The great decoupling between Albuquerque’s growth and its water use, with total use down another 3 percent in 2015, continuing a trend that over two decades has led to a 24 percent drop in water use, even as population has grown 25 percent. I don’t have population numbers yet that I need to do the calculation right, but my preliminary estimate is that we’re down around 131 gallons per capita per day of water use (or better, depending on the final population numbers). That is a very low number. When our conservation efforts got underway 20 years ago, we were using 250 gpcd.
This decoupling stuff is everywhere. I’m currently looking at a dataset from the Metropolitan Water District of Southern California that shows 2015 consumptive water use at its lowest since 1991, even as population has grown by 3 million people in Met’s service area.
As the graph shows, most of Albuquerque’s savings have been in outdoor water use, which is down 36 percent since 1995. Water nerds will recognize the importance of that, because it’s the outdoor use that’s fully consumptive. Albuquerque is one of those communities that returns its treated sewage to the system for full reuse (in our case it is returned to the Rio Grande where it is available for ecosystem, agricultural, and municipal use downstream). So in trying to manage our long term supplies, it is that outdoor consumptive fraction that matters the most. That the water we really use up rather than just borrowing from the system and then returning.
Also worthy of note: in 2015 the Albuquerque Bernalillo County Water Utility Authority pulled 1,358 acre feet of water from the aquifer that had been stored through percolation in previous years. It is a small amount, just a proof-of-principle project, but is the first recovery from an aquifer storage-and-recovery project in New Mexico history. I know, y’all in other western states who have been doing this for years are all, like, “Wait, they’re only now starting to do that?”