In 1991 a study of two urban streams in Hamilton and two urban stormwater detention ponds in Guelph was initiated to detem1ine the degree of pesticide contamination in these systems. Water was tested for phenoxy acid herbicides (i.e. 2,4-D, mecoprop, dicamba, MCPA), for neutral herbicides (i.e. trifluralin, atrazine, metolachlor), and for organophosphorus insecticides (i.e. diazinon, dimethoate, chlorpyrifos), during base flow and during runoff events. Sediment was collected and analyzed for persistent organochlorine compounds and for selected pesticides. A questionnaire was circulated to the residents of two Guelph subdivisions to determine the types and amounts of pesticide used by householders. Canadian Water Quality Guidelines (CWQG) for Drinking Water were not exceeded for any of the pesticides. Concentrations of 2,4-D did exceed the

In 1991, trace metal levels were monitored over a nine month period in two urban creeks in the Hamilton Harbour watershed and in two urban stormwater detention ponds in Guelph, Ontario. Samples were collected both during dry or non$event periods and immediately after wet weather events. Both water and surficial sediment samples were tested for cadmium, copper, lead, mercury, nickel and zinc. In almost aU cases wet weather concentrations of lead, copper and zinc in the water collected from the two urban streams exceeded the Canadian Water Quality Guidelines (CWQGs) for the protection of freshwater aquatic life. While not designed for water quality improvement, both stormwater ponds reduced the levels of 1netals in discharged water, but in the process trace metals accumulated in sediment to levels above the lowest effect level guideline for the protection and management of aquatic sediment in Ontario, and in the case of 7Jnc above the severe effect level guideline. Although these levels are above guidelines, further investigation is needed to establish a relationship between metal contamination and biological impacts. This is particularly important for ponds intended for the dual purposes of stormwater treatment and as habitat for biota. 17. I Introduction In order to characterize water quality from two streams whose watersheds have been partially urbanized (10-40%) and two urban residential stormwater detention ponds, a sampling program involving both baseline (dry weather) and

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