Science Advisory Report 2009/024

Science Evaluation of the Environmental Impact Statement for the Lower Churchill Hydroelectric Generation Project to Identify Deficiencies with Respect to Fish and Fish Habitat

Summary

• The exclusion of the receiving environment below Muskrat Falls, including Lake Melville from the project description within the EIS was viewed as a major deficiency.
• Additional effort is required to document local knowledge of fish use and fish habitat, especially in addressing the area below Muskrat Falls, including Lake Melville.
• The magnitude of expected ‘Changes to fish habitat’ and fish populations needs to be considered relative to the ‘Loss of fish habitat’. The area of altered habitat is considerably larger than the area of lost habitat, and has the potential to have a more significant impact on the ecology of fishes of the Lower Churchill system.
• Predictions that the new reservoirs will ‘advantage’ certain species and ‘disadvantage’ others are not well described in the current documentation.
• There is uncertainty that the resultant reservoirs will exhibit a similar fish habitat usage pattern as is presently described for Winokapau Lake, especially in the stabilization period.
• Limitations, assumptions and uncertainty must be clearly stated and incorporated into the final assessment. It is not necessary to list all analytical information within the EIS overview documents but it is necessary to supply enough information to allow an informed reader to refer to such analysis, especially when broad statements on potential impacts are being made.
• A description of future monitoring programs has not been well described in the current EIS documents. This was a requirement of the EIS guidelines and these monitoring programs should include monitoring objectives, schedules, sampling design as well as spatial and temporal coverage for each monitoring parameter.
• Although specifically stated as ‘required mitigation measures’ within the EIS guidelines, neither an ‘instream flow needs assessment’ during reservoir filling and operation or a ‘fish habitat compensation strategy’ was presented in the EIS.
• The hydrological regime of the expected Gull Island reservoir needs to be modeled. This modelling is required in order to make any predictions regarding future productivity of this area possible. This information is also required for predicting elevated mercury concentrations.
• A number of the component studies used to describe the aquatic environment had small sample sizes and were limited both in spatial and temporal coverage. These limitations add an increased level of risk and uncertainty of any predictions or analysis based on these data.
• Fish passage was not assessed for Muskrat Falls either through a directed study or other biological indicators of fish movement. Isotopic data in the mercury analysis may be used as a first step.
• There are a number of uncertainties associated with using the La Grande hydroelectric system to predict potential changes within the Lower Churchill system. A more robust comparison could be made by using more than one large reservoir system from north temperate areas with a variety of flushing rates and morphological features which are more similar to the Lower Churchill.
• Potential cumulative effects within the aquatic environment were not well addressed in the EIS. In addition, potential interactions with climate change, based on regional models that have been developed for Labrador (i.e. extreme events in spring/fall) were not presented.
• The impact of direct fish mortality from turbine operations was not addressed in a population context.
• The description of the aquatic environment would have benefited by consistently presenting information required to evaluate potential project related effects on a species-by-species basis, and, by the inclusion of an ‘ecosystem overview synthesis’.

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