2020-06-26_GENERAL DOCUMENTS - C1981041

• Permit No: C1981041
• IBM Index Class Name: General Documents
• Doc Date: 6/26/2020
• Doc Name: Correspondence
• From: Law Offices of John R. Henderson, PC
• To: DRMS
• Email Name: CCW
• Email Name: JDM
• Media Type: D
• Archive: No

POWDi'RHORN COAL COMPANY
1992 ANNUAL HYDROIAGIC REPORT
OCTOBER 1, 1991 THROUGH SEPTEMBER 30, 1992
Introduction
Operations continued at Powderhorn's Roadside Mine and remained
idle at the Cameo No. 1 Mine during the 1992 hydrologic year (the
year). Production for the year was 285,954 clean tons. Most of
the hydrologic information since 1979 was input on a new
hydrology program in our Powder River Coal Company office. Many
of the tables and graphs in this AHR were generated by the
program. As with any new program some refinement may be made in
future reports. Unless otherwise noted, average values are
arithmatic averages rather than flow weighted averages.
Surface water
For the sixth year in a row, the average flow in the Colorado
River at USGS station 09095500 was below the long term average.
The following is a listing of flows reported in past AHR's along
with current information.
Also included in the list is an estimated TDS loading flowing
past the station each year as calculated in previous AH -R's. This
number is calculated using the sum of monthly average
conductivity times total monthly flows divided by the total
annual flow to get a mass average conductivity. Using the
conductivity, total flow and a conductivity/TDS ratio of 1.43 the
approximate load is calculated. The conductivity/TDS ratio was
calculated in an earlier AHR.
All available Colorado River monitoring done by Powderhorn and
its predecessors was input into the hydrologic data base noted in
the Introduction. Tables S92-1 and S92-2 were prepared to show
statistical summary of previous monitoring. The "Censored Data',
is samples where the results were below the detection level of
the lab. Diagrams S92-1 and S92-2 were prepared to show a
comparison between upper and lower Colorado River dissolved
VON 'AN.ARI VX I I I B IT I I
URMS Mt. #SL -I I
Total
% of
TDS Load
Water Year
Acre-feet
1934 - 1992 Ave
(million tons)
1934 - 1992
2,794,000
100%
1984
5,521,000
198%
1985
4,304,000
154%
1986
4,156,000
1491
1987
2,596,000
93%
1.82
1988
2,154,000
77%
1.62
1989
1,859,000
67%
1.53
1990
1,643,000
59%
1.34
1991
2,174,000
78%
1.39
1992
1,867,000
67%
1.42
Also included in the list is an estimated TDS loading flowing
past the station each year as calculated in previous AH -R's. This
number is calculated using the sum of monthly average
conductivity times total monthly flows divided by the total
annual flow to get a mass average conductivity. Using the
conductivity, total flow and a conductivity/TDS ratio of 1.43 the
approximate load is calculated. The conductivity/TDS ratio was
calculated in an earlier AHR.
All available Colorado River monitoring done by Powderhorn and
its predecessors was input into the hydrologic data base noted in
the Introduction. Tables S92-1 and S92-2 were prepared to show
statistical summary of previous monitoring. The "Censored Data',
is samples where the results were below the detection level of
the lab. Diagrams S92-1 and S92-2 were prepared to show a
comparison between upper and lower Colorado River dissolved
VON 'AN.ARI VX I I I B IT I I
URMS Mt. #SL -I I