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2007 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-54 <br />through 57 includes information supplied by USGS on this site in 2007. The total flow at this <br />site for the Year was 2,333,000 acre-feet which is 85% of the normal average flow for the period <br />1934 - 2007 (2,760,000). The estimated TDS load for the Year was 1.48 million tons. This <br />estimate is made using the values for dissolved solids reported on page SQ-56 times the <br />monthly flow in acre feet. The low flow for the Year was recorded as 1020 CFS on January 17, <br />2007. The river was carrying approximately 0.87 tons of TDS per acre-foot on February 15, <br />2007, the closest data point. This flow and TDS load equates to approximately 1,760 tons of <br />Total Dissolved Solids, TDS, being carried by the river past the mine that day. The mine <br />discharge on January 10`h (the closest monthly analysis), was 280 @ 1043 mg/I TDS; resulting <br />in approximately 1.75 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 0.10%. <br />This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are included on <br />data .pages SG-43, SH-27, and SI-27. Flow at SWGS-001 is presented graphically on data <br />page SG-44. At site SWGS-01, the stilling well was frozen 1/08/07 through 2/15/07. The clock <br />mechanism stopped working 12/4/06 through 12/18/06. As usual, the flow in these Creeks is <br />largely controlled by the City of Palisade, depending upon their need for domestic water. Also, <br />irrigation water is diverted from the creeks by private water right holders at various locations. <br />Table S07-1 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 explained above. <br />Minimum recording levels of the flumes are listed at the bottom of Table S07-1. <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 />