A WATER QUALITY BASELINE FOR THE TAOS VALLEY WATERSHED: RIO HONDO, NM

The Rio Hondo is a tributary to the Rio Grande and serves as source to local agriculture (through an acequia system) as well as the base of a popular recreation destination. Additional stakeholders include the Taos Ski Valley. It is sourced primarily by snowmelt and precipitation in the high-elevation Sangre de Cristo mountain range in northern New Mexico. This study provides baseline water quality data and includes samples taken from multiple times in 2010-2011 from tributaries of the Rio Hondo, longitudinal samples of the Rio Hondo, spring-water, and private wells.

We report on water quality parameters including major ion chemistry. These baseline analyses provide a useful record for assessing potential effects of climate change. Regional climate studies project scenarios which include a 30-50% increase in the number of drought months per year (defined as soil moisture content) beginning around 2025 and lasting to at least 2100. This may have a deleterious effect on water quality and quantity. A substitution of a short temporal interval, 2011 drought, for an extended climatic interval, persistent 2025 drought, may give insight into the direct effects of climate change on water quality in northern New Mexico. Comparing the USGS stream flow data with the TDS data for the Rio Hondo, it appears that reduction in flow may have a minor short-term effect on the river’s chemistry. In June, flow was about 90 cfs and TDS for sample site RHR2 = 206 ppm and RHR4 = 123 ppm, and in September flow decreased to 10-20 cfs and TDS increased with sample site RHR2 = 295 ppm and RHR4 = 201 ppm. If climate change causes increased temperature for the southwest and a subsequent increase in snow sublimation and water evaporation, the reduction in stream flow would result in reduced quantity of water and, possibly water of poorer quality for the people of Taos and their acequia farmland. Baseline monitoring, including the use of continuous water quality sensors, may provide a useful tool for water management.