Groundwater samples were collected from 60 piezometers and 23 domestic wells from March 1991 to April 1992 as part of a study to quantify NO−3 and pesticide contamination of the Abbotsford Aquifer, located in the lower Fraser Valley, southwestern British Columbia, Canada. A new contaminant, 1,2,2-trichloropropane (1,2,2-TCP), was detected and confirmed in 296 of the 514 samples by purge and trap GC/MS, and its concentration was determined in 150 of the samples collected between January and April 1992. The contaminant was detected in 34 (57%) of the piezometers sampled, and 10 (44%) of the domestic wells sampled. Mean 1,2,2-TCP concentration (±1 SD) was 0.12 ± 0.11 µg L−1 in 123 piezometer samples and 0.14 ± 0.09 µg L−1 in 27 domestic well samples. The highest 1,2,2-TCP concentrations measured were 0.62 and 0.32 µg L−1 for piezometers and domestic wells, respectively. The probable nonpoint sources of the contaminant are the synthetic pesticides, Telone (mixture of 1,3-dichloropropene and 1,2-dichloropropane) and Telone II (1,3-dichloropropene), used to control pathogenic nematodes in raspberry (Rubus idaeus L.) production. Analyses of Telone and Telone II confirmed the presence of 1,2,2-TCP as impurities in both products. The study demonstrates that an impurity present in pesticide formulations in trace quantities, which is persistent in soil and water, has the potential to result in significant groundwater contamination under the appropriate soil and climatic conditions.