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II. Hydrologic Balance -Rule 4.05 A) Water Quality Standazds and Effluent Limitations The Colorado Water Quality Control Commission has assigned classifications to the main stem of Thompson Creek and its tributaries. Thompson Creek is described as from the headwaters to the confluence with the Crystal River. Tributazies include North, Middle and South Thompson Creeks. The classification is Aquatic Life Cold 1, Recreation 2, Water Supply and Agriculture. Receiving Stream Standazds have been established by the Colorado Department of Public Health and Environment (CDPHE). The CDPHE has issued a Colorado Dischazge Permit System (CDPS) permit to Minrec, Inc for surface runoff and mine water discharges from the North Thompson Creek Mines [Rule 4.05.1(3)]. The current CDPS permit has no application to runoff from reclaimed disturbed azeas at the loadout site. The Colorado Water Quality Control Commission has also established basic standazds for ground water. B) Sedimentation Ponds Sediment ponds aze no longer required to treat runoff from areas of surface disturbance. Areas of disturbance have been reclaimed and runoff from them has been determined to meet effluent requirements, or the areas of disturbance and associated watersheds aze so small that other control procedures than sediment ponds were/aze employed [Rule 4.05.2(1)]. In 1992, the Division granted an exemption from the use of a number of sediment ponds for sediment control. This exemption was granted after the operator demonstrated that the vegetation on the reclaimed mine site was sufficient to reduce to compliance limits the sediment levels in disturbed area runoff. A Partial Phase II Bond Release was approved by the Division in November of 2001 for the greater portions of the mine site and all of the loadout site, and sedimentation ponds were no longer required. Two former sedimentation ponds were retained as described under Impoundments below. C) Impoundments Impoundments currently on the mine site include three treatment ponds for mine water discharges, the former sedimentation pond P-9 that has been perntted to used either as a portion of the water treahnent system or as a stock pond, and the former Refuse Area Sedimentation Pond, that has been permitted to be retained as a stock pond. There aze no impoundments located at the loadout site. D) Surface and Ground Water Monitoring 1. Surface Water Monitoring North Thompson Creek water quality is monitored within, above, and below the mine site. The results ofmonitoring aze presented below in the discussion on probable impacts 14