Vol. 186 Great Lakes Update January 2012 

Page 1 	 	

2011 Annual Summary

This article will summarize water level and 

overall basin conditions during 2011. 

Precipitation, runoff and evaporation are the 

largest contributors to water level fluctuation and 

2011 saw interesting patterns for each variable. 

This article will also summarize Lake Superior 

regulation decisions, including a short 

explanation of experiments done to study sea 

lamprey mating habits near the regulation 

structures on the St. Marys River. The regulation 

of Lake Ontario and some other relevant Great 

Lakes topics will be discussed. 

The Great Lakes – St. Lawrence River system 

extends southerly and easterly from the 

headwaters of tributary streams in northern 

Minnesota and western Ontario, to the Gulf of the 

St. Lawrence in the Atlantic Ocean. The drainage 

basin, (figure 1) which includes the surrounding 

land and water surface, covers more than 400,000 

square miles from Duluth, Minnesota in the west 

to Trois Riviéres, Quebec on the St. Lawrence 

River. Eight U.S. states and two Canadian 

provinces border on the Great Lakes – St. 

Lawrence River system. 

The U.S. Army Corps of Engineers is tasked with 

various missions relating to the Great Lakes. 

Water level forecasting, data collection and 

analysis, Lake Superior regulation out of the 

Detroit District and Lake Ontario regulation out 

of the Buffalo District are just a few of the water 

management missions. 

Figure 1: The Great Lakes – St. Lawrence River Basin 

2011 Water Level and Basin Summary

All water levels mentioned in this article are 

monthly mean surface elevations in feet on the 

International Great Lakes Datum of 1985 (IGLD 

85). All values shall be considered preliminary 

until final levels are coordinated between U.S. 

and Canadian agencies, sometime in early 2012. 

The official period of record for Great Lakes 

water levels is 1918 – 2010. Official water level 

statistics and historical water levels are located on 

the internet at the following address. 

http://www.lre.usace.army.mil/greatlakes/hh/grea

tlakeswaterlevels/historicdata/

Great Lakes

Update 
Vol. 186 Great Lakes Update January 2012 

Page 2 	 	

At the end of this article are a series of charts 

showing 2011 monthly mean water levels 

compared to long-term averages. 

 

Water levels on Lake Superior remained below 

their long-term averages in 2011. In fact Lake 

Superior is in its longest stretch of continuously 

below average water levels. The last time Lake 

Superior was at or above a monthly mean was 

April of 1998. 

In January 2011, Lake Superior was at 600.4 ft, 

or thirteen inches below its long term average and 

in the midst of its seasonal decline. Its decline 

continued through March, when the level was 

600.0 feet and thirteen inches below average. 

The total decline from September 2010 to March 

2011 was thirteen inches, which is the average 

decline in a given season. 

Lake Superior reached its 2011 seasonal peak in 

August, at 601.3 ft. Lake Superior’s annual rise 

was sixteen inches, when on average it rises 

thirteen inches. Lake Superior’s December 2011 

monthly mean was 600.7 ft, or twelve inches 

below its long-term average. 

Evaporation from Lake Superior during the fall of 

2011 was below average. The autumn (Sept, Oct, 

Nov) months often see significant evaporation 

rates from all the Great Lakes, since water 

temperatures can be much warmer than the 

overriding air temperature. 

See Figure 2 for autumn 2011 modeled 

evaporation totals compared to average for all of 

the Great Lakes. Note that all the Great Lakes 

had below average modeled evaporation rates 

during the fall of 2011. 

Figure 2: Autumn 2011 Evaporation 

Precipitation in the Lake Superior basin was 

below average in 2011, with the majority of the 

year’s precipitation falling in the spring (March, 

April and May) months. See figure 3 for the 

2011 precipitation for each Great Lake 

precipitation compared to average. 

Figure 3: Great Lakes 2011 precipitation 

Lake Michigan-Huron, considered one lake 

hydraulically due to the Straits of Mackinac, is 

also in its longest stretch of continuously below 

average water levels. Levels on Lake MichiganHuron ranged from twelve to twenty inches 

below average in 2011. The last time Lake 

Michigan-Huron recorded a monthly mean at or 

above a monthly mean was 1998. 
Vol. 186 Great Lakes Update January 2012 

Page 3 	 	

January 2011 saw a mean level of 576.8 ft on 

Lake Michigan-Huron. This level was nineteen 

inches below average. From July 2010 to 

February of 2011, the lake declined eighteen 

inches, while its average seasonal decline is 

eleven inches. 

