Colorado's Plan for Future Depletions

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Colorado's Plan For Future Depletions January 12, 1998 Documentation as Required by Cooperative Agreement, ' Page 3 Milestones W6-1, W7-1, W8-1, and Tab 3B(I)E Interactive Sareadsheet Tool and Suanortin2 Documentation The interactive spreadsheet tool for Colorado's Plan for Future Depletions was developed to illustrate the cumulative accretive and depletive effects on South Platte river flows from future population growth in the South Platte basin of Colorado and from the water supply sources used to meet the water needs associated with that growth. The interactive tool includes the accretive and depletive effects of a mix of six categories of water supply sources: transbasin diversions, nontributary (Denver Basin) groundwater, agricultural conversion, water conservation, water reuse and native South Platte water development. The tool does not include any accretive effects associated with increased runoff from impervious surfaces due to urbanization. Similarly excluded are any depletive effects that may be due to future changes in the hydrologic interaction between the Denver Basin aquifers and the South Platte River and its tributaries. While both of these phenomena were the subject of study in the Denver Basin and South Platte River Basin Technical Study, the results of this study are still undergoing peer review. The tool has been implemented in a Microsoftt' Exce197 workbook. This documentation is organized according to the worksheets included in the workbook. 1 Hydrology Map The Hydrology Map depicts the South Platte River basin withiri the State of Colorado. With the exception of the area labeled "Denver Basin Aquifers", all information was obtained from USGS maps. The area labeled "Denver Basin Aquifers" was obtained from a map entitled "Aquifer Map of the Denver Basin", included in the Denver Basin and South Platte River Basin Technical Study, Senate Bill 96-074, Draft Report, prepaxed by Hal D. Simpson, State Engineer and Chuck Lile, Colorado Water Conservation Board Director, dated October 1997. 2 Regiona{ Map The Regional Map depicts the South Platte Basin within Colorado divided into three Regions: the North Region (blue), the Central Region (pink/salmon) and the South Region (green). The three Regions were formulated to reflect the fundamentally different water supply options available to each region. The North Region includes those portions of Boulder, Larimer, Weld, Morgan, Washington, Logan and Sedgwick Counties located within the South Platte River basin. These counties are located in whole or in part within the Northern Colorado Water Conservancy District. Most municipal water providers within the North Region therefore have access to water from the Colorado-Big Thompson and Windy Gap transbasin diversion projects. The North Region also includes a majority of the irrigated agricultural land within the South Platte basin in Colorado.