Comprehensive Study Report

Chapter 5 of Volume 1 of the draft-design report describes the alterations to the physical environment associated with the project and the foreseeable impacts on the natural and human environment. Chapter 5 and Appendix A outline the method used by the proponent to analyse and evaluate the impacts, while Appendix B of the same document contains the complete list of mitigation measures mentioned in Chapter 5 of the report.

The section that follows summarizes the environmental changes and provides an assessment of the main environmental effects resulting from the project, including the effects of any malfunctions or accidents that may occur in connection with it, as well as the cumulative effects. The primary mitigation measures are also mentioned.

It should be noted that the impact assessment prepared by the proponent is based on a worst-case scenario in which peak flow at the new Grand-Mère power station would vary between 200 m³/s and 1 040 m³/s every day during the winter. The most significant impacts will occur mainly during the first few years after commissioning, when the proponent is still adjusting its operating mode.

7.1. Impact assessment methodology

The proponent evaluated the impacts before and after the implementation of mitigation measures, for all the different components of the natural and human environment concerned. However, no residual impacts were identified in relation to elements of the physical environment. As a result, the discussion centres on modifications in components and the term "impact" is not used in this context. The method used by the proponent to predict impacts consists in first delineating alterations to the physical environment and then assessing the effects on living components of the environment, namely humans and fauna and flora. Suitable mitigation measures are then applied to each element to obtain the lowest possible residual impact.

The significance of each impact, qualified as either low, medium or high, was evaluated using a grid comprising three descriptors, namely duration, extent and intensity.

This nomenclature differs from that used to define the environmental effects of a project under the CEAA, in which an adverse effect must be defined as either significant, non-significant or unknown.

In its complementary report, the proponent stated that a high impact corresponds to a significant effect, as defined in theCEAA, whereas a medium or low impact, corresponds to a non-significant impact.

DFO agrees with that approach.

Table 2 presents the impact assessment prepared by the proponent for all the environmental components likely to be affected by the project. DFO's comments with respect to those evaluations are provided in the sections below. Certain environmental components that will be subject only to non-significant environmental effects are not covered in the summary below (water quality, air quality, noise environment, etc.).

Table 2: Assessment of impacts prepared by the proponent for the different environmental components affected by the project

7.2. Alterations to the physical environment associated with the project

The main project effect on the physical environment consists in the alteration of the ice regime resulting from the operation of the new works during the winter period. Hydrological and hydrodynamic changes are also anticipated, as are soil profile and bathymetric modifications.

Water-level fluctuations caused by daily variations in flow during the winter will create cracks, ice-push ridges and water seepages in the ice cover along the riverbanks, which may hinder access to the water and ice fishing activities. Modification of the hydraulic management mode used in winter will also increase the risk of pressure being exerted on the ice sheet, making the sections of ice cover between the Grand-Mère power station and Ile Frigon, as well as between the Shawinigan complex and Madeleine Falls, unsuitable for traffic to various extents, given the surface roughness and risks of downstream ices movement. The significant impacts anticipated on the ice regime and the associated mitigation measures are discussed in Section 7.6.2 of this report, which deals with the effects of the environmental changes on socio-economic conditions.

As a result of the modifications in the hydrological regime, the shoals located downstream from the new control structure will be completely eroded by average floods. Some 50 000 m³ of sand, pebbles and rock will be entrained by the flow. Coarse sediments will be deposited in the local study area, whereas finer sediments will settle out farther downstream, in the extended study area. This impact, deemed as non-significant from a sedimentological viewpoint, will nonetheless have repercussions on the fish fauna. This aspect is dealt with in Section 7.3.1 below.

Low impacts are anticipated with regard to shoreline erosion (detachment of ice and water current velocity), since the project should only affect a few highly eroded talus slopes without destabilizing any additional ones. Follow-up will moreover be conducted in this regard, and stabilization measures will be implemented to deal with any shoreline erosion and any sensitive elements requiring protection.

7.3. Effects of the project on environmental components

7.3.1. Fish fauna and fish habitat

The changes in the hydrological regime resulting from the orientation of the new spillway as well as from the water-level fluctuations attributable to the new peak generating mode used at the power station in winter are the main factors likely to have impacts on fish habitat. The new operating mode used at the facility will exert an effect through active erosion caused by ice scour on the bottom, the banks and the riparian and aquatic vegetation.

