As has been shown in earlier posts, Michigan has experienced a hot and dry summer. These conditions have not only affected Michigan’s land, but also the Great Lakes. The chart above shows the historical long-term averages and record highs and lows for the each lake in the Great Lakes basin for the month of September. The month of September was chosen because it is the end of summer and the current month. Lake Michigan and Lake Huron are grouped as one throughout this post as they are hydraulically the same body of water. Also, throughout this post it must be kept in mind that Lake Superior is the largest and deepest of the lakes followed by Lake Michigan/Huron, Lake St. Clair, Lake Erie, and then Lake Ontario.
The above five charts show the historical data on water levels in the Great Lakes since 1918; each chart only looks at water levels in the month of September. All the charts show there has been an overall trend of water levels declining from where they are at in previous years. This trend began in 2009 for lakes Superior, Huron, and Michigan while the remaining three have seen water levels begin to steadily drop only about a year or two ago. Keith Kompoltowicz, chief of watershed hydrology at the U.S. Army Corps of Engineers Detroit office, said some researchers and media outlets like to look for a 15 or 30 year trend to the flucuation of the water levels. However, he said no short-term or long-term trends can be determined since U.S. Army Corps of Engineers has only been keeping data since 1918. Currently, U.S. Army Corp of Engineer data shows that if September, October, and November continue to experience low amounts of precipitation lakes Michigan and Huron will likely drop below record water levels. As water levels begin to drop this also has an affect on the ecosystems which live in and around these lakes.