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Hydrographs were created by using all available historical water levels from a given well. <br />Using this historical record, the data set was filtered to include only the first late winter/early <br />spring (February to April) water level measurement of a given year. These water level <br />measurements were used to generate a hydrograph for a given well. Measurements taken in the <br />late winter/early spring will most accurately represent the average water level conditions for <br />that year since they minimize the effects of water level fluctuations due to summer pumping for <br />irrigation. Hydrographs for the 40 wells in the Denver Basin are presented in Section 3.3. <br />2.0 Water Level Database <br />One of the objectives of Task 44 was to create aHydroBase-compatible database with water <br />level data from the Denver Basin Region. This section describes the HydroBase tables that are <br />used to store water level data. <br />2.1 Database Structure <br />HydroBase is the State of Colorado's database used to manage hydrologic data. Appendix C <br />provides a detailed listing of the database and fields from HydroBase that contain water level <br />information. <br />Four data tables contain aquifer water level data used for analysis and mapping of groundwater <br />data. These named WELLS, WELL_MEAS, REF_LOC_ACCURACY and <br />REF_ELEV_ACCURACY. <br />The WELLS table contains the location, well elevation, permit number, well depth, and other <br />information about wells. The WELLS table is the core table that links well information data with <br />water level, geophysical log, and aquifer test data. <br />The WELL_MEAS table contains the water level data. This table is linked to the WELLS table by <br />the well_id field. The WELL_MEAS table contains the measurement date, measuring point <br />height, and the depth to water for each measurement. This information linked with the ground <br />surface elevation in the WELLS table allows the water level elevation to be calculated. <br />The REF_LOC_ACCURACY table includes comments on the siting accuracy of the location <br />(X,Y) data. <br />The REF_ELEV_ACCURACY table includes comments indicating the source and accuracy of <br />the elevation value. <br />2.2 Database Quality Control <br />A series of quality control steps were undertaken once the data were compiled into a common <br />electronic format. These steps were performed to check on the accuracy of the data before <br />submitting it to the State for uploading into HydroBase. <br />Numerical data from each of the sources were initially entered into a Microsoft Excel® <br />spreadsheet. The data were then checked for accuracy by comparing the entered data to the <br />original hard copy data. New data received in electronic format were checked with the original <br />SPDSS Phase 3 Task 44.2 TM -Final 11 <br />11/28/2006 <br />