Peak Water in the Rio Grande Basin?

According to an article in the Alamogordo News from New Mexico, “people who live in the Rio Grande Basin will have to take dramatic steps if they hope to have a future that involves more than just dust.”

Apparently, the “El Paso Times, a partner newspaper with the Sun-News, will attempt to bring attention to those problems and place special emphasis on ways the area's dwindling water supply problem might be solved.”

The story goes on to claim the following:

Experts say population in the region has swelled during unusually wet years, leading to growth and creating habits that tree rings and other scientific data indicate we shouldn't expect in the future.

Stream flows measured at the Otowi Gauge on the Upper Rio Grande were well above historical norms between 1980 and 2000, when El Paso's and Albuquerque's populations grew 42 percent and 38 percent, respectively.

Add climate change – which an overwhelming majority of those who study it say is happening – and you have a future that might not be very promising for cities such as El Paso, Juarez, Las Cruces and Albuquerque.

The expected effects of a changing climate are drier winters, a smaller snowpack at the Rio's headwaters and faster evaporation – all punctuated by infrequent-but-violent storms.

The fact-checking can start with the claim that “stream flows measured at the Otowi Gauge on the Upper Rio Grande were well above historical norms between 1980 and 2000.”  Streamflow data for the Rio Grande at Otowi Bridge (New Mexico) hydrometric station are available online from the USGS.  The annual streamflow data apparently begin only in 1971, so I'm not sure how reliable claims can be made that the 1980-2000 period had streamflows “well above historical norms.”  There is no significant difference in the annual streamflows from 1971 to 1979 when compared the 1980 and after period, nor is there a significant trend in annual streamflow since 1971.

There are other USGS streamflow monitoring stations on the Rio Grande in Colorado, New Mexico, and Texas.  At none of the hydrometric stations on the Rio Grande through these three states has there been a significant decline in annual streamflow since 1970 – which is the period over which the National Climate Assessment tells us that the impacts of anthropogenic climate change should be most evident.  Furthermore, at the sites that have long-term annual streamflow records dating back into the early 1900s, it appears that there was more streamflow in the Rio Grande during the first half of the 20th century.

Overall, there isn't a significant post-1970 trend toward lower streamflows in the Rio Grande watershed, and streamflows during the 1980-2000 period – when El Paso's and Albuquerque's populations grew rapidly – don't appear to be above historical norms.  Similarly, there are no significant declining trends in annual or wintertime precipitation since records began in 1895 in any of the climate divisions within the Rio Grande's watershed.  This collective information seems to contradict the Alamogordo News article and the climate predictions therein.

As with much of the southwest region, water is naturally in short supply, and the population is growing quickly.  Eventually, there will need to be a reckoning between the two.  But far more caution is warranted before throwing climate alarmism into the mix.