Great Lakes Water LevelsDecember 10th, 2012 at 10:30 am by Bill Steffen under Bill's Blog, News, Weather
Lake Michigan/Huron is down 2″ in the last month and is now down 17″ in the last year. The lake is now 28″ below the long-term December average and very close to the record December low level back in 1964. The other Great Lakes have not seen quite that big a drop. Lake Superior is unchanged in the last month and down only one inch from one year ago. The lake is 12″ below the long-term average. Lake Erie and Lake Ontario are both down 2″ on the last month. Lake Erie is down 23″ from one year ago, but is only 7″ below the December average. Lakes Erie and Ontario fluctuate at a much greater rate in the near term. Lake Erie was well above average one year ago. Lake Ontario is down 14″ in the last year and is 11″ below the century average. Grand Rapids had only 0.49″ of precipitation in November, the 3rd driest November ever. That followed a very wet October with 6.32″ of precipitation (3.06″ above average). Grand Rapids has actually had above average rainfall over the last 22-months combined. I have not had the time to research precipitation throughout the Great Lakes basin, but it’s puzzling to me to see such a drop when you see overall precipitation closer to average. I’ve had people tell me that they are pumping more water down the Chicago River to keep the level of the Mississippi (I could not find any evidence of that) and that the dredging of the Detroit and St. Clair Rivers has allowed more water to escape to Lake Huron. I’ve also had people ask if there is a “hole” in the bottom of the lake where water is escaping. Here’s a plot of ice cover on Lake Michigan. Here’s a plot of each winter from 1973-2002. The water level of the lake reached its lowest point in 1964 and its highest level in 1986-87…now down in 2011-12…about a 23-year cycle of late, though that may mean nothing. If and when I have time, I’ll do some more scouting around and see what I can find.