Great Lakes water levels lower than 2020 heading into spring rise

DETROIT — Great Lake water levels in 2021 are tracking below last year’s levels, though Lakes Superior,
Michigan, Huron, St. Clair and Erie remain well above long-term average levels, according to U.S. Army
Corps of Engineers officials who track and forecast Great Lakes water levels.
Lake Ontario recently fell slightly below long-term average levels. The February monthly mean water
levels ranged from 7 to 23 inches below levels from this time last year.
Since November 2020, the Great Lakes basin experienced four consecutive months of below average
precipitation. This combined with a cold air outbreak during February led to increased evaporation
across the lakes and caused a St. Clair River ice jam to develop. When ice jams occur, water levels
downstream of the restriction decline, while water levels upstream of the restriction rise.
“Drier conditions this winter aided in seasonal declines on all the lakes,” said Detroit District
Watershed Hydrology Branch Chief Chris Warren. “However, as water levels begin their seasonal rise there
is still potential for coastal impacts since water levels remain high.”
Late winter and early spring are typical Great Lakes seasonal rise periods because of increased rainfall
and runoff. Water levels typically peak in the summer or early fall. Even with lower lake levels some
lakes are still well above average and coastal flooding and shoreline erosion are possible, especially
during periods of active weather and increased wave action.
The most recent six-month forecast of Great Lakes water levels predicts levels to remain below record
high levels, but above average on all lakes, except Lake Ontario. Lake Ontario is forecast to remain
near average levels.
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