Municipal landfill impacts on a natural stream located in an urban wetland in regional Niagara, Ontario

Landfills constructed on the Niagara Escarpment may threaten natural biota in the region, which was designated a UN Ecological Biosphere Preserve Area in 1989. The effect of water flowing from an urban landfill on the sediment chemistry and biotic community structure of a small forested creek in southern Ontario, on the edge of the Niagara Escarpment, was studied. The headwaters of Leawood Creek are immediately below this municipal landfill. Creek waters and sediments had high iron and zinc levels compared with those in nearby unimpacted creeks, probably due to metal components in the landfill. Upper and lower parts of the creek had substantially different biota, and aquatic invertebrates also were substantially different before and after creation of the landfill, with pollution-sensitive species being replaced by pollution-tolerant species.