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results of the gauging stations along Trout Creek indicate that the monitoring program is being placed on-line eazly enough <br />in the year to record flow prior to the peak runoff period for each year. The individual data points show the monthly average <br />flows and give some indication of the variability between mild winters (winters of less snow accumulation) and harsh <br />winters. The graph showing 2003-2005 data indicates a decrease in total streamflow in 2005 from 2003 and consistent <br />values when compared with 2002 levels. The 1996-2005 graph suggests that 2005 was a mild winter for the past decade. <br />The flow record for 2005 shows a peak flow to have occurred in May as it did during 1996, 2000, 2001 and 2004. <br />The runoff from the mine site was lower in 2005 than in previous years due to less snowpack on the mine site and the on-set <br />of warmer temperatures occurring earlier in the spring. The flow data presented in Figure 1 consists only of information <br />derived from continuous flow records. Instantaneous flow measurements obtained between 1989 and June 1994 for this <br />location are provided in Appendix A, Prior to that time, instability of the stream channel caused by a (984 flood precluded <br />the installation of any type of monitoring station in the vicinity. The old Stevens chart recorders were replaced with <br />electronic streamflow recorders in Apri12003. <br />The bridge located immediately downstream of TR-a was replaced in the fall of 2001 potentially altering the current <br />stage rating curve. Therefore, the decision was made to update the stage/discharge curves for TR-a and TR-b. Over the 2001 <br />season, a total of nine cross-sections and associated velocities were measured at each cross section location. This data was <br />used to compute a stage rating curve at each location. <br />The stage rating curve For TR-a was developed from flows ranging from 11 cfs to 145 cfs. The curve equation and <br />rz for the curve are as follows: y = 44.469x3.zxoe where y =flow in cfs and x =depth of flow; r2 = 0.98. Flows for July and <br />August of 2005 were below the 1 l cfs used to develop the rating curve; therefore, these calculated flows may to be low. <br />The stage rating curve for TR-b was developed from flows ranging from 13 cfs to 144 cfs. The curve equation and <br />rz For the curve are as Follows: y = 65.049xz.asi where y =flow in cfs and x =depth of flow; r2 = 0.99. Flows for August of <br />2005 were below the 13 cfs used [o develop the rating curve; therefore, this calculated flow may [o be low. This data <br />appears to indicate a good correlation between the upstream and downstream flows along Trout Creek. A channel cross- <br />section was developed using survey results that verifies streambed stability (Drawing 1). This cross-section is provided in <br />Appendix A. <br />Irrigation ditch flow observations were made in April, May, June, July, August and October of 2005. The TR-A <br />site was observed with flow except for October 20, 2005. Flow observations are provided in tabular format in Appendix A. <br />NPDES MONITORING <br />Monitoring of point discharges from sedimentation impoundments is accomplished under Colorado Department of <br />Public Health and Environment Colorado Permit Discharge System Permit CO-0032638. Copies of required Discharge <br />Monitoring Reports are provided to the Division of Minerals and Geology under sepazate cover, and are included in this <br />report by reference. <br />2 <br />