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of grasses at 25% each, if a conservative case is chosen and an assumption made that the salt tolerance for red top is about the same as the least tolerant of those three, a slightly higher overall tolerance would be effective, but for this analysis, the most conservative number will be used to create a limiting value. Assuming that the maximum "limiting" value for TDS is 467 mg/I to avoid material damage, a calculation must be made of the degree ofdilution of the mine effluentwater (from CDPS Point 007) by water from Trout Creek. For this evaluation, flows and concentrations aze used that appeaz representative over the last several yeazs. Using a flow from monitoringpoint 007 of 10 cfs with aTDS concentrationof-3600 mg/1, (typical May/June values) a flow at Trout Creek above the Mine of 152 cfs with 100 mg/1 total dissolved salts, the dilution required to render the total imgation water below the limiting value, can be calculated. X (x concentration in Trout Creek) + (1-~ x (conc. aJ 007) = 467 mg/1 X (100 mg/l) + (1 - X) x (3600 mg/1) = 467 mg/1 yielding a value of 0.895 for X. So 90% of the irrigation water in May must come from an upstream source on Trout Creek to dilute Edna Mine effluent at the 007 dischazge point from its measured level of 3600 mg/1 to 467 mg/I - the limiting value to avoid material damage. In May ] 996, the flow from discharge point 007 was 0 cfs. So a volume equal to 90 cfs would be required to obtain sufficient dilution, more than half the measured flow of Trout Creek upstream of the Edna Mine and more than the total water allotment P&M has on Trout Creek. Subirrigation by groundwater within the Trout Creek alluvium is also suspect for creating material damage. Groundwater is monitored right now in the alluvium upgradient from the mine (TR 1.5), adjacent to the mine (TR 3 and 4) and within the West Ridge spoils aquifer (WR-1). Groundwater in the Trout Creek alluvium adjacent to the mine has, to this point, varied between 300 and 600 mg/l TDS, a concentration consistentwith groundwaterin the area. The spoils aquifer, measured in WR- 1 is, of course, considerably higher, measuring with reasonable consistency azound 4000 mg/1 TDS. Potential concerns arise, however, when analyses from the upgradient well aze considered. For yeazs the concentration of TDS at well TR 1.5 ranged the same as the other Trout Creek alluvial wells - as low as 200 some yeazs up to >] 000 in the early 1990s. In the last several years, however, the level of salts has risen to >2000 mgll and stayed there for several years. It has been assumed that dilution from upgradient would mitigate by dilution the impact of the groundwater from the spoils. However, that effect will be much less with the diluting groundwater carrying more than 2000 mgfl TDS itself The potential for material damage by such high-TDS water in the subsurface is also real. A conclusion is reached that surface imgation of the Trout Creek alluvial valley floor in Sections Ed~u Mine 29 Parmi~ Renewal No. 3