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particular point in time and are sensitive to pumping in that year. Filling in the missing areas <br />on the potentiometric surface maps requires a considerable amount of engineering judgment <br />and is contrary to the objective of presenting the data in a relatively unprocessed format. <br />Table 3 summarizes the number of water level measurements available in the late winter/early <br />spring (February to April) time period for the years selected for contouring. The resulting water <br />level contour maps and associated discussion are presented in Section 3.1. In the cases where <br />there are not 10 or more water level measurements for a given aquifer (such as for 1968) the <br />potentiometric surface was not contoured. Undivided and lower aquifers were grouped for the <br />purposes of contouring and are called the Arapahoe and Dawson Aquifers respectively. <br />Table 3: Number of Bedrock Water Level Measurements by Aquifer and Date <br /> <br />Year Upper <br />Dawson Lower <br />Dawson <br />Dawson <br />Denver Upper <br />Ara ahoe Lower <br />Ara ahoe <br />Ara ahoe Laramie- <br />Fox Hills <br />Total <br />1968 0 0 0 0 0 0 3 2 5 <br />1978 0 1 32 3 0 0 3 104 143 <br />1990 8 6 19 41 7 11 47 52 191 <br />2001 8 8 8 43 3 9 50 46 175 <br />2003 9 6 18 40 3 9 41 39 165 <br />2005 7 9 19 46 3 10 50 43 187 <br />1.5 Water Level Trend Analyses <br />Changes in groundwater levels in the bedrock aquifers were evaluated both spatially and <br />temporally. <br />Spatial Anale <br />Historical groundwater elevation data were utilized to identify regional groundwater trends for <br />each of the bedrock aquifers. First, individual well data sets were analyzed to determine the <br />number of data points and the most recent water level measurement. A well was selected for <br />further spatial analysis if the well had at least three water level measurements in three different <br />years. The preference was to use wells with data that extended to the 2000-2005 time period to <br />better reflect recent pumping conditions. However, for there to be sufficient wells to contour <br />the water level trends in the Lower Dawson, Denver, Lower Arapahoe and Laramie-Fox Hills <br />aquifers, the most recent data for some wells were earlier in time than the year 2000. Table 4 <br />provides a summary of the number of wells and time periods used in the water level trend <br />analysis for these aquifers. The Upper Dawson and Upper Arapahoe Aquifers were determined <br />to be unsuitable for trend analysis due to the limited number of wells that could be used in the <br />development of water level contours. <br />SPDSS Phase 3 Task 44.2 TM -Final 9 <br />11/28/2006 <br />