Still, the city's director of roads reassured residents the bridges are safe.
"The piers, the abutments on either side of the bridges, are right down to bedrock. What that means is what they are standing on is absolutely tied to the ground," Ryan Jestin said in a video posted on the city's website, standing in the rain overlooking the flooded Bow River downtown.
Meanwhile, Calgary police said they were patrolling evacuated areas to ensure that vacant homes and businesses would remain as safe as possible.
Authorities declared a state of emergency in several cities, including the mountain town of Canmore, where on Thursday, raging water tore out a portion of the Trans-Canada Highway.
Rescue crews used heavy construction equipment to rescue people from homes and businesses Thursday in High River, the network reported.
Canada's military was pitching in with helicopters and other assets to help local officials with rescue and evacuation efforts, Prime Minister Stephen Harper said.
The flooding was caused by a slow-moving storm that dumped 154 millimeters (more than 6 inches) of rain on the region from Wednesday to Thursday, CNN meteorologist Sherri Pugh said. As much as another inch of rain, about 25 millimeters, is possible northwest of Calgary on Friday, and yet another front is expected Monday, bringing the threat of more rain.
Calgary, near the Canadian Rocky Mountains, is perhaps best known for its rodeo, held each July. More than 1.4 million people attended last year, organizers say.
This year's Stampede events are due to begin in 13 days. It was unclear if the flooding would affect the event, but organizers did say on their website that other events scheduled at the park where the Stampede is held have been canceled through Sunday.
Calgary authorities are using the park as a staging area for flood response efforts.