In the local study area, the cofferdam and in-stream excavation work will cause the abandonment of the spawning ground situated near the left gravity dam. The commissioning of the new control structures will cause major hydrodynamic modifications to the environment. A shoal consisting of pebbles and boulders in a sand matrix which is located downstream from the left gravity dam will be seriously damaged when the first average flood occurs. In all, 30 000 m³ of sediment will be displaced. The spawning ground in this zone which is used by smallmouth bass (150 m²) and sucker (1 547 m²) will probably disappear once the new generating station starts up. In addition, the spawning ground located downstream from Simard Point will be silted up over an expanse of about 3 100 m², or 30% of its present area.

The majority of sediments that are displaced will be deposited in the local study area. The finest sand particles will settle out at a slow rate (1 mm per year), in the still water zones or in deeper sections within the extended study area, where sand entrained during the flood is deposited. The project will not cause any changes in the sedimentation and erosion zones that exist at present in the sector. Consequently, the risk of siltation of potential spawning grounds or nursery areas in the aquatic beds is considered very low.

The spawning and feeding areas located in the afterbay within the extended study area are situated in sheltered zones and will undergo less shoreline erosion as a result of ice cover movement associated with the new winter operating mode. The aquatic beds should not be affected by this phenomenon, given their rooting depth. Riparian herbaceous meadows, a habitat likely to contain spawning sites for yellow perch, may however be affected by ice scour and so may be replaced by herbaceous plants that are better able to adapt to these conditions.

Monitoring of the aquatic beds and riparian habitats will be done to assess the effect of the project on these environments and, if necessary, to implement appropriate mitigation measures or compensation options if fish habitat losses are observed.

The enhancement structures for smallmouth bass, located in the sector between Ormes Point and the Hêtres Rapids, will probably not be affected by the new management method to be used at the Grand-Mère power station in winter, since these enhancements are designed to withstand average spring flows (2 600 m³/s), which are higher than the peak winter flow (1 040 m³/s) that will be generated by the new generating station.

Two embankments are to be built downstream from the existing power station, encroaching on the aquatic environment over an area of roughly 5 700 m². Nonetheless, these structures will be located in a sector of little interest for aquatic fauna, given the present flow velocity at the outlet from the existing station. The unconsolidated material that is to be used for these rockfill embankments will also provide supporting structures and shelters for aquatic fauna once the hydrological conditions in the sector become more favourable, following the commissioning of the new power station. The excavation of the headrace and tailrace will increase the size of the aquatic habitat by about 45 000 m².

The access road that is to be built will, however, create an encroachment of about 300 m² onto a small marsh at the back of the bay, on the left bank, near the Highway 153 bridge. This site, which is located near a known nursery area, may possibly be used by certain fish species for spawning, such as yellow perch.

In all, roughly 4 800 m² of known spawning grounds and some 300 m² of potential fish spawning areas may be permanently destroyed as a result of the project.

The effect that the construction and operation of the project will have on fish habitat is considered significant and requires an authorization under subsection 35(2) of the Fisheries Act. In accordance with the no net loss principle set out inDFO's Policy for the Management of Fish Habitat, the authorization will be issued only if compensation is provided for the habitat losses.

The compensation measure to be implemented consists in the creation of a multispecies spawning ground (for smallmouth bass, walleye and suckers) downstream from the left gravity dam and a spawning area for yellow perch in the small marsh located on the left bank of the river, in the forebay.

The spawning ground to be created just downstream from the Grand-Mère Dam (about 9 000 m²) will be composed of rocky substrate material of varying diameter: between 5 and 30 cm to suit the needs of walleye and suckers; large boulders over 80 cm in diameter and fine particles about 5 cm in diameter for smallmouth bass. The shelf underpinning this new spawning area will be made by excavating five straight trenches to create a variety of depths and flow velocities across the entire site.

The spawning ground upstream from the Grand-Mère facility will be created by planting shrubs (alder) at the base of the access road embankment in the marsh, at an elevation that will allow the vegetation to be submerged in the spring. This enhancement may be used by yellow perch, which typically spawn in such habitats.

Various measures will be applied also to mitigate the effect of the construction work on water quality, and the use of explosives will adhere to the directives aimed at protecting fish fauna (Wright and Hopky, 1998).

7.3.1.1. Fish-pass and fish guards

Subsection 20(1) of the Fisheries Act states that "Every obstruction across or in any stream where the Minister determines it to be necessary for the public interest that a fish-pass should exist shall be provided the owner or occupier with a durable and efficient fish-way or canal..." The presence of migratory species in a stream that contains an obstruction to the movement of fish may justify installing a fish-way.

American eel and Atlantic salmon are two migratory species that may occur at the Grand-Mère site. Given the uncertainty over the presence of an eel population in the facility's afterbay and its absence in the upstream area, and given the occasional presence of specimens from a non-indigenous population, namely Atlantic salmon, in the same afterbay, and the absence of measures adopted by provincial officials (in charge of managing the fish resource) in this regard, based on our present knowledge there appears to be no justification for building a fish-pass to allow those species to swim upriver.

