After two years of record-breaking water levels on Lake Ontario and the St. Lawrence River, the International Joint Commission (IJC) chose in February 2020 to order an immediate and thorough review of the outflow management plan for the lake.
The project, called the Expedited Review of Plan 2014, includes two phases. The first phase, now complete, focused on providing information quickly enough to aid the response to any near-term recurrence of extreme high water events. The second phase, just beginning, will provide for a more sweeping analysis of the outflow regimen known as Plan 2014.
The Phase 1 effort included an innovative application that the IJC’s International Lake Ontario-St. Lawrence River Board can now use to better understand the potential consequences of the outflow decisions they make under extreme high water circumstances.
The information needed to support board outflow decisions became the focus of Phase 1 because Lake Ontario remained very high when decisions were being made about the review in early 2020. Many were concerned spring flooding could recur.
For the Plan 2014 expedited review, the IJC concluded that gathering data to support the board’s decision making was the fastest way to prepare for a possible return of extreme high water. The IJC’s Great Lakes-St. Lawrence River Adaptive Management (GLAM) Committee is conducting the review.
“The conditions in 2017 and 2019 were record-breaking and beyond those ever experienced by the board,” said Wendy Leger, Canadian co-chair of the GLAM Committee. “The board needs more data on how adjustments to outflows might help or harm the situation across interests and regions, should such extreme conditions return in the future.”
Plan 2014, which regulates outflow of water from Lake Ontario into the St. Lawrence through a dam on the upper river, went into effect in January 2017. The six-member board oversees the operation of Plan 2014 and has authority to change the planned outflow from the lake, or “deviate” from the plan, when levels reach extreme high or low trigger points.
The board works in the background most of the time, though it gets plenty of attention during times of extreme high water.
Such was the case in 2017, 2019 and early 2020 when the board was very active in addressing damaging high water and some called for it to do even more.
In 2017, unprecedented precipitation and increased supply from the upper Great Lakes drove waters to record-breaking levels, causing serious flooding and other impacts. Even higher water levels occurred in 2019, resulting in another round of severe impacts.
Edgemere Drive in Greece, New York, flooded by Lake Ontario, May 2017. Credit: IJC
Home flooded in Beauharnois, Quebec, June 2019. Credit: IJC
The evidence is clear that natural factors and weather patterns caused the high water conditions in 2017 and 2019. Nonetheless, some stakeholders asked if Plan 2014 had played a role. To ensure that these questions were addressed, the IJC ordered the expedited review to be started at once.
Because an outflow change can lower levels in one part of the system but raise them in others, it is important for board members to understand potential impacts throughout the system. Better information about these incremental impacts of an outflow decision during high water conditions became the focus of Phase 1.
As part of the Phase 1 review, the GLAM Committee collected information on high water impacts in 2017 and 2019 from water system operators, marinas and yacht clubs, tourist venues and municipalities. The committee gathered data from more than 3,000 shoreline respondents to online questionnaires and analyzed geospatial imagery to estimate shoreline impacts and conducted on-site visits. The GLAM Committee also studied ecosystems of Lake St. Lawrence, assessed ice conditions and conducted an economic analysis to determine impacts on commercial shippers.
GLAM developed a decision support tool to help integrate and present this information in a meaningful way.
The tool incorporates data on high-water impacts and synthesizes this data to project potential impacts for the coming six months and shows how a proposed outflow strategy or deviation would change those impacts.
“The tool brings together all of the gathered data into maps, charts and graphs that display how water levels and associated impacts might change if an alternative outflow strategy were pursued,” said John Allis, US co-chair of the GLAM Committee.
The GLAM Committee further supported the board by identifying potential new strategies to adjust outflow limits set in Plan 2014 that govern outflow when water levels are very high. These strategies will be further explored in Phase 2 of the plan review.
Amid its technical work and data gathering efforts, the committee opened new lines of communication with the public, shoreline business owners and municipalities, and Indigenous Nations affected by water level changes in the Lake Ontario and St. Lawrence River system.
Phase 2 of the Expedited Review of Plan 2014 is tentatively scheduled to end in late 2024.
The GLAM Committee's Phase 1 report on the Expedited Review of Plan 2014 will be published in the coming weeks.
Steve Orr is a science writer in Rochester, New York, who has been assisting the Great Lakes-St. Lawrence River Adaptive Management Committee with the Plan 2014 expedited review.