Upper Lillooet River Power Limited Partnership C/O Julia Mancinelli, Environmental Manager, Innergex Renewable Energy Inc

Ecofish Research Ltd. Suite F – 450 8th Street Courtenay, B.C. V9N 1N5

Phone: 250-334-3042 Fax: 250-897-1742 [email protected] www.ecofishresearch.com

MEMORANDUM TO: Upper Lillooet River Power Limited Partnership c/o Julia Mancinelli, Environmental Manager, Innergex Renewable Energy Inc. FROM: Autumn Cousins, B.Sc., Heidi Regehr, M.Sc., Ph.D., R.P.Bio., and Deborah Lacroix, M.Sc., R.P.Bio., Ecofish Research Ltd. DATE: November 20, 2017 FILE: 1095-54

RE: Upper Lillooet Hydro Project Environmental Assessment Certificate #E13-01 Amendment Application for Schedule B to Seek Approval to Remove Requirement for Signalling System and Signage per Condition 35

1. INTRODUCTION The Upper Lillooet Hydro Project (the Project) is located northwest of Pemberton, British Columbia (BC), on the Upper Lillooet River (Map 1). The Upper Lillooet River Hydroelectric Facility (HEF or Facility) is one of the facilities of the Project, which was recently commissioned by the Upper Lillooet River Power Limited Partnership (ULRPLP). ULRPLP is seeking to modify Condition #35 of Schedule B (Table of Conditions (TOC)) of the Project’s Environmental Assessment Certificate (EAC) (#E13-01, EAO 2013). This condition, in part, requires that the Certificate Holder must, prior to operations, install an alarm or other signalling system acceptable to the Ministry of Forests, Lands and Natural Resource Operations (FLNRO) at the Pebble Creek Hot Springs and at the powerhouse to warn of potentially dangerous flow releases and that signs must also be posted at both locations to inform the public on how to respond to the signals. As per Schedule A of the EAC, operations begin once the Leave to Commence Operation is issued (#E13- 01, EAO 2013). ULRPLP is requesting that the requirement for the alarm and associated signage be removed from Condition #35 of the TOC. When considering the requirements related to the alarm system and signage specified in Condition #35 of the TOC, it is important to understand the history and context of this condition. During the environmental assessment (EA), the Proponent identified the potential for risk to human safety during recreational use, due to the possibility of water level fluctuations in the Upper Lillooet River at the Pebble Creek Hot Springs (Map 2) and at the powerhouse. The Application for an EAC (EA Application) proposed that further analysis be conducted to determine if a signal system or other form of mitigation would be warranted at the hot springs (SNC 2012a; Appendix AR - Table 5). Further, although potential safety risk was identified at the powerhouse, this was associated with recreational kayakers, which the EA Application specified (SNC 2012a; Appendix AR - Table 7) that

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Transport Canada would be responsible for addressing if necessary (i.e., through approval(s) received under the Navigable Waters Protection Act (1985)). It is also relevant to note that the draft Condition #35 arose from the EA Application, not from any public, Aboriginal groups, or agencies’ input. During the strengthening of the draft EAC language that occurs towards the end of the EA process, the two safety issues were combined and the draft language evolved such that the signal system became mandatory rather than subject to assessment to determine if it is appropriate mitigation. This evolution in language is illustrated by the following excerpts of the draft working versions, retained by ULRPLP, and the final wording of Condition #35 (underline added for emphasis):

• Draft condition as of August 28, 2012: “An alarm will be considered for installation as a safety measure at the Hot Springs to warn bathers of a change in water flow if the Dam Break Study demonstrates a significant stage change that may be a safety concern”

• Draft condition as of September 9, 2012: “Prior to Project operation, the Proponent must install an alarm as a safety measure at the Pebble Creek Hot Springs to warn bathers of a change in water flow if the Dam Break Study demonstrates a significant stage change that may be a safety concern.”

