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<br />5.0 SURFACE WATER MIGRATION PATHWAY <br />The Rito Seco River flows through the Battle Mountain Gold San Luis Project permit area <br />Overland flow coming into contact with the reclaimed historic heap leach pad and the N~ ~`-- <br />current mine pits and waste rock areas enters the Rtto Seco River. Aqueous and <br />sediment samples were collected from the Rtto Seco River at locations upstream and <br />downstream of site operations. Sediment sample BM-SE-06/MHBS45 was collected from <br />the unnamed drainage pathway downstream of the mill/tailings facility (Figure 3). <br />Release Data <br />Surtace water samples collected from the Rtto Seco River indicate elevated levels of <br />aluminum, iron and manganese at locations downgradient of mining operations. The <br />aluminum concentration detected in Rito Seco water at station 8M-SW-03/MHCR73 is <br />greater than three times the concentration detected in sample BM-SW-01/MHCR71 <br />collected from upstream of site operations. tt is anomalous that sample BM-SW- <br />02/MHCR72 collected upstream of sample BM-SW-03/MHCR73 and downstream of site <br />operations did not contain aluminum at a concentration greater than three times the <br />adjusted background value (Table 1). Manganese and iron were also detected at <br />concentrations exceeding three times background concentrations in Aito Seco surface <br />water at locations downgradient of site operations. The iron conoerrtration reported for <br />sample BM-SW-03, 1,090 micrograms per liter (pg/L), exceeds the freshwater Aquatic <br />Water Ouality Criteria (AWQC/AALAC) of 1,000 pg/L for iron (SCDM, 1994). <br />Sediment samples collected from the Rito Seco and the unnamed drainage downgradierrt <br />of the mill-tailings faality did not contain elevated metals concentrations. <br />Cyanide was not detected in any of the aqueous or sediment samples collected during <br />this Sl. Previous detections of cyanide and mercury in Rito Seca River water <br />downgradient of site operations, as discussed in the SAP (MK, 1995), were not <br />reproduced with analysis of SI samples. <br />Targets <br />The Rtto Seco River bed contains a variety of wetland types downstream of the Barite <br />Mountain Gold operating permit boundary. Seasonally flooded, palustrine scrub-shrub <br />type wetlands occur along the Rtto Seco within and beyond the permit boundary (USDI, <br />1992}(Fgure 1). Recent beaver dam construction was noted along the Rito Seco channel <br />a~ml7suul•oermmnc - 6 - mR a mnw~ <br />