Ft.

-1

0

+ 1

+ 2+ 3+ 4+ 5

M.

-0.3

0

+ 0.3

+ 0.6

+ 0.9+ 1.2+ 1.5

2016

FEB

1952

MAR

1952

APR

1973

MAY

1973

JUN

1952

JUL

1947

AUG

1947

SEP

1947

OCT

1945

NOV

1945

DEC

1945

2017

JAN

1946

FEB

1952

1936

MAR

19521935

APR

19731935

MAY

19731935

JUN

19521935

JUL

19471934

AUG

19471934

SEP

19471934

OCT

19451934

NOV

19451934

DEC

19451934

2018

JAN

1946

1935

FEB

1952

1936

MAR

19521935

APR

19731935

MAY

19731935

JUN

19521935

JUL

19471934

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

2016

FEB

1987

MAR

1986

APR

1985

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2017

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

2018

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

2016

FEB

1986

MAR

1986

APR

1986

MAY

1986

JUN

1986

JUL

1986

AUG

1986

SEP

1986

OCT

1986

NOV

1986

DEC

1986

2017

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

2018

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

602.53183.65601.94183.47602.69

183.70

1986

599.84182.83

1926

601.44183.32

MichHuron

579.82176.73578.97176.47

581.30

177.18

1987

576.02175.57

2013

578.38176.29

St.

Clair

574.90

175.23574.77175.19576.77

175.80

1986

570.47173.88

1936

573.62174.84

Erie

572.01

174.35571.82174.29573.69

174.86

1987

568.27

173.21

1935

570.87

174.00

Ontario

245.51

74.83

244.82

74.62

246.59

75.16

1946

242.16

73.81

1935

244.62

74.56

JANUARY MEAN LAKE LEVELS

(IGLD 1985)

* 2018 Ft.

M.

2017 Ft.

M.

** MAX.

Ft.

M.

Yr.

** MIN.

Ft.

M.

Yr.

** AVG. Ft.

M.

* provisional** Average, Maximum and Minimum for period 1918-2016

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

January 2018

According to preliminary estimates, basin-wide precipitation was below average for all of the Great Lakes, at 73% of 

average precipitation. Both Lake Superior and Lake Michigan-Huron were representative of this and received 71% 

of their average January precipitation. Lake Erie was comparable and received 69% of its average January 

precipitation. Lake Ontario received the most precipitation at 90% of its average January precipitation. Over the last 

12 months, the total precipitation has been just above average for the Great Lakes basin on the whole. January net 

basin supplies were above average for all but Lake Superior. Outflows in January were above average for all lakes. 

All of the lakes were above their January long-term average water levels. From December to January, most of the 

lakes’ levels declined, where Lake St. Clair fell by 5 inches, Lake Superior fell by 3 inches, and Lakes MichiganHuron and Erie fell by 2 inches. On the contrary, Lake Ontario rose by 2 inches. This January’s levels were 2 to 10

inches above last year’s level. All of the lakes were below their record high levels in January. Lake Superior’s

January level was 2 inches below its record January high level, while other lakes were 13 to 22 inches below.

PRELIMINARY PRECIPITATION (INCHES)

BASIN

January 12-Month Comparison

2018

Average

Diff. % of 

Average

Last 12 

months 

Average

Diff. % of 

(1900-2014) (1900-2014) Average

Superior 1.37 1.94 -0.57 71 33.58 30.52 3.06 110

Michigan-Huron 1.52 2.15 -0.63 71 34.26 32.57 1.69 105

Erie 1.73 2.50 -0.77 69 34.93 35.65 -0.72 98

Ontario 2.47 2.74 -0.27 90 40.94 35.87 5.07 114

Great Lakes 1.61 2.21 -0.60 73 34.98 32.76 2.22 107

 LAKE

January Net Basin Supplies1(cfs) January Outflows2(cfs)

2018

Average

(1900-2008) 2018

Average3

(1900-2008)

Superior -31,000 -13,000 73,000 69,000

Michigan-Huron 101,000 60,000 172,000 161,000

Erie 43,000 29,000 223,000 196,000

Ontario 64,000 32,000 252,000 222,000

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