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populotions indicate a slightly different trend. It appears that although the salmonids <br />• (trout) may have been affected by the mine in the past, effects are very loco) and <br />recovery is rapid downstream. Table 2.7-23 indicates o general improvement in the <br />salmonid population in the vicinity of the Edna Mine over the post four years. <br />Standing crops at the upper stations (Station I and 2) hove more Than doubled, witha <br />shift from predominately Rainbow Trout to Brown Trout. Brook Trout are important <br />only at the upper station. Trout appear to be extending their range downstream in <br />Trout Creek. As seen in Toble 2.7-23, trout were uncommon at Station 3 and absent <br />from Station 4 in 1975 and 1976. However, in 1979 a healthy trout population <br />occurred at Station 3, and Brown Trout were present at Station 4. <br />Goettle and Edde (1980) stated that the results of their study in 1975 and 1976 <br />did not indicate any direct effects of mining operations on the distribution of fish <br />in Trout Creek. However, they felt possible effects may have been masked by <br />changes in the following: <br />• Elevation <br />• Stream flow due to irrigation water withdrawal <br />• Higher water temperatures as a result of agricultural irrigation return <br />flows <br />• • Sirea mbank cover as a result of moving out of the canyon (predominately <br />pine forest) near Station) into the more open areas dominated by willow <br />• Livestock grazing -from Station I downstream grazing by cattle and sheep <br />increase to where at Station 4 streamside vegetation is severely reduced <br />and sloughing of streambanks is common <br />• Sireambed alterations occurring during spring runoff <br />• Presence of numerous beaver dams. This has the effect of segmenting the <br />stream into small units, especially during the fall. As seen in Table 2.7- <br />23, Brown Trout are The dominant salmonid. This species spawns in the <br />fall, and may be adversely effected by restricted movements during their <br />spawning season. <br />Canton and Ward (1978) concluded that The presence of a buffer zone of <br />unmined land between the stream and The mine spoils mitigated the majority of <br />impacts of the mine on the stream. Chemical evidence pointed to the fact that <br />many parameters exhibited higher values as they left the mine spoils than when they <br />• entered the stream (Skogerboe et al., 1979). It was also pointed out that much of <br />the degraded water quality occurs during spring runoff and that the invertebrates in <br />Revised 7-81 2.7-67 <br />