Ft.

-1

0

+ 1

+ 2+ 3+ 4+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9+ 1.2+ 1.5

2014

JAN

1946

FEB

1952

MAR

1952

APR

1973

MAY

1973

JUN

1952

JUL

1947

AUG

1947

SEP

1947

OCT

1945

NOV

1945

DEC

1945

2015

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

2016

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

2014

JAN

1987

FEB

1987

MAR

1986

APR

1985

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2015

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

2016

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

2014

JAN

1986

FEB

1986

MAR

1986

APR

1986

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2015

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

2016

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

602.33183.59

602.36

183.60

603.05

183.81

1985

600.13182.92

1925

601.71

183.40

MichHuron

579.23176.55579.17176.53

581.56177.26

1986

576.15

175.61

2012

578.51

176.33

St.

Clair

574.54175.12574.57175.13576.77

175.80

1986

571.65174.24

1964

573.82

174.90

Erie

571.42174.17571.42174.17573.79174.89

1986

568.21

173.19

1934

570.83173.99

Ontario

244.32

74.47

244.29

74.46

246.72

75.20

1945

241.93

73.74

1934

244.49

74.52

DECEMBER MEAN LAKE LEVELS

(IGLD 1985)

* 2015 Ft.

M.

2014 Ft.

M.

** MAX.

Ft.

M.

Yr.

** MIN.

Ft.

M.

Yr.

** AVG. Ft.

M.

* provisional** Average, Maximum and Minimum for period 1918-2014

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 2015

Precipitation over the Great Lakes basin during the month of December was well above average, especially over 

Lakes Superior and Michigan-Huron, which received 143% and 166% of average December precipitation, 

respectively. As a result of the high precipitation and warm temperatures, supplies were above average on all 

lakes, but especially high on Lakes Superior and Michigan-Huron. In fact, water supplies to Lakes Superior and 

Michigan-Huron were the highest they have ever been during the month of December. The tables below list 

December precipitation and water supply information for the Great Lakes basin.

Water levels went up on all lakes over the month of December. For Lake Superior, this marks the first time in the 

period of record (1918-2014) that water levels went up during the month of December. Monthly mean levels were 

above long term average December levels on all lakes but Ontario, which was 2 inches below its average 

December level. Lakes Superior and Erie were both 7 inches above long-term December average levels, and 

Lakes Michigan-Huron and St. Clair were both 9 inches above their long term average December levels.

PRECIPITATION (INCHES)

BASIN

December 12-Month Comparison

2015

Average

Diff. % of 

Average

Last 12 

Months

Average

Diff. % of 

(1900-2012) (1900-2012) Average

Superior 2.88 2.01 0.87 143 29.16 30.43 -1.27 96

Michigan-Huron 3.91 2.36 1.55 166 29.50 32.48 -2.98 91

Erie 2.87 2.68 0.19 107 33.20 35.59 -2.39 93

Ontario 2.96 2.95 1.80 100 31.88 35.83 -3.95 89

Great Lakes 3.37 2.36 1.01 143 30.03 32.68 -2.65 92

 LAKE

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

2015

Average

(1900-2008) 2015

Average3

(1900-2008)

Superior 91,000 -22,000 85,000 72,000

Michigan-Huron 244,000 34,000 200,000 183,000

Erie 22,000 21,000 214,000 201,000

Ontario 36,000 27,000 246,000 234,000

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