Canadian Environmental Assessment Agency

Backgrounder

Mitigation measures and adaptive management plans for partial diversion of the Portneuf and Sault aux Cochons rivers

The Hydro-Québec projects to partially divert the Portneuf and Sault aux Cochons rivers will clear the federal environmental assessment phase, provided Hydro-Québec addresses mitigation measures described in two separate comprehensive study reports, and that it develops an adaptive management plan, to be approved by Fisheries and Oceans Canada, for each of the two projects, targeting navigation on the Portneuf and Sault aux Cochons rivers.

Some examples of mitigation measures that will be implemented are outlined below.

Partial Diversion of the Portneuf River

Portneuf River

• Implementation of a fish pass at the site of the regulating structure
• Development of spawning grounds totalling, at minimum, 5,000 m²
• Recovery of unwatered gravel and cleaning of fine sediments accumulated on existing spawning beds

Minimum Flow

• Maintenance of a minimum flow of 1m³/s, except in the event that winter conditions so prevent, at the eastern outlet of Itomamo Lake
• Follow-up of brook trout production will permit the reassessment of the relevance of increasing the mean annual flow up to 3 m³/s
• Modulation of flows at the outlet of Portneuf Lake to increase the summer minimum flow and to ensure a minimum flow of 2m³/s or of 4m³/s at all times between May 1 and November 1

Other Measures

• Construction of the dam and regulating structure at the end of the summer, beyond the tourist traffic associated with the opening of, and during, the fishing season

Partial Diversion of the Sault aux Cochons River

Sault aux Cochons River

• A minimum flow of 1 m³/s at the Sault aux Cochons Reservoir dam will be maintained
• Navigation conditions between km 114 and 115 and between km 122 and 128.5 as well as the condition of access to the shoreline will be confirmed before and after the implementation of the diversion. Corrective measures will be taken if obstructions to navigation are identified.

Sault aux Cochons Reservoir

• The reservoir will be maintained above an elevation of 425 m if construction works are carried out during the spawning season (October) or if they must continue during the critical periods of egg incubation and fry emergence (October to May).
• An impassable obstacle (vertical waterfall) measuring at least 3 m (2 m net) will be built downstream from the diversion channel in order to prevent species present in the Lionnet River and Pipmuacan Reservoir from accessing the basin of the Sault aux Cochons River.

Adaptive management plans

The adaptive management plans for each of the projects will:

• be required as a condition to Fisheries and Oceans Canada's approvals;
• be developed by Hydro-Québec in consultation with stakeholders, and approved by Fisheries and Oceans Canada;
• identify the existing navigation conditions;
• identify how the effects on navigation will be measured, monitored and compared to the predictions in the comprehensive study reports;
• identify the threshold at which corrective measures will be required to ensure no significant effects on navigation;
• identify actions to be taken should the measured effects be greater than the set threshold;
• identify the parties that would participate in the review of the monitoring results, and that would determine which actions will be required; and
• identify the time frame over which the plan will be in place and at what point it no longer needs to be in effect.

For more information:

Robert Deslauriers
Senior Communications Advisor
Canadian Environmental Assessment Agency
Tel.: (819) 953-9407