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DISCUSSION <br />During the winter of 1998199, 661 wells were measured in the Northern High Plains Designated <br />Basin. An attempt was made to measure all the wells within a six week period beginning approximately <br />in late -December 1998. This goal was achieved due to the mild winter throughout the basin. All wells <br />were measured prior to February 10, 1999. By measuring the wells in a short time period, it is hoped <br />that seasonal fluctuations will be dampened and that the hydrographs and comparison of water level <br />change will more accurately reflect the true ground water conditions. The three hydrographs for wells <br />with continuous recorders show that the aquifer receives recharge up to the beginning of the irrigation <br />season and that measuring the wells at the same time each year is critical to obtaining consistent data. <br />Throughout the Northern High Plains, the water levels continue to show the regional decline <br />which is to be expected when water is being "mined". This year considerable areas show small rises in <br />water levels. The map contained in the appendix shows the relative change in water levels since last <br />year. <br />The average rate of decline for the past year about one-half that for the preceding year (0.33 feet <br />during 1998/1999 as compared with 0.7 feet in 199711998). The well hydrographs contained in Appendix <br />L show representative water level trends in areas throughout the basin. Based on previous work, the <br />overall decline of 0.33 feet equals approximately 300,000 acre-feet which have been removed from <br />storage. A decline of 1 -foot is equal to a depletion from storage of approximately 900,000 acre feet. <br />Over the past ten years (1990 to 1999) the basin -wide water level has declined approximately 4.94 feet <br />representing a depletion of approximately 4,500,000 acre-feet or 4 % of the estimated 1965 storage in the <br />aquifer. <br />