Environmental Monitoring of La Grande-2-A and La Grande-1 Projects Danielle Messier McGill University,

La Grande Complex

Context of the monitoring Required by the certificates of authorization of projects constructed during phase II of the La Grande Complex Section 22 of the James Bay and Northern Québec Agreement (1975)

The projects on the Grande Rivière Addition of La Grande-2A underground generating station beside Robert- Bourassa's (PK 112) Construction of La Grande-1 run-of-river generating station (PK 37)

Sources of modifications Increase of the designed flow from 4300 m 3 /s to 5920 m 3 /s –Changes in the production pattern: increase flow in winter time, decrease in summer time Creation of La Grande-1 reservoir –Area of 70 km 2 Operation of La Grande-1 generating station

Objectives of the monitoring To verify the actual modifications of the environment following impact assessment study To detect unpredicted impacts and take action to avoid or mitigate them To enhance impact assessment and mitigation measures

Criteria used for the monitoring Components of the monitoring program must reflect the changes Changes must be measurable Methods must be accepted Changes must be beyond natural variability

Components of the monitoring Hydrology –discharge, water level, temperature, current Erosion of river banks Water quality Riparian and aquatic vegetation Fish Mercury in fish Underice freshwater plume Eelgrass

Main periods of the monitoring Reference period : Transitory period : Monitoring period :

Modifications of the discharge

Hydraulic Modifications downstream from La Grande-1 Phase IPhase II Mean annual variation of water level : 4,7 m Mean annual variation of water level : 4,0 m Mean current : 0,90 m/sMean current : m/s Summer temp.: 8–12 °C Winter temp.: near 0°C Summer temp.: 8–14 °C Winter temp.: 0–0,15 °C Thin ice cover; (air temperature and discharge) Many openings

River banks erosion Transitory : Exploitation : Upstream LG-1: m 3 material eroded Upstream LG m 3 material eroded Downstream LG-1: m 3 material eroded Downstream LG-1: m 3 Construction of protection structures

River banks erosion The Grande Rivière is enlarging to adapt to increased mean annual discharge 3 large landslides occurred : –3.5 M m 3 in 1987 –1.5 M m 3 in 1989 –> 1 M m 3 in 2003

Fish Communities Few changes in the fish communities of La Grande-1 reservoir and estuary No transfer of fish between Grande Rivière and other tributaries of James Bay

Mercury in fish Impoundment of La Grande-1 reservoir did not change mercury concentrations in fish The effect of the Grande Rivière on James Bay fish is restricted to the summer plume area

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The freshwater underice plume Increasing the discharge from 1700 m 3 /s to more than 4400 m 3 /s extends the plume area from 1600 km 2 to 2100 km 2 or 3500 km 2, depending on ice conditions

The La Grande plume in 1995

Eelgrass in James Bay General distribution of eelgrass beds in James Bay shows high stability from up to 1996 Massive decline in along James and Hudson Bays, due to wasting disease

Production of eelgrass Data from 1988 to 2000 High annual variation at all stations and all depths Meterological conditions are responsible for annual variations Isostatic uplift causes long term disappearance in shallow waters

Variation in eelgrass production

Variation in salt marshes 10 permanent stations from 1991 to 1999 Vegetation changes under isostatic uplift Noticeable expanses of vegetation

Changes in salt marshes

Conclusions Most environmental changes in the Grande Rivière were observed during phase I Commissioning of La Grande-2A and La Grande-1 generating stations did not generate cumulative effects The main changes are direct hydrological conditions, including the increase of the freshwater underice plume