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The Loadout and TAHR are located in the Dry Creek and Sage Creek drainages approximately <br /> two miles north of the Williams Fork Mountains. The permit area is underlain by the Lewis <br /> shale, a predominantly dark-gray to bluish, marine shale of Cretaceous age. The Lewis shale <br /> dips a few degrees generally northward into the Sand Wash Basin. The shale beds have <br /> weathered out to form gently sloping hillsides on either side of the nearly level alluvial valley <br /> floors and terraces found along Dry Creek. <br /> Surface waters do not appear to be in hydrologic communication with the Twentymile <br /> Sandstone, a significant regional aquifer that underlies the Lewis shale. Ground water <br /> movement is described below and in Tabs 7, 14 and 15 of the PAP. <br /> More detailed geologic information, including geologic maps and a generalized geologic cross- <br /> section, can be found in Tab 6 of the PAP. <br /> Soils <br /> Soils in the Dry Creek area range from clays to loams. The soils are of limited agricultural use <br /> due to high concentrations of sodium and salt. Information on soils can be found in Tabs 9 and <br /> 19 of the PAP specific findings related to soils are described in Section B, Item IV of this <br /> document. <br /> Surface Water Hydrolo2y <br /> Surface water information is found in the following sections of the PAP: Tabs 7, 12, 13, 14, 15 <br /> and 16 and Exhibits 12-2, 12-3, and 12-4. A summary of this information is included below, in <br /> the Description of the Operations Plan and in Section B, Item III of this document. <br /> The majority of the permit area associated with the Loadout drains to Dry Creek. A small, <br /> northern portion of the railroad loop drains directly into the Yampa River. Three drainages, <br /> Stokes Gulch, Dry Creek, and Sage Creek, run through the permit area associated with the <br /> TAHR. The Walker irrigation ditch crosses the northern portion of the permit area. The Yampa <br /> River lies about one mile north of the permit area. <br /> Precipitation averages approximately 16 inches annually in the permit area and the volume of <br /> runoff is limited. Most runoff comes from snowmelt or intense thunderstorm events. Flows in <br /> Dry Creek have ranged from 0 to 126 cfs (cubic feet per second)upstream of the Loadout to <br /> from 0 to 225 cfs downstream. Two sediment ponds handle runoff at the loadout: the Truck <br /> Loop Pond usually discharges during spring snowmelt; the Rail Loop Pond has rarely <br /> discharged. <br /> Stream flow in Dry Creek generally increases downstream although some sections are <br /> ephemeral. During the growing season, diversions of water from Dry Creek above the permit <br /> can significantly reduce and even periodically eliminate streamflow in the vicinity of the <br /> Loadout, while at the same time return flows from surrounding irrigated fields can discharge <br /> small volumes of water to Dry Creek below the Loadout. <br /> 6 <br />