Furthermore, the proponent has not provided for any fish guards at the Grand-Mère facility because of: (1) the absence at this site of species capable of migrating; (2) technical constraints related to the strong flows from the generating station (design flow of 275 m³/s) which would quickly clog such structures; and (3) the absence of other preventive measures deemed truly effective at the present time.

The proponent has indicated that the risk of fish being entrained into the turbines is considered low, since there are no migratory species at the site. Resident species are less likely to be present near the water intakes, because their movement is not linked to the type of downstream migration that is part of the life cycle of migratory species. It has nonetheless been reported that some resident species, mostly fry, may become entrained in the turbines.

Since the mortality rate associated with the Kaplan turbines that are to be installed is lower on average than with the present Francis turbines, the new facility is not likely to have a greater impact than at present in terms of fish mortality. The project can therefore be considered to have a non-significant effect in this regard.

7.3.2. Avifauna

The anticipated effects on forest-dwelling birds will occur only in the local study area and are essentially linked to the loss of some 15.5 ha of forest habitats which will result from the construction of the new works (power station and sending-end substation), the work site facilities, the management of excavated rock material and the construction of access roads and transmission line right-of-ways. The proponent considers this loss of forest cover a relatively low impact in relation to avifauna, considering the abundance of such habitats in the region.

In addition, owing to the low abundance of wetlands and the presence of scarped banks, waterfowl are not well represented within the local and extended study area. Given that the aquatic beds in the extended study sector will probably be altered only a little by ice movement, the proponent has indicated that there is reason to believe that the project's impact on waterfowl will likewise be limited.

The proponent is of the view that there will be no impact on bank swallow colonies, since the sandpit sector that is likely to harbour such populations will not be affected by the project.

According to the proponent, the effect of the project on avifauna can therefore be considered minor.

However, since the Hydro-Québec study does not provide precise information on the species present in the area that will be affected by the construction work (new works, access roads, transmission lines and excavated material disposal sites) and does not permit assessment of effects on avifauna, Environment Canada has asked that the proponent conduct a series of inventories at the site prior to the start of construction in order to carefully evaluate this impact. The inventories will have to be done during the month of June prior to construction.

To minimize the effects on avian fauna, the proponent will have to clear as little forest as possible and perform the work (tree felling and access road construction, excavation material disposal and transmission lines) outside the nesting period (June and July).

The impact of the project on avifauna may be considered non-significant provided the proponent adheres to the above-mentioned mitigation measures and the inventory results provide no evidence of species in difficulty or species of particular socio-economic, cultural or scientific significance.

If those inventories reveal the presence of such species, the proponent will have to propose suitable mitigation or compensation measures deemed satisfactory by Environment Canada.

7.3.3. Riparian and aquatic vegetation

The vertical movement of ice associated with the proposed new winter operating mode is not likely to have significant environmental effects on the riparian and aquatic vegetation.

The shrub species forming the lower tier of the riparian scrubland may be altered by the movement of ice, favouring the establishment over the longer term of herbaceous species that are more tolerant of water-level fluctuations.

Plants that typify wet meadows and emergent weedbeds are also likely to be affected by ice scour. This type of impact may occur in spring, when shore ice breaks off due to the effect of the wind, storms and waves, entraining sediments and the portion of the roots of plants that is anchored in the sediment. According to the proponent, this phenomenon can already be observed every spring in the Saint-Maurice River and it will not be aggravated by the new wintertime facility management method.

Given their rooting depth, the species found in aquatic beds will probably not be affected very much by the project. A study done in the Gentilly sector shows that the thickness of the sediment layer detached by the ice will probably be small relative to the rooting depth of perennial plants.

Construction of the access road for the works will result in a 0.03 ha encroachment onto a 1.2-ha marsh located at the back of the bay on the left bank, upstream from the existing weir, whereas the disposal site planned for excavated material necessitates filling in a swamp and an artificial pond (0.5 ha) located in a sandpit.

The effect of the project on riparian and aquatic vegetation is considered non-significant. Follow-up will make it possible to check the accuracy of the proponent's predictions .

7.3.3.1. Federal Policy on Wetland Conservation

The main objective of the federal policy with respect to wetland conservation is to promote the conservation of Canada's wetlands to sustain their ecological and socio-economic functions, now and in the future. Accordingly, the goals are to strive to ensure that there is no net loss of wetland functions: (1) on all federal lands and waters (2) in areas affected by the implementation of federal programs where the loss or degradation of wetlands has reached critical levels; and (3) in sectors where federal activities affect wetlands which have been designated as having ecological or socio-economic significance for a region.

