n light of record floods in the early 1950's, the governments of Canada and the United States asked the IJC to investigate whether water levels could be regulated for the benefit of property owners on Lake Ontario, while "having regard to all other interests" in the basin and how they would be impacted by such regulation. The IJC found that Lake Ontario could be regulated between a low of 74.15 m in the navigation season and a high of 75.37 m (243.29 and 247.29 feet, respectively) based on water supplies recorded between 1860 and 1954. The governments approved this target range of water levels and the regulation plan recommended by the IJC, called Plan 12-A-9. While this particular regulation plan was never implemented, it was used to calculate river profiles and design channel excavations for safe navigation through the seaway. The target range of Lake Ontario levels, however, was retained in subsequent plan development.