Update on Lake and River Levels

Bill's Blog

The above pic. is the South Manitou Island Lighthouse (NPS photo). I haven’t posted lake levels in the past few weeks, so let’s get caught up:

Graph of the Water Level of Lake Superior

The water level of Lake Superior is unchanged over the last month, but it’s down 8″ in the last year and down 12″ since July 2019. It’s now only one inch above the average July water level.

Graph of the Water Level of Lake Michigan/Huron

The water level of Lake Michigan/Huron (one lake for lake level purposes) is up 3″ in the last month (we’ve had more rain), but still down 18″ from one year ago. That represents a loss of approximately 14.22 TRILLION gallons of water. We have more beach to enjoy this summer and the low level has caused a more robust dredging of some of the channels this summer. Lake Michigan/Huron is still 16″ above the July average level.

Graph of the Water Level of Lake Erie

The water level of Lake Erie is up 3″ in the last month (more rain), but still down 11″ in the last year. The lake is 17″ above the average July water level, but it’s now 14″ below the high level of July 2019.

Graph of the Water Level of Lake Ontario

The level of Lake Ontario is up 4″ in the last month, but down 15″ in the last year. The lake is now 8″ BELOW the average July water level and a full 39″ below the high level of July 2019.

Graph of the Water Level of Lake St. Clair

Lake St. Clair is also up 4″ in the last month (higher than average rainfall), but down 13″ in the last year. The lake is 19″ above the July average level.

International Border – Sault Ste. Marie

The pic. above is the International border crossing at Sault Ste. Marie. This is early Saturday morning and as you can see, no traffic. Hopefully, soon the border crossing will be back to “normal”.

The flow on the rivers that connect the Great Lakes continues to be mostly above average, though the flow has been reduced a bit because of the lower lake levels.

The St. Marys River at S. Ste. Marie had a flow of 72,400 cubic feet per second. The average flow for today is 89,300 cfs. The below average flow is likely the result of an east wind that would tend to blow the water back toward Lake Superior. The flow on these connecting rivers and the rivers that empty into the Great Lakes varies quite a bit with the wind direction and speed. A strong enough wind can cause rivers to actually flow backwards. On rare occasion, a strong east wind can reverse the flow under the Mackinac Bridge (usually west to east, it can become east to west for a time).

The flow on the St. Clair River at Port Huron was 229,000 cfs, compared to an average flow of 201,000 cfs.

The Grand River at Ionia has a flow of 1,990 cfs, compared to an average flow of 776 cfs. The Ionia Free Fair is on right now. There’s no river water in the fairgrounds and there won’t be this coming week. The Thornapple River at Hastings has a flow of 273 cfs, compared to an average flow of 134 cfs. The river has come down quite a bit in the last few weeks. The Kalamazoo River at Comstock has a flow of 1,050 cfs, compared to an average flow of 616 cfs. The Muskegon River at Croton has a flow of 1,780 cfs, compared to an average flow of 1,270 cfs. The St. Joseph River at Niles has a flow of 3,590 cfs. compared to an average flow of 2,180 cfs.

The Saginaw River at Saginaw has a flow of 5,140 cfs compared to an average flow of 1,700 cfs. The Fox River at Green Bay WI has a flow of 9,980 cfs, compared to an average flow of 2,490 cfs.

North American Snow and Ice Cover

While the Great Lakes are (of course) ice free right now, there is still some ice in Hudson Bay. Villages around Hudson Bay usually get their yearly supplies by boat in August and September when the Bay is ice free. If the ice lingers, the Canadian Coast Guard cuts through the ice so the ships can get through. If by chance they couldn’t do that, supplies would have to come by air and that would be more expensive. As usual, there is plenty of ice at the North Pole (Santa’s doing fine!) and Greenland keeps it’s permanent snow cover in the summer.


Daily mean temperature and climate north of the 80th northern parallel, as a function of the day of year.

The graph above from the Danish Meteorological Institute shows average temperature from 80 – 90 degrees north latitude by day for 2021 compared to average (the green line of the graph). The Arctic temperatures were will above average last winter and early spring, but they have been slightly cooler than average so far this summer. I should note that even though the air temperature was way above average last winter, it was still well below freezing and there was virtually no snow or ice melting. The melt occurs in the late spring and summer when the sun is relatively higher in the sky and temperatures climb above freezing.

At Utqiagvik (Barrow), Alaska, the average temperature for this July so far has been 39.6°, which is 2.7° cooler than average. The warmest temperature so far this month has been 56° and the warmest this summer has been 59° on June 18th. The first day that Utqiagvik reached 40° this year was June 10th.

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