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• 2005 AHR Page 2 Surface Water Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey (USGS) at various locations. The closest location is Station No. 09095500 which is located upstream approximately 7 miles north east of the mine site. Water quality and flow from this site are used as a general representation of the Colorado River up gradient of the mining operation. There is a diversion to the Government Highline Canal, the addition of Plateau Creek and the addition of other minor drainages between the monitoring site and the mine site. Data Pages SQ-43 through 49 includes information supplied by USGS on this site in 2005. The total flow at this site for the Year was 2,566,000 acre-feet which is 93% of the normal average flow for the period 1934 -2005 (2,768,000). The estimated TDS load for the Year was 1.19 million tons. This estimate is made using the values for dissolved solids reported on page SQ-41 times the monthly flow in acre feet. The low flow for the Year was recorded as 1,050 CFS on December 24 & 25, 2004. The river was carrying approximately 0.93 tons of TDS per acre-foot on December 24'" & 25"'. This flow and TDS load equates to approximately 1,937 tons of Total Dissolved Solids, TDS, being carried by the river past the mine that day. The mine discharge on January 5"' (the closest monthly analysis), was 295 @ 1420 mg/I TDS; resulting in approximately 2.52 tons of TDS being discharged. Comparing the calculated TDS load in the River at low flow and the mine discharge near the same date, the maximum increase in the • River's TDS as a result of mine discharge would have been 0.13%. This Year's mean daily flow values for the Cottonwood and Rapid Creek flumes are included on data pages SG-39, SH-26, and SI-26. Flow at SWGS-001 is presented graphically on data page SG-40. In early November 2004 the timing mechanism on the chart recorder at SWGS- 001 malfunctioned. The unit was replaced on December 16, 2004. Due to high runoff in June 2005, water overtopped SWGS-001 and washed out around the flume. It was repaired July 18, 2005. As usual, the flow in these Creeks is largely controlled by the City of Palisade, depending upon their need for domestic water. Also, irrigation water is diverted from the creeks by private water right holders at various locations. Table S05-1 was prepared to show the average monthly flows during the primary irrigation season when low flow in the creeks is critical. Gaps in information are due to problems with the recorder or flows below the minimum recording level of the recorder. Minimum recording levels of the flumes are listed at the bottom of Table S05-1. Monitoring on Coal Creek and Jerry Creek was started in 1995. The crest stage gages installed in Coal Canyon drainage and Jerry Creek in 1996 were destroyed by a storm in the summer of 1998. Discussions with DMG have indicated there is no need to monitor the upstream locations SWGS 07 and 09. The creeks will only be monitored at the lower monitoring points. The ephemeral flow in Coal Creek is measured at culverts located between the two refuse disposal areas, SWGS 06. These culverts provide a stable cross section and are accessible throughout • the year. The intermittent flow in Jerry Creek is measured at the culvert near the Highline Canal, SWGS O8. Beginning July 1999, instantaneous flows are to be monitored monthly. Data taken during the Year are listed on data pages SR-2 for Coal Canyon and SS-2 for Jerry Creek.