The wetlands affected by the Grand-Mère project do not satisfy any of the above conditions. Overall, however, the proponent adheres to the spirit of the Policy since it sets forth its procedure with respect to: (1) avoiding such habitats, (2) mitigating inevitable impacts, and (3) providing compensation for any residual impacts.

Small marsh upstream from the dam

The analysis shows that the proponent made every effort to prevent encroachment of the access road on the small marsh south of Highway 153; however, this encroachment proved to be unavoidable.

In terms of mitigation measures, the proponent plans to restrict traffic in this area, clear trees manually and install a culvert under the access road so the marsh will continue to receive water inflows from the stream that feeds it.

In addition, alder will be planted on the lower part of the access road embankment to promote yellow perch spawning in the sector. This compensation measure is deemed compatible with the environment's wildlife habitat potential and with the ecological function of the marsh.

With regard to other potential functions (production of renewable resources, habitat for other wildlife species organic carbon storage, water supply and filtering, soil conservation, recreation and tourism opportunities, scientific value, aesthetic value), owing to the small size of the sector concerned (0.03 ha), the proponent indicated that the impact is bound to be minor, especially along a watercourse as large as the Saint-Maurice.DFOagrees with this line of argument.

Floodplain swamp and pond at the disposal site for excavated material

The sandpit site chosen as a disposal area for excavated rocks contains a floodplain swamp and a pond (0.5 ha) is a solution that entails a lower impact than the option of storing the material alongside the river, considering the value of the habitats located there.

The proponent has indicated that it will avoid dumping fill in the northern part of the sandpit which features shrub swamp; however, fill material will be dumped in the westernmost part of these swampy areas. This small swamp was already altered a few years ago during the construction of an access road, which blocked natural drainage and increased the water level in the swamp. In view of the presence of submergent and emergent aquatic vegetation in certain spots, this environment may still serve as wildlife habitat, even in its present degraded state. It probably provides few other functions. This marsh is not linked to the Saint-Maurice River.

Although the possibility of preserving this zone was considered, this option was not retained since it would result in the whole area being surrounded by talus slopes more than 15 m tall by the time disposal site operations ended. The result would be a completely isolated excavation of little interest for wildlife.

With regard to the applicable mitigation measures, the proponent said that it sought to minimize the effects on wetlands and that it plans to plant shrubs on the talus slopes that will be created beside the swamp areas, thereby providing a natural transition between the disposal site and the surrounding environment. Additional measures may be proposed in light of the results of the bird survey, which is to be carried out in the spring of 1999.

The artificial pond that formed as a result of sand being extracted from beneath the water table constitutes a disturbed environment and is not covered by specific mitigation or compensation measures.

All other wetlands

As mentioned at the beginning of this section, there is little risk of impacting the riparian marshes and wetlands along the Saint-Maurice. A follow-up program will be carried out to assess this assumption and to implement mitigation or compensation measures in the event of impacts. In view of the low risk of effects on wetlands, measures of that type have not been developed yet.

The effect of the project on wetlands is considered non-significant, provided that the proponent adheres to the mitigation measures mentioned above and provided that the avifauna surveys that are to be conducted do not identify any species that are at risk or of particular socio-economic, cultural or scientific significance.

7.4. Effects of environmental changes on the physical and cultural heritage

The project's impact on archaeological potential can be considered non-significant, given that no evidence of prehistoric occupation was found and that the structures and artifacts identified so far have little industrial, architectural or heritage significance.

Should archaeological remains be uncovered during the earthwork, arrangements will be made to protect the site and the work will be halted until the Quebec Department of Culture and Communications gives the authorization to proceed. In addition, as provided in the provincial Regulation respecting archaeological research, the artifacts that are collected will be stored in the archaeology laboratory of the Quebec Department of Culture and Communications.

The construction of the new Grand-Mère hydroelectric facility will require razing the existing spillway and weir, which means that a major part of the largest dam on the Saint-Maurice will disappear. The heritage and technological significance of the area will also be diminished by the construction of new works alongside the elements that are to be conserved and by the operations that will be undertaken to decommission, dismantle and remove certain power station components or equipment. Decommissioning in and of itself will reduce the function of the existing installations.

Based on the proponent's evaluation, the project will have a considerable impact (a significant impact within the meaning of theCEAA) on built and technological heritage owing to the loss of the building's role and the demolition of the spillway structures. It points out, however, that the razing of the spillway structures is a less significant loss in terms of the region's built and technological heritage than the decommissioning of the power station.