• Final excerpt of condition as of November 26, 2012: “Prior to operations, the Proponent must install an alarm or other signaling system acceptable to FLNR at the Pebble Creek Hot Springs and at the powerhouse locations to warn of potentially dangerous flow releases. The Proponent must post signs at Pebble Creek Hot Springs and at the powerhouses informing the public of how to respond to the signals.” ULPRLP retained Knight Piésold Ltd. (KP) to re-assess the consequence of an intake failure in both sunny day and flood induced scenarios based on the final design used for construction of the facility (KP 2016). On March 31, 2017, a Senior Dam Safety Engineer of the Ministry of Forests, Lands, and Natural Resource Operations and Rural Development (FLNRORD) (formerly FLNRO) approved the results of this study (McLean 2017, pers. comm.). Specific to the potential safety risk identified in Condition 35, ULRPLP further retained KP to assess the potential safety risk to users of the Pebble Creek Hot Springs. KP modelled stage changes (changes in water level) at the hot springs and the powerhouse under a worst case operational scenario (i.e. full load rejection). The results of this KP study (provided as Appendix A) confirmed that there is no risk to users of the Pebble Creek Hot Springs pools nor to the powerhouse and associated infrastructure. Based on the results of the KP study (KP 2017), combined with the BC Environmental Assessment Office’s (EAO) Environmental Assessment Certificate Policy (EAC Policy) (EAO 2017) which advocates minimizing overlap with permitting, ULRPLP is seeking to amend the EAC to remove the requirement for a signal system and associated signage in accordance with Section 19(1) of the BC Environmental Assessment Act (BCEAA) (2002). In addition, ULRPLP requests that EAO consider

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combining all previous amendments with this amendment into one consolidated EAC to increase clarity for all parties. An Application for an EAC amendment requires that all valued components (VCs) identified during the EA process that may be impacted by the proposed change are assessed to determine if the residual effects predicted in the original EA Application will be affected. Ecofish Research Ltd. (Ecofish) was retained to determine if the conclusions of the EA, on which the Ministers based their decision to grant Project approval, are maintained with the proposed change.

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Map 1. Location of the Upper Lillooet River Hydroelectric Facility.

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2. PROPOSED CHANGE AND RATIONALE ULRPLP is requesting to amend Condition #35 of Schedule B of the EAC to remove the requirement for a signalling system, and associated signage, to be installed at the Upper Lillooet River HEF powerhouse and Pebble Creek Hot Springs. Condition #35 also requires that a trail must be created to access the Upper Lillooet River near the hot springs. This part of the condition has been completed and would remain unaltered through the proposed amendment. There are two components to ULRPLP’s rationale for the requested change. First, in accordance with the original intent of the EA prescription, a safety analysis determined that there is no risk to users of the Pebble Creek Hot Springs and negligible risk to the powerhouse related to flow changes in the Facility’s diversion reach. Thus, as specified in the original EA mitigation, the implementation of safety mitigation is unnecessary. Results of this pivotal safety analysis, which are critical in the assessment of the VC that interacts with the proposed change, is summarized in Section 4.1. Secondly, a key component of this amendment request is that other federal and provincial agencies are currently addressing public safety due to water level changes in their authorizations. The EAO’s EAC Policy (EAO 2017) states that conditions should be directed at “addressing the risk of adverse effects on valued components that are not sufficiently addressed in permitting and the regulatory framework.” This significant policy change was clarified through the finalization of the EAC policy after the Project was certified, which further supports the rationale for this amendment request. This issue and its role in the assessment of the proposed change are further discussed in Section 5.

3. ASSESSMENT METHODS During the EA process, potential adverse effects were identified and evaluated for selected VCs for all phases of Project development and mitigation measures were prescribed to avoid or minimize such adverse effects. Many of these identified constraints or conditions intended to mitigate potential effects were incorporated into Schedule B of the EAC (the TOC). Thus, because Schedule B of the EAC reflects the conclusions of the Project’s Application for an EAC, and because any changes to these conditions have the potential to modify such conclusions, the potential consequences of the requested amendment on the conclusions of the EA must be evaluated. The assessment presented in this amendment application evaluates whether the proposal to remove the requirement for the signalling system and associated signage will affect the conclusions of the EA Application, on which the Ministers based their decision to issue the EAC. The assessment methods for the evaluation of the potential consequences of the removal of the signalling system and associated signage on the conclusions of the EA Application were to firstly determine which of the VCs selected and assessed during the initial EA would interact with the proposed change. The VCs anticipated not to interact with the proposed change were discounted. The remaining VCs were then assessed for each potential adverse effect identified in the EA

