pay” for the San Joaquin Valley’s debt to nature. (See Figure 10 for their breakdown of the sources of overdraft reduction.)

The cost of ending overdraft statewide, their study estimated, would be at least $50 million per year.

That may sound like a lot of money until you put it in perspective. It would be a water cost of about $41 per acre-foot ($50 million divided by 1.2 million acre-feet), which seems very affordable compared with the Governor’s Tunnels project, which would cost somewhere between $700 to $1500 per acre-foot (depending on whom you ask). With about 60,000 farms in the Central Valley, that’s a cost of ending groundwater overdraft of about $833 per farm per year, assuming all farmers pitch in. (Isn’t that about what some people pay for a year of basic cable?)

So, either this is a tempest in a teapot, or the Lund team’s study has flaws. Or maybe both.

Silences abound in this study. The Lund team’s study results were aimed at an audience of state and federal water contractors, though this purpose is not disclosed.

While it is common practice for many top-flight scientific research publications to disclose the researchers’ funding sources, no such disclosure is found in the Lund team’s acknowledgements.

The Lund team is deafeningly silent about how Tunnels conveyance would facilitate the end of groundwater overdraft. Certainly, the Tunnels would ease connection of Sacramento Valley flows and Delta exports via water market transfers, for the sake of offsetting long-term San Joaquin Valley water mismanagement. Such deals would redirect impacts of ending the southern valley’s groundwater overdraft to the rest of the Central Valley.

Usually, careful and caring researchers disclose early in the paper the strengths and weaknesses of their method and approach. The Lund team buries their model’s limitations at the end of “Discussion”, page 16, rather than present them up front in the methods and assumptions section.

The Lund team misses an obvious reality that farm land retirement would likely reduce agricultural water demand in the future. Such retirement may be voluntary (due to water cost) or involuntary (due to salinization or climate change). But the Lund team ignores this likelihood altogether.

A more relevant and useful research priority would have been to consider keeping water in reservoirs for temperature control and water quality for both upstream protection of salmonid spawning habitat and migration corridors, and Delta estuary protection in the face of climate change—all while reducing Delta exports. What would be the long-term economic benefits of recovering these fish populations and the recreational and commercial fishing industries they support? (Just silence.)

The team concludes with a sense of faux realpolitik that “even if it is not politically and environmentally feasible to provide such substantial shifting of Delta outflows to accommodate ending groundwater overdraft, these results show that substantial pressure to increase (and not reduce) Delta exports is a likely result of recent state legislation on groundwater sustainability.” (p. 16)

Why is it logical, let alone necessary, that San Joaquin Valley farmers might shoulder just one quarter of the responsibility for ending overdraft that they themselves were fully responsible for creating?

Since insanity is when you keep doing the same thing over and over again while expecting a different result, perhaps it’s time to try a regional self-sufficiency approach to end groundwater overdraft.

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{ 4 comments… add one }
  • April 22, 2016, 8:19 pm

    Great essay, Tim! You write beautifully.

  • Kandace Korth
    April 23, 2016, 5:27 pm

    You bring an intelligent and reasoned voice to the conversation. Thank you.

  • Jay Lund
    April 26, 2016, 2:06 pm

    This essay has almost nothing to do with the paper and blog we wrote. The modeling work we did does not advocate increasing Delta exports as part of eliminating overdraft in the southern Central Valley. It merely indicates that this is the direction that the economics would want to move water to end the overdraft.
    We try to point out that the Delta’s problems and ending overdraft, both items of great public and environmental interest, are linked. The Delta’s problems are linked to other upstream activities and water uses as well. This is part of what makes the Delta’s problems so difficult – they are linked to activities in many other parts of the state. I hope people read the original work.