California is facing some worrisome pressures from increasing water demand for a growing population and decreasing supply reliability due to climate change and environmental pressures on the Bay-Delta region. What should California do, when faced with extreme drought? A new study released by the California Energy Commission recommends creating and maintaining a water storage bank underground. That is, California should store excess water underground, and then pump it out as needed when extreme drought arrives. I’ve been a fan of this idea (“Managed Aquifer Recharge” or “Managed Underground Storage” are two broad names for the idea) since I first heard about it some 6 years ago in grad school, and it’s great to see that policy advisers and think-tanks are starting to come around. If we can educate the rest of California, including politicians, then we might actually have a shot at making things happen.
I’ve mentioned before that Cadiz, Inc. is trying to get approval to extract groundwater from the Mojave desert near Cadiz to sell it to water agencies in southern California. The big part of their plan that left me confused was their plan to overextract the groundwater for 50 years, then allow the water table to recover for 50 years. Why not pump at the recharge rate, rather than at a rate at least 1.5 times the recharge rate? One obvious reason is to make money: 50,000 acre feet/year (AF/y) makes you a player in SoCal water resources; 5,000 AF/y does not.
I read through the Cadiz project’s draft EIR (the whole document is nearly 3000 pages! that’s crazy!), and their rationale is that they need to get the existing groundwater out of the way, so that they will have space for all the surface water that they’re going to store in the aquifer. If you store water in the aquifer in its current state, it will just induce faster flow towards the dry lake basins, and much of the stored water will be lost to evaporation. But if you make the space for it, you can store as much water as you need, for an indefinite period. This phase of their project is “Phase II”. Phase I was when they got about 10 smaller water agencies in southern California to sign on to buy the Cadiz water, if it’s ever produced. So, who will store their water in the Cadiz aquifer? So far, no one.
There are a couple of reasons why no one has signed up. First of all, no one has extra water. It has been pretty darn dry of late, and climatologists suggest this is the trend for the future. Second, if Metropolitan Water District of SoCal (MWD) gets extra water from the Colorado River, they store it in Lake Mead, which has plenty of space right now (51% full at the moment). The Colorado Aqueduct already operates at full capacity, so they can’t immediately deliver extra water even if they get it. Third, the State Water Project’s supply from the Bay-Delta region is up in the air, due to endangered species issues for the delta smelt, and even if a peripheral canal of some sort is built, don’t expect the other stakeholders in the California Aqueduct to go along with sending all the “excess” water towards water-hungry L.A. A fourth and final point is that in the first generation of this Cadiz project, geologists recognized naturally occurring arsenic and chromium in the Cadiz valley groundwater. Arsenic and chromium geochemistry is such that adding oxygenated surface water to the groundwater could, in fact, enhance mobilization of arsenic and chromium into the stored groundwater, making it toxic during storage, so that it would need expensive treatment before it could be delivered to customers. I certainly wouldn’t want to bank my future water supply in that aquifer without a lot more study!
I’m a big proponent of water recycling and innovative water storage solutions, such as managed underground storage, but this project is not about sustainable water management — it’s about money. And Cadiz, Inc. plans to make a lot of it by withdrawing a bunch of groundwater from a remote desert valley, regardless of whether phantom water deposits ever show up.