Flooding in the Ottawa River watershed

The flooding of the Ottawa River is affecting thousands of people, and we want to make sure that everyone is safe and has access to the resources they need.

May 16th: The Ottawa River watershed came together in this time of need. Thanks to everyone who helped their neighbours and communities, and continue to do everything they can to help those who are still affected. A lot of work remains to be done as the waters start to recede. This includes disposing of sandbags and cleaning up our shorelines. We have updated our resources below to include additional information.

April 29th: Thanks to everyone who is helping out their neighbours and communities. With water levels set to peak later this week, at levels higher than the 2017 floods, we hope that the links below will provide you with the information you need to get through this tough time.

If you have questions about the flooding not covered by the resources below, do not hesitate to contact Ottawa Riverkeeper on our Social Media platforms or by emailing communications@ottawariverkeeper.ca.

If you spot pollution or see something that doesn’t look right on the river, you can report it to our Pollution Hotline at 1-888-953-3737 or online.

Flooding resources for major cities:

The following pages are a great place to start looking for information. They cover not only information for citizens of those cities, including where to volunteer, but also general tips for flood preparedness, mitigation and emergencies. As waters recede, they will also be updated with new post-flood information.

Ottawa: https://ottawa.ca/en/residents/emergency-services/emergency-preparedness/flood-information-0

Gatineau: http://www.gatineau.ca/portail/default.aspx?p=avis_importants_alertes_urgences/20190319_crue_printaniere_2019

What to do with used sandbags: https://www.cbc.ca/news/canada/ottawa/what-happens-used-sandbags-1.5129134?__vfz=medium%3Dsharebar

What to do if your house is at risk:

The most important thing is to stay safe. If your house is at risk, ask for help on social media, people will show up. If water is starting to flood your house, turn off all electricity to avoid electrocution, and have an electrician certify that the power can be turned on again when water has gone away. Do not drink water from groundwater wells or surface water if you are anywhere near flooded areas. If your septic tank is flooded, do not flush your toilet, until water has gone back to normal levels.  

To volunteer:

Here are some groups on Facebook where you can connect to people who need help directly:

Spring Flood 2019 / Crue printanière 2019

Rockland FLOOD Relief 2017/2019

Aylmer / Aide aux Sinistrés des Inondations / Help for Flood Victims


In times of crisis, assistance from friends and family, but also from neighbours and strangers, is essential to help the people affected cope and bounce back. You can play a role in this.

Please do not visit the flooded streets. You can best help by filling sandbags to protect houses or by helping clean up streets and shorelines from debris when the water has receded.  

The city of Ottawa has a great page with tips on how to prepare to volunteer: https://ottawa.ca/en/news/what-expect-if-youre-volunteering-flood-preparations

A Message from our Volunteer Coordinator (April 29th):

I hope that you are staying safe and well during the flooding crisis that has hit us. As you probably know, the flood levels still have not reached their peak and the City of Ottawa is still calling for volunteers. We want to extend our appreciation for our volunteers who have spent and continue to spend long hours helping protect people’s homes. It is so great to see so many people from all over the watershed come together to help each other. Here is one of our volunteers in action, helping at Britannia on the weekend.

Katie Shafley, Volunteer Coordinator

To donate:

Please give time, clothing or furniture to your local community center or to the Red Cross:  call 1-800-418-1111 or donate online.

Resources for other municipalities/regions:

Quebec: https://www.securitepublique.gouv.qc.ca/en/civil-protection/floods-information-citizens.html

Clarence-Rockland: http://www.clarence-rockland.com/index.php/en/residents/flood-2019

South Nation Conservation Authority: https://www.nation.on.ca/water/watershed-conditions/flood-forecasting-warning/current-watershed-conditions

Arnprior: https://arnprior.ca/town/notices/

For information on water levels and forecasts:

ORRPB: http://www.ottawariver.ca/river-levels-flows.php

Latest updates:

May 16th: The ban on watercraft in flooded areas has been extended. The area now stretches from Mattawa to Montreal, and self-propelled craft such as canoes, kayaks, and surfboards are also banned.

April 29th: Non-emergency boats no longer allowed on sections of the Ottawa River, with heavy fines for violators (additionally, drone piloting is also restricted in flooded areas).

April 29th:Chaudière bridge closed due to water levels.

Water levels around dams:

This week, the Ottawa River is experiencing record high water levels. We are hearing about many of the communities that are being most severely impacted and, occasionally, from areas where water levels are below normal. People have questioned why water levels above some of the dams are low, while there is flooding downstream. How is this possible? Why are the dams opening up more of their gates and spillways when so many areas below these dams are flooded? Can`t they do more to control the water levels?

