Studies of the river bottom (sediment), begun in 1957, showed populations of benthic life (organisms that live in the sediment), that were characteristic of degraded conditions, i.e. the populations were smaller and there were fewer benthic species along the Canadian shoreline.
The Ministry of Environment and the Sarnia Lambton Environmental Association have done several studies of the river. These studies, begun in 1957, show areas where sediments were degraded (red) and those that were impaired (yellow). Over time the degraded and impaired areas have decreased in size to that shown on the outline of the river (1995).
More recent studies show the degraded and impaired areas decreasing even further to those shown on the graph in 1995.
The right side of the graph (above) shows three areas where testing in 1995 showed that the sediments were still impaired.