2020-03-24_PERMIT FILE - C1981019A ‎(5)‎

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 3/24/2020
• Type & Sequence: TR135
• Section_Exhibit Name: 2.04 Information on Environmental Resources
• Media Type: D
• Archive: Yes

RULE 2 PERMITS
Comparisons of mean values indicate that little difference exists between each program for similar
stations. These mean values show no significant differences except for the total suspended solids
data at Taylor Creek. Colowyo's data shows much lower mean values than does the USGS data.
This is due primarily to the greater number of samples taken by the USGS which included a greater
number of storm events and continuous measurements over these storm hydrographs. The USGS
data,in this case,is more appropriate as an absolute indicator of suspended solids values for Taylor
Creek.However,even though the absolute values are significantly different,the ratios between the
mean and the standard deviation are similarly large, reflecting the extreme natural variability of
these constituents.
Comparison of specific conductivity shows that little difference occurred in the data sets as a result
of different sampling regimes. In fact,the mean values all fall within the 95%confidence intervals
of the comparable study. Other water quality constituent levels remained similar to those collected
in the earlier periods.
As a further part of the EMRIA Program,Parker and Turk(1981)of the USGS used data collected
from Taylor Creek and Wilson Creek in a publication dealing with several watersheds in the larger
Yampa River Basin. This publication is included in its entirety in Exhibit 7A and is briefly
summarized here. They analyzed major and trace constituents in six streams in the Yampa River
drainage. The data revealed that overall stream chemistry was characterized by saturation of
common carbonate minerals such as calcium, magnesium, iron, manganese and lead. They also
determined that the solubility of the carbonate materials was a major control on the absolute and
relative concentrations of calcium, magnesium, iron, manganese and lead.
The mean concentrations in the semi-arid watersheds of Taylor Creek and Wilson Creek were
significantly higher than those from the more humid watersheds in the Upper Yampa River Basin.
Trace metals, however, were not significantly different as a function of climate or other variables.
The study also produced linear regression estimators useful in predicting total dissolved solids and
other major ion concentrations as a function of specific conductivity, which is more easily
measured.
Results of the linear regressions and statistical comparisons of the mean values showed that Taylor
Creek and Wilson Creek were different for the major concentrations. Goodspring Creek was not
included in the analysis because of its alluvial\colluvial valley floor characteristics. These
differences, however, are not inhibitory to the overall regression process and substantiate the
conclusion of highly variable water quality within the Colowyo Mine area.
The regressions are further valuable for future predictions of the major ions in each basin as a
function of possible mine disturbances. Specific conductivity measurements can be taken in the
field instead of exhaustive laboratory analysis and the major ions predicted with reliability.
The mean values of the main ions in the two watersheds showed that the major cations were
dominated by calcium, magnesium and sodium with low levels of potassium. Major anions were
dominated by bicarbonate and sulfate. Chloride levels were low in Taylor Creek, but were much
higher in Wilson Creek. Specific conductance was high. This information is in accordance with
past studies and substantiates all GVi1Glusiuiis made in pievious iepoiIs.
Rule 2 Permits 2.04-27 Revision Date: 12/20/19
Revision No.: TR-135