In 1973, Mexico worried U.S. would slip radioactive waste into Colorado River drain water?

Minute 242, an addenda to the U.S.-Mexico Colorado River Treaty, (pdf) contemplated construction of a drain to safely carry high salinity U.S. drainage past municipal and agricultural intakes and dump it into a slough near the Sea of Cortez.

It was a time of tension between the two countries over the salinity issue. (Evan Ward’s Border Oasis tells the tale.) How tense? It is fascinating to imagine the back story that left Mexico to feel this language needed to be included in the 1973 agreement:

It is understood that no radioactive material or nuclear wastes shall be discharged through this drain.

Middle Rio Grande update

Water managers increased the release this afternoon (Thurs. May 21) from Cochiti Dam into New Mexico’s Middle Rio Grande Valley to 3,000 cubic feet per second, which will increase flows yet more tomorrow through Albuquerque. As I explained yesterday,  May storms and some clever water management twiddling with stored supplies is providing the opportunity for a seasonal “pulse” that looks like the largest spring flow since 2010.

I don’t want to oversell this. The Rio Grande is a system intensively managed for flood control and water delivery such that it bears little resemblance to the meandering flood plain river that once flowed through what is now Albuquerque. Its narrow central channel isolates the river from the flood plain that flanks it, where it once would regularly get up and spread across the land. But there have been modest human efforts to mimic the old natural system, using earth moving equipment to create channels and back waters that inundate at modestly higher flows like we’re seeing now. The managers are trying to take advantage of the natural flow from storms, with some added water they’re throwing in from storage on the Chama (releases from El Vado are way up) to create a miniature version of what the river once did by itself.

I spent the afternoon out looking at the results so far. Here’s one of the newly dug channels near Albuquerque’s Tingley Beach city park:

Overbanking on the Rio Grande near Albuquerque

Overbanking on the Rio Grande near Albuquerque

For the first time since 2011, less than half of New Mexico in drought

For the first time since January 2011, less than half of New Mexico is classified in “drought” this morning in the weekly federal “Drought Monitor” (“drought” is the oranges and browns):

Drought Monitor

Drought Monitor

Driving back across the state from a meeting in Arizona last week, things looked greener than I’ve seen in a long time, though I realize that much of my drive, in western New Mexico, was still in the “drought zone”. But I’ve been out that way frequently since January, and you can see the change.

In addition, as I wrote yesterday, the May storms have (finally) brought Rio Grande spring runoff to its highest levels since 2010. But it’s important to remember what this does not mean.

Drought is no one thing. While the map above reflects good late spring precipitation, the mountain snowpack was terrible, and there’s no way to make up for that with spring storms. Drought on the landscape (greening of vegetation, shallow soil moisture) and water in the river are related, but they’re not the same. The map reflects drought on the landscape. Water in the rivers is still problematic. Flow on the Rio Grande may be up to levels we haven’t seen in five years, but that’s as much of a measure of how lousy it’s been over the last five years, as it is a measure of how good things are this year.


New Mexico’s Rio Grande, on the rise (finally)

Water from our recent storms, combined with the some clever twiddling by federal and local water managers, is pushing the Rio Grande through Albuquerque in the next few days to the highest spring runoff levels we’ve seen since 2010. Water managers are taking advantage of the May storms to add some water and create a runoff spawning spike for the endangered Rio Grande silvery minnow.

Rio Grande rising, Otowi, NM

Rio Grande rising, Otowi, NM

The U.S. Army Corps of Engineers this morning increased releases from Cochiti Dam, north of Albuquerque, to 2,000 cubic feet per second, with as much as 3,000 to 3,500 cfs by tomorrow (Thurs. 5/21). Much of the water is a pulse of runoff from the mountains north of Santa Fe (Embudo Creek last night peaked at 1,000 cfs), but the U.S. Bureau of Reclamation and the Middle Rio Grande Conservancy District are adding flows on the Rio Chama from El Vado Dam to create the spawning spike, which could hit 3,000 cubic feet per second at Central Avenue in Albuquerque by late this week or this weekend.

The remarkable turnaround is the result of a wet May (already the wettest May since 2007 in Albuquerque). Just three weeks ago, managers were scrambling for water, with little chance for a minnow spawning spike and with farmers in the middle valley on shaky ground. Now the farmers are hoping for it to dry out so they can get their alfalfa cut, and MRGCD storage upstream looks like it could have enough water, between native water and what they’ve been able to store in El Vado Reservoir, to last through the season (depending on the weather, I’m told – always depending on the weather).

The Rio Grande has spiked this high a few times in recent years as a result of summer thunderstorms and an epic September 2013 event, but this is the first time since 2010 that a peak this high has arrived at this time of year, which is the critical time for the minnow, an endangered fish whose status drives a lot of the politics and policy of the river’s management.


“Enough water will never be enough”

California’s water problems will never be solved Faith Kerns and Doug Parker argue, because cities and farms will always expand to the edge of available supply, overshoot, and then face trouble during the dry times:

There are other arenas where this phenomenon is well understood. For example, when it comes to freeways, congestion leads to demand for more lanes to be built. More lanes temporarily reduce congestion and lead to increased housing construction, and over time, that increased housing construction leads to more congestion. That, in turn, leads to demand for more lanes. This is also true with flood control: better levees lead to safer communities, which cause communities to expand and demand even better levees.

