The Ottawa Valley's busiest bridge has been closed until further notice.

The Petawawa Boulevard bridge, connecting the town with Garrison Petawawa over the Petawawa River, typically sees 17,000 vehicles per day.

However, severe erosion from the fast-flowing river, which is moving at a volume that officials say far exceeds those during the 2017 floods, has eaten away at the river banks at the base of the bridge, and there's concern about the integrity of the bridge base itself.

The closure was announced by the County of Renfrew, which is responsible for the bridge, at 9:00 a.m. on Tuesday.

Work crews arrived on scene a short time after the closure, dropping boulders into the river in an attempt to divert water away from the badly-eroded river banks.

Engineers, inspectors and contractors were also busy at the site, checking out the integrity of the structure and the utility lines that flow beneath the span of the bridge, including natural gas lines and electrical lines.

"Hopefully there's no damage, structurally or otherwise", Petawawa Mayor Bob Sweet told Star 96.7 at Town Hall on Tuesday morning.

"That's a tremendous amount of water coming down the river", Sweet added.

Until further notice, all traffic is detoured onto the Highway 17 bridge, which is the only other bridge spanning the Petawawa River, located a little farther upstream.

The current bridge has been in place since the failure of the previous bridge back in the early 1970s.

At that time, there was no detour because the highway 17 bypass was built yet, and a temporary bridge had to be put in place,

"Huge, Huge Volume Increase" On River

The volume of water flow on the Petawawa River is dramatically higher than the high level that was hit back in 2017.

Officials say in 2017, it was 437 cubic metres per second. On Monday, it was hitting 690 cubic metres per second.

"That's a huge, huge volume increase on one river", Sweet said.

On Monday afternoon, before the decision was made to close it, chunks of earth could be seen falling from the banks of the Petawawa River into the fast-flowing waterway, and by Monday evening, staff at a real estate business that sits atop the banks across from the Petawawa Legion were ordered to evacuate their building.

The town's emergency control group is monitoring this, and other hazards around town from high water and flooding.

Petawawa is one of several municipalities that's under a state of emergency because of this spring's unprecedented high water levels and flooding.

Mayor Sweet says the emergency declaration puts them in a position to respond quickly if needed.

"We've got to be vigilant and that's what we're doing", Sweet told Star 96.7.

"We're being proactive to try and protect our community".