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COLORADO DEPARTMENT OF PUBLIC HEALTH & ENVIRONMENT -Water Quality Control Division Rationale -Page 17 Permit No. COR-040000 VII. CHANGES AFTER PUBLIC NOTICE (cont.) stormwater discharges associated with mining activity still occur, the owner or operator is still responsible for the continued (albeit reduced) delivery of pollutants to the stream. 2. The differentiation between stormwater and process water at a mine or mill site. One commentor requested that the Rationale 6e expanded to make clear which sources of water at a mine site are stormwater (covered by this permit) and which sources are process water" (not covered by this permit). Response: "Process water" is a term used 6y the Division to refer to waters which when discharged, are required to have conventional permits with numeric effluent limits. These include wastewaters that were generated or used in an industrial process, or domestic wastewater. They also include mine drainage and many other sources of water from speciftc industrial categories that are defined and set fonh in federal regulatiars (40 CFR subchapter N). Several sources ofprecipitation-induced runoff from active mine sites are included in the 40 CFR, subchapter N, parr 440, Effluent Limitation Guidelines. The confusion benveen stormwater and process water at mine sites arises because the regulatory defini[ions overlap somewhat. Currently, this overlap is addressed in a Division Policy document "Definition of Process Water and Stormwater at Nan-Coal Mining Sites (policy number WQP-17). " Since this overlap in definitions is also a subject of currerst nntiowl litigation, the Division 6etieves that the policy document is the appropriate place for the lengthy discussion. This policy is available from the Division. 3. Exemptions from permittine or termination criteria: Several commentors requested that exemptions of one kind or another be included in the general permit. Two commentors questioned the assertion that srormwater discharges from inactive mines contribute to water quality problems, specifically in San Juan Coursry. A few commentors asked for an exclusion from permit requirements if it can be demonstrated that the exposed material would not be expected to degrade water quality. One commentor requested exemption from permit requirements if the mirse has been inactive since 1973 and the site is less than 2 acres. Response: Essentially, the Division is unable to grant exemptions to permitting requirements in a permit document. The federal and state rules (40 CFR 122.26 and S CCR 1002-2, § 6.4.2, respectively) set out which circumstances and which activities require permit coverage. Permits are lower in the regulatory hierarchy than rules, and cannot gram an exemption which is in conflict with rules. Exemptions would require a rules change at both the federal and stare levels, as the state rule primarily repeats the federal rule. Change in the state rule alone is limited to being no less stringent than federal rules. Reeardine the stormwmer contributions to water quality problems in San Juan Countv: Contrary to the assertion that there is no evidence that stormwater discharges from mine workt'ngs comribute to the water quality problems in San Juan County, information supports the conclusion that these sources are significant. Analysis of water quality data in the Upper Animas River basin by the Division had shown that precipitation- induced runoff from inactive mine/mil! sites is a significant part of the zinc loading in the Animas River. The contribution from these San Juan County sites appears to be most acute during the early spring snow-melt flush. The data were generated by monitoring water quality above and below individual sites, as well as extensive data collected by the Colorado River Watch Program on Cement Creek, Mineral Creek and the Upper Animas River. In addition, an unpublished PhD dissertation concluded that the majority of zinc loading in the Cement Creek watershed is contributed by old mine waste dumps (Caruso, 1995). Cement Creek has no aquatic life due in part to the toxic levels of zinc. Reeardine an exemption for uncomaminated stormwater: The regulations state that permits are required fora "...mining operatiou....that discharge stormwater contaminated by contact with or that has come into contact with, anv overburden, raw material, imermediate products, finished products, byproducts or waste products located on the site... (5 CCR 1002-2 § 6.4.2(5)(c)(iii)) (emphasis added). However, after further