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<br />7 <br /> <br />I <br />'I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Proposed ponds and pipelines on PESW A also occur on deep, excessively drained soils. The <br />soil is characterized by blowouts and dune topography. These soils absorb water rapidly <br />but have very rapid internal drainage and low water-holding capacity. Natural fertility is <br />low and there is no surface runoff. Valentine fine sands and Elmere loamy fine sands <br />comprise most of the project area soils.' Proposed well sites border Wet Alluvial land, which <br />is found directly adjacent to the river. This soil type is an accumulation of sand and gravel <br />that contains thin lenses of silty and clayey materials over deep gravel. These materials <br />make up sandbars and islands that are wet most ofthe time. <br /> <br />There are no Prime or Unique Farmlands located on the TRSW A or PESW A. A copy of <br />the NRCS clearance for prime and unique farmlands is included in Appendix D. <br /> <br />HYDROLOGY <br /> <br />The South Platte River originates along the Continental Divide in Colorado. It flows <br />generally northeast from its headwaters through the Denver metropolitan area continuing <br />northeast through Colorado and into the State of Nebraska near the Town of Julesburg in <br />Sedgwick County, Colorado. As shown in Figure I, TRSW A is located about 30 miles <br />above the state line and PESW A is located about 4 miles above the state line. The lands <br />comprising TRSW A and PESW A are on both sides of the South Platte River. The South <br />Platte River through both of these State Wildlife Areas is a sand bed alluvial meandering <br />system characterized by numerous braided channels, sloughs, and backwaters. <br /> <br />The South Platte River in Colorado and in the vicinity of TRSW A and PESW A is a gaining <br />river system. This means that the alluvial groundwater aquifer drains into the river <br />channel because water levels in the aquifer are higher in elevation than river water levels. <br />The increase in river flows as a result of the return flows from the aquifer can be 5 to 10 cfs <br />per mile as measured from an upstream point to ~ downstream point. This aquifer exists in <br />highly permeable soils and is supplied by the seepage and deep percolation from existing <br />canals, reservoirs, irrigation, and groundwater recharge programs. Numerous springs and <br />seeps occur along the banks of the South Platte River as the return flows seep back into the <br />river channel. These seeps provide the inflows to 'the warm water sloughs and backwaters <br />that currently exist at TRSW A and PESW A. <br /> <br />Average annual flow amounts of the South Platte River at the ColoradolNebraskastate line <br />are approximately 443,000 acre-feet of water. These flows provide a good surrogate for <br />river flow volumes in the vicinity of TRSW A andPESW A. The annual discharge pattern of <br />the South Platte River at the SW As is characterized by a spring runoff peak resulting from <br />snowmelt in May and June. On average, this peak amounts to about 40% of the South <br />Platte River's annual volume as measured at the Colorado - Nebraska state line. As <br />mountain snowpack melt and irrigation diversions increase, flows during the summer <br />months of July, August, and September are typically low, though strong thunderstorms can <br />create significant peaks of short duration. On average, 11 % of the South Platte River's <br />