The last big flood of the Grand River through Cambridge happened May 17, 1974, leaving behind $6.7 million in damages.

That’s $42.5 million in 2024 dollar value, according to the Bank of Canada inflation calculator.

Nobody died, but several people were rescued from the surging waters by firefighters, police and bystanders. One man was pulled from a tree in mid-river by helicopter, according to news clippings at the City of Cambridge Archives.

The river peaked at 4.8 metres – 16 feet – above normal level and inundated much of downtown Cambridge.

Remembering the Flood of 1974

Fifty years after the 1974 flood, an event remembers the flood and talks about emergency preparations for future disasters.  The free event runs May 4, 2024, at the Cambridge Fire Hall Museum and Education Centre, 56 Dickson Street, beside Cambridge City Hall.  

Displays are open 9 a.m. to 2 p.m., says Ingrid Talpak, one of the organizers.

The event is a partnership between the Cambridge Fire Department, IdeaExchange library, City of Cambridge Archives, Cycling and Trails Advisory Committee, and McDougall Cottage Historic Site.

Displays will include rescue craft used today on local waterways. For example, a fire department airboat can manoeuvre through shallow water or crunch over winter ice.

The Fire Hall Museum partnered with Jane’s Walks Waterloo Region to offer several guided walking tours from the Museum to the Idea Exchange Old Post Office. They will highlight points of interest and high-water marks from the flood of 1974.

A Beautiful, Sunny Day in May

May 1974 had been unusually wet.  On Thursday, May 16, an overnight thunderstorm dumped 50 mm of rain across the saturated Grand River Watershed.  

Upstream reservoirs behind dams couldn’t contain all the rainfall. The Grand River Conservation Authority would later say it warned officials in Cambridge at 11 p.m. Thursday that high water levels were expected.

City officials said the conservation authority didn’t hint at how bad things would get, according to news stories in the Cambridge Daily Reporter newspaper on file at the city archives.

The last big flood in the Grand River came during Hurricane Hazel in cold October weather in 1954, twenty years earlier.

Friday, May 17 dawned sunny and warm. By 11 a.m., the river was rising.  By noon, water was over the banks downtown – and still rising.

Businesses, churches and residents tried to move valuable items above the rising water.  Citizens helped firefighters rescue people from the filthy water rushing through town.  

Some downtown workers were trapped in the offices when they left for work. They didn’t learn about the rising water until too late. Some were rescued in the bucket of a front-end loader, which carried them over the flood waters.

A boil-water advisory later was issued, as government officials feared contamination of the drinking water system.

And on Water Street near Parkhill Road, a fire started in the former Hahn Motors car dealership near the river.  Flames gutted the building as firefighters struggled to reach the building by boat.

It took more than two months for downtown businesses to clean up and recover from the damage, according to Cambridge Reporter news clippings.

21 Recommendations from Flood Inquiry

There were 21 recommendations from an Ontario government inquiry into the disaster. It heard 43 days of testimony.

Key recommendations included an expanded flood prevention plan throughout downtown.   More than $20 million was spent on flood control and property purchases in the following 15 years.

For several years in the mid 1980s, construction crews blasted into bedrock to lower the river channel.  At the same time, taller flood walls and berms rose along the river, with the goal of containing another flood of the scale of 1974.

The conservation authority and city blamed each another for delayed flood warnings at the inquiry.  Judge Wilfred Leach absolved the conservation authority of blame at the inquiry.  He also insisted on a better flood warning system.

That recommendation led to a network of water-level monitors across the watershed.  Every year, flood coordinators in cities, towns, and townships across the Grand River watershed test the alerting system. 

Flood Warnings Now on Social Media

The public part of the warning system began with regular releases to local newspapers, radio and television stations. Today, public outreach includes social media, email alerts and live river-level data displayed on the conservation authority’s website. 

Every year, city public works crews also practice installing portable flood walls at ends of the three bridges along the Grand in Galt.  The bridges are lower than the raised flood walls, leaving a gap in flood protection.  

If high water is expected, city crews collect kits of pre-cut aluminum posts and logs.  The posts are dropped into pre-made sockets in the road at each end of the bridge.  In between, more sections are dropped into place horizontally.  To waterproof and buttress the temporary walls in a real flood, thousands of sandbags would be filled and stacked behind them.