Ft.

-1

0

+ 1

+ 2+ 3+ 4+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9+ 1.2+ 1.5

2017

FEB

1952

MAR

1952

APR

1973

MAY

2017

JUN

2017

JUL

2017

AUG

1947

SEP

1947

OCT

1945

NOV

1945

DEC

1945

2018

JAN

1946

FEB

1952

1936

MAR

19521935

APR

19731935

MAY

20171935

JUN

20171935

JUL

20171934

AUG

19471934

SEP

19471934

OCT

19451934

NOV

19451934

DEC

19451934

2019

JAN

1946

1935

FEB

1952

1936

MAR

19521935

APR

19731935

MAY

20171935

JUN

20171935

JUL

20171934

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

2017

FEB

1987

MAR

1986

APR

1985

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2018

JAN

1987

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

2019

JAN

19871935

FEB

1987

1936

MAR

1986

1934

APR

19851934

MAY

1986

1934

JUN

1986

1934

JUL

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

2017

FEB

1986

MAR

1986

APR

1986

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2018

JAN

1986

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

2019

JAN

19861936

FEB

19861926

MAR

1986

1934

APR

19861926

MAY

1986

1934

JUN

1986

1934

JUL

1986

1934

CHART DATUM 572.3 FEET (174.4 METERS)

ELEVATIONS REFERENCED TO THE CHART DATUM OF EACH 

Superior

602.43183.62602.53183.65602.69

183.70

1986

599.84182.83

1926

601.48183.33

MichHuron

580.09

176.81

579.82176.73

581.30

177.18

1987

576.02175.57

2013

578.41

176.30

St.

Clair

575.52175.42574.93175.24576.77

175.80

1986

570.47173.88

1936

573.62174.84

Erie

572.93174.63

572.11

174.38573.69

174.86

1987

568.27

173.21

1935

570.87

174.00

Ontario

245.51

74.83

245.51

74.83

246.59

75.16

1946

242.16

73.81

1935

244.62

74.56

JANUARY MEAN LAKE LEVELS

(IGLD 1985)

* 2019 Ft.

M.

2018 Ft.

M.

** MAX.

Ft.

M.

Yr.

** MIN.

Ft.

M.

Yr.

** AVG. Ft.

M.

* provisional** Average, Maximum and Minimum for period 1918-2017

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 and Climate Change 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) 226-6441 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 

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

Great Lakes Basin Hydrology

January 2019

Preliminary estimates indicate that the Great Lakes basin as a whole received below average precipitation in the 

month of January, following a below average December. Lake Ontario received closest to average precipitation at 

85%. Despite lower than normal precipitation, water supplies for Lakes Superior, Michigan-Huron, and Ontario were 

above average. Lake Erie was the only basin that received below average net basin supply. While warmer beginning 

of the month temperatures may have caused enhanced runoff, the very cold temperatures later in the month may 

have resulted in increased evaporation, which could explain near average supplies on Lake Erie. Outflows for all of 

the lakes continued to be above average during the month of January.

January monthly mean water levels were above their long-term average for all lakes. Lake Superior fell over the past 

month by approximately 2 inches. Levels on Michigan-Huron decreased by roughly an inch, while Lake St. Clair fell 

by over 2 inches. Both Lakes Erie and Ontario increased in levels by approximately 2 and 4 inches, respectively.

Lake Superior is below its level from last year by 1 inch, while Lake Ontario is at the same level. In contrast, Lakes

Michigan-Huron, St. Clair and Erie are 3, 7, and 10 inches above their levels from one year ago.

PRELIMINARY PRECIPITATION (INCHES)

BASIN

January 12-Month Comparison

2019 Average Diff. % of 

Average

Average Last

12 Months

Average Diff. % of 

(1900-2016) (1900-2016) Average

Superior 1.19 1.95 -0.76 61 26.72 30.58 -3.86 87

Michigan-Huron 1.70 2.14 -0.44 79 31.26 32.55 -1.29 96

Erie 1.74 2.49 -0.75 70 36.21 35.62 0.59 102

Ontario 2.33 2.73 -0.40 85 35.29 35.87 -0.58 98

Great Lakes 1.60 2.20 -0.60 73 31.02 32.77 -1.75 95

 LAKE January WATER SUPPLIES1 (cfs) January OUTFLOW2 (cfs)

2019

Average

(1900-2008) 2019

Average3

(1900-2008)

Superior -4,000 -13,000 78,000 69,000

Michigan-Huron 84,000 60,000 191,000 161,000

Erie 24,000 29,000 246,000 196,000

Ontario 35,000 32,000 257,000 222,000

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