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A discussion of the probable hydrologic impacts of mining and reclamation <br />operations is contained in Volume 2, Tab 15 of the permit application. <br />Probable Effects on Surface Water Quality: <br />Surface water runoff from the Loadout area passes through one of two sedimentation <br />ponds. Discharges from these ponds are subject to effluent limits in the mine's <br />NPDES permit. The existing ponds have performed adequately and no discharges in <br />excess of NPDES effluent limits have been reported to date. <br />Concentrations of total dissolved solids (TDS) are four times higher for water coming <br />from the Rail Loop Pond than from the Truck Loop Pond; however, TDS <br />concentrations coming from the ponds are generally less than ambient concentrations <br />in Dry Creek upstream. Existing water quality in Dry Creek is unsuitable for <br />irrigation and only marginally suitable for livestock. <br />Most runoff from the rail loop, as well as the runoff from the three small area <br />exemptions, is not treated; however, runoff from these sources do not appear to be <br />affecting water quality. No adverse impacts from mining operations were projected in <br />the HG Mine permit application and none have been observed to date. <br />Probable Effects on Surface Water Quantity: <br />Runoff from the Loadout area that is not diverted around the area of disturbance is <br />retained in sedimentation ponds for a maximum of 36 hours. Water retained in these <br />two sediment ponds experiences some evaporative and seepage losses. The Dry <br />Creek diversion downstream could potentially be impacted by losses of water due to <br />storage in these sediment ponds. <br />The acreage served by these two sediment ponds accounts for less than one- <br />thousandth of the acreage drained by Dry Creek. Since the area to be affected is a <br />fraction of the total watershed, the general watershed will not be significantly affected <br />and runoff from the permit area will continue to reach Dry Creek. <br />All waters used for dust suppression, showers, and other operations at the Loadout are <br />piped in from a well in the Yampa River alluvium (H-G Shallow Well No. 1), located <br />two miles north of the Loadout. HGTI owns the water rights for this well. HGTI <br />owns an additional 90 acre-feet of water rights in the downstream Walker Ditch, <br />which are not being utilized. <br />These water rights can be used to compensate any downstream users for loss of water <br />due to consumption at the Loadout. HGTI has also entered into an agreement with <br />the United States Fish and Wildlife Service (USFWS) to mitigate against losses of <br />water to the Yampa River as a result of water consumption at the Loadout. Please <br />refer to Volume 2, Tab 21 of the permit application and Item XII of this document. <br />19