Ft.

-1

0

+ 1

+ 2

+ 3

+ 4

+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9

+ 1.2

+ 1.5

2020

AUG

1947

SEP

1947

OCT

1945

NOV

1945

DEC

1945

2021

JAN

1946

FEB

1952

MAR

1952

APR

1973

MAY

2017

JUN

2019

JUL

2019

AUG

1947

1934

SEP

1947

1934

OCT

1945

1934

NOV

1945

1934

DEC

1945

1934

2022

JAN

1946

1935

FEB

1952

1936

MAR

1952

1935

APR

1973

1935

MAY

2017

1935

JUN

2019

1935

JUL

2019

1934

AUG

1947

1934

SEP

1947

1934

OCT

1945

1934

NOV

1945

1934

DEC

1945

1934

23

JAN

1946

1935

LAKE ONTARIO

CHART DATUM 243.3 FEET (74.2 METERS)

Ft.

-1

0

+ 1

+ 2

+ 3

+ 4

+ 5

+ 6

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9

+ 1.2

+ 1.5

+ 1.8

2020

AUG

2019

SEP

2019

OCT

1986

NOV

1986

DEC

1986

2021

JAN

1987

FEB

2020

MAR

2020

APR

2020

MAY

2020

JUN

2019

JUL

2019

AUG

2019

1934

SEP

2019

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1934

2022

JAN

1987

1935

FEB

2020

1936

MAR

2020

1934

APR

2020

1934

MAY

2020

1934

JUN

2019

1934

JUL

2019

1934

AUG

2019

1934

SEP

2019

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1934

23

JAN

1987

1935 LAKE ERIE

CHART DATUM 569.2 FEET (173.5 METERS)

Ft.

-1

0

+ 1

+ 2

+ 3

+ 4

+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9

+ 1.2

+ 1.5

2020

AUG

2020

SEP

2020

OCT

1986

NOV

1986

DEC

1986

2021

JAN

2020

FEB

1986

MAR

2020

APR

2020

MAY

2020

JUN

2020

JUL

2019

AUG

2020

1934

SEP

2020

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1964

2022

JAN

2020

1936

FEB

1986

1926

MAR

2020

1934

APR

2020

1926

MAY

2020

1934

JUN

2020

1934

JUL

2019

1934

AUG

2020

1934

SEP

2020

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1964

23

JAN

2020

1936

LAKE ST. CLAIR

CHART DATUM 572.3 FEET (174.4 METERS)

Ft.

-1

0

+ 1

+ 2

+ 3

+ 4

+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9

+ 1.2

+ 1.5

2020

AUG

2020

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2021

JAN

2020

FEB

2020

MAR

2020

APR

2020

MAY

2020

JUN

2020

JUL

2020

AUG

2020

1964

SEP

1986

1964

OCT

1986

1964

NOV

1986

1964

DEC

1986

2012

2022

JAN

2020

2013

FEB

2020

1964

MAR

2020

1964

APR

2020

1964

MAY

2020

1964

JUN

2020

1964

JUL

2020

1964

AUG

2020

1964

SEP

1986

1964

OCT

1986

1964

NOV

1986

1964

DEC

1986

2012

23

JAN

2020

2013

LAKES MICHIGAN-HURON

CHART DATUM 577.5 FEET (176.0 METERS)

Ft.

-1

0

+ 1

+ 2

M.

-0.3

0

+ 0.3

+ 0.6

2020

AUG

2019

SEP

2019

OCT

1985

NOV

1985

DEC

1985

2021

JAN

2020

FEB

2020

MAR

1986

APR

1986

MAY

2019

JUN

2019

JUL

2019

AUG

2019

2007

SEP

2019

2007

OCT

1985

1925

NOV

1985

1925

DEC

1985

1925

2022

JAN

2020

1926

FEB

2020

1926

MAR

1986

1926

APR

1986

1926

MAY

2019

1926

JUN

2019

1926

JUL

2019

1926

AUG

2019

2007

SEP

2019

2007

OCT

1985

1925

NOV

1985

1925

DEC

1985

1925

23

JAN

2020

1926

LAKE SUPERIOR

CHART DATUM 601.1 FEET (183.2 METERS)

ELEVATIONS REFERENCED TO THE CHART DATUM OF EACH RESPECTIVE LAKE

Superior

602.43

183.62

602.23

183.56

603.22

183.86

2019

600.26

182.96

1926

602.10

183.52

MichHuron

580.09

176.81

580.71

177.00

582.22

177.46

2020

576.71

175.78

1964

579.40

176.60

St.

Clair

575.89

175.53

576.54

175.73

577.56

176.04

2019

572.51

174.50

1934

574.87

175.22

Erie

572.87

174.61

573.52

174.81

574.57

175.13

2019

569.06

173.45

1934

572.01

174.35

Ontario

245.90

74.95

245.44

74.81

248.69

75.80

2019

243.24

74.14

1934

246.10

75.01

JULY MEAN LAKE LEVELS

(IGLD 1985)

* 2022 Ft.

