Risk of flooding in Ottawa Valley as heavy rain rolls through region

Heavy precipitation forecast for Thursday, combined with melting snow and heavy rain from earlier in the week, is expected to cause flooding in some low-lying areas along the Rideau River south of Ottawa.

That's according to a flood watch issued Tuesday by the Rideau Valley Conservation Authority (RVCA), which monitors water levels in the Rideau watershed.

A total of 26.4 millimetres of rain fell on Ottawa Tuesday, with another 20-30 millimetres forecast for Thursday and the possibility of up to 50 millimetres in some areas, according to Environment Canada.

"If we do get as much as forecast, we can expect fairly significant flow increases, which could cause some flooding of low-lying areas," said Patrick Larson, senior water resources technician with the RVCA.

The first area expected to experience flooding is Long Reach, a stretch along the Rideau River connecting the communities Kemptville and Kars, with flooding affecting access to Hilly Lane, Cedar Beach and Rideau Glen.

40% more water flow in Rideau

As the water makes its way downstream Friday into Old Ottawa South, flooding is a strong possibility on Belmont Avenue, Rideau River Drive, and Windsor Park.

Larson said he'll be keeping a close eye on a monitoring station setup on the river at Carleton University. 

"The average is about 320 cubic metres per second. We're looking at in the order of 450 cubic metres per second," said Larson.

Larson said the high levels and fast flowing water also present a danger for people walking along the shoreline, especially children who can easily slip on wet rock and fall into the river.

Over in Gatineau, the concern is not only flooding, but also the release of untreated stormwater and sewage into the Ottawa River, according to the Ottawa Riverkeeper's director of Quebec operations, Adèle Michon.

"The sewer pipes in Gatineau are not equipped to handle that much water," said Michon.

"The stormwater can mix with raw sewage and overload the system, then it all overflows into the Ottawa River. That's why it's important to reduce our consumption of water."