This is a long but very interesting article with a local flavor, talking about where much of the water comes from in desert areas. Sheep Creek Water Company relies exclusively on groundwater, and it is a precious resource indeed. The tunnel that was dug over one hundred years ago to move water turned out to be a water source that taps into an ancient flow, and that ancient flow has been providing water to Phelan ever since.
https://www.theatlantic.com/science/archive/2023/01/cadiz-farms-fossil-water/671652/
The science of water dating is young, but it is starting to introduce ethical considerations into California water decisions. In the high desert city of Victorville, where years of overpumping have left groundwater supplies dangerously low, Izbicki has provided his age data to water managers. “When you tell people their water is 10,000 years old, that changes the conversation,” he says. The community focused on conserving that supply, and began recharging the aquifer to sustain it—one of the three alternatives to the Cadiz project noted by the water-policy expert Jeffrey Mount. Since Izbicki’s first studies of Victorville water in 1995, Mount says, the water table has stabilized. Izbicki has since provided data to three other high-desert communities to help them manage their groundwater.
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The long failure to seriously consider the ethics of groundwater management, Groenfeldt says, is a symptom of a larger misunderstanding. When we think about water scarcity, it’s easier to picture a dry lake bed than a drained aquifer. Although groundwater constitutes the vast majority of the planet’s nonfrozen freshwater resources, most people know little about it, perhaps imagining that it collects in underground caverns or lakes. In truth, an aquifer is more like a porous sponge, a network of geologic and chemical interactions that defies reduction to simple formulas. Mount says the current crisis will force us to confront this collective ignorance.
“We’re at this once-a-century transition in water management,” Mount says. “The next generation after me is going to be obsessed with groundwater.”