Laserfiche WebLink
Isolated areas of saturated thickness separated by extensive unsaturated zones were excluded <br />from the extent. This new extent was merged with the extent presented in the Robson reports to <br />generate a more comprehensive outline of the alluvium for the mainstem of the South Platte <br />River from Denver to Greeley, the tributaries to the west of the South Platte River, portions of <br />Beebe Draw and Box Elder Creek, and the Cache la Poudre River and its tributaries. <br />The Smith et al. (1964) report focused on the Box Elder Creek and Beebe Draw region but no <br />saturated thickness limit was digitized from this report. The areal extents to which the water <br />table contours and the bottom of alluvium contours were drawn were used to approximate the <br />extent of the saturated alluvium and provide a basis for the outline in the Box Elder and Beebe <br />Draw regions. <br />The Willard Owens Associates (1971) report focused on the Upper Big Sandy Designated Basin <br />but no limit of the saturated thickness was defined in that report. In addition, the bottom of <br />alluvium contours and the groundwater level contours are not of sufficient detail to estimate <br />the extent of the saturated alluvium. The Colorado Geological Survey (CGS) developed a <br />shapefile for the Groundwater Atlas of Colorado which maps the extent of alluvial deposits in <br />Colorado (Topper et al. 2003). The CGS outline was used to map the alluvium in the Upper Big <br />Sandy Designated Basin. <br />In areas of Crow Creek, Upper Beaver Creek, Upper Box Elder Creek, and just below Chatfield <br />Reservoir on the South Platte ,where contours were manually drawn for this TM (see Section <br />1.2.2), the CGS outline and data obtained from the DWR well permit images were used define <br />the alluvium extent. <br />The final extent of alluvium was created by merging the boundaries obtained from each source <br />identified above. Using ArcGIS software, the boundaries were clipped to the extent of the <br />Denver Basin along the western, eastern, and southern margins. Finally, manual editing of the <br />alluvial boundary was performed to fill in areas of alluvium between the various sources of <br />data. <br />Division 1 decreed wells and Division 8 (Designated Basins) wells with greater than 50 gallons <br />per minute pumping capacity and with aquifer codes of "QAL" or "Groundwater" are plotted on <br />Figure 5. This figure illustrates the defined alluvial extent contains almost all of the high <br />capacity wells. It should be noted some wells shown may be completed in aquifers other than <br />the South Platte Alluvium because the aquifer code "Groundwater" may be used for aquifers <br />such as the Denver Basin Bedrock Aquifer, the High Plains Aquifer, or other aquifers. This <br />alluvial extent will be modified using a minimum saturated thickness depth and width criteria <br />under Task 48 to develop the alluvial model domain. <br />2.0 Aquifer Configuration Database <br />One of the objectives of Tasks 31 and 42 was to create aHydroBase-compatible database with <br />aquifer configuration data from the South Platte Alluvium Region. This section describes the <br />HydroBase tables used to store configuration data. The picks gathered for this TM will be <br />submitted in aHydroBase-compatible database using the format discussed in Section 2.1. <br />SPDSS Phase 3 Task 42.3 TM -Final 10 <br />11/30/2006 <br />