Ft.

-1

0

+ 1

+ 2+ 3+ 4+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9+ 1.2+ 1.5

2014

OCT

1945

NOV

1945

DEC

1945

2015

JAN

1946

FEB

1952

MAR

1952

APR

1973

MAY

1973

JUN

1952

JUL

1947

AUG

1947

SEP

1947

OCT

19451934

NOV

19451934

DEC

19451934

2016

JAN

1946

1935

FEB

1952

1936

MAR

19521935

APR

19731935

MAY

19731935

JUN

19521935

JUL

19471934

AUG

19471934

SEP

19471934

OCT

19451934

NOV

19451934

DEC

19451934

2017

JAN

1946

1935

FEB

1952

1936

MAR

19521935

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

2014

OCT

1986

NOV

1986

DEC

1986

2015

JAN

1987

FEB

1987

MAR

1986

APR

1985

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

1934

NOV

1986

1934

DEC

1986

1934

2016

JAN

19871935

FEB

1987

1936

MAR

1986

1934

APR

19851934

MAY

1986

1934

JUN

1986

1934

JUL

1986

1934

AUG

1986

1934

SEP

1986

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1934

2017

JAN

19871935

FEB

1987

1936

MAR

1986

1934

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

2014

OCT

1986

NOV

1986

DEC

1986

2015

JAN

1986

FEB

1986

MAR

1986

APR

1986

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

1934

NOV

1986

1934

DEC

1986

1964

2016

JAN

19861936

FEB

19861926

MAR

1986

1934

APR

19861926

MAY

1986

1934

JUN

1986

1934

JUL

1986

1934

AUG

1986

1934

SEP

1986

1934

OCT

1986

1934

NOV

1986

1934

DEC

1986

1964

2017

JAN

19861936

FEB

19861926

MAR

1986

1934

CHART DATUM 572.3 FEET (174.4 METERS)

ELEVATIONS REFERENCED TO THE CHART DATUM OF EACH 

Superior

602.69

183.70

602.66

183.69603.22

183.86

1985

600.46

183.02

2007

602.13183.53

MichHuron

579.99176.78579.72

176.70

581.96

177.38

1986

576.64

175.76

1964

579.07

176.50

St.

Clair

575.49

175.41

575.52175.42

576.90

175.84

1986

571.98174.34

1934

574.41

175.08

Erie

572.15174.39

572.51

174.50

573.59174.83

1986

568.83173.38

1934

571.39

174.16

Ontario

245.08

74.70

245.77

74.91

247.41

75.41

1947

242.49

73.91

1934

245.21

74.74

SEPTEMBER MEAN LAKE LEVELS

(IGLD 1985)

* 2016 Ft.

M.

2015 Ft.

M.

** MAX.

Ft.

M.

Yr.

** MIN.

Ft.

M.

Yr.

** AVG. Ft.

M.

* provisional** Average, Maximum and Minimum for period 1918-2015

1985

1985

1973 1973

1936

1934

1926 1934

LAKE ONTARIO

LAKE ERIE

LAKE ST. CLAIR

LEGEND

LAKE LEVELS

RECORDEDPROJECTEDAVERAGE **MAXIMUM **MINIMUM **

The levels on the hydrographs are shown inboth 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 shown in this bulletin are referenced to 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).
Information

Recorded water levels in this bulletin are derived from a representative network of water level gages on each lake 

(see cover map). Providers of these data are the U.S. Department of Commerce, NOAA, National Ocean Service, 

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

Corps of Engineers and Environment Canada derive historic and projected lake levels under the auspices of the 

Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data.

This bulletin is produced 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 provides a forecast of depths 

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

Monthly Bulletin of the Lake Levels for the Great Lakes may be obtained free of charge by writing to the address 

shown on the front cover, by calling (313) 226-6442 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 

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

Great Lakes Basin Hydrology

September 2016

According to preliminary estimates, the precipitation over the Great Lakes basin during September was, on the 

whole, near average. The Lake Erie and Superior basins received 21% and 10% more than average September 

precipitation, respectively. The Lake Michigan-Huron basin received average precipitation, but the Lake Ontario 

basin received just 64% of average precipitation. Net basin supplies were above average for the Lake Superior and 

Erie basins, while the Lake Michigan-Huron and Lake Ontario net basin supplies were below average for September.

The tables below list September precipitation and water supply information for the Great Lakes basin.

The monthly mean levels fell from August to September for all lakes but Superior, which had the same monthly mean 

level in August and September. All of the lakes were above their long-term average (LTA) monthly September levels,

except Lake Ontario. Lakes Superior, Michigan-Huron, St. Clair, and Erie were 7, 11, 13, and 9 inches above their 

LTA September levels, respectively. Lake Ontario was 2 inches below its LTA level. In September, Lake Superior 

was at the same level of one year ago, but Lake Michigan-Huron was 3 inches higher than its September 2015 level. 

Lakes Erie and Ontario were 4 and 8 inches below last year’s levels, respectively.

PRELIMINARY PRECIPITATION (INCHES)

BASIN

September 12-Month Comparison

2016 Average Diff. % of 

Average

Last 12 

Months

Average Diff. % of 

(1900-2013) (1900-2013) Average

Superior 3.84 3.50 0.34 110 32.98 30.48 2.50 108

Michigan-Huron 3.43 3.44 -0.01 100 34.89 32.52 2.37 107

Erie 3.91 3.22 0.69 121 34.19 35.64 -1.45 96

Ontario 2.10 3.29 -1.19 64 31.15 35.85 -4.70 87

Great Lakes 3.44 3.41 0.03 101 33.96 32.72 1.24 104

 LAKE September Net Basin Supplies1 (cfs) September Outflows2 (cfs)

2016

Average

(1900-2008) 2016

Average3

(1900-2008)

Superior 97,000 70,000 92,000 83,000

Michigan-Huron -8,000 27,000 206,000 195,000

Erie -10,000 -17,000 214,000 204,000

Ontario -14,000 5,000 260,000 249,000

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