Contamination and wildlife communities in stormwater detention ponds in Guelph and the Greater Toronto Area, Ontario, 1997 and 1998. Part II - Contamination and biological effects of contamination

Due to concerns that wildlife may be attracted to stormwater detention ponds and would be exposed to contaminants accumulating in these ponds, a field study of 15 stormwater ponds and one natural wetland in Guelph and the Greater Toronto Area, Ontario, was performed in 1997 and 1998. At 9 of 16 sites, copper levels in water exceeded the Canadian Water Quality Guidelines (CWQGs) for the protection of aquatic life. Canadian Water Quality Guidelines were also exceeded by average water concentrations for lead at four sites, for zinc at three sites, for chromium at seven sites, and turbidity at ten sites. At the natural wetland, only turbidity levels exceeded the CWQGs. Sediments from all ponds contained concentrations of at least one contaminant that exceeded the "lowest effects level" (LEL) of the Guidelines for the Protection and Management of Aquatic Sediment in Ontario. Stormwater pond sediments contained concentrations exceeding provincial sediment quality guidelines at the LEL for polychlorinated biphenyls (PCBs), gamma-hexachlorocyclohexane (g-bhc), total Kjeldahl nitrogen (TKN) and total phosphorus (TP), turbidity, oil and grease, total PAHs, chromium, zinc, cadmium, copper, lead, nickel and arsenic. Concentrations of g-bhc, TKN, TP, cadmium, copper, lead, zinc and arsenic in the sediment of the natural wetland also exceeded the LEL. Sediments at one site exceeded the provincial guideline at the severe effect level for chromium. Concentrations of lead, zinc, cadmium and total PAHs in sediments were correlated with the age of the ponds. Concentrations of organochlorine pesticides and PCBs were low (<0.08 mu g/g wet weight) in pumpkinseed (Lepomis gibbosus) collected from two ponds in Guelph. Red-winged blackbird (Agelaius phoeniceus) eggs from two ponds in Toronto contained up to 1130 ng/g pp'DDE and up to 670 ng/g total PCBs. Those concentrations were much higher than in a reference site, but an order of magnitude below concentrations associated with health effects in songbirds. Among four stormwater ponds and one natural wetland in Guelph, there was statistically lower hatching success of northern leopard frogs (Rana pipiens) eggs, and larvae Look longer to metamorphose into frogs at two stormwater ponds. Statistically fewer tadpoles survived to metamorphosis at one stormwater pond, We conclude that stormwater ponds do not offer clean ecosystems for wildlife and the monitoring of contamination and its effects within stormwater ponds is necessary.