Questa baseline and pre-mining ground-water quality investigation. 2. Low-flow (2001) and snowmelt (2002) synoptic/tracer water chemistry for the Red River, New Mexico

Water analyses are reported for 259 samples
collected from the Red River, New Mexico, and its
tributaries during low-flow(2001) and spring snowmelt
(2002) tracer studies. Water samples were collected
along a 20-kilometer reach of the Red River beginning
just east of the town of Red River and ending at the U.S.
Geological Survey streamflow-gaging station located
east of Questa, New Mexico. The study area was
divided into three sections where separate injections
and synoptic sampling events were performed during
the low-flow tracer study. During the spring snowmelt
tracer study, three tracer injections and synoptic
sampling events were performed bracketing the areas
with the greatest metal loading into the Red River as
determined from the low-flow tracer study. The lowflow
tracer synoptic sampling events were August 17,
20, and 24, 2001. The synoptic sampling events for the
spring snowmelt tracer were March 30, 31, and April 1,
2002.
Stream and large inflow water samples were
sampled using equal-width and depth-integrated
sampling methods and composited into half-gallon
bottles. Grab water samples were collected from
smaller inflows. Stream temperatures were measured at
the time of sample collection. Samples were
transported to a nearby central processing location
where pH and specific conductance were measured and
the samples processed for chemical analyses. Cations,
trace metals, iron redox species, and fluoride were
analyzed at the U.S. Geological Survey laboratory in
Boulder, Colorado. Cations and trace metal
concentrations were determined using inductively
coupled plasma-optical emission spectrometry and
graphite furnace atomic absorption spectrometry.
Arsenic concentrations were determined using hydride
generation atomic absorption spectrometry, iron redox
species were measured using ultraviolet-visible
spectrometry, and fluoride concentrations were
determined using an ion-selective electrode. Alkalinity
was measured by automated titration, and sulfate,
chloride, and bromide were analyzed by ion
chromatography at the U.S. Geological Survey
laboratory in Salt Lake City, Utah.