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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT, Water Quality Control Division Rationale — Page 12, Permit No. C00036251 6. Salinity Regulations — In compliance with the Colorado River Salinity Standards and the Colorado Discharge Permit System Regulations, the permittee shall monitor for total dissolved solids on a Quarterly basis. Samples shall be taken at outfalls 001A, 001B, 002A, 002B and 002C. An evaluation of the discharge of total dissolved solids indicates that the Cotter Corporation facility does not exceed the threshold of 1 ton/day or 350 tons /year of salinity. To determine the TDS loading from this facility, the average reported TDS values were multiplied by the average flow, then by 8.34. The average was determined to be 0.083 tons /day for outfall 001A, and 0.07 tons /day for outfall 002A. At this time, Cotter Corporation is exempt from further requirements other than monitoring for TDS. 7. Stormwater — Pursuant to 5 CCR 1002- 61.3(2), active and inactive metal mining facilities are required to obtain permit coverage for discharges of stormwater associated with industrial activities from the facilities to state waters. The 4 renewal permit included both process water and stormwater provisions. For the 5 renewal stormwater provisions have been removed and the operator has obtained coverage in accordance with the CDPS General Permit for Stormwater Discharges Associated with Metal Mining Operations and Mine -Waste Remediation. The JD -7 Mine has coverage under Certification COR040259 and the JD -9 Mine has coverage under COR040260. 8. Economic Reasonableness Evaluation — Section 25- 8- 503(8) of the revised (June 1985) Colorado Water Quality Control Act required the Division to "determine whether or not any or all of the water quality standard based effluent limitations are reasonably related to the economic, environmental, public health and energy impacts to the public and affected persons, and are in furtherance of the policies set forth in sections 25 -8 -192 and 25 -8- 104." The Colorado Discharge Permit System Regulations, Regulation No. 61, further define this requirement under 61.11 and state: "Where economic, environmental, public health and energy impacts to the public and affected persons have been considered in the classifications and standards setting process, permits written to meet the standards may be presumed to have taken into consideration economic factors unless: a. A new permit is issued where the discharge was not in existence at the time of the classification and standards rulemaking, or b. In the case of a continuing discharge, additional information or factors have emerged that were not anticipated or considered at the time of the classification and standards rulemaking." The evaluation for this permit shows that the Water Quality Control Commission, during their proceedings to adopt the Classifications and Numeric Standards for Gunnison and Lower Dolores River Basins, considered economic reasonableness. Furthermore, this is not a new discharger and no new information has been presented regarding the classifications and standards. Therefore, the water quality standard -based effluent limitations of this permit are determined to be reasonably related to the economic, environmental, public health and energy impacts to the public and affected persons and are in furtherance of the policies set forth in Sections 25 -8 -102 and 104. If the permittee disagrees with this finding, pursuant to 61.11(b)(ii) of the Colorado Discharge Permit System Regulations, the permittee should submit all pertinent information to the Division during the public notice period.