Laserfiche WebLink
' • <br />• South Platte at Julesburg <br />The specific reaches and time periods over which the USGS gain/loss study were undertaken <br />will not be repeated in this task if the USGS data and methods are found to be acceptable and <br />consistent with the methods used in this task. However, it is anticipated that some <br />reformatting of the results from the USGS study will be needed in order to be compatible with <br />the results computed under this task. <br />The stream gage and diversion data used to estimate stream gain/loss will be obtained from <br />HydroBase using TSTools. Additional records will be used in the analysis, including gage <br />data from tributary streams (including Big Thompson, St. Vrain Creek, and Clear Creek), <br />diversion records and data from discharge from municipal wastewater treatment plants and <br />other key discharges. Data on municipal and industrial discharges will be obtained from <br />records available from the Colorado Department of Health and Environment or EPA. Missing <br />data will be filled using techniques similar to those applied under Task 2, undertaken by the <br />CU/Water Balance Contractor. <br />• Estimating inflows from ungaged tributaries such as Box Elder Creek will be evaluated on a <br />case-by-case basis. The Groundwater Contractor will meet with the CU/Water Balance <br />Contractor to determine the appropriate methods to estimate ungaged inflows and outflows <br />and will discuss these with the State before proceeding, to be consistent with the methods and <br />Ieve1 of accuracy of existing records. <br />• Estimates of stream gain/loss will be computed using the Pilot Point method as implemented <br />by the State on the Republican and Rio Grande Basins. This method is based on mean daily <br />flows with a 61-day moving average applied to smooth the results. <br />• The method used to estimate stream gain/loss and the specific reaches over which the <br />estimates are developed may be modified based on the available data, the suitability of the <br />method to the situation and the ability to perform the computations within the available <br />budget. The Contractor will discuss with and obtain approval from the State any potential <br />changes in the methods and stream reaches being used. <br />• The estimates of stream gain/loss will identify the groundwater discharge to or from the <br />groundwater recharge from the South Platte River and Cherry Creek. This information will be <br />used in Task 48 during calibration of the groundwater model, to compare simulated to <br />observed gains or losses in the river. <br />Deliverables: <br />• The Groundwater Contractor will develop a submittal of up to 5 pages in length (with <br />additional pages for data tables and figures) that contains a description of the data used in the <br />calculations, the methods of calculation and the calculation results. The stream gain/loss <br />estimates will be presented in hard-copy and electronic (ArcGIS or equivalent) formats on a <br />suitable base map of the alluvial aquifer study area and tables or gain/loss hydrographs for <br />each reach. The results will be added to the geospatial database being developed and used <br />SPDSS Phase4_gw_SOW_09-] 5-06.doc $ <br />