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Application to determine whether conclusions of the EA would be affected if the requested change was made and whether or not additional or alternate mitigation would be required. The assessment process therefore involved: 1) identifying VCs with the potential to interact with the proposed change; 2) evaluating potential effects relevant to the proposed change; and 3) evaluating whether conclusions drawn in the Project’s EA Application with respect to the residual effects, characterization of residual effects, and determination of significance, are affected by the proposed change. Although not directly related to the assessment of the proposed change on the VCs identified in the EA, overlap with permitting is an important additional consideration for the need for mitigation to be specified in the EAC. Consistent with EAO’s EAC Policy (EAO 2017), Ecofish has assessed, as described in Section 5, that the consideration of public safety is addressed by subsequent statutory decision makers. Consultation with Aboriginal groups, which had occurred during development of the amendment application, was also documented, as was relevant context from Working Group Members.

4. ASSESSMENT OF PROPOSED CHANGE The only VCs that have the potential to interact with the proposed change are the VCs within the Social Impact Type. Because the signalling system and associated signage required by Condition #35 is directed at people, there is no potential for any environmental VC to interact with the proposed change. Further, the signalling system and associated signage is strictly associated with safety in the Project’s operations phase. Although the Health Impact Type also addressed safety issues, this impact type considered only construction and operational site safety (SNC 2012b). Similarly, although use of the Pebble Creek Hot Springs area was documented as a gathering place for spiritual people in the Traditional Use Study (SNC 2012b), the assessment of heritage effects as part of the Heritage Impact Type (SNC 2012c), was focused on assessment of traditional use and culturally valued areas, not safety. The Navigation VC also does not interact with the proposed change (Table 1). Although the approval received by the Upper Lillooet River HEF under the Navigable Waters Protection Act (1985) included conditions on the installation of a signalling system at the powerhouse and associated signage at the powerhouse and kayaking put in and pull out locations (Transport Canada 2013), this is directed at ensuring safety for kayakers using the diversion reach. Safety due to flow changes was not identified as a potential effect for the Navigation VC in the EA, where only changes to kayaking potential due to flow changes were considered. Although prescribed mitigation included providing safety signage, the intent of this is to mark hazards, thereby encouraging kayakers and providing a service, and to address Facility-related liability. The intent of this signage was not to address risk from operational flow changes, rather to address (as stated in Transport Canada (2013)) ‘the effect of your work on navigation’. EAO’s assessment report (EAO 2012; p. 105, section 7.2.3) also states

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(in relation to the Navigation VC) that “any potential effects to users would be addressed during permitting under the Navigable Waters Protection Act. …”. The potential risk to human safety from changes in flow during Upper Lillooet River HEF operation was identified in the EA as a potential effect for the Pebble Creek Hot Springs VC, and therefore this VC interacts with the proposed change to the signalling system and associated signage (Table 1). The EA Application states that “Pebble Creek Hot Springs is not an established recreation site, although it is relatively well known to residents of Pemberton. The springs are known to receive various levels of use throughout the summer and fall months, with occasional use in the winter. Users have constructed simple pools at the site to enhance the hot spring experience.” As shown in Figure 1 and Figure 2 and in Map 2, there are three small pools directly adjacent to the river’s edge. Table 1. Summary of valued social components and their potential to interact with the proposed removal of signage and signalling requirements for the Pebble Creek Hot Springs and powerhouse.

Subject Area Valued Components Interaction with Removal of Signalling System and Signage

Recreation and Tourism Commercial access and use No Non-commercial access and use No Pebble Creek Hot Springs Yes Navigable Waters Navigation No Public Impact Visual quality for Keyhole Falls No Visual quality for the transmission line No Pemberton Creek Community Watershed No First Nations Lil'wat First Nation access issues No

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Figure 1. Pebble Creek Hot Spring looking downstream, October 4, 2017.

