2017 High Water - Questions & Answers

The following background information was prepared and reviewed by staff of the International Joint Commission (IJC) and its International Lake Ontario-St. Lawrence River Board (ILOSLRB).


Causes of the 2017 high water event

  • What were the causes of the 2017 high water event?

  • Did precipitation set records?

  • Did Plan 2014 cause the high water levels?

  • Did Plan 2014 hold water back on Lake Ontario?

  • Could dams on the Ottawa River have been operated to reduce flows to the St. Lawrence River?

Operations in 2017

  • Why wasn’t more water released from Lake Ontario in the spring of 2017?

  • Why wasn’t more water released in 2016 when downstream flooding was not an issue

  • Would the Board have had more flexibility to release water if Plan 1958DD had been in place in 2017?

  • Why were flows reduced for navigation?

  • Why did the Board not set flows at a rate that would have resulted in temporary navigation stoppages, such as those that occurred in 1993?

  • Why were flows reduced in October for boat haul out?

  • What actions can be taken to lower water levels and prevent a flood in 2018?

  • Why not draw Lake Ontario down each fall so that there is sufficient storage to prevent flooding in the spring?

  • How did outflows under Plan 2014 during fall 2017 differ from those that would have occurred under Plan 1958DD?