Laserfiche WebLink
Table 4: Aquifers, Time Periods, and Water Level Trends Parameters <br /> Number of <br /> Wells Used Date Range of <br /> Total for Water Water Level <br /> Number Level Trend Measurements <br />A uifer of Wells Analysis1 Used to Contour <br />Lower Dawson 134 69 Feb 57 -Apr 06 <br />Denver 278 117 Au 56 - Ju106 <br />Lower Arapahoe 307 137 Mar 54 - Ju106 <br />Laramie-Fox Hills 554 64 Ju148 - Ju106 <br />1 Represents the number of wells that had at least 3 measurements over three different years <br />and at least one measurement subsequent to 1980. <br />Once the data sets were selected for each aquifer, charts of the historical groundwater elevations <br />for each well were generated. A trend line was fit to the historic water level measurements to <br />determine the average annual change in water level. Each chart was manually inspected to <br />determine whether the trend line appeared appropriate for the data. The inspection included a <br />determination of whether skewing by pumping season or isolated data value was occurring. If <br />amore appropriate water level trend was apparent during this inspection a new trend line was <br />drawn on the chart and the average annual water level change was calculated. Wells with water <br />level data heavily influenced by pumping, or that contained too few water level measurements <br />to determine a trend, were omitted from the analysis. <br />After groundwater elevation trends were analyzed for individual wells, the calculated trends <br />were posted by aquifer in ArcGIS at the locations corresponding to the individual wells. The <br />posted trends were used to generate color-fill maps and contours to display regional <br />groundwater elevation trends in each aquifer. The regional trend maps cover the entire aquifer <br />for each aquifer where sufficient data existed. This is in contrast to the water level elevation <br />maps of distinct time periods because the regional trends are intended to present the general <br />large-scale changes in water levels over time. These maps are interpretive in nature and may <br />not accurately depict the water level surface of any individual snapshot in time, which is the <br />purpose of the water level maps described in Section 1.4. The resulting water level trend maps <br />and associated discussion are presented in Section 3.2. <br />Temporal Anal <br />Water level trends over time at individual wells were used to create hydrographs for 40 wells <br />located throughout the Denver Basin Region. Hydrographs provide a detailed record of water <br />level changes over time at individual locations. Wells were selected based upon the period of <br />record available, existence of recent data, aquifer location, and their spatial distribution over the <br />study area. A total of 2 wells in the Upper Dawson, 5 wells in the Lower Dawson, 7 wells in the <br />Denver, 3 wells in the Upper Arapahoe, 3 wells in the Arapahoe, 4 wells in the Lower <br />Arapahoe, and 16 wells in the Laramie-Fox Hills were selected. A successively greater number <br />of wells were selected in the deeper aquifers due to their larger geographic extent and the desire <br />to have a relatively consistent representation of each aquifer by area. <br />SPDSS Phase 3 Task 44.2 TM -Final 10 <br />11/28/2006 <br />