Spring Freshet: Heightened Surveillance

The spring freshet has been happening since April 13, and Power Operations specialists have been preparing for it for several months now. They are monitoring the situation very closely and adjusting operations every day according to forecasts.

The combination of high temperatures in recent weeks, present and future record rain events, and the crest of the flood has resulted in a greater than normal upward trend in the level of Lac Saint-Jean.

Around May 19, Lac Saint-Jean will reach a level of 16.5 feet and will continue to rise. It is currently at 15.2 feet.

The rain that has fallen since Sunday, and the rain that we may receive during the week, is considerable. The scenarios are still highly variable and dependent on future weather forecasts. For example, if current rainfall forecasts come to pass, the probability of reaching 17 feet is at 50% as of today.

Stéphane Larouche, General Manager at Power Operations, said: “We need to remember that we control only 25% of the inflows to Lac Saint-Jean, specifically those from Peribonka River. All significant runoff operations have been implemented in the past several weeks to control the rise and minimise the impact of the flood. All spillways are open at full capacity on Petite Décharge and Grande Décharge rivers.”

We are in constant communication with civil security and community representatives to ensure public safety, which is Rio Tinto’s number one priority.

Be careful around hydroelectric facilities, both upstream and downstream!

Booms, an array of buoys used as a hazard warning, have not been installed on Petite Décharge and Grande Décharge rivers yet. Until they are installed, boating and land surveillance is in place around the spillways to raise awareness of boating safety near hydroelectric facilities.

It is important to stay away from the hydroelectric facilities, as the current increases around them.

During freshet, the flow of a river can change abruptly and rapidly at any time. Always follow existing signage and safety measures, such as gates, fences, and sound signals.

To follow the progress of the freshet, subscribe to the À prop’EAU newsletter HERE.