The collection consists of approximately 50,000 high-quality negatives and transparencies showing ice cover impact on navigation or hydroelectric operation from 1963 to 1973. Coverage is not systematic or complete. Indexing has not been undertaken, but latitude and longitude of flight line begin and end points are logged. Photos from many flights have been made into photomosaics that can be used on-site as a gross index to the 9-inch roll negatives. Photographic flights were carried out by a U.S. Air Force photomapping wing, using flight lines selected by NOAA Lake Survey Center (now Great Lakes Environmental Research Laboratory). The analog material that is this data set moved to the University of Colorado (CU) Libraries Archives in August 2018, where it is part of the Roger G. Barry glaciology collection. If you are interested in this analog collection, you can search for "Great Lakes Aerial Photos of Ice Conditions" from the CU search interface, but be aware that it may not yet be catalogued, or it may be catalogued under a different name. If you have questions, contact sca@colorado.edu.