Rio Grande overbanking May 3, 2023 finally topped my little bike trail north of Albuquerque’s Central Avenue Bridge. ~4k cubic feet per second.

We have a chance this year to watch a fascinating intersection of climate-change driven changes in the Rio Grande through Albuquerque as filtered through both physical infrastructure and what we call the “institutional hydrograph”.

The tl;dr

Dust on snow is likely to accelerate Rio Grande headwaters snowmelt, meaning all that stored water comes off earlier. With nowhere to store it (see below, it’s an issue of both rules and physical infrastructure problems), we’ll be operating this year in a run-of-the-river situation on the middle Rio Grande through Albuquerque. Even though there’s still a lot of snow right now, once it comes off we’ll be down to base flow on the Rio Grande. Absent good summer rains, the river could dry through Albuquerque again this year.

Dust on Snow

The driver is a phenomenon researchers have identified in the past two decades called “dust on snow“. It’s when dry spring winds sweep across the arid uplands of, in our case, the Colorado Plateau, kicking up a layer or layers of dust that is then deposited atop the mountain snows in the high country. You can get multiple dust  layers, and when the melt reaches them, the snow warms up and melts quicker. There’s a climate change connection to all of this, as hotter, drier springs seem to lead to more dust (which makes intuitive sense, and is discussed in Painter, Thomas H. et al. “Response of Colorado River runoff to dust radiative forcing in snow.” Proceedings of the National Academy of Sciences 107 (2010): 17125 – 17130.

We’ve got that going on this year in the Rio Grande headwaters. From this morning’s Downtown Albuquerque News:

April’s dry and windy conditions have deposited a lot of dust in the Rio Grande headwaters, so the snow will be generally less reflective and absorb more heat. That, in turn, “means runoff will likely be advanced, leaving less for the later summer months,” reported Angus Goodbody, a Natural Resources Conservation Service hydrologist.

The Physical Plumbing: El Vado Dam

In the “before times” (before the creation of the Middle Rio Grande Conservancy District in the early 20th century, which led to the construction of El Vado Dam) communities in New Mexico’s Middle Rio Grande depended on the run of the river. When the runoff dwindled in the summer, they couldn’t irrigate. (This is part of the reasoning behind our argument in the new book that claims that there once were ~125,000 acres irrigated in the Middle Valley are not credible.) Construction of El Vado allowed communities to do the classic “dams move water in time” thing – store some of the big spring peak and stretch it out through summer.

El Vado is busted, though, unusable while it undergoes repairs. As Dani Prokop reported last month, the repairs are dragging:

The dam’s unique steel faceplate is causing challenges for the contractors and storing water in 2024 is impossible, said Jennifer Faler, the area manager at the Bureau of Reclamation office in Albuquerque. Faler said the dam will possibly store some water in 2025, when another phase of construction on a spillway is underway.

That means no storage (other than a little bit in Abiquiu Reservoir for Native American communities) for irrigators, which means that once the snow is melted, the river will dwindle.

The Institutional Plumbing: Article VI

Even if El Vado wasn’t broken, though, we’d sorta be in the same bind thanks to Article VI of the Rio Grande compact, which says….

Within the physical limitations of storage capacity in such reservoirs, New Mexico shall retain water in storage at all times to the extent of its
accrued debit.

New Mexico’s compact debt to Texas – the net we’ve underdelivered in recent years – is 93,000 acre feet. So even if El Vado wasn’t broken, any water we were able to store up to 93,000 acre feet would have to stay there. (This is why the Middle Rio Grande Conservancy District has reduced its diversions this year to 80 percent of what the district otherwise be sending down its canals – to get more of that water to Elephant Butte Reservoir, to try to reduce compact debt, so they can usefully store water once El Vado is fixed. This is a whole other blog post, because the discourse around this has been fascinating as I do the “embedded writer” thing at MRGCD for my book research.)

Hydrology in the 21st century: understanding the rules

I was down at the Rio Grande yesterday morning to record an interview about western water stuff with a crew from Italian public television. (The were neat! It was fun!) A bosque walker asked what we were doing and Luca, the TV guy, explained that they were interviewing the professor (pointing to me). The woman asked if I was a hydrologist. No, I replied, I do water policy.

That’s the thing. To understand the flow in the river we were standing next to, you need to understand the physical science – climate, hydrology, and such. But then, crucially, you needs to think about how the actual wet water is filter through the system’s human-built physical plumbing, which then requires understanding who it all is filtered through the rules.

A note on sources, methods, and business models

At this point in a post like this, I often drop in a thanks to my supporters, who make this work possible, including the Utton Center and Inkstain’s contributors. But I’d also point you to the linked information sources above – Downtown Albuquerque News is subscription-supported and one of my favorite local news reads, and Source NM (Dani Prokop’s employer – she’s doing great water stuff, invaluable to the community). Information is a public good, and as my economist friends like to point out, because of the free rider problem, public goods are under-provided.