Ft.

-1

0

+ 1

+ 2+ 3+ 4+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9+ 1.2+ 1.5

2015

JAN

1946

FEB

1952

MAR

1952

APR

1973

MAY

1973

JUN

1952

JUL

1947

AUG

1947

SEP

1947

OCT

1945

NOV

1945

DEC

1945

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

APR

19731935

MAY

19731935

JUN

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

2015

JAN

1987

FEB

1987

MAR

1986

APR

1985

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

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

APR

19851934

MAY

1986

1934

JUN

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

2015

JAN

1986

FEB

1986

MAR

1986

APR

1986

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

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

APR

19861926

MAY

1986

1934

JUN

1986

1934

CHART DATUM 572.3 FEET (174.4 METERS)

ELEVATIONS REFERENCED TO THE CHART DATUM OF EACH 

Superior

602.17183.54602.33183.59603.05

183.81

1985

600.13182.92

1925

601.71

183.40

MichHuron

579.10

176.51

579.23176.55

581.56177.26

1986

576.15

175.61

2012

578.51

176.33

St.

Clair

574.54175.12574.54175.12576.77

175.80

1986

571.65174.24

1964

573.85

174.91

Erie

571.42174.17571.42174.17573.79174.89

1986

568.21

173.19

1934

570.83173.99

Ontario

244.29

74.46

244.32

74.47

246.72

75.20

1945

241.93

73.74

1934

244.49

74.52

DECEMBER 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

December 2016

During December, precipitation within the overall Great Lakes basin was near average according to preliminary 

estimates. The precipitation experienced by Lake Superior exceeded its December average precipitation by 13%. In 

addition, precipitation to Lake Michigan-Huron was near average. Lakes Erie and Ontario received precipitation in 

December that was 18% and 9% below average. The only Great Lake to experience above average net basin 

supplies in December was Superior. Lakes Michigan-Huron and Ontario received below average net basin supplies, 

while the net basin supply to Lake Erie was near average. The tables below list December precipitation and water 

supply information for the Great Lakes basin.

All of the lakes continued their seasonal decline in the month of December. All of the lakes were above their longterm average (LTA) monthly December levels except Lake Ontario. Lakes Superior, Michigan-Huron, St. Clair, and 

Erie were 6 to 8 inches above their LTA December levels. Lake Ontario, however, was 2 inches below its LTA level. 

Also, Lakes Superior and Michigan-Huron were 2 inches below their levels from December 2015, while the lower 

lakes were at about the same level as they were last December.

PRELIMINARY PRECIPITATION (INCHES)

BASIN

December 12-Month Comparison

2016 Average Diff. % of 

Average

Average Last 

12 months 

Average Diff. % of 

(1900-2014) (1900-2014) Average

Superior 2.28 2.02 0.26 113 32.81 30.52 2.29 108

Michigan-Huron 2.29 2.35 -0.06 97 32.87 32.57 0.30 101

Erie 2.20 2.68 -0.48 82 33.53 35.65 -2.12 94

Ontario 2.69 2.97 1.80 91 32.31 35.87 -3.56 90

Great Lakes 2.30 2.37 -0.07 97 32.98 32.76 0.22 101

 LAKE

December Net Basin Supplies1 (cfs) December Outflows2 (cfs)

2016

Average

(1900-2008) 2016

Average3

(1900-2008)

Superior -9,000 -22,000 85,000 72,000

Michigan-Huron -10,000 34,000 198,000 183,000

Erie 18,000 21,000 221,000 201,000

Ontario 21,000 27,000 244,000 234,000

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