RESEARCH

ABSTRACT

Raw river and irrigation water in the Oldman River Basin in southern Alberta was tested for the presence of two bacterial pathogens, Escherichia coli O157:H7 and Salmonella spp., over the last 2 yr (2000-2001). The number of E. coli O157:H7 and Salmonella spp. isolated from raw water peaked during the summer months. While E. coli O157:H7 was only isolated from 11/802 0.3%) of raw water samples over the entire sampling season in 2000 and from 16/806 (2.0%) of the samples in 2001, the pathogen was isolated one or more times from 10135 (28.5%) sampling sites in 2000 and from 13140 (32.5%) sampling sites in 2001. Salmonella was isolated from 441802 (5.5%) of raw water samples in 2000 and from 1221822 (14.9%) of the samples in 2007; the pathogen was isolated one or more times from 25135 (71.4%) sampling sites in 2000 and from 29140 (72.5%) sampling sites in 2001. Certain sites had multiple pathogen isolations in the same year and from year to year. Salmonella Rublislaw was the most common Salmonella serovar isolated in both years, accounting for 52.4% of isolates.