Water levels continue to rise along Ottawa River

Minor flood levels have been reached in multiple locations along the Ottawa River between Mattawa, Ont., and the Montreal region, with major floods expected east of Lac Coulonges, authorities say.

Water levels are expected to remain 45 to 100 centimetres below historic 2019 levels, according to the latest Ottawa River Regulation Planning Board update Monday afternoon. 

They've passed the 2017 peak in Pembroke, Ont., as of Tuesday morning and are forecast to pass that peak in Lac Coulonge, which is between Whitewater Region, Ont., and Mansfield-et-Pontefract, Que.

All seven monitoring stations from Pembroke to Grenville, Que., are at least 75 centimetres above average. Three are a metre above that daily average.

The City of Gatineau is urging shoreline property owners to remain vigilant, as water levels around Hull are expected to rise over the coming week by 50 to 60 centimetres compared to last week's peak.

At a press conference, Mayor France Bélisle said the city is "still facing a difficult situation."

"So far, we're looking at 1,000 lots that might be affected and around 250 houses and businesses that might be affected by the flooding," she said.

Shoreline property owners who were visited by Gatineau fire safety officials in the last few weeks are the same ones whose properties will be affected, according to a Monday update from the city that includes the latest sandbags, volunteering and other information.

The city added that traffic may be restricted on certain streets in the event of flooding. Highway 50's eastbound ramp to rue Saint-Louis closed Monday night.

Based on the latest weather forecast, water levels are expected to rise by the following amount in these areas over the coming week:

• Mattawa: 45 to 50 centimetres compared to May 1.
• Pembroke: 40 to 45 centimetres compared to May 1.
• L'Iles-aux-Allumettes/Lac Coulonge: 50 to 55 centimetres compared to April 21-23.
• McNab/Braeside/Arnprior/Chats Lake: 25 to 30 centimetres compared to April 21-23.
• Constance Bay/Aylmer/Lake Deschênes: 25 to 30 centimetres compared to April 21-23.
• Hull to Montreal: 50 to 60 centimetres compared to April 21-23.

Ottawa River Basin 'problematic', expert says

Beth Gooding, director of the City of Ottawa's public safety service, wrote in an emailed statement that Chats Lake and Lake Deschênes water levels are expected to exceed their major flooding thresholds over the coming week.

That city has an online hub with information on sandbags, toilets and water and more.

Gooding added that areas prone to flooding between the Ottawa-Gatineau and Montreal regions may experience light flooding.

"It's the Ottawa River Basin that's problematic right now," Brian Stratton, a spokesperson with the Rideau Valley Conservation Authority (RVCA), said in an interview with CBC's All In A Day.

"We had a lot of snow and then we did experience some some quick melting and then we got some heavy rains."

Based on information from the Ottawa River Regulation Planning Board, he said water levels in the Ottawa River are going to continue to increase until at least Thursday.

Stratton said the areas of greatest concern over the coming week are Cumberland and along Britannia Bay, where he expects the water levels will rise by up to 20 centimetres this week.

In Britannia Bay, he said flooding is expected to be mostly "backyard flooding only."

In Cumberland, Stratton said some people can expect to see "floodwaters come very close to their houses or possibly above their foundation levels."

"[People] are going to have to make sure that their sandbags are in place this week to prevent any major damage," he said.

Cataraqui Conservation also issued a flood watch Monday for the Cataraqui watershed and Gananoque River system due to excessive rainfall in recent days.

Rideau Valley looking 'pretty good'

The flood situation in the Rideau Valley looks "pretty good," Stratton said, despite the area receiving 40 to 60 millimetres of rain over the weekend.

He said the rainfall has caused a spike in water levels, "but for the most part they're not at flood levels, and some of the streams are … already declining."

Still, he said, a flood watch remains in place for Bobs Lake and Christie Lake in the upper watershed.

"Bobs Lake is a reservoir lake which basically feeds the Rideau River during the summer months," he said, adding that the lake is currently at its capacity.

As a result, Stratton said water will be released from Bobs Lake into Christie Lake.