After reaching its seasonal low of 576.7 ft in 

February, Lake Michigan-Huron rose nineteen 

inches to a seasonal peak of 578.3 ft in July. On 

average, Lake Michigan-Huron rises eleven 

inches during the spring. Following a fall with 

lower than average evaporation, Lake MichiganHuron’s monthly mean in December was 577.6 ft, 

or eleven inches below its long-term average. 

Precipitation in 2011 was above average in the 

Lake Michigan-Huron basin. Spring saw 139% 

of average precipitation, which led to the above 

average spring rise. 

Snow water equivalent across the northern Great 

Lakes was estimated to be near average in the 

spring of 2011. Figure 4 shows the estimated 

snow water equivalent across the northern Great 

Lakes near the end of March. Runoff from 

snowmelt provides a large percentage of the 

water supply to the Great Lakes during their 

periods of seasonal rise. 

Figure 4: 2011 Snow Water Equivalent at the End of 

March 

Lake St. Clair began 2011 at 572.4 ft, or fourteen 

inches below average. Levels in January and 

February were impacted by an ice jam in the St. 

Clair River. Ice often hinders the natural flow of 

water in the delta of the St. Clair River, which 

causes the water level of Lake St. Clair to fall 

dramatically. While the level of Lake St. Clair 

drops, levels upstream of the ice jam rise quickly. 

Once the ice jam breaks, water level conditions 

often return to pre jam conditions. Figure 5 

shows ice conditions near St. Clair, Michigan in 

early March. 

Figure 5: St. Clair River Ice

Heavy spring rainfall led to a drastic rise in water 

level beginning in March. In total, Lake St. Clair 

rose thirty inches in 2011, to a June peak of 574.9 

ft. Lake St. Clair’s average rise in a given year is 

sixteen inches. By December, Lake St. Clair was 

at a level of 574.4 ft or seven inches above its 

long-term average. 

Below average water level conditions on Lake 

Erie existed in early 2011. January’s level was 

570.3 ft, or six inches below the long-term 

average. After reaching its seasonal low of 570.1 

ft in February, Lake Erie began a substantial rise. 

Bolstered by intense rainfall and a large amount 

of snowmelt runoff, Lake Erie rose thirty three 

inches in 2011. Lake Erie’s normal rise is close 
Vol. 186 Great Lakes Update January 2012 

Page 4 	 	

to twelve inches. At the seasonal peak in June, 

Lake Erie was ten inches above average. 

The December lake wide mean water level of 

Lake Erie was 572.2 ft. This level was seventeen 

inches above the December long term average. 

Precipitation in the Lake Erie basin in 2011 was 

145% of average. Over twelve inches of 

precipitation fell during the months of April and 

May alone. Then in the fall, over fifteen inches 

of precipitation were recorded in September 

through November. 

The water level of Lake Ontario began 2011 at 

244.4 feet, which was three inches below 

average. After reaching its seasonal low of 244.1 

ft in February, Lake Ontario began a very steep 

seasonal rise, again due to increased snowmelt 

runoff and heavy rainfall. 

By June, Lake Ontario was at 247.2 ft, or eleven 

inches above average. The lake rose three feet 

from February to June compared to an average 

rise of about a foot and a half. 

During the spring months, the Lake Ontario basin 

received 155% of its average precipitation and in 

April alone, over five inches of precipitation fell. 

Based on provisional data, the April precipitation 

on the Lake Ontario basin is a new all time 

maximum for the month. By September, the 

water level of Lake Ontario had returned to near 

its long-term average. Lake Ontario ended 2011 

at 244.8 ft or four inches above its long-term 

December average. 

Lake Ontario’s outflow is regulated on a weekly 

basis. Representatives of the Corps of Engineers 

Buffalo District and Environment Canada 

recommend outflow strategies based on current 

water levels and basin conditions. 

Recommendations are made to the International 

St. Lawrence River Board of Control, which 

operates under the auspices of the International 

Joint Commission (IJC). 

More information on Lake Ontario regulation 

activities can be found here. 

http://ijc.org/conseil_board/islrbc/en/main_accuei

l.htm

Lake Superior Regulation

The Detroit District also advises the Lake 

Superior Board of Control (Board) on regulation 

activities in the St. Marys River. The Board is a 

bi-national body that reports to the IJC on 

boundary water management issues including 

Lake Superior outflows. The regulation of the 

outflow of Lake Superior is governed by Orders 

of Approval from the IJC. 

