Erosion lowers water levels on Lakes Michigan and Huron

This story from MLive.com is interesting especially in light of current lake levels. In essense, Lake Huron is 9 inches up from one year ago but may have been substantially higher if not for dredging and riverbed erosion in Lake St Clair:

Erosion at the bottom of Lake St. Clair has caused a significant dropoff in water levels on Lake Huron and Lake Michigan for more than a century, says a privately funded report released Monday. The dropoff, apparently caused by dredging and other human activities on the river, has caused the two lakes to decline 32 inches since around 1860, the report said. The volume of water they have lost during that time would fill Lake St. Clair 28 times.

Authorities were long aware that Lakes Huron and Michigan, which are geologically linked, had declined relative to the level of Lake Erie to the south, which receives their outflow, the report said. But a dropoff of 8 to 13 inches since a shipping channel was dug in the river in 1962 has gone undetected until now, said the report by W.F. Baird & Associates, a coastal engineering firm. It indicates that continuing erosion is punching an ever-larger hole at the foot of the river, allowing water to rush from Lake Huron faster than anyone knew.

The $200,000 study was commissioned by the research arm of the Georgian Bay Association, a group representing about 17,000 people who live on the islands and coasts of the sprawling bay on the eastern side of Lake Huron. Members wanted to find out whether low water levels in recent years were being caused by something other than the usual cyclical fluctuations, said its president, John Pepperell.