2005-04-08_GENERAL DOCUMENTS - C1980007

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bearing strata and the lack of transmissivity in the strata of the sequence. Generally, springs in the permit area seem to act independently of the bedrock water leasing zones and appear to be surface features related to weathered and fractured bedrock. Flow from these springs tend to be highly ephemeral and only discharge during spring snow melt. These springs recharge and dischazge in relatively small azeas. Inflows from faults and fractures located outside stream valleys generally dry up with time or flow intermittently at discrete points along the fault or fracture. Those which continue to flow have flow rates which diminish to a trickle. Such inflows may represent the dewatering of lenticular sandstone units with limited recharge areas, or may represent flows through fracture zones extending to the surface which have narrow recharge zones on steep slopes. Discharge of groundwater occurs through 83 seeps and springs located in the life-of--mine area. The locations of these springs can be found on Map 37 and 37A, Springs and Stock Ponds Location and Springs and Ponds c. Surface Water The North Fork of the Gunnison River is the major drainage for the mine area. Smaller streams in or adjacent to the life-of=-mine areas are all tributary to the North Fork. Figure 2 of this document contains the drainage map of the study area with the locations of streams and reservoirs which are described in the following discussion. The North Fork has an average annual streamflow at Somerset of approximately 313,500 acre-feet per year (1962-1979). The flow is regulated by the Paonia Reservoir on Muddy Creek five miles upstream of the town of Somerset. The reservoir became operational in 1962. Water yields during that period have ranged from a high of 601,800 acre feet per year in water year 1984, to a low of 82,270 acre feet in water year 1977. Flow records for the North Fork of the Gunnison River near Somerset are given in Table 1 of this document. Water quality parameters for the North Fork are given in Table 2 of this document. As indicated, water in the North Fork is a calcium bicazbonate type. There are also moderate levels of sulfate and salinity averages less than ] 00 mg/l. Raven Creek flows for approximately 2000 feet through the extreme northeast corner of the permit area. The stream and its riparian zone ate protected from undermining and subsidence by a buffer zone of 660 feet (1/8 mile) on either side of the stream, as stipulated in Lease COC-67011. Mining approved by PR-11 will terminate to the south of Raven Creek because of that buffer zone. 48