The U.S. Army Corps of Engineers determined design flood levels on the Great Lakes and connecting channels based on frequency curves of annual maximum instantaneous water levels.  The flood levels and the analysis are described in these two reports.

• Great Lakes Open-Coast Flood Level Report, Phase 1 - Great Lakes (2,100 Kb) 
• Great Lakes Open-Coast Flood Level Report, Phase 2 - Connecting Channels (1,800 Kb)