WSP05652

• File Number: 8273.300
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - USGS
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1997
• Author: USGS
• Title: Interim Results of Quality-Control Sampling of Surface Water for the Upper Colorado River National Water - Quality Assessment Study Unit - Water Years 1995-96
• Water Supply Pro - Doc Type: Report/Study

STATE LINE
0 0 CONCURRENT REPLICATES
~ CAMEO 0
~ 6 SEQUENTIAL REPLICATES
~
DOTSERQ [}
[J) GUNNISON 0
LU AT 32 ROAD
....
Ui
(!) EAST 0 0
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::;; GORE 0
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BAKER

JFMAMJJASON
1995

1-1
Dl J F M A M J J A SON 01

1996

Figure 3. Distribution of collection of concurrent- and sequential-replicate sampies, 1995-96.

DATE

Concurrent and Sequential Replicates

Concurrent and sequential replicates differ
from the split replicates in that two separate samples
are collected from the river. In the conCUITent repli-
cate, one sample is collected concurrently wilh the
environmental sample using a second collection
team or second set of colleclion equipment. In the
sequential replicate. a replicate is collected as close
in lime as possible to the environmental sample. Each
sample is processed through all the normal steps of a
typical waler-quality sample. For each step of sample
processing. the environmental sample is processed
first. and then the replicate sample is processed. The
replicate samples arc processed using a clean filter
and equipment. The concurrent and sequential repli-
cales include all the potential sources for variation
as with the pre-processing split replicates as well
as the variation due to sample-collection technique
and short-tenn environmental variations in the river.
The distribution of collection of the concurrent and
sequenlial replicates by site and date is shown in
figure 3.
Seven concurrent- and three sequential-
replicate samples were collected during water
years 1995-96. The comparison of environmental
and concurrent-replicate samples and environmental

and sequential-replicate samples for general chemical,
nutrient. and organic carbon constituents is presented
in Ihe following sections. Concurrent- and sequential-
replicate data for trace elements are nol presented
because only one concurrenJ and no sequential repli-
cates for trace elements were collected.

Comparison of General Chemical Constituents

Results of comparison between environmenlal
and concurrent-replicate samples and between envi-
ronmental and sequenlial-replicate samples for general
chemical constituents are listed in lable 9. A summary
of the differences between thc environmental and the
concurrent-replicate samples for the constituents Iisled
in table 9 is given in table 10. The sequential-replicate
comparisons are not summarized because only three
samples are available. The majority of the differences
agree wilhin plus or minus Ilowesl rounding unit with
the exception of laboratory specific conductance and
residue on evaporation. The majority of the conduc-
tance differences agree within plus or minus 2 lowest
rounding unils. One-half of the differences for residue
on evaporation are within plus or minus 2 lowest
rounding units and probably indicate the precision of
the laboratory method. Shaded cells in table 'i repre-
senl differences greater than plus or minus I lowest

QUALITY-CONTROL SAMPLING PROGRAM 1S