Pocatello Wells Affected by TCE

Note: Even though some of the the highest concentrations in upgradient wells occurred in 1994, individual annual average concentrations averaged over all wells in 1998 are 7% higher than in 1994, and 92% higher than in 1993; 1997 concentrations are 65% higher than in 1993. Average concentrations in individual wells showed an overall average increase of 13% between the first three years and the last three years of record; considering downstream wells only (wells 36, 12, 30, 16) increases of 14 to 40% were observed. These trends indicate that the plume's total solvent mass is not decreasing with time.