REP38458 - Laserfiche WebLink

Home Browse Search

PowDERHORN COAL COMPANY 1990 ANNUAL HYDROLOGIC REPORT OCTOBER 1, 1989 THROIIGH SEPTEMBER 30, 1990 INTRODUCTION Operations continued at Powderhorn's Roadside Mine during the 1990 water year with a production of 187,493 clean tons. The Cameo No. 1 Mine was idle during this period. There were no changes in hydrologic monitoring methods during the year. SIIRFACE WATER For the fourth year in a row the total flow in the Colorado River was below the normal. The following is flow in the river for the past 5 years as recorded by the USGS at station 09095500 which is located a couple of miles up stream from the mines: Water Year Total Acre-feet $ of 1933-1988 Ave. 1933-1988 2,860,000 100$ 1986 ¢ .9", 156, 000 320$ 1987 2,596,000 91$ 1988 2,154,000 75$ • 1989 1,859,000 65$ 1990 1,643,000 57$ Approximately 1.34 million tons of dissolved solids flowed past this USGS station during the 1990 water year. This figure was calculated using the monthly mass average conductance of 860 umhos/cm and a conductance/TDS ratio of 1.43 calculated for the river in an earlier AHR. Measured flows in Cottonwood Creek and Rapid Creek were also lower than normal. Monitoring continued this year with Steven's recorders on Parshall fl-~uaes. Tables 590-1 through 590-8 were prepared using an average of 4 evenly spaced readings from the charts each day. The low limits of recording on each of the flumes was even more obvious this year than last. SWGS-02 flow was below recordable limi*_s from mid-June through Sep*_embe'r with part of that time being dry. SWGS-03 flow was below recordable limits starting before the recorder was installed in May through September with much of the summer being dry. SWGS-01 flow was below the recording limit approximately half of the summer. A good representation of the lower flow this year than in previous years was the peak runoff in SWGS-01 of 5.30 CFS compared to 25-70 CFS peaks measured during the previous 5 years. •