Frequently Asked Questions

Q 1: Who is the Board and what do they do?

A: The Board consists of seven members who represent Canada (3 members), Ontario (2 members), and Quebec (2 members). The member agencies that make up the Board are:

  • Ministère du Développement durable, de l'Environnement et des Parcs du Québec
  • Ontario Ministry of Natural Resources
  • Hydro Québec
  • Ontario Power Generation
  • Environment Canada
  • Public Works and Government Services Canada
  • Canadian Coast Guard
The mandate of the Board is to formulate regulation policies and criteria leading to integrated management of the principal reservoirs of the Ottawa River basin. The Board also aims, through integrated management, to minimize flooding along the Ottawa River and its tributaries and particularly in the Montreal region and, at the same time, maintain the interests of the various users, particularly hydroelectric production.

Q 2: What is "integrated management"?

A: The term "integrated management" means that all the different dam operators in the basin operate their facilities with knowledge of what the other operators are doing and the consequences of operational decisions elsewhere in the Ottawa River basin. This type of management allows the reservoirs in the basin to be used in order to minimize flood damages. However because of the nature of the basin, the limited storage capacity and the location of the storage, flooding cannot always be avoided.

Q 3: How is "integrated management" achieved in the Ottawa River basin?

A: In order to provide integrated management in the Ottawa River basin there is a continuous flow of information between the agencies of the Ottawa River Regulating Committee (ORRC). The ORRC reports to the Board. The ORRC is comprised of the agencies who manage the principal structures in the basin. They are responsible for the day-to-day operations at the dams. The Ottawa River Regulation Secretariat is the executive arm of the Board. The Secretariat assists the ORRC in all aspects of its work and also acts as a data processing centre. During the spring freshet, or other unusually high flow events, there is a daily exchange of data between the agencies of the ORRC and the Secretariat. The data received from the agencies includes real time data collected from remote sensing equipment located throughout the basin as well as declared operations at their structures for a period of ten days. The Secretariat combines this data with forecasted inflows for all tributaries and other points in the basin as input to a flow routing model and an optimisation model that predict water levels and flows at different points throughout the basin. The model results are evaluated by the ORRC and Secretariat and discussed at a conference call during critical periods to confirm or change operational strategy in order to minimize the impacts of flooding. This process is repeated every day and once a week outside of freshet period.

Q 4: Instead of checking your website everyday, can I receive daily level updates by email?

A: The Ottawa River Regulation Secretariat does not have the resources available to be able to offer this type of service. You will have to check the website or toll-free information telephone line for daily updates during the spring freshet and once a week outside the freshet period.

Q 5: Why is the water level in my area so high that there is flooding, while the water level in other areas is lower than usual?

A: In spring, the amount of runoff increases causing the watercourses to swell, which naturally increases the water levels throughout the river system. However, in some areas upstream and in close proximity to “run-of-the-river” hydroelectric stations, the opposite can happen where operators lower water levels to limit upstream flooding.

It should be noted that, due to the natural characteristics of some areas of the river, the water level upstream of a hydroelectric facility can create a backwater effect over several kilometres. In some cases this effect can extend upwards of more than 50 km. Consequently, as the river flow increases, some stations must lower their water levels to limit flooding in communities located far upstream by maintaining water levels as close as possible to natural conditions, i.e. conditions before the generating station was built.

During this period when levels are kept low, the flow of water through the facility is the same as the flow of the river. Attempting to hold back any water and maintaining higher water levels upstream of the dam could pose serious risks to shoreline residents and to the run-of-the-river facilities that have a limited reservoir capacity.

The locations within the watershed where this phenomenon can be observed include the areas upstream of Chats Falls, Carillon, Paugan and Chelsea generating stations. It is not unusual for operators of these facilities to maintain low water levels upstream for several weeks to ensure the spring freshet has subsided and river flows have decreased to a safe threshold. For example, the level immediately above the Carillon generating station is usually lowered 0.6 m during the spring thaw.

Q 5.1: Why is the water level so low at Deux-Rivières (above the Des Joachims generating station) when levels are very high and flooding immediately downstream on the river?

A: Flood impact reduction during the spring freshet and other high flow events is achieved mainly by storing the spring runoff in the thirteen principal reservoirs that are subject to integrated management under the 1983 Agreement. Seven of these reservoirs can influence the flows of the Ottawa River between Rolphton and Fort Coulonge. The six northernmost (from Lake Timiskaming and further north in the Abitibi area) have a significant storage capacity and are the first to be utilized in the regulation strategy to minimize flood impacts. The timing of the refill at these locations is optimized to mitigate flooding all along the Ottawa River below Lake Timiskaming. These measures aim at reducing northern discharges while local uncontrolled tributary rivers such as the Petawawa and the Coulonge reach their peak and start to recede.

The Des Joachims facility, which includes the seventh reservoir, can create a backwater effect all the way upstream to Mattawa (similarly to facilities described in Q5). This is why the spring refill strategy at Des Joachims consists of two stages. The purpose of the two stage refill is to balance the risk of flooding in upstream and downstream areas.

During the first stage of the refill, the water is brought up only about halfway to the top of the reservoir. This enables low water levels to be maintained upstream of the facility to limit the amount of backwater effect created and assist with the mitigation of downstream flooding by using some reservoir storage. These low (“natural”) levels are sometimes remembered only by elders who have known the river before Des Joachims was constructed in 1950.

The second stage of the refill, when the rest of the reservoir is filled, is completed once the probability of upstream flooding in Mattawa is reduced. It is only then that dam operators return to normal operating levels.

Residents along Lac Coulonge will observe similar flood mitigation strategies with the lowering of water levels above the Rocher Fendu and Bryson facilities. At these facilities, water levels are maintained at a lower elevation during spring freshet when required in order to minimize upstream levels.

Q 6: Where can I find information regarding water levels and flows in the Lac des Deux Montagnes / Montreal region during the spring freshet?

A: The Ministère du Développement durable, de l'Environnement, de la Faune et des Parcs du Québec has a web site with current and forecast water levels and flows available for the Montreal area at the following URL:


Q 7: My water supply comes from a well. I would like to know the condition of the water table this year. I would also like to know if my well is built correctly.

A: Your local municipality, ministry of environment or conservation authority are best suited to answer these types of questions. Several conservation authorities in Ontario are participating in a provincial groundwater quality and quantity study. The Mississippi Valley Conservation Authority has a Groundwater information page at the following URL:


Consult Ottawa River Water Levels and Flows