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2008 AHR Page 2 <br />The general format of this report is the same as in previous years. <br />Surface Water <br />Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey (USGS) <br />at various locations. The closest location is Station No. 09095500, which is located upstream <br />approximately 7 miles north east of the mine site. Water quality and flow from this site are used <br />as a general representation of the Colorado River up gradient of the mining operation. There is <br />a diversion to the Government Highline Canal, the addition of Plateau Creek and the addition of <br />other minor drainages between the monitoring site and the mine site. Data Pages SQ-58 <br />through 60 includes information supplied by USGS on this site in 2008. The total flow at this <br />site for the Year was 3,484,000 acre-feet which is 126% of the normal average flow for the <br />period 1934 - 2008 (2,770,000). The estimated TDS load for the Year was 1.56 million tons. <br />This estimate is made using converting values for conductivity reported on page SQ-56 to TDS <br />per acre feet and multiplying by the monthly flow in acre feet. The low flow for the Year was <br />recorded as 1150 CFS on January 3, 2008. The river was carrying approximately 0.87 tons of <br />TDS per acre-foot on February 6, 2008, the closest data point. This flow and TDS load equates <br />to approximately 1,960 tons of Total Dissolved Solids, TDS, being carried by the river past the <br />mine that day. The mine discharge on January 11"' (the closest monthly analysis), was 285 @ <br />• 1233 mg/I TDS; resulting in approximately 2.11 tons of TDS being discharged. Comparing the <br />calculated TDS load in the River at low flow and the mine discharge near the same date, the <br />maximum increase in the River's TDS as a result of mine discharge would have been 0.11 %. <br />This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are included on <br />data pages SG-45, SH-27, and SI-27. Flow at SWGS-001 is presented graphically on data <br />page SG-46. At site SWGS-01, the stilling well was frozen 12/17/07 through 2/13/08. Water <br />dislocated the chart pen and the flume was plugged by debris from 5/21/08 to 5/30/08. The <br />flume was full and overflowing from 6/7/08 to 6/30/08 and the flume was full of sediment from <br />7/1/08 to 7/20/08. As usual, the flow in these Creeks is largely controlled by the City of <br />Palisade, depending upon their need for domestic water. Also, irrigation water is diverted from <br />the creeks by private water right holders at various locations. Table S08-1 was prepared to <br />show the average monthly flows during the primary irrigation season when low flow in the <br />creeks is critical. Gaps in information are explained above. Minimum recording levels of the <br />flumes are listed at the bottom of Table S08-1. <br />Monitoring on Coal Creek and Jerry Creek was started in 1995. The crest stage gages installed <br />in Coal Canyon drainage and Jerry Creek in 1996 were destroyed by a storm in the summer of <br />1998. Discussions with DMG have indicated there is no need to monitor the upstream locations <br />SWGS 07 and 09. The creeks will only be monitored at the lower monitoring points. The <br />• ephemeral flow in Coal Creek is measured at culverts located between the two refuse disposal <br />areas, SWGS 06. These culverts provide a stable cross section and are accessible throughout <br />the year. The intermittent flow in Jerry Creek is measured at the culvert near the Highline <br />Canal, SWGS 08. Beginning July 1999, instantaneous flows are to be monitored monthly. Data