Vol. 185 October 2011

Great Lakes Data Coordination

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 waters of this vast 

system of lakes and their outlet channels are 

shared by the United States and Canada and are 

the largest fresh water system in the world. Joint 

use of these waters requires internationally 

coordinated basic hydraulic and hydrology data.

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

Coordinating Committee on Basic Hydraulic 

and Hydrology Data

Prior to 1953, responsible Federal agencies in 

Canada and the United States independently 

collected and compiled data pertaining to the 

hydraulic and hydrologic characteristics of the 

Great Lakes and St. Lawrence River, with only 

superficial and informal coordination of some of 

the data. As a consequence, the same basic data 

developed on different bases and datum planes, 

were often not compatible. To remedy this 

situation, a concerted effort to study and evaluate 

the data used by both countries was required.

With the advent of extremely high lake levels in 

1952 and the impending hydroelectric power and 

navigation developments in the St. Lawrence 

River system, Canadian and U.S. agencies 

recognized that continued independent 

development of basic data would be illogical. 

They realized that early agreement on the 

hydraulic and hydrologic characteristics of the 

system was of paramount importance. Therefore, 

the U.S. Army Corps of Engineers and the 

Canadian Departments of Transport, Mines and 

Technical Surveys and Resources and 

Development, opened negotiations early in 1953 

for the purposes of establishing a basis for 

development and acceptance of identical data by 

both countries. The negotiations culminated in a 

meeting of representatives of the interested 

agencies in Ottawa on 7 May 1953.

Great Lakes

Update
- 2 - Great Lakes Update October 2011

At that meeting, the Coordinating Committee on 

Great Lakes Basic Hydraulic and Hydrologic 

Data was established. This committee serves in 

an advisory capacity to the agencies of the United 

States and Canada who are charged with the 

responsibility for collecting and compiling the 

Great Lakes hydraulic and hydrologic data. 

Currently the Committee is made up of six 

members; a chairperson, member and secretary 

for each of the two countries. Agencies 

represented on the Committee include:

U.S. Army Corps of Engineers

National Oceanic and Atmospheric 

Administration

U.S Geologic Survey

Environment Canada

Natural Resources Canada

Fisheries and Oceans Canada

Canadian Hydrographic Service

The Committee generally meets twice year.

Three subcommittees make up the inner workings 

of the larger body. They are the Vertical Control 

– Water Levels, the Hydraulics and the 

Hydrology subcommittees. Technical studies are 

performed by the subcommittees and any 

recommendations resulting from those studies are 

then passed on to the full Coordinating 

Committee for consideration. Sub-committee 

meetings are usually held a few times per year.

The roster Committee and Subcommittee 

members can be found at the following website.

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

/ccglbhhd/

Vertical Control – Water Levels

Major accomplishments of the Vertical Control -

Water Levels Subcommittee include the 

establishment of the International Great Lakes 

Datum (IGLD) 1955 and the revised IGLD 1985. 

The revision to the datum was required due to the 

continued effects of crustal movement, new 

surveying methods, and the deterioration of the 

zero reference point gauge location. 

Additionally, vertical movement is studied to 

provide an estimate of the change expected 

between the published dynamic heights related to 

the IGLD 1985 and true dynamic heights 

continuously changing with time. This helps 

planning for future upgrades of the datum. 

The next planned datum update will occur in 

2015 and the Vertical Control – Water Levels 

Subcommittee will again have an active role in its 

development and implementation.

The Vertical Control - Water Levels 

Subcommittee also works extensively on water 

level gauging activities. The National Oceanic 

and Atmospheric Administration (NOAA) 

operates and maintains fifty-three gauges in the 

Great Lakes - St. Lawrence River basin; the 

Canadian Hydrographic Service (CHS) operates

and maintains thirty-three gauges; and the U.S. 

Army Corps of Engineers operates and maintains 

eleven. Coordination on all elements required for 

a quality gauging station is continuous. The 

subcommittee has also published the "History of 

Water Level Gauges" for the basin. These reports 

document the history of the operation of water 

level gauges on the Great Lakes and their outflow 

rivers including locations, bench marks, 

relocations and maps.
- 3 - Great Lakes Update October 2011

Hydraulics

The Hydraulics Subcommittee has documented 

methods for conducting hydraulic field 

measurements. Discharge data in the connecting 

channels of the Great Lakes are important data 

elements in all studies of levels and flows. As 

such, consistency in the collection of these data 

sets is important. 

Additionally, a report documenting all sites at 

which discharge measurements had been made in 

the past was completed. This report includes 

location maps, measurement techniques, 

computation methods, water level readings and 

tables of the actual discharges.