With reference to the definitions of terms used by the proponent in analysing the project effects, an impact is deemed of high intensity if, as is the case for decommissioning of the Grand-Mère generating station, it affects or limits the use of a component in a significant and irrevocable manner. Taking into account the value of the component and the extent and duration of the impact, based on the grid used to evaluate the magnitude of impacts the effect is deemed considerable, despite the adoption of various mitigation measures. According to the methodology used, the loss of function of the former generating station cannot be mitigated.

The effects of the project on the built and technological heritage will have to be addressed by implementing specific mitigation measures aimed at preserving the facility's heritage value.

The proponent has proposed various mitigation measures to protect and develop the value of the built, technological and historic heritage. The main ones are as follows:

• Promote the in situ conservation of certain installations or equipment based on their heritage significance or place them in appropriate storage as applicable. The proponent proposes to keep in its own collection some 40 components of interest that are part of the existing station;
• Record the operations to dismantle a piece of equipment or a heritage installation (photographs and technical notes) and take aerial photos of the spillways and weir during the razing operation;
• Encourage a multifunctional scheme for using the building which will alter the architectural quality as little as possible;
• Promote the architectural integration of the old and new elements;
• Form a committee composed of representatives from Hydro-Québec and the local community to determine the use to be made of the existing building and a method of deriving value from the decommissioned equipment, thereby helping to preserve the region's industrial heritage.

In addition to these mitigation measures, Parks Canada recommends that a video be commissioned to illustrate the overall operations of the power station (covering everything from technology through maintenance) and that it include a commentary or schematic explanations. It also recommends that one of the six turbine units be preserved to permit the situ conservation of an element attesting to the facility's former use for power production.

DFO is of the opinion that adherence to the proposed mitigation measures related to the preservation or recording of the present heritage property, preservation of the building and consultations with the community to determine what role the existing station should play provide satisfactory means of mitigating the effects on built heritage resulting from the reduced function of the current station and the razing of certain works. The residual impact on heritage value following mitigation is therefore considered non-significant.

Preserving the existing power station building would be a positive step provided the characteristics that make it a facility of exceptional significance are maintained. Moreover, the new works should not significantly alter the heritage significance of the Grand-Mère hydroelectric facility owing to the distance separating them from the structures that are retained and the conserved structures and the proponent's concern with this matter.

7.5. Effects of the environmental changes on human health

The project is not likely to have impacts on human health. It will not cause a change in water quality, nor will there be any resuspension of sediments that exhibit exceedances of the established criterion for lead and mercury.

7.6. Effects of the environmental changes on the socio-economic situation

7.6.1. Economy and employment

Construction of the new facility will generate regional spinoffs estimated at $115 million, or about 34% of the total cost of the construction work. It will also create an estimated 1 000 person-years of employment in the region for the duration of the project. This is a significant positive impact.

7.6.2. Recreation and tourism

In the forebays of the Grand-Mère, Shawinigan and La Gabelle power stations, the new mode of operations in winter will cause the formation of cracks and ice-push ridges along the riverbanks, which may curb access to the middle of the river for winter sports (snowmobiling, all-terrain vehicles, skating, cross-country skiing, walking, car race, etc.). This change may also make vacation homes located on islands less accessible and reduce the attractiveness of fishing sites near the shoreline.

The water-level fluctuations and the presence of more irregular ice cover will prevent the practise of such activities in the fast-flowing sections of river downstream from the Grand-Mère and Shawinigan plants. However, those sectors are not used very much at present for winter recreation.

Furthermore, it will no longer be possible to reach snowmobile trail No. 347 from the point of access located on the left bank upstream from the existing weir, because the ice cover will be unstable in that area.

To mitigate those impacts, the proponent plans to reach agreement with the authorities concerned to move the snowmobile trail in order to provide access to the left bank of the river from the local network; it will also take the necessary steps to maintain river access for snowmobiling and all-terrain vehicle activities during the winter season, as of the first year of operations.

The proponent will adjust its hourly peak generating mode to promote a stable ice cover, but it will not be able to ensure safe access to the river in fast-flowing areas, no more than it can at present.

The proponent will install a winter boom upstream from the Hêtres Rapids to improve formation of the ice cover and its stability, and to prevent the occurrence of an ice jam near the rapids. As well, signage will be installed in the areas at risk and the public will be kept informed about the progress of the construction work and the new conditions that will prevail on the river.

A system for monitoring the ice cover will be established to determine whether the operating mode for the structures needs to be adjusted, in accordance with the objective of ensuring the compatibility of power station management with the recreational use of the river. It should be noted that the proponent has agreed to take the necessary measures to maintain the accessibility of the ice cover in the middle of the river.

