Centre-du-Québec

Spring flooding on the Rivière Saint-François: Our run-of-river stations do not have reservoirs to hold back water

In the Centre-du-Québec region, Hydro-Québec operates two hydropower generating stations on the Rivière Saint-François: Chute-Hemmings and Drummondville. These facilities are run-of-river stations, which means that they cannot store water. They can only let the river’s natural flows, which are inherently unpredictable, run through them.

Managing the river: A team effort

Barrage Mékinac
Chute-Hemmings generating station

Hydro-Québec is not the only hydropower producer on the Saint-François; there are 18 dams present in the river’s watershed. Operating the river is a collaborative effort between partners. Every drop of water in the Saint-François is monitored by the Conseil de gouvernance de l'eau des bassins versants de la rivière Saint-François (COGESAF).

The COGESAF brings together the various agencies that participate in managing the waters of the Rivière Saint-François watershed, including the regional environment councils of the Centre-du-Québec, Estrie and Chaudière-Appalaches regions, and the Ministère de l’Environnement et de la Lutte contre les changements climatiques du Québec. Ensuring the safety of the public and facilities is a key priority guiding all COGESAF decisions.

Higher river levels in the summer thanks to our facilities

Located in the heart of the city of Drummondville, our facilities do much more than generate energy. As part of our efforts to enhance the integration of our facilities into their host communities, we increase the water level upstream of Chute-Hemmings generating station in the summer, creating a navigable stretch of river for the region’s boaters to enjoy.

Chute-Hemmings Generating station
Chute-Hemmings Generating station
Hydro-Québec personnel installing flashboards.
Hydro-Québec personnel installing flashboards.

After every spring flood, once the flow of the Saint-François is safe, Hydro-Québec temporarily lowers the river level upstream of Chute-Hemmings dam so that our personnel can install mobile panels, called flashboards, on the dam's overflow crest. These panels raise the water level, which remains higher-than-normal upstream of the facility throughout the summer months. Since they would not withstand spring and fall ice jams, the flashboards are removed in autumn, before freeze-up. If they were kept in place, they would cause ice build-up at the dam and would most likely be torn off and carried over the dam’s crest.

Want to be the first to know about the installation and removal dates for the flashboards? Sign up for our Project News bulletins by writing to projets.mauriciecentreduquebec@hydroquebec.com.

We maintain an ecological flow in the river to meet the needs of aquatic wildlife

The Saint-François is home to a variety of aquatic wildlife, including lake sturgeon, a protected species. During the spring spawning period, which runs from about April to June, Hydro-Québec maintains an ecological flow in the river to promote the spawning success of several fish species. This measure is the subject of a cooperation agreement with the Ministère des Forêts, de la Faune et des Parcs du Québec. We therefore cannot raise the water level above certain predetermined values.

Lake sturgeon
Lake sturgeon
Source : ministère des Forêts, de la Faune et des Parcs du Québec.

Important reminder: In the event of a flood, contact your municipality. They will advise the Ministère de la Sécurité publique du Québec, which coordinates all flood-related operations.

Questions on how Hydro‑Québec facilities are managed? Contact us at projets.mauriciecentreduquebec@hydroquebec.com.

Frequently asked questions

In an emergency situation related to spring flooding or any other flood, what are the roles of Hydro-Québec, the Sécurité civile and municipalities?

Hydro-Québec collaborates with the Sécurité civile and municipalities and informs them about the management of its facilities. The Sécurité civile and municipalities are responsible for managing emergency response operations for floods.

What is a flashboard? What is it used for?

A flashboard is a mobile panel that is placed on top of a weir to raise the water level in the spring in preparation for the summer season. Flashboards are used to keep water levels high in the summer to make boating possible on the upstream stretch of a river or other body of water.

Why is the river level being lowered earlier than in previous years in the fall?

For safety reasons, and due to the exceptional weather conditions of the last few year, we are now lowering the level of the Saint-François in mid‑October.

Is the public notified of the water level variations linked to the installation and removal of the flashboards?

Yes. Public notices are published in the local weekly newspaper (L'Express). In addition, residents and organizations can sign up to receive this information by email. To register, contact: projets.mauriciecentreduquebec@hydroquebec.com.

When the flashboards are installed, does Hydro-Québec generate more megawatts?

Yes, to some extent, but they are installed mainly to make navigation possible on the river.

Why not close the gates completely to speed up the raising of the river level in the spring?

A minimum flow must be maintained at all times in the Saint-François to supply the municipal water intake and ensure fish spawning.

Why does it take so long, even when the gates are closed, for the level upstream of Chute-Hemmings generating station to reach its summer level?

The rise in the river level depends on the flow of water. For example, during periods of no precipitation, the water level will rise slowly. In addition, a minimum flow must be maintained at all times to supply the municipal water intake and ensure fish spawning.