At the beginning of April, 2021, all of the Great Lakes were at least 24 cm above their chart datum level.
Lake Superior’s beginning-of-April level was 20 cm above average, which is 16 cm lower than last year.
Lake Michigan–Huron’s beginning-of-April level was 60 cm above average and 34 cm lower than it was last year. This is the 9th highest in the period of record, with a level that is 34 cm lower than the previous beginning-of-month record for April, set in 2020.
Lake Erie was 44 cm above average at the beginning of April and 45 cm lower than the record high last year at this time.
Lake Ontario’s level at the start of April was 21 cm below average and 68 cm lower than the water level from last year.