DFO feels that the effect of the project on river access will not be significant, since some mitigation measures may be developed in conjunction with the community and they may even be stepped up in response to information collected under the proponent's programs for monitoring ice cover and the use of the Saint-Maurice for recreation and tourism purposes.

It is noteworthy that the forebay of the La Gabelle station is already affected in winter by water-level fluctuations with a range of about one metre, which cause the formation of ice-push ridges and cracks along the shoreline, and that fishing and snowmobiling activities (Trans-Québec trail No. 3) are currently practised in the sector. The fluctuations in winter therefore do not represent an entirely new situation for the local population.

It is possible that the water-level fluctuations will necessitate adjustments in such activities; however, the changes will probably not be significant, since similar conditions already exist in the vicinity of the La Gabelle facilities and since mitigation and monitoring measures will be implemented.

With regard to summer activities, moving the generating station to the left bank will cause hydrological changes which may affect the fishing spots that are currently used just downstream from the facility. Some fishing sites will disappear, but new ones will also be created. The portage road will be moved, and a boat launch ramp will be built near the future power station in order to compensate for the loss of access to the river resulting from the new infrastructure. These facilities may contribute to local recreation and tourism development, since at present there is no access road to the left bank in that sector.

7.6.3. Land use

The only possible impact identified in relation to the planned use of the land is the change in vocation of the decommissioned power station.

A joint committee made up of representatives from Hydro-Québec, the community, the municipality of Grand-Mère and Abitibi-Consolidated is currently studying the possibility of using the existing station for other purposes (educational and cultural uses, industrial use or use as office space).

Based on a study by the proponent on the multiple uses of the site (Tecsult, 1996), commercial or residential use of the generating station is not an option owing to various factors, such as quality of life, the huge cost of refurbishing the building, problems of access and parking and the isolation of the site.

Of the various options studied, commercial use of the site is the only option that would require modifying the building and possibly altering its architectural characteristics and heritage value. This type of use is very unlikely, given the above-mentioned constraints.

Educational or cultural use of the site does not appear to have much appeal, in view of the present socio-economic situation, the constraints associated with access to the building and the cost of redeveloping the facilities, and the fact that the existing regional infrastructure is adequate.

Based on the findings of that study, industrial use of the building for storage is the most promising option.

According to the proponent, there would be no impact from preserving the decommissioned building and using it for purposes other than generating hydroelectricity, provided that the station's new vocation does not result in changes to the zoning plan or an increase in traffic on the paper mill site, which has to traversed to reach the existing building.

It is unlikely that the stated options for the future use of the existing generating station will have important effects on land use. In addition, since the paper company has representatives serving on the joint committee charged with determining the fate of the former power station, it will presumably be able to defend its point of view if any significant adverse effects on land use are anticipated.

However, the evaluation of the project impacts associated with a future change in the site's vocation does not fall within the scope of the present study, since the choice of a future vocation for the power station is not linked to the authorization of the proposed facility. The project that is approved therefore constitutes a separate project within the meaning of the CEAA, since there is no interdependence or link between the proposal for the new facility and the project related to the future role of the existing station. There would be a situation of interdependence if the main project could not be implemented properly without undertaking another structure or another activity, but that is not the case at present. In addition, there is no connection between the two projects, because the decision regarding the execution of the main project does not make it necessary to build other works or carry on other activities. In fact, the fate of the existing generating station can be determined separately from the decision on whether or not to authorize the proposed hydroelectric project.

The impact that the future vocation of the generating station has on land use is thus considered independent from the project currently under evaluation. The redevelopment option that is eventually chosen should have the least possible effect on the architectural quality of the station and it should be subject to established assessment procedures in keeping with the nature of the proposal that is submitted.

7.6.4. Quality of life

The effect of the project on quality of life is deemed non-significant. Monitoring is planned in order to check the predictions made in the impact study and to ensure compliance with existing noise level standards.

7.7. Effects of environmental changes on the present traditional use of the land and resources by Aboriginal peoples

The project is not likely to have an impact in this regard since Aboriginal communities do not use the land in the sector and the construction site is not part of the land claim by the Atikamekw Nation Council.

7.8. Effect of the environment on the project

Natural events such as earthquakes and strong floods have been taken into consideration by the proponent in designing the different structures (see Section 7.9). The areas that are likely to be flooded if the Grand-Mère Dam ever breaks concurrently with breaches in the dams upstream are shown in Table 3 of the supplement to the draft-design report prepared by the proponent.

Moreover, the new facility is designed so that any exceptional flood can flow over the spillways, leaving a water level upstream from the station that is equal to or lower than the level at the existing generating station, even in the event of a 1000-year or longer-interval flood (9 480 m³/s) or the maximum probable flood (12 350 m³/s).

