IR# JRP.166 Downstream Effects below Muskrat Falls INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT Requesting Organization – Joint Review Panel Information Request No.: JRP.166 Subject – Downstream Effects below Muskrat Falls References: EIS Guidelines, Section 4.5.1 (Environmental Effects General) Related Comments / Information Requests: IR # JRP.43, IR # JRP.149, IR # JRP.153 Information Requested: a. Nalcor hydrology studies indicate the Churchill River exerts a strong influence on the estuarine regime in Goose Bay and concerns have been expressed by a number of participants regarding the downstream effects of the Project. Explain the specific criteria used in Nalcor's response to Information Request (IR) JRP.43 to predict no measurable effect on downstream total phosphorus and total suspended solids, transport distances, fish productivity, salinity, velocity and thermal profiles from Goose Bay to Lake Melville, ice dynamics, ringed and harbour seal use of Lake Melville, bank stability, fish habitat utilization and fish migration. Identify whether and how these predictions apply to the period of reservoir impoundment, and the post‐impoundment transitional period before water quality stabilizes. Response: The influence of the lower Churchill River freshwater hydrology on Goose Bay and Lake Melville is recognized by Nalcor Energy (Nalcor) and has been central to limiting downstream effects to the extent possible. The minimal change in flow regime below Muskrat Falls as a result of the Project as described in IR# JRP.43, IR# JRP.149 and IR# JRP.153 mitigates most potential effects in terms of changes in salinity, circulation/current influenced by freshwater flows of the Churchill River, shoreline erosion (due to changes in water levels), tributary access, fish movements, habitat utilization and transportation distances. Discussion of the downstream effects below Muskrat Falls is assisted by delineating various features as the Churchill River meets Goose Bay and beyond. Figure 1 illustrates the area of consideration and offers labels for distinct features (sub areas and/or boundaries). These features will be referred to when describing the extent of downstream effects below Muskrat Falls. Nalcor’s response to IR# JRP.166 (a) is based upon the documentation contained in the EIS, Component Studies, previous responses to IRs, and other supporting material that has been gathered over a number of years. In order to provide additional analytical support and clarity to EIS predictions and responses (e.g., IR# JRP.43 and IR# JRP.152), additional dispersion modelling was conducted to further describe the extent of potential downstream effects related to variables of interest such as mercury, phosphorus, and temperature (Oceans 2010) (Attachment A). IR# JRP.166 (a) is organized to provide some background on the body of work supporting the conclusions, and then comments on each of the parameters of interest. JOINT REVIEW PANEL – IR# JRP.166 PAGE 1 INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT JOINT REVIEW PANEL – IR# JRP.166 PAGE 2 INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT Background Nalcor has considered downstream effects on the aquatic environment in a number of component and supporting studies. Some of these studies have used the mouth of the river at Goose Bay (e.g., JWEL 2000; AMEC and Sikumiut 2007) or Goose Bay Estuary as the downstream boundary (e.g., AMEC – BAE 2001; JWEL 2001) and some have included Lake Melville (e.g., JWEL 2001; Sikumiut 2007). Figures 2 and 3 illustrate the study limits for various attributes studied in detail as part of this Project. They clearly extend well beyond the mouth of the river, with some overlapping extensively with Goose Bay and Lake Melville. The rationale for defining the downstream boundaries for the EIS was based on two main premises: 1. The mouth of the river is the end of the riverine habitat; and 2. With a few potential exceptions (discussed later), Goose Bay dilutes any effects originating from upstream to “no measureable effects” level on the key indicators (KI) The term “no measureable effects” as used in the EIS means that any effect or changes to the KIs, if they occur, are within the range of natural variability. Dilution in the area of Goose Bay is caused by freshwater inputs from a number of sources and by mixing with the salt water that enters Goose Bay from Lake Melville. The Churchill River accounts for between 38 to 81 percent of the freshwater input to Lake Melville, Northwest River 13 to 61 percent, and the Goose and Kenamu Rivers 2 to 28 percent (Coachman 1953 in AMEC ‐ BAE 2001). The percentages vary seasonally with precipitation and the operating regime of the