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7-Eleven/Stockton 16 May 1990 Analyses Of the groundwater monitoring data indicate that groundwater elevations have increased an average of 0.21 foot during this three-month reporting period. The depth-to- groundwater at the site is approximately 45-feet below around surface. The groundwater-table elevation is approximately 32-feet below sea level. Since the first set of groundwater monitoring data were collected in May 1986, local groundwater-table elevation has declined steadily. The decline in the groundwater levels is depicted in the hydrographs for Mw-7, Mw-8 and MW-9 (Figure 4) . Monitoring wells MW-7 and MW-8 are representative of the majority -° of wells at the site. The one exception to the general water- level decline is the data from MW-9 which reflect a mounding of the groundwater surface due to a leaking water pipe at the rear of the 7-Eleven Store. In April 1989, this leaking water pipe �d was repaired and the mounding condition has been corrected. According to National Weather Service local climatological low-normal annual precipitation has data for the Stockton area, be been recorded for the past five years. However, in 1982 and r. 1983, just prior to this drought period, annual precipitation was nearly twice normal. Therefore, the steady decline in the groundwater-table elevation may be in response to prolonged drought conditions combined with an abnormally-elevated groundwater level at the beginning of the monitoring period. The Groundwater Gradient Maps for January, February and March, 1990, (Figures 5, 6, and 7) , represent the interpreted groundwater-table elevations beneath the site for each of the three months in this reporting period. The regional groundwater- gradient .direction remains to the east, as reported in the past. The gradient has declined from 0.005 ft/ft to 0.002 ft/ft since the last reporting period. 10 GIZOLINDLI'.ATF.R TW I NC)LOGY.INC.