2025-May-20
May 18 Water Levels Report
Lake Michigan-Huron is 8 inches below its level at this time last year.
From a month ago, the water levels on Lakes Superior, Michigan-Huron, St. Clair, Erie & Ontario are up 6, 4, 4, 4 & 7 inches, respectively. Lakes Superior, Michigan-Huron, St. Clair & Erie are lower by 2, 8, 7, & 6 inches, respectively, than they were at this time last year. Lake Ontario is up 1 inch. Lakes Superior, Michigan-Huron & Ontario are 4, 6 & 2 inches below their long-term May averages. Lakes St. Clair and Erie are 3 & 5 inches above their long-term May averages, respectively. All the lakes remain well below their May record highs.
In a month, Lakes Superior, Michigan-Huron, St. Clair & Ontario are expected to rise by 4, 2, 1 & 3 inches, respectively. Lake Erie levels are predicted to fall by 1 inch.
Lake Superior’s outflow into the St. Marys River is expected to be below average for May. Lake Michigan-Huron’s outflow through the St. Clair River, Lake St. Clair’s outflow through the Detroit River, and Lake Erie’s outflow through the Niagara River are projected to be above average for May. Lake Ontario’s outflow through the St. Lawrence River is forecasted to be near average in May.
With regard to the forecast graph below and the more recently updated first graph in this report, the USACE is predicting that the most likely outcome is that the Lake Michigan-Huron level will continue to rise through June, level off in July, and then drop in August and September.
Monthly mean water levels for the previous year and the current year to date are shown as a solid line on the hydrographs. A projection for the next six months is given as a dashed line. This projection is based on the present condition of the lake basin and anticipated future weather. The shaded area shows a range of possible levels over the next six months dependent upon weather variations. Current and projected levels (solid and dashed lines) can be compared with the 1918-2021 average levels (dotted line) and extreme levels (shown as bars with their year of occurrence). The legend below further identifies the information on the hydrographs.
