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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale - Page 7. Permit No. CO-0032115. V. PERFORMANCE HISTORY 2. State Sampling: State sampling results for Trapper Mine are summarized in Table V-2 for the period of March, 1987 to the present. No violations were reported. Table V-2 - Summary of State Sampling Results Parameter Diach. Point Value No. of Samples Flow, MGD 002 0.09 1 Flow, MGD 005 0.06 1 TSS, mg/1 002 13 1 TSS, mg/1 005 12 1 T. Iron, mg/1 002 0.58 1 T. Iron, mgll 005 0.14 1 pH, s.u. 002 7,4 1 pH, s.u. 005 8.4 1 011 and Grease, mg11 002 None Visible 1 011 and Grease, mg/1 005 None Visible 1 B. Compliance with Terms and Conditions of Previous Permit A review of the information available to the Division has shown several permit violations for pH (see Data Summary, Table V-1 ). The permittee has determined that these violations, which occur during the summer, are due to algae blooms in the ponds, which can raise the pH. The permittee used an herbicide, Cutrine, for a short time, but discontinued its use at the Division's request due to the presence of copper in the compound. Since then, the permittee has installed C02 bubblers to lower the pH. This has worked for the moat part, but same violations still occur. Given that the elevated pH is due to the algae, and not the mining activities, this permit will allow a pH variance at discharge points 001, 002 and 005, from June through September, with the maximum allowable pH limit set at 9.S.s.u. The new limit is based on the maximum pH recorded by the permittee at these points while using a C02 bubbler. The use of a C02 bubbler on the effluent will be required as a Best Management Practice at the site whenever the variance is applied. Since the receiving streams are usually dry and do not have strict classifications, no impacts to water quality are expected from allowing the variance.