REP29181 - Laserfiche WebLink

Home Browse Search

• the creek between TR-B and TR-D have also become marshes due to numerous beaver dams. Periodically, this general pattern is interrupted, as occurred in 1986, 1988, 1991, 1993 and 1995. The "spikes" in TSS levels during these years appear to be related to peak flow conditions along the creek. The 1986 and 1988 occurrences are probably residual effects of the initial channel restabilization while the latter years reflect high peak flows. Specific Conductivity Specific conductivity levels (Figure 5) from September 1992 through the end of the report period were similar to values obtained prior to October 1990. Data taken between October 1990 and August 1992 are believed to be invalid due to instrument errors. All four sites exhibited a marked increase in specific conductivity for the October 1990 and August-October 1991 readings. TDS values obtained during these same periods do not reflect the increases, therefore it is believed that the data excursions can be attributed to errors with the instrumentation rather than a reflection of actual field • conditions. After the October 1990 reading, the equipment was repaired and used until July 1991, when a mechanical malfunction required switching to alternate instrumentation. It is believed that the alternate equipment was improperly calibrated or defective, resulting in inaccurate readings. New field equipment has been used since September 1992 along with laboratory verification. The values shown in Figure 5 from 1992 through 1999 are the laboratory values. Since the field values and laboratory values have been in close agreement since 1992, values provided beginning in 1995 are field values. Total Dissolved Solids Total Dissolved Solids (TDS) concentrations (Figure 6) in Trout Creek exhibit an expected pattern. As stream flow passes the mine, TDS levels increase while adjacent to the mined areas and then begin to decline downstream due to inflow from undisturbed lands below the active mine. Peak TDS levels in Trout Creek occur in early spring prior to the period of peak flow. This is caused by the uptake of dissolved solids during the spring runoff from the portion of the watershed in which the Edna Mine is located. • Although TDS concentrations in the mine runoff may be quite high when compared to concentrations occurring above the mine, the mine runoff is small relative 9