Ecosystem Recovery Analysis of Amos Palmer Drain, in Milan, Michigan

Abstract

The purpose of this study was to determine how the North Branch of Amos Palmer Drain (Wayne County, Michigan) stream ecosystem changed after a mining company stopped discharging waste water into the stream in 2003. Macroinvertebrates, stream morphology, habitat, and water chemistry samples were collected in 2010 at a site on Amos Palmer Drain and other similar sites within the watershed and were compared to samples collected at the same locations from 1997, 1999 and 2002 using t-tests, correlations and box plots. At NB of Amos Palmer Drain, significant increases were found in the number of families from 1997 to 2010, and average tolerance scores of the macroinvertebrate community from 1997, 1999, and 2002 to 2010. Significant decreases were found in all of the flow measurements, pH, and conductivity between 1999 and 2002, and 2010. Macroinvertebrate assemblage changes were likely due to changes in overall habitat, caused primarily by a decrease in flow to a more natural flow regime with levels reflecting conditions found in similar sites in the watershed. The variables measured were comparable to other local sites of similar size. Evidence supports the hypothesis that the NB of Amos Palmer Drain has reverted back to its state prior to mining drainage, though the state of the site previous to pollution was not assessed.