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• 2002 Annual Hydrologic Report Page 2 <br />Surface Water <br />Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey <br />(USGS) at various locations. The closest location is Station No. 09095500 which is located <br />upstream approximately 7 miles north east of the mine site. Water quality and flow from <br />this site are used as a general representation of the Colorado River up gradient of the <br />mining operation. There is a diversion to the Government Highline Canal, the addition of <br />Plateau Creek and the addition of other minor drainages between the monitoring site and <br />the mine site. Data Pages SQ-28 through 33 include information supplied by USGS on this <br />site in 2002. The total flow at this site for the Year was 1,268,000 acre-feet which is 45% <br />of the normal average flow for the period 1934 -2002 (2,799,000). The estimated TDS <br />load forthe Yearwas 1.0 million tons. This estimate is made using the values fordissolved <br />solids reported on page SQ-32 times the monthly flow in acre feet. The low flow for the <br />Year was recorded as 1,050 CFS on December 26, 2001 and again on January 26,2002. <br />The river was carrying approximately 0.97 tons of TDS per acre-foot on December 13`h <br />This flow and TDS load equates to approximately 2,002 tons of Total Dissolved Solids, <br />TDS, being carried by the river past the mine that day. Worst case mine discharges <br />• occurring on January 10, 2002 (the closest monthly analysis), were: 001 - 50 GPM @ 770 <br />mg/I TDS; 002 - 80 GPM @ 1500 mg/I TDS; resulting in approximately 0.95 tons of TDS <br />being discharged. Comparing the calculated TDS load in the River at low flow and the <br />mine discharge near the same date, the maximum increase in the River's TDS as a result <br />of mine discharge would have been 0.05%. <br />This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are <br />included on data pages SG-33, SH-25, and SI-25. Flow at SWGS-001 is presented <br />graphically on data page SG-34. As usual, the flow in these Creeks is largely controlled <br />by the City of Palisade, depending upon their need for domestic water, Also, irrigation <br />water is diverted from the creeks by private water right holders at various locations. Table <br />S02-1 was prepared to show the average monthly flows during the primary irrigation <br />season when low flow in the creeks is critical. Gaps in information are due to problems <br />with the recorder or flows below the minimum recording level of the recorder. Minimum <br />recording levels of the flumes are listed at the bottom of Table S02-1. <br />Monitoring on Coal Creek and Jerry Creek was started in 1995. The crest stage gages <br />installed in Goal Canyon drainage and Jerry Creek in 1996 were destroyed by a storm in <br />the summer of 1998. Discussions with DMG have indicated there is no need to monitor <br />• the upstream locations SWGS 07 and 09. The creeks will only be monitored at the lower <br />