Each month we summarize reports and data from the Army Corps of Engineers – Detroit District’s Monthly and Weekly reports for Great Lakes Water Levels and Great Lakes Water Level History. We present a single-page view of the changes in lake levels from month to month are presented for Lakes Huron-Michigan, Lake Superior, Lake Erie, Lake Ontario, and Lake St. Clair.
Table of Contents
Great Lakes Basin Weather Conditions Over the Past Month Affecting Water Levels
In the month of April, the Great Lakes region saw precipitation levels rise to about 25% above the average, meaning there was more rain and snow than usual. Remarkably, Lake Superior had over 60% more precipitation than its average for the second April in a row.
The basins of Lakes Michigan-Huron and Ontario also experienced above-average levels of precipitation. However, Lake Erie did not follow this trend and received less precipitation than average. If we look at the past year, the total precipitation for each lake basin was either close to or less than the average. Lake Superior significantly exceeded its average in terms of water supplies, while Lakes Michigan-Huron and Ontario also had more than their usual supplies. Conversely, Lake Erie’s water supply was below average.
Outflow Estimates Affecting Great Lakes Levels
In April, the outflows of the connecting channels for every lake were higher than average. The amount of water flowing out of Lake Superior through the St. Marys River, and out of Lake Michigan-Huron through the St. Clair River, is predicted to be more than usual for May. Similarly, the water flowing out of Lake St. Clair through the Detroit River, out of Lake Erie through the Niagara River, and out of Lake Ontario through the St. Lawrence River, is also expected to be above the average for this month.
Observations as of May 12, 2023 – Last weekend through Wednesday, the weather in the Great Lakes area was typical for this time of year. The warmest day was Sunday, with temperatures soaring above 80 degrees Fahrenheit in cities like Chicago, IL, Fort Wayne, IN, and Detroit, MI. Aside from 1.1 inches of rain in Sault Sainte Marie, MI, and 1.5 inches in Fort Wayne, IN, over the weekend, there wasn’t a lot of rain in the Great Lakes area over the past week.
This coming weekend, most of the Great Lakes region will start off warmer than usual, with high temperatures reaching the upper 70s on Friday. But by Sunday and continuing into the early part of next week, temperatures will be near or slightly below the usual for this time of year. Duluth, MN, is the exception where the temperature could near 80 degrees on Monday. Rain showers are expected in the southern part of the Great Lakes region on Friday.
Compared to Last Year, Lake Ontario & Superior Are Higher, Michigan-Huron Lower, St.Clair, and Erie Are the Same
The water levels in Lakes Superior, Michigan-Huron, and Ontario on May 12th are predicted to be 6 to 11 inches higher than they were just a month ago. In contrast, Lakes St. Clair and Erie are only 1 to 2 inches above their levels from last month. Looking at the levels from a year ago, Lakes Superior and Ontario are expected to be 9 to 10 inches higher on May 12th, while Lake Michigan-Huron is actually 2 inches lower than it was at this time last year. Lakes St. Clair and Erie’s water levels are about the same as they were a year ago.
Furthermore, the water levels for all these lakes on May 12th are higher than the usual levels for May. Over the next 30 days, Lakes Superior, Michigan-Huron, and St. Clair are predicted to rise by 3, 3, and 1 inches, respectively. On the other hand, Lakes Erie and Ontario’s water levels are expected to go down by 1 to 2 inches by June 12th.
Great Lakes Hydrographs
On the hydrographs, monthly mean water levels for the prior year and the current year are depicted as a solid line. A dashed line represents a forecast over the following six months. This forecast is based on the current state of the lake basin and forecasted future weather. The shaded region depicts a range of probable values during the following six months based on weather changes. Current and forecast levels (solid and dashed lines) can be compared to the 1918-2021 average and extreme values (dotted lines) (shown as bars with their year of occurrence). The legend below identifies the information on the hydrographs in further detail.
Lakes Michigan-Huron Water Levels Remain Above Average
Current Month’s Water Levels for Lakes Michigan-Huron
Lake Michigan-Huron is currently experiencing its usual seasonal increase in water level. The average water level of the lake rose 5 inches from March to April, reaching 579.27 feet. This April average was 6 inches higher than the Long Term Average (LTA) for April, 4 inches lower than the level in April 2022, and 29 inches lower than the record high for April set in 2020. The above-average rainfall and runoff in April also led to a higher-than-normal water supply to the lake.
According to the latest 6-month water level report, Lake Michigan-Huron will continue to rise until July. The lake level is predicted to be 2 to 3 inches lower than last year’s levels in May and June, almost the same as last year’s levels in July and August, and 2 to 4 inches higher than last year’s levels in September and October. Additionally, over the next 6 months, Lake Michigan-Huron is expected to be 7 to 9 inches above its LTA levels and 24 to 31 inches below the record high levels.