7.9. Impacts caused by malfunctions or accidents

The rupture or overflowing of a cofferdam by a flood exceeding the design flood, the complete or partial breach of a dam owing to wear and tear or external effects, such as an earthquake or seismic activity caused by a rockburst or flooding, and an accidental spill of oil or other substances during the construction work, are the main incidents or malfunctions potentially associated with the project.

The main precaution for cofferdam construction consists in ensuring that the design criteria take into account the duration of use of all such structures. The longer they are to be used, the greater the flood recurrence interval that must be used in designing them.

The overflowing or rupture of cofferdams would result in the materials used in their construction (sand, wood and earth) being carried off downstream along with lightweight equipment. The latter could possibly be recovered after the flood. For safety's sake, a "dam emergency" committee will decide whether the work site should be evacuated on a precautionary or emergency basis, as applicable. If time permits, steps will be taken to reduce the effects on the environment.

In view of the nature of the anticipated impacts and the very low risk, any situation of overflow, rupture or failure involving diversion structures should not have significant environmental consequences.

Chapter 1.3.4.1 of the supplement to the draft-design report provides an evaluation of the impacts that would result from a breach of dams on the Saint-Maurice River. This assessment is based on the worst-case scenario out of a total of three scenarios studied, and emergency plans have been drafted on that basis.

According to the worst-case scenario, a breach of the Gouin Dam and the dams situated farther downstream would affect 45 000 people and cause the loss of cultural and historical property, disruptions in municipal services and public utility operations (aqueduct systems, highways, telecommunications and electricity), commercial and industrial losses, losses of employment income and of private property. The physical environment would also be affected (shoreline erosion, increase in water flow velocity and rupture of the ice cover). The zones at risk of being flooded are shown in Table 3 of the supplement to the draft-design report produced by the proponent.

In terms of prevention, even after it is rebuilt the Grand-Mère Dam will continue to have the most stringent possible level of monitoring. Inspections will be done at monthly intervals until the behaviour of the structure has stabilized. In addition, the frequency of instrumentation checks will be double that for a facility whose operating behaviour is already known.

The proponent describes its emergency plan for such an incident in Chapter 4.6 of Volume 1 of the draft-design report, and provides a decision tree chart for emergencies, a list of the duties of the emergency response coordination centre and documents related to such activities. Procedures for taking action to deal with an oil spill and to manage contaminated waste and soil are also discussed.

DFO considers this assessment of impacts satisfactory, along with the precautionary measures, emergency response actions and emergency plans that are proposed by the proponent.

7.10. Effects of the project on renewable resources

The project is not likely to have significant effects on renewable resources such as water, forests, fisheries and soil.

There will be no change in the daily river discharge budget and water quality will not be altered by management of the new power station. The impact on forestland will be minimal, affecting only a very small area (15 ha) of trees with a low commercial value. The fisheries will not be affected since the spawning grounds that will be destroyed in the project will be replaced through a compensation measure. The soils that will be affected by the construction work are described as being of poor quality and having no value for agriculture.

The replacement of the generating station and associated works, which are considered obsolescent, will provide the opportunity to increase the installed capacity by 70 MW at the existing site. This approach is beneficial from a sustainable development viewpoint, since it involves enhancing the efficiency of an existing facility before considering the develoment of new sites.

7.11. Cumulative effects

This section is intended as a summary of Part 2 of the supplement to the draft-design report which deals with the assessment of the cumulative effects that will result from the construction of a new hydroelectric development at Grand-Mère. The method used to analyse these effects are in accordance with the relevant requirements of the CEAA.

The proponent identified five main issues and the environmental components associated with them following consultation withDFOand the Canadian Environmental Assessment Agency. They are discussed below. The area of study for the purpose of assessing cumulative effects is bounded by the municipality of La Tuque in the north and by the mouth of the Saint-Maurice River in the south. The time frame used for the analysis was the period 1989 to 2004, that is, from 10 years before to 10 years following construction of the new facility.

7.11.1. Physical and cultural heritage

The Grand-Mère project's effect on physical and cultural heritage consists in adding an element to the equipment upgrading projects to be implemented along the Saint-Maurice; it also contributes to the evolution of this industrial sector (e.g. discontinuation of log drives on the river). These changes have a cumulative impact on the region's industrial heritage. According to the proponent, the upgrading projects will take a heavy toll on the region's built and technological heritage.

However, many projects such as the Centre d'interprétation de l'industrie forestière at Grandes-Piles (a forestry interpretation centre focussing on river driving), the Cité de l'énergie at Shawinigan (an interpretation centre on hydroelectricity), the Centre d'interprétation de Saint-Étienne-des-Grès (showcasing the historical heritage of the La Gabelle power station), and the preservation of historically significant components at the hydroelectric facilities already upgraded by Hydro-Québec (La Gabelle, Shawinigan and La Tuque) represent means of developing the industrial heritage of the Mauricie region.

