Scope and Contents: Ice cover is an important environmental factor affecting physical and biological processes in the coastal region of the Great Lakes. However, computerized ice thickness data along the shores of the Great Lakes prior to about 1965 are extremely sparse. The presence or absence of a stable ice cover in shallow spawning grounds in northern Lake Michigan has been shown to affect whitefish recruitment. A stable ice cover can also contribute to increased under ice zooplankton activity and to decreased re-suspension of particulate matter in the water column.  These reports contain qualitative descriptions of ice conditions and quantitative information on ice thickness in specific near shore areas of the Great Lakes. There are approximately 530 pages of reports spanning the winters from 1899 to 1970.