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Environmental Monitoring of La Grande-2-A and La Grande-1 Projects

Environmental Monitoring of La Grande-2-A and La Grande-1 Projects. Danielle Messier McGill University, 2003-09-25. La Grande Complex. Context of the monitoring. Required by the certificates of authorization of projects constructed during phase II of the La Grande Complex

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Environmental Monitoring of La Grande-2-A and La Grande-1 Projects

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  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 m3/s to 5920 m3/s • Changes in the production pattern: increase flow in winter time, decrease in summer time • Creation of La Grande-1 reservoir • Area of 70 km2 • 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

  12. River banks erosion

  13. River banks erosion • The Grande Rivière is enlarging to adapt to increased mean annual discharge • 3 large landslides occurred : • 3.5 M m3 in 1987 • 1.5 M m3 in 1989 • > 1 M m3 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 m3/s to more than 4400 m3/s extends the plume area from 1600 km2 to 2100 km2 or 3500 km2, 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

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