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D R A F T January 4, 2012 such as volatile organic compounds or certain metals, that have not been addressed. In this regard, the Board notes that the City's analytical monitoring results from June 2000 through August 2006 indicate that there are no data for the great majority of pollutants with maximum contaminant levels identified in the Title 22 regulations.27 The Central Valley Water Board has taken steps to address this lack of data by imposing expanded monitoring requirements in Order No. R5-2007-0113. For example, the Central Valley Water Board required additional monitoring of wastewater in the storage ponds to assess degradation in the underlying groundwater and "to derive appropriate numerical groundwater quality objectives for the Facility that are consistent with the Basin Plan.i28 Likewise, the Central Valley Water Board required the City to conduct an industrial influent characterization study to "determine the potential impacts of the untreated waste on the underlying groundwater quality.i29 The Board notes, however, that the City is required to monitor the pond wastewater, the wastewater mixture applied to the agricultural fields, and the groundwater itself for priority pollutants, other than certain metals, only once during the permit term.30 One sampling event is unlikely to provide sufficient data to assess the potential impacts of discharging priority pollutants on groundwater. In any event, the lack of data in the current record leads to the conclusion that an exemption from Title 27 is not justified at the present time. 3. Evidence in the Record on Basin Plan Compliance In the area near the White Slough Facility, the regional groundwater flow direction appears to be from the Delta waterways in the west toward a large groundwater depression to the south and east. The current regional flow regime is profoundly influenced by intensive groundwater withdrawals in an area bounded by Highway 99 on the west and the foothills to the east and by Highway 12 to the north and the city of Stockton to the south. The deep groundwater depression caused by pumping draws groundwater toward it from all directions. At the center of this depression, the local water table elevation is as much as 70 feet below the nearly sea level elevation of the Delta's waterways. In the area just to the east of the White Slough Facility, the local expression of this regional groundwater flow regime results in eastward flow. The groundwater level in the Delta area to the west is lowered in some areas by 27 AR,vol. 2, item 32, attach. F,Table F-14 at pp. F-61 through F-63. 2e Order No. 135-2007-0113, attach. F at p. F-65. 29 Id. at F-72. 30 Id., attach. E,VIA, VII.B., VIII.B. 12.