M.

2021 Ft.

M.

** MAX.

Ft.

M.

Yr.

** MIN.

Ft.

M.

Yr.

** AVG. Ft.

M.

* provisional

** Average, Maximum and Minimum for period 1918-2021

LEGEND

LAKE LEVELS

RECORDED

PROJECTED

AVERAGE **

MAXIMUM **

1985

1985

1973 1973

MINIMUM **

1936

1934

1926 1934

AUGUST 2022

US Army Corps

of Engineers

Detroit District

MONTHLY BULLETIN OF

LAKE LEVELS FOR THE

GREAT LAKES

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. 

The levels on the hydrographs are shown in

both feet and meters above (+) or below (-) 

Chart Datum. Chart Datum, also known as 

Low Water Datum, is a reference plane on 

each lake to which water depth and Federal 

navigation improvement depths on navigation 

charts are referred.

All elevations and plots are referenced to the

International Great Lakes Datum 1985 (IGLD 1985). 

IGLD 1985 has its zero base at Rimouski, Quebec 

near the mouth of the St. Lawrence River 

(approximate sea level). 

Visit our website for more information:

https://www.lre.usace.army.mil/greatlakes
Information

Recorded monthly mean water levels in this bulletin are results from a representative network of water level gages 

on each lake (see cover map). Providers of these data are U.S. Department of Commerce, NOAA, National Ocean 

Service, and Integrated Science Data Management, Department of Fisheries and Oceans, Canada. Detroit District, 

Corps of Engineers and Environment and Climate Change Canada derive historic and projected lake levels under 

auspices of Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data.

The Corps makes the bulletin monthly as a public service. The Corps also, on a weekly basis publishes online the 

Great Lakes, Connecting Channels and St. Lawrence River Water Levels and Depths, which supplies a forecast of 

depths in connecting rivers between Great Lakes and International Section of St. Lawrence River. This Monthly 

Bulletin of the Lake Levels for the Great Lakes is available free of charge by writing to address shown on front cover, 

by calling (313) 226-6441 or emailing hhpm@usace.army.mil. Notices of change of address should include the name 

of the publication. This information is available on the internet at 

https://www.lre.usace.army.mil/Missions/GreatLakesInformation.aspx.

Great Lakes Basin Hydrology

July 2022

July preliminary precipitation estimates show Great Lakes basin received below average precipitation at 89 percent 

of average. Preliminary estimates show Lakes Superior, Michigan-Huron, Erie, and Ontario basins received 97, 82,

95, and 81 percent of average July precipitation, respectively. Precipitation is near average across Great Lakes basin 

over the past 12 months. July streamflow was near normal across the Great Lakes basin. Provisional estimates 

show July water supplies were near average for Superior and Ontario basins, and below average in Michigan-Huron 

and Erie basins. Outflows from all the Great Lakes were above average in July.

From June to July, water levels rose on Lake Superior by 2 inches and Lake Michigan-Huron levels did not change.

Lake St. Clair fell 1 inch, Lake Erie fell 3 inches, and Lake Ontario fell 7 inches. Great Lakes 6-month water levels 

forecast projects Lake Superior to continue a seasonal rise into August before declining, Lake Michigan-Huron will 

begin a seasonal fall, and Lakes St. Clair, Erie, and Ontario will continue to decline.

PRECIPITATION (INCHES)

BASIN

July 12-Month Comparison

2022 Average Diff. % Of

Average

Last 12 

Months

Average Diff. % Of

(1900-2018) (1900-2018) Average

Superior 3.16 3.27 -0.11 97 30.07 30.59 -0.52 98

Michigan-Huron 2.48 3.03 -0.55 82 30.08 32.87 -2.79 92

Erie 3.27 3.43 -0.16 95 33.94 35.91 -1.97 95

Ontario 2.57 3.19 -0.62 81 35.37 36.34 -0.97 97

Great Lakes 2.80 3.15 -0.35 89 31.14 32.99 -1.85 94

Lake

July WATER SUPPLIES1 (cfs) July OUTFLOW2 (cfs)

2022 Average3

(1900-2008) 2022 Average3(1900-2008)

Superior 130,000 127,000 94,000 81,000

Michigan-Huron 92,000 128,000 214,000 195,000

Erie -1,000 7,000 234,000 213,000

Ontario 19,000 23,000 305,000 261,000

Notes: Values (excluding averages) are based on preliminary computations; cfs denotes cubic feet per second.

1 Net basin supply is the net result of precipitation falling on the lake, runoff from precipitation falling on the land which flows to 

the lake, and evaporation from the lake. Negative net basin supply denotes evaporation exceeded runoff and precipitation. 

The net total supply can be found by adding the net basin supply and the outflow from the upstream lake.

2 Does not include diversions.

3 Lake Ontario average water supplies and average outflows are based on period of record 1900-2005