Guest commentary by Geoff Vanden Heuvel, Director of Regulatory and Economic Affairs, Milk Producers Council:
“I remember being surprised when attending a local Groundwater Sustainability Agency meeting and I first saw a schematic that visually depicted the various levels of groundwater underneath one of the Central Valley’s numerous subbasins. There was a horizontal line going across the chart that said “base of freshwater”. Beneath the freshwater line there was another line labeled “top of basement”. I asked the subbasin hydrologist about what occupied the space between those lines and he explained that it was ancient salt water that occupied the lowest depths of the aquifer. He said a study done decades ago had identified that the salt water was there, but they were now guessing about exactly where, because other than that one study done many years ago, no one had a reason to drill down into it to attempt to characterize it. Why does this matter? If you are going to estimate how much fresh water is contained in a groundwater basin, you need to know how deep it is.
This story is just one example of what has been going on in the Central Valley over the past few years since the adoption of the Sustainable Groundwater Management Act (SGMA) by California in 2014. … ”