The Hydraulics Subcommittee also coordinates 

actual monthly flow values for the St. Clair, 

Detroit and Niagara Rivers. These are done 

periodically and are reported for use in further 

Great Lakes studies, such as the recent 

International Upper Great Lakes Study. Ice and 

weed retardation values are generally agreed 

upon at the same time. Hydraulic modeling

methods are currently being coordinated by the 

subcommittee. Methodologies and standards for 

modeling are being agreed upon and modeling 

efforts are underway for all connecting channels 

and the St. Lawrence River.

Hydrology

The Hydrology Subcommittee spends a great deal 

of effort in coordinating forecasted water levels 

for the Great Lakes and official water level 

statistics. It is important that there is one 

coordinated information base issued to the public 

so there is not confusion about which set of 

numbers an individual should use.

The Monthly Bulletin of Water Levels for the 

Great Lakes, which accompanies this article, is a 

prime example of a coordinated Great Lakes 

product. Each month staff from the U.S. Army 

Corps of Engineers in Detroit, MI and staff from 

the Environment Canada office in Cornwall, 

Ontario produce separate forecasts, using a 

variety of scientific methods. Prior to release, the 

forecasts from each office are meshed into the 

final product, which is then distributed to 

customers on both sides of the international 

border. The actual data values that make up the 

forecast bulletins are coordinated as well as the 

graphics and text on the document itself.

Many individual pieces of hydrometeorologic 

data go into the forecasting process and must also 

be coordinated to ensure the same base of 

information is being used for all work. Monthly 

mean water levels, outflows, precipitation and net 

basin supplies are all discussed. These data are 

also used in many Great Lakes studies.

The official datasets can be obtained by sending 

an email to hhpm@usace.army.mil or by calling 

1-888-323-2322 and selecting option 1. The 

Monthly Bulletin of Lake Levels for the Great 

Lakes can be viewed online at the following 

website. 

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

tlakeswaterlevels/waterlevelforecasts/monthlybull

etinofgreatlakeswaterlevels/

Coordinated monthly mean water levels and 

hydrographs can be downloaded at this website.

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

tlakeswaterlevels/historicdata/

Other Committee Actions

Occasionally, ad-hoc subcommittees are formed 

in order to accomplish certain tasks. An ad-hoc 

group was created to oversee the development of 

a consistent model to simulate the regulation and 

routing of outflows and levels in the Great Lakes 

to be used by all agencies. Another ad-hoc group 

had been created to assist in the updating of 
- 4 - Great Lakes Update October 2011

coordinated physical data for the Great Lakes 

basin. The group looked at drainage areas, 

shoreline lengths, lake volume and depths and 

general dimensions, storage capacities and basin 

delineations. Many of these data themes have 

been analyzed in the past, but due to many new 

technologies, the resultant physical data from 

these analyses will be more accurate. Having the 

data available for use in a geographic information 

system base will also be an excellent 

improvement.

Reports published by the Coordinating 

Committee can be downloaded here.

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

/ccglbhhd/committeepublications/

The Coordinating Committee on Great Lakes 

Basic Hydraulic and Hydrologic Data was created 

to ensure the agencies of the United States and 

Canada, charged with the responsibility for 

collecting and compiling relevant data, had a 

mechanism for agreeing on past and present data 

concerns. This has led to an excellent working 

arrangement between agencies in the two 

countries and an overall best management of the 

key resources of the Great Lakes basin. While the 

objectives of the committee and each 

subcommittee have experienced small changes 

over the years, the Committee's existence for over 

50 years is a testament to necessity, acceptance 

and cooperation.

International Joint Commission Boards of 

Control Meetings

Recently, the three Great Lakes related, 

International Joint Commission (IJC) boards of 

control, held their mandated semi-annual 

meetings.

The International Lake Superior Board of Control 

met on Tuesday, August 30 in Sault Ste. Marie, 

MI. The minutes of this meeting as well as the 

Board’s Semi-Annual Report can be downloaded 

from the following website.

http://www.ijc.org/conseil_board/superior_lake/s

uperior_pub.php?language=english

The Board’s mandated annual meeting with the 

public also occurred on August 30 in Sault Ste. 

Marie, Michigan.

Similarly, the IJC’s International St. Lawrence 

River Board of Control and International Niagara

Board of Control held their mandated semiannual meetings on September 13 and 14 in 

Quebec City, Quebec.

More information can be found at the following 

websites.

International St. Lawrence River Board of 

Control

http://www.ijc.org/conseil_board/islrbc/en/main_

accueil.htm

International Niagara Board of Control

http://www.ijc.org/conseil_board/niagara/en/niag

ara_home_accueil.htm