Lakes Michigan-Huron is expected to stay at or slightly above its long-term monthly mean water level well into 2023.
Lake Superior Water Level
Current Month’s Water Level For Lake Superior
Lake Superior started its usual increase in water level in April. The average water level for the month rose 2 inches from March to reach 601.97 feet. This level was 8 inches higher than the Long Term Average (LTA) for April, 9 inches higher than the level in April 2022, and 8 inches lower than the record high for April.
The lake received a lot of water in April, making it the third-highest April since 1900. This was largely due to about 60% more rain than usual. The latest 6-month forecast expects Lake Superior to keep rising into the summer. Over the next half year, the lake’s level is predicted to be 3 to 8 inches higher than last year’s averages, 6 to 11 inches above the LTA, and 5 to 9 inches below the record highs.
Lake Superior is expected to stay at or slightly above its long-term monthly mean water level well into 2023.
Lake St. Clair Water Level
Current Month’s Water Level for Lake St. Clair
In April, Lake St. Clair continued its usual seasonal increase, rising 5 inches from March. The average water level for the month was 575.52 feet. This level was an inch higher than April last year, 14 inches above the long-term average for April, but still 19 inches below the record high set in 2020.
The most recent 6-month forecast suggests that Lake St. Clair’s water level will stay around its April level for the next month. From May to September, the lake’s level is predicted to be 2 to 4 inches lower than last year’s levels. However, it’s expected to be about the same as last year’s level by October. Additionally, over the next six months, Lake St. Clair’s water level is expected to be 9 to 11 inches above the long-term average and 21 to 28 inches below the record high levels.
Lake St. Clair is expected to stay above its long-term monthly mean water level well into 2023.
Lake Erie Water Level
Current Month’s Water Level for Lake Erie
In April, the water levels on Lake Erie continued to rise. The average water level for the month was 572.97 feet, which was 4 inches higher than in March. This level was also 15 inches above the Long Term Average (LTA) for April, 2 inches above the level from last year, but 16 inches below the record high set in 2020. Lake Erie was the only lake that received less rain and water than usual in April.
The most recent 6-month forecast suggests that Lake Erie has reached its highest point for the season and will likely start to decrease in May. Over the next six months, the lake’s water levels are expected to be 1 to 2 inches lower than last year’s levels, 8 to 11 inches above the LTA, and 18 to 25 inches below the record-high levels.
Lake Erie is expected to stay slightly above its long-term monthly mean water level well into 2023.
Lake Ontario Water Level
Current Month’s Water Level for Lake Ontario
Lake Ontario’s average water level rose significantly in April, going up 10 inches from March to reach 246.49 feet. This level was the same as the level from April of last year, 9 inches above the Long Term Average (LTA) for April, and 20 inches below the record high for April. Lake Ontario received more water than usual in April, mainly because of about 40% more rain than average.
The latest 6-month forecast predicts that Lake Ontario will continue to rise into May. From May to October, the lake’s levels are expected to be 2 to 17 inches above the LTA, 10 to 13 inches higher than last year’s levels, and 14 to 22 inches below the record-high levels.
Lake Ontario is expected to drop below its long-term monthly mean water level in 3Q 2023.
Great Lakes Water Levels History Data 1919-2021
Below are the historical monthly mean average water levels for each of the Great Lakes. All levels are referenced to the International Great Lakes Datum of 1985 (IGLD 85). Water levels have been coordinated with Canada for 1918-2020.
Dynamic Great Lakes – Lake Level Viewer – From NOAA
Key Questions on Great Lakes Water Levels
Are Great Lakes water levels climbing or receding?
All the Great Lake water levels remain above their long-term average. Except for Lake Superior, all the Great Lakes are expected to remain above their long-term averages through 3Q 2023
Why are Great Lakes water levels staying so high?
Water levels follow a seasonal cycle where water levels rise in the spring due to increased precipitation and enhanced runoff from snowmelt. In the fall, the lakes generally decline due to an increase in evaporation as temperatures decline and cold air moves over the relatively warm lake waters. However, the high rates of precipitation in the Upper Great Lakes have kept overall lake levels high.
What is the elevation of Lake Ontario above sea level?
Lake Ontario is 245 feet above sea level. Lake Ontario is the last Great Lake before entering the St. Lawrence seaway and the Atlantic Ocean.
What is the elevation of Lake Erie above sea level?
Lake Erie is 569 feet above sea level. Lake Erie is the fourth largest Great Lake and hosts the largest fishery of all the other Great Lakes combined.
What is the elevation of Lake Michigan-Huron above sea level?
Lake Michigan-Huron is 577 feet above sea level. The Straits of Mackinac connect the two lakes together.
What is the elevation of Lake Superior above sea level?
Lake Superior is 600 feet above sea level. Fun fact: Lake Superior’s deepest parts are 733 feet below sea level and maintain a temperature of 39°F.
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