Near the beginning of each month, a coordinated 

outflow recommendation is determined between 

representatives of the Detroit District and 

Environment Canada. This outflow is determined 

following guidelines in Plan 1977-A for the 

regulation of Lake Superior. The plan’s aim is to 

balance the levels of Lake Superior and Lake 

Michigan-Huron with respect to their long-term 

averages. Flow changes resulting from monthly 

Lake Superior regulation are accomplished by 

varying the amount of water allocated to 

hydropower production and, when necessary, 

opening or closing gates in the Compensating 

Works at the head of the St. Marys Rapids. 

During 2011 Lake Superior water levels ranged 

from ten to fourteen inches below LTA. Due to 

the persistent lower than average water levels on 

Lake Superior, the regulated outflow was at the 

minimum allowed by Plan 1977-A for most of the 

year. See figure 6 for 2011 Lake Superior 

outflows compared to long-term average. 
Vol. 186 Great Lakes Update January 2012 

Page 5 	 	

Figure 6: 2011 Lake Superior Outflow 

Special outflow strategies existed during the 

summer months to aid in a sea lamprey trapping 

experiment performed by the U.S. Fish and 

Wildlife Service. Sea lampreys are an invasive 

species and nearly decimated the sport fish 

population in the Great Lakes. Trapping efforts 

during the past several decades have allowed 

predatory fish populations to grow, while lamprey 

populations continue to decline. 

During the experiment, the Brookfield Renewable 

Power’s hydropower plant in Canada and the 

Cloverland Electric Cooperative’s hydropower 

plant in the U.S. alternated high and low flows 

during evening hours. Odd numbered days saw 

high flows, while the even days saw lower flows. 

Normal operations at the power plants call for 

lower flows during overnight hours, to match low 

demand for electricity. 

It was hypothesized that high flows during the 

night attracted more sea lamprey to the traps near 

the plants. Preliminary results were positive and 

showed a larger number trapped sea lampreys. 

Because of the plants’ need to pass higher flows 

during overnight hours, the IJC granted special 

permission to the Board to allocate extra water 

for hydropower production in June. The extra 

flow allocation was small and had a negligible 

effect on the water level of Lake Superior. The 

experiment continued in July, but conditions 

allowed the hydropower companies to meet the 

experiment requests without an extra allocation. 

Water Level Forecast

La Nina conditions are again expected across the 

Great Lakes basin this winter, which may bring 

increased snowfall and periods of very cold 

temperatures. Figure 7, (credit to NOAA) shows 

forecasted precipitation chances through February 

of 2012. According to NOAA, the Great Lakes 

region has a better chance for increased 

precipitation this winter. 

Figure 7: Winter Precipitation Forecast 

As mentioned earlier in the article, all of the 

Great Lakes experienced higher than average 

seasonal rises in the spring of 2011, due to wet 

conditions and a significant snowpack. If similar 

conditions are realized this winter and spring, the 

Great Lakes could again see larger than average 

seasonal rises. 

The latest Monthly Bulletin of Water Levels for 

the Great Lakes, which accompanies this article 

projects water level through June 2012. 
Vol. 186 Great Lakes Update January 2012 

Page 6 	 	

The upper and lower boundaries represent the 

possible range of water levels that could occur if 

the lake were to receive water supply much above 

or much below the averages usually expected 

each month. These upper and lower boundaries 

are based on actual past water supply records, and 

represent very wet and very dry conditions. 

The best estimate or most probable water level 

forecast is primarily based on the current 

hydrologic conditions in the drainage basin. Key 

pieces of environmental data used in the forecast 

include recent precipitation, amount of water in 

the snow pack, frost depths, status of the 

groundwater table and air/water temperatures. 

One and three month forecasts of temperature and 

precipitation are also used. These forecasts are 

provided by the National Weather Service. 

The January version of the Monthly Bulletin

projects monthly mean water levels through June 

2011. The water levels making up the by most 

probable forecast are shown in the following 

tables. For comparison purposes, the 

corresponding 2011 monthly mean water levels 

and long-term averages also shown. 

