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2006 AHR Page 2 <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-50 <br />through 53 includes information supplied by USGS on this site in 2006. The total flow at this <br />site for the Year was 2,627,000 acre-feet which is 95% of the normal average flow for the period <br />1934 -2006 (2,766,000). The estimated TDS load for the Year was 1.36 million tons. This <br />estimate is made using the values for dissolved solids reported on page SQ-52 times the <br />monthly flow in acre feet. The low flow for the Year was recorded as 1,350 CFS on December <br />11, 2005. The river was carrying approximately 0.84 tons of TDS per acre-foot on January 10, <br />2006, the closest data point. This flow and TDS load equates to approximately 2,303 tons of <br />Total Dissolved Solids, TDS, being carried by the river past the mine that day. The mine <br />discharge on January 5'" (the closest monthly analysis), was 282 @ 1204 mg/I TDS; resulting in <br />approximately 2.04 tons of TDS being discharged. Comparing the calculated TDS load in the <br />River at low flow and the mine discharge near the same date, the maximum increase in the <br />. River's TDS as a result of mine discharge would have been 0.09%. <br />This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are included on <br />data pages SG-41, SH-26, and SI-26. Flow at SWGS-001 is presented graphically on data <br />page SG-42. At site SWGS-01, the stilling well was frozen 12/08/05 through 12/29/05 and <br />01/12!06 through 01/30/06. The recording pen was knocked out of place by high water <br />05/05/06 through 05/16/06. The clock mechanism stopped working 07/13/06 through 07/30/06 <br />and the recording pen was out of ink 08/03/06 through 08/06/06. As usual, the flow in these <br />Creeks is largely controlled by the City of Palisade, depending upon their need for domestic <br />water. Also, irrigation water is diverted from the creeks by private water right holders at various <br />locations. Table S06-1 was prepared to show the average monthly flows during the primary <br />irrigation season when low flow in the creeks is critical. Gaps in information are explained <br />above. Minimum recording levels of the flumes are listed at the bottom of Table S06-1. <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 <br />taken during the Year are listed on data pages SR-3 for Coal Canyon and SS-3 for Jerry Creek. <br />