Upper Churchill Facility. The Goose and Traverspine rivers enter Goose Bay proper and the Northwest and Kenamu rivers enter at the entrance to Goose Bay. In addition, there are several tributaries below Muskrat Falls that provide freshwater inputs to the Churchill River. Erring on the conservative side, these rivers were not typically included in the modelling exercises involving the Churchill River below Muskrat Falls. Other biological (e.g., uptake), physical (e.g., settling) and chemical (e.g., photochemical) processes not accounted for in the modelling will also tend to dampen any effects going downstream. The dilution predictions in the EIS are further refined by a modelling exercise conducted using the MIKE3 dispersion model (Oceans 2010). As stated in the EIS, the shallows at Goose Bay Narrows act as a hydraulic control that slow exchange with Lake Melville (Hatch 2008a) and likely provide at least a partial barrier to plankton and fish because of the abrupt vertical mixing of fresh and saline water at this location. In the case of increased mercury in fish (a potential effect of the project as predicted in the EIS), the main pathways are water, total suspended solids (TSS), plankton and fish. Water, TSS and plankton are progressively “diluted“ going downstream from Muskrat Falls and most sediment will settle out along the way; the Narrows will further “block” sediment, plankton, and fish to some degree. Many freshwater species cannot tolerate abrupt changes in salinity thus limiting their movement past the Narrows. JOINT REVIEW PANEL – IR# JRP.166 PAGE 3 INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT JOINT REVIEW PANEL – IR# JRP.166 PAGE 4 INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT JOINT REVIEW PANEL – IR# JRP.166 PAGE 5 INFORMATION REQUESTS RESPONSES| LOWER CHURCHILL HYDROELECTRIC GENERATION PROJECT Effects Assessment Criteria Environmental effects assessments under the Canadian Environmental Assessment Act (CEAA) must meet certain prescribed criteria. In Canada, the Valued Environmental Component (VEC) and the KI are common approaches and were used in the EIS. The criteria used to characterize potential environmental effects for VECs and KIs are described below. The criteria that are listed below are consistent with those outlined in CEAA guidance documents and the EIS Guidelines. • nature: the ultimate long term trend of the environmental effect (e.g., positive, neutral or adverse); • magnitude: the amount or degree of change in a measurable parameter or variable relative to existing conditions; • geographical extent: the area over which the environmental effect will occur; • timing: the Project phase within which the environmental effect will occur; • frequency: the number of times during the Project or a specific Project phase that an environmental effect might occur (e.g., one time or multiple times); • duration: the period of time over which the environmental effect will occur; • reversibility: the likelihood that a VEC or KI will recover from an environmental effect, including consideration of active management techniques (e.g., habitat restoration works). This may be due to the removal of a Project component/activity or due to the ability of a VEC or KI to recover or habituate. As well, reversibility is considered on a population level for biophysical VECs. Therefore, although an environmental effect like mortality is irreversible to an individual animal, the environmental effect on the population may be reversible; • ecological or social context: the general characteristics of the area in which the Project is located, as indicated by existing levels of human activity and associated disturbance; and • level and degree of certainty of knowledge: level of confidence in the knowledge that supports the prediction. In order to support the CEAA‐compliant effects assessment as described above, a variety of baseline, analytical and modelling studies were conducted. Many of these used criteria specific to the particular exercise. For example, the STELLA® Version 8.0 modelling software was used to develop a water quality model for TP and TSS for the proposed Project (Minaskuat 2008) and MIKE3 software was used to model sediment plumes during construction (Hatch 2008b). Baseline data on water and sediments included JWEL (2000), Minaskuat (2007), and AMEC ‐ BAE (2001). Specific Criteria for effects prediction: The relevant VEC in IR# JRP.43 and as described in Volume II A, Section 9.2 of the EIS, is the Aquatic Environment and the KI is Fish and Fish Habitat. The measurable parameters or specific criteria that were used to assess effects of the Project on Fish and Fish Habitat included: • Habitat quantity in units / hectares