New Mexico Geological Society Annual Spring Meeting — Abstracts

The Jemez River drains the Jemez Mountains of northern New Mexico, and receives input from a number of hydrothermal features along its reach. A base line study was conducted to determine salt and metal loading effects of spring inputs to Jemez River water quality. Ten sites (stream and springs) were sampled along a 25-km reach of the river through San Diego Canyon and analyzed for major and selected trace element concentrations (Ca, Mg, Na, K, Cl, SO₄, HCO₃, Si, Br, B, Li, Ba, F, and As) under summer and baseflow conditions in 2006. Hydrothermal inputs examined include Soda Dam, Jemez Springs, and Indian Springs, and water chemistry results are consistent with earlier reports (Trainer, 1984; Goff, 1994; and Goff and Shevenell, 1987). Jemez River water displays a tenfold increase in total dissolved solids (TDS) and metals reflecting hydrothermal inputs between San Antonio Creek and the confluence with the Guadalupe River. Chemical trends for conservative ions (Cl, Br) are consistent with mixing/dilution of a low TDS (1,000 ppm) sodium chloride water at typical (baseflow) discharges of 30-40 ft³ /sec. The Guadalupe River dilutes these contributions; however, concentrations again increase along the Jemez River between the Guadalupe River and village of San Ysidro due to additional hydrothermal inputs. Loading calculations for TDS and arsenic under a variety of flow regimes typical of the Jemez River indicate that As levels of approximately 100 ppb and TDS of 500 ppm are likely to occur in the reach between Soda Dam and the Guadalupe River beginning at discharges below 140 ft³ /sec. In 2006, flows measured at the USGS gauging station near Jemez Springs were below this threshold value for all but a few days.