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The observation wells can be subdivided into two types: those which lie within or very near the South Platte River floodplain, and those located in tributary valleys. The number of observation wells in tributary valleys exceeds the number along the South Platte floodplain by 19. An evaluation of the data of beginning water levels as compared to Spring 1998 levels reveals that approximately 50.8% of the wells have experienced a water level decline which compares to a 60.3% decline in the 1997 report. By comparison, 24.5% of the wells experienced a rise in the Spring 1998 as compared to the Spring 1988 water level. This percentage is slightly less than the 1997 report value (27%). Declines of Spring 1988 to Spring 1998 range from -0.04' to -12.3' as compared to the range of -0.23' to -18.63' in the 1997 report. Declines on the order of 0.01' are insignificant in that such changes can be caused by wind, earth movement, and the effect of evapotranspiration and phreatic consumption or maybe errors in data recording. The table following this narrative entitled "Table of Water Level Trends of the South Platte Alluvium through Spring 1998" recaps the statistics to date for this ongoing report in terms of all wells, tributary valleys, and the South Platte main stem/floodplain. These data also reveal that the averages of the water level changes from Spring 1988 to Spring 1998 wells within the tributary valleys (both rises and declines) are greater than the averages of the South Platte floodplain alluvium. By comparison, in 1997 the average rise and declines of Spring 1988 vs. Spring 1997 changes in the tributary valleys were also greater than those in the South Platte floodplain. The average annual water level change compared to the previous year over the past ten years has averaged -0.08 ft/yr in the South Platte floodplains and -0.18 ft/yr in the tributary valleys. -2-