WSP04065

• File Number: 8200.100.10
• Description: Colorado River Basin - Description - Meteorologic-Climate Data
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1997
• Author: USGS
• Title: Precipitation-Chemistry Data at Selected Sites in Northwestern Colorado - 1980-1994
• Water Supply Pro - Doc Type: Report/Study

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Colorado, using methods described in Fishman and
Friedman (1989), After May 1991, samples were
filtered through O.45-micrometer filters, Aliquots for
cations were preserved with concentrated nitric acid,
whereas aliquots for ammonium were preserved with
mercuric chloride. The chemical data were checked
using cation:anion balances and comparisons of
measured and calculated specific conductance.
Alkalinity was not measured because pH typically was
low enough to make alkalinity minimal, The buckets
used to collect precipitation were cleaned by
scrubbing with a nylon brush and rinsing with
deionized water. Bias and precision data for the
chemical analysis done at the V.S, Geological Survey
National Water-Quality Laboratory are published
yearly in V,S, Geological Survey Water-Resources
Investigations reports (peart and Sutphin, 1987; Lucey

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and Peart, 1988; Lucey and Peart, 1989a, 1989b,
1989c; Maloney and others 1992, 1993, 1994).

RESULTS OF PRECIPITATION VOLUMES
AND CHEMICAL CONCENTRATIONS

Specific conductance, precipitation chemical
concentrations, and calculated charge balance are
presented in tables 1,3, and 5, Daily precipitation
volumes are reported in tables 7...J}. Summary statis-
tics (tables 2, 4, and 6) of specific conductance and
chemical concentrations (means, medians, standard
deviations, and minimum and maximum values)
follow each data table, Seasonal variations ofprecipi-
tation chemistry at each site are shown in the box plots
in figures 2-10.

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MR . Marvin. Ranch
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INTERQUARTILE RANGE (THE
INTERQUARTlLE RANGE IS THE
DISTANCE BETWEEN THE 26TH AND THE
75TH PERCENTILE)
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76TH PERCENTILE
MEDIAN
215TH PERCENTILE
Ui TIMES THE INTERQUARTlLE RANGE

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SEASON

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Figure 2. Seasonal variability 01 hydrogen-ion concentration.

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RESULTS OF PRECIPITATION VOLUMES AND CHEMICAL CONCENTRATIONS 3

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