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 pond s 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 Gre ater Toronto Area, Ontario, was performed in 1997 and 1998. At 9 of 16 site s, copper levels in water exceeded the Canadian Water Quality Guidelines (C WQGs) 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. S ediments from all ponds contained concentrations of at least one contaminan t that exceeded the "lowest effects level" (LEL) of the Guidelines for the Protection and Management of Aquatic Sediment in Ontario. Stormwater pond s ediments contained concentrations exceeding provincial sediment quality gui delines at the LEL for polychlorinated biphenyls (PCBs), gamma-hexachlorocy clohexane (g-bhc), total Kjeldahl nitrogen (TKN) and total phosphorus (TP), turbidity, oil and grease, total PAHs, chromium, zinc, cadmium, copper, le ad, 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 se vere effect level for chromium. Concentrations of lead, zinc, cadmium and t otal PAHs in sediments were correlated with the age of the ponds. Concentra tions of organochlorine pesticides and PCBs were low (<0.08 mu g/g wet weig ht) in pumpkinseed (Lepomis gibbosus) collected from two ponds in Guelph. R ed-winged blackbird (Agelaius phoeniceus) eggs from two ponds in Toronto co ntained up to 1130 ng/g pp'DDE and up to 670 ng/g total PCBs. Those concent rations were much higher than in a reference site, but an order of magnitud e below concentrations associated with health effects in songbirds. Among f our stormwater ponds and one natural wetland in Guelph, there was statistic ally 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 po nd, We conclude that stormwater ponds do not offer clean ecosystems for wil dlife and the monitoring of contamination and its effects within stormwater ponds is necessary.