City task force prepares for spring thaw
The City of Ottawa's spring freshet task force is applying the lessons learned from the floods of 2017 and 2019 to prepare for the possibility of flooding this year.
In a memo to councillors, general manager of emergency and protective services Anthony Di Monte said the city is working with external partners to monitor water levels.
Right now, those levels are normal or close to normal along the Ottawa River basin. There's no river flooding in the forecast right now — but that could change, he said.
West Carleton-March Coun. Eli El-Chantiry, who has taken the lead on council to oversee the spring freshet, said the province has agreed to address recommendations made by an independent special adviser who reviewed the 2019 spring floods.
It's not until around mid-April that the city starts to see signs of any potential flooding along the Ottawa River, said El-Chantiry.
Will there be significant flooding this year? It's too early to tell.
“The main drivers are the amount of snow, the temperature and significant rain,” said Brian Stratton, manager of engineering services at the Rideau Valley Conservation Authority.
“A couple of years ago, we had a massive snow pack and a very slow thaw. It melted over the course of a couple of weeks. If it had melted over the course of a couple of days, it would have been different.”
So far, there is an average amount of snow through most of the Rideau Valley watershed, which covers about 4,000 square kilometres from Upper Rideau Lake to the City of Ottawa. The city and the Rideau Valley Conservation Authority have started this year's ice breaking and clearing operations along the Rideau River.
Snow alone doesn't dictate if there will be a flood, said Jennifer North, the Mississippi Valley Conservation Authority's water resources technician. It also depends on how the snow dissipates, the amount of rainfall, how quickly the temperature rises and how much storage there is in the system. So far that's normal for this time of year on the Mississippi system, she said.
“Things can change in a couple of days. If we see the rest of winter unfold under normal conditions, it will be average-normal — as long as things don't get too wonky with a big melt and a lot of rain,” said North.
The Mississippi Conservation Authority has posted an interactive watershed map on its website that lets users check on water levels and current conditions in the watershed.
The Rideau Valley Conservation Authority has installed new technologies that will make “data tools” available to the public in real time, including four flood gauges in four vulnerable communities inside the City of Ottawa — Cumberland, North Gower, Richmond and Brantwood Park.
A new water gauge in Cumberland with updated technology will help local residents compare current water levels to past floods so they can predict what's coming and prepare accordingly, said hydrometric data co-ordinator Justin Robert.
The conservation authority has also posted new neighbourhood flood maps that show where and how flood waters could breach during two-, five-, 10-, 20-, 50- and 100-year floods for 20 vulnerable communities along the Ottawa and Rideau rivers.
The maps can help homeowners decide how to protect their properties, whether it's choosing a spot to sandbag or taking movable objects to higher ground.
The city began planning for the 2021 freshet last fall. The task force is developing a communications strategy and educational materials on flooding preparedness and is looking into revised operational and tactical procedures and exploring opportunities to purchase new flood mitigation and prevention assets, Di Monte said.
The city's plans have taken the possibility of potential provincial COVID orders into account.