This report, prepared in cooperation with El Paso Water Utilities, presents the results of an investigation to determine the chemistry and age of ground water on the southwestern side of the Hueco Bolson. The radioactive isotope carbon-14 was used to estimate the length of time that water from wells has been isolated from the atmosphere, which is the modern carbon-14 reservoir.
Nine wells on the southwestern side of the
Hueco Bolson were sampled for analysis of common
constituents, nutrients, total organic carbon, trace
elements, stable isotopes, and radioactive isotopes.
Dissolved-solids concentrations in water from the
wells sampled ranged from 269 to 2,630 milligrams per
liter. Sodium concentrations generally increased
linearly with chloride concentrations, possibly
indicating mixing of dilute recharge water with sodium
chloride brine. Concentrations of nutrients and trace
elements generally were small. The deuterium and
oxygen-18 composition in all samples except those
from wells adjacent to the Rio Grande indicates that
infiltration of precipitation is the main source of water
to these wells and that evaporation has not affected the
isotopic composition of the water. The source of water
from wells adjacent to the Rio Grande is probably not
the same source as the water from wells adjacent to the
Franklin Mountains. The calculated apparent carbon-
14 ages ranged from 12,100 to 25,500 years.
Additional Publication Details
USGS Numbered Series
Chemistry and age of ground water in the southwestern Hueco Bolson, New Mexico and Texas