Great Lakes Water Levels
Great Lakes water levels constitute one of the longest high quality hydro meteorological data sets in North America with reference gage records beginning about 1860 with sporadic records back to the early 1800's. These levels are collected and archived by NOAA's National Ocean Service.
Water Level Plots
Daily levels compared with last year's levels
Michigan, Huron, St. Clair, and Erie
Daily levels compared with monthly Min, Max, and Mean levels
A hydrograph provides a way of seeing seasonal and yearly changes in the flow or discharge of a waterway. The hydrographs for the Great Lakes period of record (starting in 1860 or 1900) illustrate different water regimes over time.
The data files below contain the annual average water level for every year as well at the long-term mean level in meters, IGLD85.
What is a seiche? (pronounced "saysh")
Like water sloshing in a bathtub, seiches are tide-like rises and drops in Great Lakes coastal water levels caused by prolonged strong winds that push water toward one side of the lake, causing the water level to rise on the downwind side of the lake and to drop on the upwind side. When the wind stops, the water sloshes back and forth, with the nearshore water level rising and falling in decreasingly small amounts
on both sides of the lake until it reaches equilibrium.