USE OF CONTINUOUS WATER QUALITY SENSORS TO EXAMINE HEADWATER RESPONSE TO SNOWMELT: VALLES CALDERA, JEMEZ MOUNTAINS, NM

Many hydrological factors influence stream water quality, including variations in annual snowpack, monsoonal precipitation, and climate change factors. We examine two years (2018-2019) of water quality time-series data from streams located in the Valles Caldera National Preserve, Jemez Mountains, New Mexico. The Jemez river is the single river discharging from the caldera, and is a tributary to the Rio Grande in addition to supplying recharge to the northwestern Albuquerque basin. The Jemez river exhibits a snowmelt-dominated annual hydrograph, with important monsoonal inputs in mid-late summer. SNOTEL data show that 2018 was well below average snowpack, and 2019 was well above average. Thus the study years represent very different runoff conditions. Due to increase in drought in New Mexico, years with increased precipitation have less impact on long term mitigation.

We show measurements of temperature, dissolved oxygen (DO), pH, and turbidity using Yellow Springs Instruments model 6920 V2 sondes from several sites within the caldera. We report on two consecutive years at 15-minute intervals between April to October in 2018 and 2019. Reference stream discharge data are from the USGS Jemez River gauge (downstream of the study area) and SNOTEL data are from the Quemazon site near to the study area. Data analysis is accomplished with AQUARIUS (Aquatic Informatics). Regional drought monitoring information was collected from NIDIS and NASA sources.

In 2018, the Jemez mountains had minimal snowpack and dissolved oxygen levels were consistently high throughout the year. Increases in snowmelt for 2019 increased turbidity to maximum measurable levels (1200 NTU) based on evidence from multiple sondes. The dissolved oxygen levels from the sites were considerably lower than 2018.

Strong snowmelt-runoff in spring 2019 had significant changes relative to conditions in 2018, where strong variations are noted. This study is part of a long-term monitoring effort to gain a better understanding of the headwater hydrologic variability in a mountain watershed in response to interannual snowpack variability in addition to watershed management policies.