People living in the Sherbrooke area remain on high alert for more flooding as the Saint-François River is at a critical depth of just over five metres, and is expected to keep rising over the next 24 hours.

At 4:20 a.m. Thursday, the river reached a depth of 4.5 metres.

An automated machine called the 'mediaphone' started calling homes in the area to warn them about possible flooding.

Since then, the water level has risen more than half a metre.

Sherbrooke's emergency services coordinator Gaétan Drouin said the city will start evacuating homes if the river reaches 6.4 metres.

Evacuation has already begun at a camp site near the river.

"We're evacuating about 50 trailers at the Île-Marie Camping, and we'll probably have to evacuate the whole site during the day," Drouin said.

Sherbrooke had some flooding in the Rock Forest area at the beginning of the week. Sixty homes were affected.

Drouin said this much flooding is unusual at this time of the year.

He said river flow is about the same as during the spring thaw.

The weather forecast calls for little rain Thursday, but Drouin said Friday's forecast of showers could cause the river to overflow.