There are many dams throughout the Ottawa River watershed but only a small number have reservoirs large enough to hold back significant volumes of water. Most of these are located upstream of Lake Temiskaming. These dams in the upper part of the watershed lower the water levels in their reservoirs in late March and early April to make room for the spring rains and snowmelt and hold back the water from the upper part of the watershed as much as possible. The rest of the dams in the watershed have minimal capacity and are unable to significantly change the flow of water moving through the watershed.

The reservoirs have begun to fill up but, at the start of the spring melt, the majority of the water impacting the water levels comes from the central and lower part of the watershed. To accommodate this increased volume at this time of year, some of the dams do lower the levels to reduce the flooding which can occur many kilometers upstream of the dam. Since the dams in the lower and central part of the Ottawa River have no reservoir capacity, their gates are adjusted to allow the volume of water to pass through at the same rate it is arriving. This returns the river, in some ways, to a pre-development /pre-dam state.

When additional gates are opened, it is because more volume is arriving from upstream. Areas with low water are reaches in the river where water can move through quickly based on the geomorphology of the river channel. Where flooding is occurring, it is because there is some type of natural impediment (such as a narrowing of the stream channel) which does not allow the same volume of water to pass through that part of the river as quickly as it is arriving. As a result the water backs up and floods the area upstream. There is an explanation for this phenomena on the ORRPB site which also includes a list of locations where this occurs, including at the Carillon Dam.

6 responses to “Flooding in the Ottawa River watershed”

  1. Terry W Johnston says:

    Why is the water level allowed to climb before ice out when as in this year it was evident that there would be high volumes of water. If each dam was not brought to capacity before the flood we would not begin with an artificial river level at the start. I live on Chats lake and saw the river rise at least 6ft before ice out. The distance between the two dams is 40 kms that is a lot of water we did not need . How much would it help I do not know but it would give us a better staring point.

    • Matthew Brocklehurst says:

      Hello Terry, thanks for the question. As we mention in the blog, the ORRPB has a great answer for this question (http://ottawariver.ca/faq.php#q5) but in brief: they do lower water levels before the spring freshet. However, features of the natural landscape of the river also contribute to water levels. In fact, the FAQ question in the link specifically mentions Chat Falls as one of the areas where this phenomenon can be observed, so that the water levels at the dams are lowered to minimise flooding upstream, however the topography of this area limits water flow naturally which is why there is flooding in Chats Lake.

  2. Ian says:

    I know the watersheds of the Ottawa and Rideau rivers differ but most years when the Ottawa is very high the Rideau is too. This seems to not be the case this year. Any thoughts?

    • Matthew Brocklehurst says:

      Hi Ian, great question. The Rideau River watershed is a sub-watershed located in the southern portion of the Ottawa River watershed. As a tributary of the Ottawa River, the Rideau River flows into the Ottawa River and can influence water levels there. However the reverse is not true; the Rideau River is not influenced by water levels upstream of the Ottawa River or its tributaries (water levels which are related to the current flooding). As a result, peak water levels and flow on the Rideau River do not always coincide with that of the Ottawa River.

      In early April, flood warnings were issued for the Rideau River, particularly for areas in the upper part of the Rideau River watershed. These warnings, which were subsequently downgraded to flood watches, were largely due to melting snow and the same precipitation events affecting the Ottawa River watershed. As of April 29th, the Rideau Valley Conservation Authority has reported that water levels in the Rideau River watershed have declined and are reaching seasonal levels in all waterways with the exception of two upstream reservoir lakes, Bob’s Lake and Christie Lake, where levels will likely continue to increase. Parks Canada staff are closely monitoring water levels in these lakes and operations at the nearby Bolingbroke Dam will work to balance out these water levels. Currently there are no flood warnings for the Rideau River and its tributaries.

  3. Brad says:

    Have the watershed management systems in place; that set and regulate levels changed over last 4 years?
    I know you have said they reduce water levels before spring fresher, but I have noticed higher levels maintained above all damns in system.
    Commission predicted increased flooding was an acceptable risk with these increased levels. Who decides what level is an acceptable risk?

  4. Shawn Bashaw says:

    I understand the reason for lowering the reservoirs to receive the spring melts.
    I live in Constance Bay and up until the last five years there was never high water all summer and in the fall.
    The Ottawa river was lowered for the spring melts.
    Why may you explain that in the past five yrs the water is left high and now we have been flooding past the 100 yr flood mark?