Figure 2. Pebble Creek Hot Spring looking upstream, October 4, 2017.

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4.1. Assessment of Pebble Creek Hot Springs VC One of the proposed changes to TOC Condition #35 is to remove requirements for a signalling system and signage at the Pebble Creek Hot Springs. As such, the most important information required to assess whether the conclusions of the EA may be affected by this change is to consider the safety analysis that was conducted to specifically address this question (Appendix A). The results of this analysis, and the conclusions of the assessment in light of this analysis, are provided in the sections below. 4.1.1. Safety Analysis In addition to the KP assessment of the consequence of an intake failure in both sunny day and flood induced scenarios (KP 2016), in 2017 KP assessed the safety related consequences of the changes to the stage (water level) in the Upper Lillooet River at the Pebble Creek Hot Springs and at the powerhouse that would result from a full load rejection during Upper Lillooet HEF operations (KP 2017; provided Appendix A). A full load rejection, which represents the maximum impact that the Facility could have on flow rate changes during operations, is an emergency stop of the HEF at maximum licenced water diversion (when operating within the appropriate seasonal Instream Flow Release (IFR)) during which all flows are suddenly released at the intake into the diversion. The safety analysis (Appendix A) was conducted using the model developed to assess the impact of a hypothetical sunny day dam breach scenario and assessed the effect of the full load rejection scenario using the final design and the as-built conditions of the Upper Lillooet River HEF Intake. This safety analysis also considered results of the dam breach study, which investigated the consequences of failure of the intake structures, and documented that results of the full load rejection and the sunny day dam breach were similar. It also discusses the history of previous studies and subsequent design changes. Key results from the safety analysis are summarized here. Study methods involved firstly determining under what conditions the worst case scenario for stage change would occur. The largest expected change in water depth (i.e., stage change) within the diversion reach would occur if a full load rejection occurred when the proportion of the flow in the diversion reach was equal to the IFR (i.e., only the IFR is being released into the diversion) and the HEF was operating at full capacity of 53 m3/s. Under these conditions, the riverflow in the Upper Lillooet River upstream of the HEF would be equal to 53 m3/s plus the applicable IFR and the potential for change in stage would be greater than all other scenarios in which the HEF was operating at full capacity. This is because in other scenarios, some of the flow would be spilled over the intake and remain in the river, reducing the magnitude of the stage increase if load rejection occurred. Thus, during the most severe scenario, all flows previously diverted to the powerhouse and all riverflow (i.e., IFR plus the previous facility flow) would be redirected over the intake in a short period of time. Although this scenario is unlikely, it does represent a potential operational scenario. Given the seasonally varied IFR of the Upper Lillooet River HEF (there are three season- specific IFR requirements), the highest IFR (4.5 m3/s from May 1 to September 30) was selected for

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the analysis because this would represent impacts to the highest water level elevation and would therefore have the greatest potential to affect the pools of Pebble Creek Hot Springs. Moreover, the time period also coincides with the highest public use of the hot springs. Modelling results indicated that, following a full load rejection, rise in flows and water levels will occur over approximately 2 minutes and will progress downstream through the diversion reach, causing stage (water level) to begin to increase at the Pebble Creek Hot Springs and the Upper Lillooet River HEF powerhouse after 17 and 27 minutes, respectively, of the initial full load rejection. Stage increase was estimated to be 0.67 m and 0.69 m at the Pebble Creek Hot Springs and at the powerhouse, respectively (see Figure 3 of Appendix A). Evaluation of the risk associated with the stage changes that would result from a full load rejection were based on the predicted magnitude and timing of the stage changes in relation to what occurs during natural events. Comparison of modelling results under a full load rejection to natural water elevations indicated that natural variability in water elevations far exceeds potential stage changes during a full load rejection. During the most extreme scenario (when the facility is operating at full capacity and the flow in the diversion reach is at an IFR level) and water level increases 0.67 m at the hot springs, peak water level would be well below the lowest hot spring pool and below the highest mean monthly riverflow in July. The study concluded that there is no risk to human safety in the hot springs pools and negligible risk to the powerhouse and its associated infrastructure. While there is risk within the water or along the water’s edge anywhere within the diversion reach (owing to the potential speed of the change in water level), this risk is similar to what would be expected in the diversion reach of other run-of-river facilities. 4.1.2. Evaluation of Potential Changes to Residual Effects Characterization Potential effects on the Pebble Creek Hot Springs VC during Project operations were assessed in the EA to include restricted access and sudden fluctuations in water levels in the Upper Lillooet River due to extreme flow adjustments at the Upper Lillooet River HEF. Of these, only the potential for water level fluctuations is relevant to the proposed amendment. Based on mitigation measures to consider installing an alarm and/or other measures to ensure safety to hot springs bathers when changes in water flow occurred, no residual effects were predicted. Thus, given the results of the KP safety study (Section 4.1.1), which concluded that there is no risk to the pools or the trail above the pools without the prescribed mitigation, the proposed change to the TOC does not affect the conclusions of the EA of no residual effects for the Pebble Creek Hot Springs VC.

