1. Environmental Monitoring of La Grande-2-A and La Grande-1 Projects Danielle Messier McGill University, 2003-09-25

2. La Grande Complex

3. 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)

4. 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)

5. 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

6. 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

7. 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

8. 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

9. Main periods of the monitoring Reference period : 1985-1990 Transitory period : 1991-1992 Monitoring period : 1992-2000

10. Modifications of the discharge

11. 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 : 1 - 2 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

12. River banks erosion Transitory : 1991-1993Exploitation : 1997-1999 Upstream LG-1: 500 000 m 3 material eroded Upstream LG-1 200 000 m 3 material eroded Downstream LG-1: 100 000 m 3 material eroded Downstream LG-1: 75 000 m 3 Construction of protection structures

13. 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

14. 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

15. 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

16. 22HQme0901

17. 23HQme0901

18. 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

19. The La Grande plume in 1995

20. Eelgrass in James Bay General distribution of eelgrass beds in James Bay shows high stability from 1986-87 up to 1996 Massive decline in 1998-1999 along James and Hudson Bays, due to wasting disease

21. 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

22. Variation in eelgrass production

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

24. Changes in salt marshes

25. 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