Hydro-Québec's policy and the proposed mitigation measures for protecting and developing the built heritage, along with the proponent's desire to collaborate in the process of determining the new vocation of the building and agreeing on ways to exploit the decommissioned equipment, will also help to preserve the region's industrial heritage and ensure that this impact is minimized as much as possible in the circumstances.

DFO is also of the opinion that this impact is not significant within the meaning of the CEAA, taking into account the above-mentioned mitigation measures (see Section 7.4).

7.11.2. Recreation and tourism

The cumulative effects of the different projects that will help to enhance the boating infrastructure (expansion and consolidation of marinas and boat launch ramps) and environmental quality with a view to facilitating the practise of water-related activities (sewage treatment, shoreline cleaning and discontinuation of timber driving) will promote greater use of the Saint-Maurice corridor for recreation and tourism. The expansion of summertime activities is likely to have a snowball effect on winter recreation owing to the development of visitor infrastructures.

As mentioned earlier (Section 7.6.2), the Grand-Mère project may affect recreation and tourism activities by reducing access to the river because of the change in the ice regime that will result from the new peak generating approach adopted at the power station. Over the years, the Grand-Mère project may also have cumulative effects if reduced river access ends up diminishing the area's ability to attract vacationers.

The proponent concluded by stating that the project's cumulative effects on recreation and tourism will be negligible, provided the mitigation measures are effective and the community shows a favourable response to the new conditions of river access. In fact, it states that the monitoring program and the mitigation measures developed in cooperation with the community will ensure that the residual impact is limited.

In view of the proponent's undertakings with respect to maintaining access to the ice cover in the middle of the river, the fact that ice-push ridges and cracks occur along the shore at present in the region (La Gabelle sector) and do not prevent the practise of winter activities, and the fact that mitigation measures and monitoring will be carried out in this regard,DFOconsiders that the cumulative effects of the project on recreation and tourism are not significant.

7.11.3. State of the riverbanks

As mentioned earlier (Section 7.2), the effect of the Grand-Mère project on riverbank erosion is considered small. Erosion may increase in certain sectors that are already heavily eroded, for example, at the base of very unstable talus slopes.

Considering other causes of erosion, namely the increase in boating activity following the discontinuation of timber driving, the proponent indicates that the cumulative effects may be most noticeable in the forebay of the Grand-Mère facility and, to a lesser extent, in the forebays and afterbays of the Shawinigan complex, as well as in the forebay of the La Gabelle facility.

DFO considers that the mitigation measures and a rigorous monitoring program will serve to ensure that the residual cumulative impacts on shoreline erosion are negligible.

7.11.4. Fish habitat

Different types of projects (filling, hydrodynamic changes, dredging, etc.) may cause a loss of fish habitat and necessitate compensation in accordance with the no net loss principle set out in DFO's Policy for the Management of Fish Habitat.

In its analysis of the cumulative effects on fish habitat, the proponent mentioned only the projects for which such compensation has been requested, specifically the La Gabelle hydroelectric development projects and the present project at Grand-Mère, for which replacement spawning grounds will be created.

In the Grand-Mère project, aquatic beds and marshes possibly containing still-water spawning sites and nursery areas might be adversely affected by the winter water-level fluctuations and ice scour associated with the new peak generating mode at the generating station. Increased personal watercraft traffic in shallow river areas used for spawning may also interfere with this reproductive activity.

Since the habitat loss attributable to the project is to be compensated through the creation of new spawning areas, and since a program will be undertaken to monitor the riparian and aquatic vegetation, thus providing a means of verifying the accuracy of the impact predictions (i.e. the predicted low impact on fish habitat),DFOfeels that the project should not have significant cumulative effects on fish habitat.

7.11.5. Management of excavated material

Considering that the quantity of excavated rock material (500 000 m³) may meet local needs for 10 years, if market conditions do not change, Hydro-Québec has assessed the possibility of recovering the material and using it in keeping with the principles of sustainable development. However, this alternative may cause serious prejudice to existing quarries, along with important impacts on the noise level in nearby residential neighbourhoods and effects on highways associated with rock crushing and haulage of this material. In addition, these impacts are viewed as more significant than the current effects from the operations of the two existing quarries. That is why the proponent has opted to bury the surplus excavation material in the sandpit operated by Excavation Gaston Trépanier.

DFO is of the opinion that the cumulative effects of managing the excavated rock material resulting from the Grand-Mère project are negligible.