Laserfiche WebLink
Geology <br /> The Loadout and Tie -Across -Haul Road (TAHR) are located in the Dry Creek and Sage Creek <br /> drainages approximately two miles north of the Williams Fork Mountains. The permit area is <br /> underlain by the Lewis shale, a predominantly dark-gray to bluish, marine shale of Cretaceous <br /> age. The Lewis shale dips a few degrees generally northward into the Sand Wash Basin. The <br /> shale beds have weathered out to form gently sloping hillsides on either side of the nearly level <br /> alluvial valley 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 movement <br /> is described below and in Tabs 7, 14, and 15 of the permit application package (PAP) <br /> More detailed geologic information, including geologic maps and a generalized geologic cross- <br /> section, can be found in Tab 6 of the permit application. <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. Information on soils can be found in Tabs 9 and 19 of the <br /> PAP. Specific findings related to soils are described in Section B, Item IV of this document. <br /> Surface Water <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 here in <br /> the Description of the Operations Plan and in Section B, Item III of this document. Co <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 ranges from 0 to 126 cubic feet per second (cfs)upstream of the Loadout to 0 to <br /> 225 cfs downstream. Two sediment ponds control runoff at the loadout: the Truck Loop Pond <br /> usually discharges during spring snowmelt; the Rail Loop Pond has rarely discharged. <br /> Stream flow in Dry Creek generally increases downstream, although some sections are <br /> ephemeral. During the growing season, diversions from Dry Creek above the permit can <br /> significantly reduce and periodically eliminate streamflow in the vicinity of the Loadout, while at <br /> the same time return flows from surrounding irrigated fields can discharge small volumes of <br /> water to Dry Creek below the Loadout. <br /> The dominant cations in Dry Creek water are magnesium, calcium, and sodium. The dominant <br /> 5 <br />