Laserfiche WebLink
PowDERHORrr coAL coMPAx3t <br />• 1992 ANNUAL HYDROLOGIC REPORT <br />OCTOBER 1, 1991 THROUGH SEPTEMBER 30, 1992 <br />Introduction <br />Operations continued at Powderhorn's Roadside Mine and remained <br />idle at the Cameo No. 1 Mine during the 1992 hydrologic year (the <br />year). Production for the year was 285,954 clean tons. Most of <br />the hydrologic information since 1979 was input on a new <br />hydrology program in our Powder River Coal Company office. Many <br />of the tables and graphs in this AHR were generated by the <br />program. As with any new program some refinement may be made in <br />future reports. Unless otherwise noted, average values are <br />arithmatic averages rather than flow weighted averages. <br />Surface Water <br />For the sixth year in a row, the average flow in the Colorado <br />River at USGS station 09095500 was below the long term average. <br />The following is a listing of flows reported in past AHR's along <br />with current information. <br /> Total ~ of <br />Water Year Acre-feet 1934 - 1992 Ave <br />• 1934 - 1992 2,794,000 100$ <br />1984 5,521,000 198$ <br />1985 4,304,000 154$ <br />1986 4,156,000 149 <br />1987 2,596,000 93~ <br />1988 2,154,000 77$ <br />1989 1,859,000 67$ <br />1990 1,643,000 59$ <br />1991 2,174,000 78$ <br />1992 1,867,000 67~ <br />TDS Load <br />(million tons) <br />1.82 <br />1.62 <br />1.53 <br />1.34 <br />1.39 <br />1.42 <br />Also included in the list is an estimated TDS loading flowing <br />past the station each year as calculated in previous AHR's. This <br />number is calculated using the sum of monthly average <br />conductivity times total monthly flows divided by the total <br />annual flow to get a mass average conductivity. Using the <br />conductivity, total flow and a conductivity/TDS ratio of 1.43 the <br />approximate load is calculated. The conductivity/TDS ratio was <br />calculated in an earlier AHR. <br />All available Colorado River monitoring done by Powderhorn and <br />its predecessors was input into the hydrologic data base noted in <br />the Introduction. Tables 592-1 and 592-2 were prepared to show <br />statistical summary of previous monitoring. The "Censored Data" <br />is samples where the results were below the detection level of <br />. the lab. Diagrams 592-1 and 592-2 were prepared to show a <br />comparison between upper and lower Colorado River dissolved <br />