Few studies have documented spatial and temporal variations in ground water quality in areas with high densities of animal farming operations (AFOs), or the long-term effects on surface-water quality. Changes in ground water quality were characterized in an irrigated area with a high density of AFOs in southern Alberta, Canada to evaluate the effect on ground water quality of manure application to fields. Fifty-five piezometers in the oxidized zone were sampled once or twice annually from 1995 to 2001, and temporal changes were analyzed using mixed model analysis. Average NO3- -N increased significantly from 12.5 to 17.4 mg L(-1) and average Cl- increased significantly from 19.4 to 34.4 mg L(-1) in piezometers installed in an unconfined sand aquifer at locations receiving fertilizer and manure. Compared with these manured locations, nitrate and chloride concentrations were significantly lower in shallow aquifer water in areas of pasture or native range, and concentrations did not change significantly with time. Nitrate and chloride concentrations in shallow ground water in fine-textured manured locations did not change significantly. Ground water below about 6 m in till and fine lacustrine sediments contains 18O signatures indicative of recharge under preirrigation or glacially influenced conditions, suggesting this ground water has a low vulnerability to agricultural contamination. Evaluations suggest that shallow ground water discharge will cause NO3- -N and Cl- in the Oldman River to increase by factors of at least 4.3 and 1.3, respectively, with more significant effects in smaller streams and under low-flow conditions.

Environmental concerns related to manure often focus on land application and the negative effects on soil and water quality. However, there is also potential for contamination of soil and water directly from feedlot sites. The objective of this study was to determine if a newly constructed feedlot in southern Alberta would change soil and groundwater quality under the feedlot within the first four years of operation. A cattle feedlot was constructed at the Agriculture and Agri-Food Canada Research Centre in Lethbridge, Alberta, in 1995 and 1996. Sixteen groundwater wells were installed at the feedlot in 1996. Groundwater chemistry and microbiology were monitored from 1996 to 2000, which included a baseline period of 3 months at the start before the feedlot was stocked with cattle. Soil samples (0- to 0.15-m, 0.15- to 0.3-m, and every 0.3-m to 1.5-m depth) were collected in 1996 and 1999. Mean water-table depth ranged from 1.23 to 2.50 m. Some soil chemical properties, PO4-P, NO3-N, NH4-N and K, were only significantly affected in the top 0.15-m layer. Other soil properties, EC, SAR, SO4-S, Mg, Ca and Na, increased significantly to a depth of 0.6 m. Chloride content increased significantly to a depth of 1.5 m. Groundwater analysis indicated that contaminants had leached to the water table. Chloride concentrations, E. coli counts and total coliform counts increased in the wells within the pen area, whereas there was little change in the wells outside the pen area.

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A three-year study was conducted at Lethbridge, on a 1-ha field (clay loam soil) with a history of previous herbicide applications, to determine herbicide levels in shallow (0.3-5.8 m) groundwater and the effect of seasonal events such as herbicide application and rainfall/irrigation. A mass-selective detector, gas chromatographic method was used to analyze for seven different herbicides.Samples were collected from 6-m monitoring wells at various intervals (9-32 d) after herbicide applications made in 1991-1993. 2, 4-D (0.05-5.2 ppb), bromoxynil (0.03-8.4 ppb), diclofop (0.1 -11 ppb), MCPA (0.2-0.3 ppb) and triallate (0.1 -0.5 ppb)were detected in 17-61% of the wells sampled. Herbicide levels depended upon the interval and the timing and amounts of rainfall/irrigation after spraying. All levels were below the Canadian drinking water guidelines except for one detection of bromoxynil (8.4 ppb) and diclofop (11 ppb). We concluded there are large seasonal and spatial variations in herbicide levels in shallow Alberta groundwater. Levels 883