The original Great Lakes bathymetric data were compiled by a NOAA (NESDIS-NGDC and OAR-GLERL) and Canadian Hydrographic Service team from archival U.S. and Canadian soundings spanning more than 75 years. Dr. David Schwab (GLERL) generated a gridded 3-arc second dataset from the NOAA-CHS project and provided it to Google to form the basis for the Great Lakes topography.