Great Lakes water levels trended downward in September. The pins on the maps below reveal plots of the current year’s daily lake levels (blue) compared with last year’s levels (black) and last year’s annual average (dark red). The monthly averages are shown as a step plot through the daily averages. Plotted in the background are the coordinated (official) averages (green), record highs (cyan), and record lows (brown):
The water level of Lake Superior is down 2″ in the last month and down 4″ in the last year. The lake is still 10″ above the average October level, but is now 5″ below the record highest October average level set in 1985.
The water level of Lake Michigan is down 4″ in the last month. It’s even with the level of October 3, 2019 and it’s 8″ below the record high water level of October 1986. The lakes are still 33″ above the October average level.
The water level of Lake Erie is down 6″ in the last month and is also down 4″ in the last year. The level is still 26″ above the October average level, but it’s 8″ below the record level reached in 1986.
The water level of Lake Ontario is down 8″ in the last month and down 14″ in the last year. The level is now 6″ above the average October level, but is 18″ below the record highest October level set in 1945.
The water level of Lake St. Clair is down 7″ in the last month and down 4″ year-to-year. The level is still 29″ above the October average level, but it’s now 9″ below the record highest level set in 1986.
Here’s a map showing the rivers that connect the Great Lakes. All the rivers that connect the Great Lakes have above average flow. Keep in mind that with these rivers, the wind direction and speed change these numbers. A strong northwest wind will help push water out of Lake Superior. A strong north wind will push water down the St. Clair River.
The St. Mary’s River (early Sat. AM) had a flow of 101,000 cfs. The St. Clair River at Port Huron MI had a flow of 260,000 cfs, compared to an average flow of 193,000 cfs.
The Grand River in G.R. has a flow of 2,440 cfs, compared to an average flow of 1,670 cfs. The Kalamazoo River at Comstock has a flow of 783 cfs, compared to an average flow of 534 cfs. The Tittawabassee River at Midland has a flow of 882 cfs, compared to an average flow of 625 cfs and the Fox River at Appleton WI has a flow of 5,240 cfs, compared to an avearge flow of 2,880 cfs.
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