SECTION 3: High Water Levels and Flows in the St. Lawrence River Q 3.1: Does regulation of Lake Ontario outflows make spring flooding conditions worse in the Montreal area?
• No. The Order requires no less protection for riparian interests downstream than would have occurred under pre-project conditions. Regulation of Lake Ontario outflows has actually reduced spring flooding in the Montreal area. Montreal is threatened by flooding since it is located at the confluence of the Ottawa and St. Lawrence Rivers. The spring runoff from the Ottawa River basin is largely uncontrolled and can be very significant. Timely adjustment of the Lake Ontario outflow has repeatedly helped avoid serious flooding in the Montreal and Lake St. Louis areas during Ottawa River floods. Lake Ontario outflow reductions are typically offset by higher flows prior to the Ottawa River flood, or shortly following it.