Accepting this fundamental paradox doesn’t mean that we should throw our hands in the air and do nothing — and in fact, we aren’t. We should be, and are, looking at augmenting supplies and increasing conservation efforts. We need to pursue all of these options in order to have healthy communities, healthy agriculture and a healthy environment.

We also need to recognize, however, that these options will never fully eliminate future scarcity.

This generalizes across the arid West. The full piece is worth reading.

Update: Forgot the best pull quote:

If it were simple, it would already have been done.

In defense of “vapor pressure deficit”

If you follow weather forecasts, you’ve heard about “relative humidity” (RH). But it’s one of those maddeningly less-than-useful measures of our weather that probably needs to be just retired. That’s wishful thinking, of course. But in an interesting introduction to their latest research into the increasing dryness of the air and the risk of fire that attends thereto, Richard Seager and his colleagues make another plea. Paraphrasing a 1936 paper by D.B. Anderson, they write:

Anderson (1936) points out that RH is not an absolute measure but merely a ratio of two known quantities expressed as a percentage.

If you can do the math quickly in your head, you can keep an intuitive grasp of the meaning of RH in a given situation. But using a measure that requires your audience to do math in their head to make sense of what you’re telling them is a bad communication strategy. Riffing off of Anderson, Seager and colleagues argue for the importance of a different measure that requires no such math – “vapor pressure deficit”. I’ll skip their equations for this:

VPD gives an absolute measure of the atmospheric moisture state independent of temperature. For example, for a given wind speed and atmospheric stability, above a surface that is not water-limited, a specific VPD leads to the same rate of evaporation, regardless of temperature.

Why should we care? Because vapor pressure deficits are rising in the southwestern United States, and are closely linked to wildfire risk. The public communication element of “VPD” vs. “RH” is really just a sidelight to an important new paper about rising fire risk as the southwest warms. (In particular they look in detail at VPD and the Rodeo-Chediski and Hayman fires.) But I found it intriguing. I’d love to have it added to my daily forecast page.


Creeping toward shortage: Lake Mead now headed for bigger drop next year than we thought

Folks worried that Lake Mead might drop below elevation 1,075 and trigger a first-ever Lower Colorado River Basin shortage now have more to worry about. The latest monthly model runs from the U.S. Bureau of Reclamation (pdf) have increased the odds, and suggest that Mead (currently at 1,077.03) could drop all the way to 1,054 by the end of the 2016 “water year” – 18 feet lower than projected just one month ago.

This is all a result of the interaction of two important water management rules – one that calls for holding more water upstream in Lake Powell to keep that reservoir from dropping too far, and a second that calls for curtailing water deliveries to Arizona, holding the water back in Lake Mead, outside Las Vegas.

The latest monthly Bureau model runs, released this afternoon, point toward a likely need to cut releases from Lake Powell, on the Colorado River along the Arizona-Utah border, beginning Oct. 1. That would result in less water being delivered to Lake Mead, downstream, increasing the chances of a first-ever shortage declaration and cascading shortfalls in Arizona as early as Jan. 1. So far odds are against that second eventuality – Arizona cuts beginning Jan. 1. But it’s very close right now, with projected Jan. 1 levels of 1,075.92, just 11 inches from the trigger point.

Regardless of whether we hit the 1,075 trigger this time around, however, reduced releases from Lake Powell would ensure huge drops in Lake Mead next year.

This is all part of the complicated operating rules adopted in 2007 intended to balance shortfalls in Powell, the main upper basin storage reservoir, and Mead, the main reservoir downstream for use by Nevada, Arizona, and California. Powell has been hovering right around a trigger point (elevation 3,575 feet above sea level on Jan. 1) that would require cutbacks to keep more water in Powell. There’s a lot of “if this then that” rules stumbling over one another here, but if the August monthly modeling run shows Powell is too low, that automatically invokes a rule to hold more water in Powell and release less water to Mead. And less water in Mead translates to increased risk of triggering a second rule that would keep more water in Mead next year by cutting deliveries to Arizona.


The federal role in western drought

The federal government, through its water agencies (and the funding providing via taxpayers in other places) used to be a major player in the development of the West. This Michael Doyle story, in describing a Congress up to its axles in California drought and unable to move an inch, suggests that is no longer the case:

Five months into a new Congress, and deep into a lasting drought, California water legislation still stymies and splits the state’s lawmakers.

Clearly Californians have not passed the first important hurdle for federal action on state-level water issues – unanimity within the state about what should be done. Traditionally a state gets its act together and presents a united position to Congress as a necessary precondition to federal action. But one of the reasons such unanimity is harder today than it used to be is a reduced federal ability to throw vast sums of money at internal state water conflicts. Used to be that part of a deal was federal dollars to build a big canal or dam or something that all the state players could get behind. We’re done with that.

Second is a deeper values division about the best way to deal with our water problems. California has always had a north versus south problem, but now…. Water for the environment? Ag versus urban? This may be greatest hurdle.