Environmental quality assessment of Lake St. Clair in 1983 as reflected by the distribution of benthic invertebrate communities
In May of 1983, the Ontario Ministry of the Environment conducted a benthic invertebrate and sediment chemistry survey of Lake St. Clair to evaluate the environmental quality of the lake and determine the impact of major contaminant sources, particularly the St. Clair River, on the aquatic environment of the lake. Analysis of the invertebrate and sediment chemistry data suggested that the environmental quality of Lake St. Clair, Anchor Bay and the lower reach of the St. Clair River was generally good. Mesotrophic conditions prevailed in the central basin of the lake and Anchor Bay and in the lower part of the St. Clair River, while oligo-mesotrophic conditions were present in the shallower nearshore areas of the lake and Anchor Bay. Sediment concentrations of metals in the lake were low and generally considered non-polluted according to the US EPA's and Ontario MOE's guidelines. Neither the St. Clair or Thames rivers, the two largest tributaries and potential sources of contaminants, had any perceivable effect on the environmental quality of the lake. Local minor impairments of environmental quality were observed at the mouths of the Puce, Belle and Ruscom rivers and near the town of St. Clair Shores, Michigan. Reduced environmental quality related to organic matter enrichment was observed at deeper sites near the St. Clair River delta. Notwithstanding these localized minor effects from rivers and shoreline towns, the distribution of benthic invertebrates in the lake was primarily related to the physical characteristics of the environment, eg. sediment grain size and water depth, and not to pollution.
Biological Surveys/Investigations Reports