Lake Superior Most Probable Forecast 

 Jan Feb Mar Apr May Jun 

2012 600.5 600.3 600.2 600.3 600.6 601.0 

2011 600.4 600.2 600.0 600.1 600.5 600.9 

LTA 601.5 601.3 601.2 601.3 601.6 601.9 

Lake Michigan-Huron 

Most Probable Forecast 

 Jan Feb Mar Apr May Jun 

2012 577.4 577.4 577.4 577.6 577.9 578.1 

2011 576.8 576.7 576.8 577.1 577.8 578.1 

LTA 578.4 578.4 578.4 578.7 579.0 579.2 

Lake St. Clair Most Probable Forecast 

 Jan Feb Mar Apr May Jun 

2012 574.1 574.0 574.0 574.3 574.3 574.5 

2011 572.4 572.5 573.1 573.8 574.6 574.9 

LTA 573.6 573.5 573.8 574.3 574.5 574.7 

Lake Erie Most Probable Forecast 

 Jan Feb Mar Apr May Jun 

2012 572.0 571.9 571.9 572.1 572.2 572.2 

2011 570.3 570.1 571.0 571.5 572.4 572.8 

LTA 570.8 570.8 571.1 571.6 571.9 572.0 

Lake Ontario Most Probable Forecast 

 Jan Feb Mar Apr May Jun 

2012 245.1 245.5 245.7 246.2 246.4 246.4 

2011 244.4 244.1 244.8 245.6 246.8 247.2 

LTA 244.6 244.8 245.0 245.7 246.1 246.2 

2011 Update Articles

 

Update articles like this one are issued four times 

per year. In 2011 topics covered in the updates 

included: 

January 2011 – 2010 Annual Summary 

Mar 2011 – Lake Winnebago Regulation 

July 2011 – Great Lakes Spring Summary 

October 2011 – Great Lakes Data Coordination 

Past Update Articles going back to the 1980s are 

available here: 

http://www.lre.usace.army.mil/greatlakes/hh/new

sandinformation/pastupdatearticles/
Vol. 186 Great Lakes Update January 2012 

Page 7 	 	

Delivery of the Monthly Bulletin

The Monthly Bulletin can be viewed in few 

different ways. The first of which is by postal 

mail. Over 4000 Bulletins are mailed out each 

month to locations across the United States. The 

mailed version is black and white and usually 

arrives to the subscriber by the middle of the 

month. A smaller graphic of each lake is shown 

on an 11 by 17 folded newsletter. Also included 

is a look at the past month and past 12-month 

precipitation, outflow in the connecting channels 

and water supply information. 

Another method of getting the Bulletin is by 

email subscription. The Detroit District of the 

Corps of Engineers posts a full color version of 

the Bulletin to its website once it is completed, 

usually in the first few days of the month. A user 

can download the 11 by 17 product or a full one 

page look at an individual lake. The webpage is: 

http://www.lre.usace.army.mil/greatlakes/hh/grea

tlakeswaterlevels/waterlevelforecasts/monthlybull

etinofgreatlakeswaterlevels/

If you wish to remove yourself from the postal 

mail subscription list, change your address or to 

add your email address to our online database 

please send an email with your name information 

to hhpm@usace.army.mil. 

In addition to the Monthly Bulletin, the Detroit 

District issues the Weekly Great Lake Water 

Level Update and the Weekly Great Lakes 

Connecting Channels and Depths. Both 

products are updated each Thursday and can be 

located here: 

http://www.lre.usace.army.mil/greatlakes/hh/grea

tlakeswaterlevels/waterlevelforecasts/

The Detroit District welcomes comments on all of 

our forecast products. Please email questions and 

comments to hhpm@usace.army.mil. To contact 

the District by phone call toll free 1-888-694- 

8313 and select option 1. 

The Detroit District’s mailing address is: 

Department of the Army 

Detroit District Corps of Engineers 

ATTN: CELRE-HH-W 

477 Michigan Avenue 

Detroit, MI 48226 
 

243

244

245

246

247

248

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake Ontario

Recorded Monthly 

Mean (ft)

Long Term Average 

(ft)

LEGEND

599

600

601

602

603

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake Superior

576

577

578

579

580

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Michigan- Huron

572

573

574

575

576

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake St. Clair

569

570

571

572

573

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Lake Erie

The 2011 monthly mean levels on the 

hydrographs and the1918 - 2010 Long 

Term Average (LTA) are shown in feet. 

All elevations and plots shown in this 

bulletin are referenced to the

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).