The City of Las Cruces is concerned about water quality in a reach
of the Rio Grande that receives outfall from the City of Las Cruces
wastewater-treatment plant. Water-quality samples were collected from
the Rio Grande at Picacho Bridge near Las Cruces, New Mexico; from the
sampling site at the City of Las Cruces wastewater-treatment plant; and
from the Rio Grande at Calle del Norte Bridge near Mesilla, New Mexico.
The samples were collected on 12 days from August 6, 1996, to February
28, 1997, and were analyzed for a suite of dissolved and total constituents
including trace metals. Instantaneous stream discharge was measured
concurrently with collection of the Rio Grande samples. At the wastewater-
treatment plant, the City of Las Cruces provided instantaneous discharge
rates concurrent with sampling. Quality-control measures used in this study
to ensure analytical accuracy included replicate sampling, replicate
analysis of split samples, ambient blanks, equipment blanks, and analysis
of standard reference water samples.