5. OVERLAP WITH FEDERAL AND PROVINCIAL PERMITTING This amendment request is consistent with EAO’s EAC Policy (EAO 2017) that supports minimizing overlap with permitting. The EAC Policy states that “A mitigation measure should only be included in the certificate/order when”, among other things, “permitting or other regulatory frameworks do not fully address the effects and required spatial and temporal scope of the

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mitigation measures.” In this case, three other agencies consider safety risks when determining any required mitigation in their authorizations: Transport Canada (TC), Recreational Sites and Trails BC (RSTBC) and FLNRORD. As stated in the EA (SNC 2012a), TC addresses safety issues when these are related to navigational issues, which is relevant to the part of Condition #35 that requires safety measures to be implemented at the powerhouse. The HEF received approval (Transport Canada 2013) under the Navigable Waters Protection Act (1985) and this approval included two conditions related to requirements for an alarm system and warning signage in relation to public safety during recreational use at the powerhouse location. Condition #7 of the approval (8200-2009-500434-001 (8200-09- 8432)) (Transport Canada 2013) requires that an audible alarm system be installed at the powerhouse that will warn kayakers of a substantial changes in flow, and Condition #8 requires that warning signage detailing the meaning of the alarms be installed and maintained at put in and pull out locations. Condition #9 required signage to be posted upstream of the powerhouse during construction and upstream of the tailrace once construction is completed. The installation of signage related to flow changes from the tailrace has been installed and the alarm warning signage would be installed prior to operations (Mancinelli 2016). Since the issuance of the approval, Lillooet River was declassified as a navigable water under the Navigation Protection Act (1985). The Facility’s Conditional Water Licence (CWL) (C1306136) (Clause l(3)) and Leave to Commence Diversion Approval (Clauses 21-22) address public safety concerns, by requiring that a dam safety analysis and documents (i.e. Dam Failure Consequence Classification, Operations, Maintenance and Surveillance Plan and Dam Emergency Plan) be prepared and approved to meet FLNRO (now FLNRORD) Dam Safety Regulation. In addition, Clauses 23 and 24 of the Facility’s Leave to Commence Diversion Approval issued by FLNRO (now FLNRORD) (FLNRO 2016), which is relevant to the part of Condition #35 that requires safety measures to be implemented at Pebble Creek Hot Springs, required the installation of safety related signage at the Pebble Creek Hot Springs, subject to approval by RSTBC. The installation of signage to meet this requirement has been completed and approval from RSTBC has been obtained (Mancinelli 2016). Thus, while FLNRORD will determine what, if any, requirements for signage or other mitigation when they consider issuing the Leave to Commence Operations, currently public safety at the hot springs from changing water levels is addressed in the Leave to Commence Diversion (FLNRO 2016). In addition, ULRPLP has worked closely with RSTBC throughout all phases of the Project to minimize development impacts to the Recreational Features in the Project area, including the non- established Pebble Creek Hot Springs recreational site. These commitments and mitigation measures are detailed in the Key Principles Agreement and Memorandum of Understanding in which RSTBC has not required any mitigation to address risk from operational flow changes. In contrast, a serious public safety risk at the hot springs has been human-bear interactions due to the presence of bear attractants (food and garbage) from recreational users at the site. This has led to an initial temporary

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closure of the hot springs and trail on June 23, 2016 (https://news.gov.bc.ca/releases/2016FLNR0131-001138), and the indefinite closure on May 10, 2017 (https://news.gov.bc.ca/releases/2017FLNR0098-001202; https://www.piquenewsmagazine.com/whistler/keyhole-falls-closed-indefinitely-over-concerns-of- bears/Content?oid=3432107).

