National Ocean Service (Continued) 
Hydrograph of Monthly Mean Water Levels of the Great Lakes 
Publication Date 
or Interval: Annually 
Location: Great Lakes and Lake St. Clair 
Period of Coverage: 1900-present 
Contents: Hydrograph of Monthly Mean Water Levels of the Great Lakes is a 
graphic depiction of monthly mean levels in feet for each of the Great Lakes 
and Lake St. Clair since 1900, with low water datums shown. All elevations 
are referred to the International Great Lakes Datum (1955). 
Available From: Distribution Branch, N/CG 33 
National Ocean Services 
National Oceanic and Atmospheric Administration 
Riverdale, MD 20737 
(301) 436-6990 
ITI-12 
