Nature, not human error, to blame for Ottawa River flooding: report

Nature, not human error, to blame for Ottawa River flooding: report

Officials at the province's electrical utility did everything they could to mitigate flooding on the Ottawa River earlier this year, a new report from Ontario's special flood adviser concludes.

The independent review, conducted by flood expert Doug McNeil and made public Thursday morning, found Ontario Power Generation (OPG) properly managed water flowing through the dams and reservoirs it controls along the river, but was overwhelmed by "the sheer amount of water" this spring.

Nothing pointed to human error or the negligent operation of water-control structures as the cause for the flooding this past spring. - Ontario Natural Resources Minister John Yakabuski

"Flow changes were performed strategically with regard for impacted areas and ultimately, with a mindset of providing as much flood mitigation as possible," McNeil wrote in the report.

"Measures taken by the water managers everywhere were effective in reducing the magnitude of flooding."

McNeil, a former Manitoba deputy minister who held senior positions at the Manitoba Floodway Authority, was appointed by the Ford government to review the response to record-breaking flooding in several locations across the province earlier this year, including the Muskoka River, North Bay-Mattawa and Ottawa-Gatineau. 

A perfect storm

The flooding in late April and early May forced dozens of people from their homes as the Ottawa River rose rapidly. The communities of Mattawa, Ont., Pembroke, Ont. and Gatineau, Que., were hit especially hard, some for the second time in two years.

According to the report, OPG facilities along the Ottawa River basin simply don't have the storage capacity to contain the amount of water generated in what McNeil calculated was a 100-year flood.

"Nothing pointed to human error or the negligent operation of water-control structures as the cause for the flooding this past spring," said John Yakabuski, Ontario's natural resources minister, at a new conference Thursday where he unveiled the report.

This finding is backed by public comments from the Ottawa River Regulation Planning Board, the agency that oversees the river, which previously blamed the flooding on "natural disaster" rather than mismanagement.

McNeil found the 2019 floods were caused by the perfect storm of cold temperatures lasting well into spring, above-average snowpack left on the ground, and higher-than-average precipitation levels. When the rain came down and the snow melted rapidly at the same time, disaster struck.

OPG water managers faced public pressure

The provincial government and officials at OPG came under significant pressure from angry residents and local politicians as people questioned how it managed the dams at four power generating stations it operates along the Ottawa River — Otto Holden, Des Joachims, Chenaux and Chats Falls.

Specifically, people pointed to a dry section of river near Deux-Rivières, Ont., and a nearly empty reservoir near the Des Joachims generating station, about 200 kilometres northwest of Ottawa, as places where water levels could have been raised to alleviate flooding downstream in Pembroke, Ont.

But McNeil's report said the criticism is misplaced. In Deux-Rivières, the water level was low because of the natural shape of the river, which he noted can act as a "control point" during high flow conditions.

Additionally, while filling the reservoir near Des Joachims may have provided some relief to residents in Pemroke, it would have spelled disaster for people far upriver in Mattawa.

"Using the storage capacity at Des Joachims Generating Station to alleviate downstream flooding would have had a large impact on Mattawa and provided negligible to no benefits at Pembroke," said the report.

The report included 66 recommendations for how the province can improve resiliency to flooding. 

One of the recommendations for OPG was to improve communication with the public by producing explainer materials, such as illustrations or video, to help the public better understand how it manages changes in water levels.

In April, Conservation Ontario said the provincial government cut funding for flood management programs in half, forcing local conservation authorities to absorb the budget cut even as they fought off rising waters.