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.