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Quebec ministry determines fish mortality caused by dissolved gas supersaturation

An investigation by Quebec’s Ministry of the Environment and the Fight against Climate Change has determined that recent fish kills in the Lievre and Ottawa rivers were caused by dissolved gas supersaturation.

After extensive fieldwork and rigorous research, carried out by departmental officials with the support of the Ministry of Forests, Wildlife and Parks (MFFP), Lievre Power LP and Brookfield Power Services Inc. have been identified as responsible for episodes of fish kills in recent weeks. Indeed, certain conditions of operation of the Masson hydroelectric power station the two companies operate caused a phenomenon of supersaturation in dissolved gas, causing the death of many fish.

Masson is a 105-MW hydro plant that began operating in 1933.

Under section 114 of the Environment Quality Act, the Minister intends to order the following actions:

  • Operate the Masson hydroelectric plant to limit the risk of supersaturation of dissolved gas in the water discharged at the outlet of the plant in the Lievre River;
  • Ensure close monitoring of the situation at all times;
  • In the short term, continuously measure the rate of supersaturation in dissolved gas, by setting up certain specialized equipment;
  • Notify the Ministry without delay of any level of dissolved gas saturation exceeding a threshold considered critical for aquatic wildlife.

“Fish mortality in the Lievre and Outaouais rivers has caught the government’s attention. Today, we are in a position to argue that the cause of these events must be attributed to the Masson hydroelectric facility, operated by LP Lievre Power and Brookfield Power Services Inc.,” Charette said. “That is why I deem it imperative to send a clear message to its leaders that their activities must be carried out with respect for the environment and, in this case, for aquatic life. “

Additionally, the Minister previously said that he intends to require the companies to contract a recognized expert to carry out a study to identify the operating conditions that are likely to cause the phenomenon in question. This study must be submitted to the MELCC and propose recommendations concerning the measures or operating procedures of the plant and the dam to be installed or avoided, which the companies will then have to respect.