Dicamba was not found in municipal water supplies in Alberta, but it was detected on two occasions (out of 48 analyses) in municipal water supplies in Manitoba and in about 6% of private wells monitored in southern Ontario, with a maximum recorded concentration of 2.3 µg/L. Dicamba has occasionally been detected in trace amounts in surface waters of Manitoba and Ontario. It was present in 18% of surface water samples in the Thames River basin, Ontario.
Based on the residue tolerance limits set by the Food Directorate of the Department of National Health and Welfare and on average Canadian consumption patterns, the theoretical maximum dietary intake of  dicamba for an adult Canadian would be 0.0003 mg/kg bw per day, or less than 3% of the acceptable daily intake (ADI) established by the Department of National Health and Welfare, assuming that every crop for which it is registered for use contained it at the maximum tolerable level of 0.1 µg/g. Actual intake will be less than this "worst-case" assumption. The theoretical maximum dietary intake in the United States is about 10 times this value, 33% of the ADI, because of higher residue tolerances and a greater number of registered crop uses. Dicamba was not included in total diet residue surveys in either Canada or the United States.

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