Lake Michigan's Drain
WBEZ reports on a recent press conference by the Army Corps of Engineers predicting that if the current Midwestern drought continues long enough, Lake Michigan water levels will fall below the gradient of the Chicago River, effectively re-reversing the river to flow back toward the lake.
The original flow of the south branch of the Chicago River was reversed by excavating the Sanitary & Ship Canal below the height of the low continental divide just west of Chicago which defined the natural watershed of Lake Michigan. Locks were later built at the mouth of the Chicago River to control the flow of lake water into the canal.
Though Lake Michigan water levels fluctuate over long cycles, dredging the St. Clair River which drains Lake Michigan and Lake Huron is suspected to be increasing the outflow from the lakes. Lake levels are normally low in winter due to low precipitation, but the lingering 2012 drought, as well as increased evaporation from a lake that does not freeze over as often as in the past due to climate change, have reduced Lake Michigan to record low levels.