Laserfiche WebLink
3.0 Surface Water <br />As previously mentioned, Trout Creek is monitored for water quality at sites TR-A, <br />TR-B, TR-C and TR-D and for flow at sites TR-a and TR-b. The following section discusses <br />quantity and quality of surface water at the Edna Mine. <br />3.1 Gauging Stations <br />Chart 1 shows the continuous streamflow records for Trout Creek at TR-a and TR-b. <br />The flow measurements along Trout Creek indicate that the monitoring program is being <br />placed on-line early enough in the year to record flow prior to the peak runoff period for each <br />year. The individual data points show the monthly average flows and give some indication of <br />the variability between mild winters (winters of less snow accumulation) and harsh winters. <br />The streamflow during 2007 slightly decreased from the previous year. The chart indicates <br />that 2007 was an average/mild winter for the past two decades. <br />The flow record for 2007 shows a peak flow to have occurred in May. The peak flow <br />historically occurs in either May or June. The runoff from the mine site was lower in 2007 <br />than the majority of previous years probably due to less snowpack on the mine site and the on- <br />set of warmer temperatures occurring earlier in the spring. <br />The flow data presented in Chart 1 consists only of information derived from <br />continuous flow records. Instantaneous flow measurements obtained between 1989 and June <br />1994 for TR-b are provided in Table 1. Prior to 1994, instability of the stream channel caused <br />by a 1984 flood precluded the installation of any type of monitoring station in the vicinity of <br />TR-b. The Stevens chart recorders were replaced with electronic streamflow recorders in <br />Apri12003. <br />The bridge located immediately downstream of TR-a was replaced in the fall of 2001 <br />potentially altering the stage rating curve. Therefore, the decision was made to update the <br />stage/discharge curves for TR-a and TR-b. Over the 2001 season, a total of nine cross-sections <br />and associated velocities were measured at each cross section location. This data was used to <br />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 <br />cfs. The curve equation and rz for the curve are as follows: y = 44.469x3.zao6~ where y =flow <br />in cfs and x =depth of flow; rz = 0.98. Flows for July and August of 2007 were below the 11 <br />cfs used to develop the rating curve; therefore, this calculated flow may to be low. <br />The stage rating curve for TR-b was developed from flows ranging from 13 cfs to 144 <br />cfs. The curve equation and rz for the curve are as follows: y = 65.049xz.431, where y =flow in <br />cfs and x =depth of flow; rz = 0.99. Flows for July, August September and October of 2007 <br />were below the 13 cfs used to develop the rating curve; therefore, these calculated flows may <br />to be low. This stream flow data appears to indicate a good correlation between the upstream <br />2 <br />