SITE INFORMATION AND CORRESPONDENCE

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Mr. Peter MacNicholl 6/12/2007 Page 3 sections and hydrographs show substantial influence of pumpage on water levels and thus on groundwater flow. 3. Section 2.3.4.2 A short description indicating approximate annual pumpage and recharge for each zone in cu ft/ day or year and acre-feet per year should be added, indicating whether there are seasonal variations in operation of the treatment system. 4. Section 2.3.5 Vertical Gradients. This section needs to be expanded and the patterns on the Figures 2-6 and 2-7 described. The trend for overall vertical gradients to increase gradually in proportion to vertical screen separation is consistent with the idea of the aquifer as having a gradual, somewhat haphazard increase in confinement with depth. The overall vertical gradient between layers 1 and 4 increases from south to north, being lowest at the south end of A-A' and highest at the northern end, corresponding to the areas of vertical flow mentioned above. 5. Section 2.3.6.2. The hydrographs do not appear to be substantially influenced by operation of the extraction/injection system, unless the system is operated in a agricultural/municipal pumping pattem. The hydrographs show marked seasonal decline and recoveries in an 'aquifer-test-drawdown and recovery' pattern. This pattern is typical of high dry season demand type pumping. The pattern is subtle because of the delay between rainfall and the actual arrival of the recharge to the aquifer. 6. 2.3.6.2 Recharge. The hydrographs show two responses to rainfall, one prompt, and one slow. The immediate response to cessation of winter rain is instigation of heavy pumpage within a month or two. In 2001, there was enough rain to delay the start of the pumping season by two months, and to shorten its duration. However, groundwater levels did not respond proportionately to the rainy winter. Instead, 2002 was dry, and irrigation never really ceased, yet groundwater recovered more in fall of 2002 than it did in fall 2001. This suggests that it takes a year for the physical water to reach the aquifer. 7. Section 2.6.3 Inspection of Figures 2-13 and 2-14 confirms a one-year lag between high rainfall and high recharge, or low rainfall and low fall groundwater level recovery. Figure 2-16 suggests the recharge lag is closer to two years in this area. This section should be revised to better describe the relation between pumping, recharge, and changes in water levels. Also, two of the three preceding years were very wet, and the high groundwater levels at the beginning of the hydrographs undoubtedly show some residual effects of previous years' _ rain.