The benefit-cost analysis presented in this report identifies the primary activities affected by changes in water quality, namely, fishing. By estimating the recreational fishing value of the existing stock of rivers impacted by the cyanide dischargers, an approximation of the recreational loss sustained by changing the cyanide standard can be made. Although this analysis certainly does not include all possible benefits, it is considered a close approximation. Treatment costs for the discharger provide the balancing factor in determining feasible effluent levels.