Water levels rose an average of 175.5 feet between January 1997 and November 1998. The increase in groundwater elevation for Well 16 during this period was 186.8 feet. The increases occurred predominantly in the latter part of 1998, most likely the result of substantial precipitation.

The potentiometric maps indicate a southerly groundwater flow direction. Recent pumping of groundwater appears to have influenced the water table at CSSA, though it is unknown if pumping significantly affects off-base groundwater flow.

TCE, cis-1,2-DCE, PCE and trans-1,2-DCE concentrations increased in Wells 16 and D between January 1997 and November 1998. This represents the first increase in all four analytes in Wells 16 and D since 5 November 1992, and is associated with the high October 1998 rainfall.

PCE, TCE and cis-1,2-DCE concentrations are observed in Wells MW-1 and MW-2, and trans-1,2-DCE concentrations are observed in Well MW-1. Since the first groundwater sampling event for these two wells was in April 1996, more data is needed to identify trends for these wells.

Lead was detected above its action level in Well G by 0.005 mg/L in October 1997. Lead has previously exceeded its action level for Well 1 (December 1995, January 1996, March 1996 and January 1997), Well D (January 1997) and Well G (January 1996, February 1996 and January 1997).