Response of fecal bacteria and water chemistry in an agricultural drain to remedial construction activities on livestock farms

Remedial construction activities, aimed at restricting the loadings of agricultural and domestic waste to agricultural waterways, were conducted in the autumn of 1986 by the Ausable Bayfield Conservation Authority on three farms (one dairy and two livestock operations) in the headwaters of the Desjardine Drain, Huron County, Ontario. A significant improvement in the bacterial (Escherichia coli, fecal streptococci) and chemical (biological oxygen demand, nutrients) water quality conditions was measured the following summer immediately downstream from each farm, relative to an upstream reference site. However, only improved bacterial water quality conditions were noted downstream of all farming operations in the drainage basin. The study suggests that the utilized remedial construction activities could reduce the loadings of fecal bacteria to Lake Huron beaches, but would have little effect on the loadings of organic matter and nutrients.