WSP00398

• File Number: 8200.760
• Description: Yampa River General
• State: CO
• Basin: Yampa/White
• Water Division: 6
• Date: 4/1/1980
• Author: USGS
• Title: Analysis of Stream Quality in the Yampa River Basin - Colorado and Wyoming - 1980
• Water Supply Pro - Doc Type: Report/Study

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Table 6.--RegionaZ regression relationships for major inorgania constituents in streams
of the Yampa River basin, as oomputed from historio data

[Predicted variable, in milligrams per liter=a+b.(specific conductance-, in micromhos per
centimeter at 25.C); data from lorns, Hembree, Phoenix, and Oakland (1964)]

Standard Cerre-
Inter- error of lation
Predicted variable cept Slope estimate coeffi -.
(a) (b) of cient
predicted (d
variable
Calclum-------------- 7.06 0.0860 7.27 0.90
Magnesium3----------- -2.43 .0465 3.73 .91
Sodium--------------- -1.16 .0426 2.35 .92
Potassium------------ .197 .00758 .24 .97
Sodium and potassium3 -4.93 .0741 8.52 .86
Total hardness-----..- 7.84 .404 21. 1 .96
Bicarbonate---------- 14.6 .406 22.2 .95
Sulfate3------------- -13.0 .182 13.4 .92
Chlorlde3------------ -1.98 .0277 8.50 .51
Calculated dissolved
sollds------------- 4.48 .586 5.81 .99
Measured dissolved
solids------------- 7.35 .628 10.0 .99
Nltrate-N4----------- s .104 6 .0927
Sillca4-------------- 511. 3 64.64

Number
of data
pai rs 1

62
62
14
3
57

62
96
87
73

5

35
57
55

Range of specific
conductance2
(micromhos per
centimeter at 25.C)

Minimum Maximum
20 831
20 831 .
59 219
116 308
20 831
20 831
17 831
17 831
17 229.
59 308

39
20
20

831
831
831

IOata for 96 samples collected at 34 sites were used in this analysis.
2Range of specific-conductance values for analyses used to determine the regression
equation.
30ue to randomness of the data, appl ication of the equation at the .lower-end of the
specific-conductance range may result in negative estimates for the predicted variable.
4The alternative model, predicted value = mean ,value, is given because of small
values of r.
sMean.
6Standard deviation.

Simulation results for annual mean discharge-weighted concentrations of
dissolved solids for the Yampa River near Maybel1 were almost identical using
the three equations (regional, and site-specific for 1951-75 and 1966-72)
appl icable to this site (fig. 5). Moreover, the fit to the observed .values
used here is good through 1970 (fig. 5). (The term "observed values" is used
here to describe annual mean discharge-weighted concentrations calculated
from measurements of dissolved solids and stream discharge.) Deviations
since 1970 may be attributed largely to changing from composited to monthly
samples for determining annual mean concentrations.

Agreement among the
observed data generally is
as for dissolved sol ids.

three applicable equations and the fit to the
not as good for individual chemical constituents
This is exempl ified by the observed and simulated

27