I went on a bike ride this morning to get a look at the Rio Grande through Albuquerque. Flows dropped below 100 cubic feet per second Thursday evening for just the second time since we moved here in 1990. Flows this low are hard to measure – we didn’t get a numerical picture of just how bad things are until the USGS river measurement people calibrated their Central Avenue gauge Friday morning.
The other time we had flows this low during my tenure as an Albuquerque resident was September 2013 (I remember it well, I was covering the heck out of the river for the Albuquerque Journal at the time). But it’s worth looking back in time, because the flows we’re seeing this year, which are freaking me out, used to be a nearly annual affair. Here’s a plot of annual minimum flow, based on USGS data:
This is a classic result of what I’ve come to call “an institutional hydrograph”. A hydrograph is a graph of flow on a river over time. In its normal form, it responds to seasons, weather, and climate. But in its institutional form, it responds to rules and policies and norms of human behavior in managing the river.
Those zero-flow points on the left half of the graph are institutional. From the mid-1940s to the early 1980s, we dried the river through Albuquerque almost every year. I phrased it that way on purpose – not “the river went dry” but “we dried the river”. If you look at upstream gauges, there was water in the Rio Grande, flowing into the central valley where Albuquerque sits. But the irrigation agency that provides water to this valley’s farmers diverted it all, running its ditches full, so that by the time the Rio Grande reached Albuquerque, it was dry.
I’m hazy on some of the history, but by the time I started paying attention to the Rio Grande in the 1990s, a combination of community environmental values and the strictures of the Endangered Species Act had triggered changes in irrigation management. As a matter of policy we now leave water in the river. So for my generation of river-watchers, this is a really striking thing to see: