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there was no flow in lower Hamilton Creek at its confluence with Naturita Creek, <br />below where it received water from the proposed permit area. This indicates that <br />either the flow event was extremely short-lived, or that flow infiltrated prior to <br />reaching the confluence with Naturita Creek. <br />Except during infrequent high precipitation events, surface ntnoff within the permit <br />azea is insufficient to routinely mobilize constituents and transport them to receiving <br />waters. During an average yeaz, runoff from the site is calculated to contribute <br />between 13 and 69 tons/day dissolved constituents as TDS which may not, however, <br />actually enter Naturita Creek or the San Miguel River. Infiltration, evaporation, and <br />evapotranspiration will reduce runoff, sometimes to nothing. As an extreme <br />example, in the low flow year 1977, when the San Miguel River at Naturita had a <br />total flow of 1.6 cfs, it is possible that there was no flow from most or all of the <br />drainages into Naturita Creek, nor from Naturita Creek itself for an extended period <br />of time. In the case of a high precipitation event, the amount of dissolved <br />constituents carried from the site is expected to increase and the concentrations <br />decrease as a direct result of the increased volume of water after an initial flushing <br />effect. <br />Runoff volumes of the area being worked during mining activities are expected to <br />increase somewhat due to compaction by equipment and exposure of materials with <br />higher clay and silt content than that currently at the surface. This effect is expected <br />to be offset by low precipitation, minor ponding of precipitation in the working area, <br />retention of nmoff in the sediment ponds, evaporation and infiltration. Pit <br />dewatering was not required. TDS and other constituents of concern, sulfate in <br />pazticulaz, aze expected to have minimal or insignificant effect on the water quality <br />of the receiving waters as the volume of the runoff will be extremely low. No <br />material damage to receiving waters is expected. <br />Post-mining contours and revegetation are expected to reduce runoff and erosion <br />below current conditions, thereby reducing potential impacts after reclamation. This <br />reduction will result from increased infiltration and evapotranspiration due to <br />reduced rates of overland flow during higher precipitation and snowmelt events, and <br />increased vegetative cover. Surface water monitoring will adequately characterize <br />runoff quality and quantity so that changes, if any, will be detected and potential <br />impacts can be analyzed. <br />An analysis of Probable Hydrologic Consequences of the Hamilton Mine has been <br />supplied with the application, in accordance with Rule 2.05.6(3). Any impacts that <br />may occur are not expected to impact the hydrologic balance of the area. The <br />operations as proposed have been designed to prevent material damage to the <br />hydrologic balance outside the permit area. Appropriate measures are outlined in the <br />application to ensure protection of surface and ground waters in the permit and <br />adjacent areas from adverse effects due to the proposed mining operations. <br />IV. Topsoil <br />16 <br />