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combination with localized intensive "flood-type" irrigation, travels laterally through the shallow <br /> soils and fractured sandstone eventually flowing back into the West Lateral slightly downstream. <br /> The combination of fractured, weathered sandstone channel bottoms in the ditch and localized <br /> "flood-type" irrigation along these two gaining reaches likely resulted in the measured gains in <br /> flow. <br /> Flows in Calamity Draw, which is roughly parallel to the southern boundary of NHM, generally <br /> reflect local irrigation practices. Water from the West Lateral Ditch's return irrigation flow is its <br /> primary source. Very little supplemental flow is derived from precipitation and snowmelt runoff. <br /> In 1987, measured flow rates in Calamity Draw varied from 0.605 cfs in April to 13.4 cfs in July. <br /> Flow in Calamity Draw varied from 1.04 to 2.06 cfs during the non-irrigation period. Shallow <br /> ground water alluvial sources provide a large portion of this low flow period's water. This ground <br /> water flow is related to local irrigation practices but is consolidated into a more uniform and regular <br /> flow by the permeability of these near surface alluvial deposits. The drainage system at the NHM <br /> site has been designed to provide adequate capacity and storage times to completely collect all <br /> runoff from the mine site and should actually lower present total suspended solids (TSS) <br /> contribution from this area over the life of the mine. Increased TDS levels in this water from <br /> mining disturbances are expected, but are projected to be within acceptable discharge levels and <br /> will be mitigated by dilution. Regular monitoring of these flow rates and water quality will give <br /> adequate control of this current water source to protect water quality in Calamity Draw. The <br /> discharges from the mine enter Calamity Draw at a point about 2.5 miles above the confluence of <br /> Calamity Draw and the San Miguel River. <br /> The above-mentioned parks consist of recent undifferentiated aeolian silts and sands overlaying <br /> the Dakota and Burro Canyon Formations. The perennial flow nature of both Tuttle and Calamity <br /> Draws is largely due to the local irrigation practices. Over the years, this more or less constant <br /> source of water in these drainage systems has encouraged the growth of vegetation. This has <br /> resulted in the channels becoming more erosionally stable but more incised. <br /> Surface water monitoring practices and frequencies are described within the permit application. <br /> Also see Findings Section B, Item II E, of this document for a summary of surface and ground <br /> water monitoring practices to which ERMR has committed. <br /> D. Ground Water <br /> The NHM lies in a ground water basin defined by the Nucla Syncline. This broad northwest <br /> trending syncline is recharged along the Uncompahgre uplift to the northeast and discharges <br /> southwest toward the major rivers flowing through the area. <br /> Near surface ground water in the Nucla area is partially recharged by irrigation return flow through <br /> Quaternary aeolian and alluvial deposits. The lower Dakota and underlying Morrison Formations <br /> are regional aquifers, although water from the Dakota Formation is not heavily utilized due to its <br /> high salinity. The Morrison Formation water is widely used for stock and domestic wells. <br /> Very little hydrologic documentation is available regarding the alluvium found along the small <br /> tributaries draining the area. Peabody, the former operator, drilled one well in the alluvium of <br /> 13 <br />