:“In 1962, a shipping channel was dredged out of the St. Clair River that effectively opened a bigger drain hole in the Great Lakes,” said John Pepperell, president of Georgian Bay Association, a Canadian non-profit organization which coordinated the six-month study by W.F. Baird & Associates Coastal Engineers for GBA Foundation, a registered Canadian research charity. “Everyone knew about the one-time loss of water that was caused when that channel was first opened. However, we have now discovered that ongoing erosion is making the outlet from Lake Huron larger, allowing water to leave faster than had been recognized.”
According to the report, the channel is eroding and is now over 60 feet deep at critical sections near the outflow. It only needs to be 30 feet deep for shipping. Pepperell said that “without implementation of corrective measures, this drop represents an irreversible and ongoing decline in the long-term average levels of Lakes Michigan and Huron.”
You can read the whole report here (PDF 141 pages), the press release here,and the Army Corps of Engineers' rebuttal here. From Leelanau, surrounded by Lake Michigan, it's hard to ignore what seems to be ever-widening beaches. Lake levels do come up after a hard rain, but they drop soon after. We have been several winters without good ice cover on Lake Michigan (ice prevents evaporation) and big snowfalls to melt and replentish the lakes.