6. CONSULTATION Consultation with working group members is an important component of the pre-application phase of the amendment application process, and the EAO strongly encourages Certificate Holders to work with government agencies and Aboriginal groups to resolve any potential issues of concern prior to submitting their amendment application (EAO 2016). As such, ULRPLP has conducted consultation with government agencies and Aboriginal groups. A summary will be provided to EAO by ULRPLP separately.

7. CONSOLIDATION OF ALL AMENDMENTS TO EAC If approved, this amendment would become the Project’s eighth amendment to date. In order to increase clarity for all parties, ULRPLP requests that EAO consider consolidating all amendments into one document. Given that all previous amendments have been approved, no additional analysis regarding potential effects or mitigation would be required to support this consolidation request. Recognizing that the BCEAA (2002) does not include explicit provisions for issuing a consolidated EAC, ULRPLP proposes that, if this eighth amendment is approved, the main body of the amendment states that the relevant sentences have been removed from Condition #35, and a consolidated Certified Project Description (CPD) as well as a consolidated TOC would be added to the amendment as Schedule A and Schedule B, respectively.

8. SUMMARY AND CONCLUSIONS ULRPLP is seeking to remove the requirements to install and operate a signaling system, including associated signage, at the powerhouse and Pebble Creek Hot Springs, from Condition #35 of the TOC. The rationale for this request is based on the safety analysis (Appendix A) that determined that there is no risk to users of the Pebble Creek Hot Springs pools, on the trail above the hot pools nor to the powerhouse and associated infrastructure related to flow changes in the HEF’s diversion reach.. This amendment application assessed all VCs identified during the EA process that may be affected by the proposed change to determine if the conclusions of the EA Application, on which the Ministers based their decision to issue the EAC, will be affected. It also considered potential overlap with the EAC condition by other agencies, specifically that other federal and provincial agencies are currently addressing public safety, due to water level changes, in their authorizations.

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The only VC that has the potential to interact with the proposed change was the Pebble Creek Hot Springs VC, for which a potential effect of sudden fluctuations in water levels in the Upper Lillooet River due to extreme flow adjustments at the Upper Lillooet River HEF was identified in the EA. However, the safety analysis conducted by KP (Appendix A), and their conclusions that there is no risk to persons using the Pebble Creek Hot Springs pools or associated trail even if the Facility were to experience a full load rejection, indicated that the mitigation prescribed in Condition #35 is not a necessary safety measure and the conclusion of no residual effects would be maintained without this mitigation. In addition, FLNRORD is currently requiring mitigation for the hot springs through signage and will determine if any additional signage or mitigation is required when considering issuing the Leave to Commence Operations. Further, given that TC regulates navigational safety, removal of the requirement at the powerhouse, which is focused on kayakers and not users of the hot springs, will also not affect the conclusions of the EA. Thus, this assessment concluded that, due to a lack of change to the conclusions of the EA following re-assessment of the VC that interacts with the proposed change, along with the consideration of public safety by other agencies, the safety requirements specified in Condition #35 of the TOC should be removed. Yours truly, Ecofish Research Ltd.

Prepared by: Reviewed by: Signed Signed Autumn Cousins, M.Sc. Deborah Lacroix, M.Sc., R.P.Bio. Lead Regulatory Strategy, Wildlife Biologist, Project Manager Environmental Compliance

Heidi Regehr, M.Sc., Ph.D., R.P.Bio. Wildlife Biologist

Disclaimer: The material in this memorandum reflects the best judgement of Ecofish Research Ltd. in light of the information available at the time of preparation. Any use which a third party makes of this memorandum, or any reliance on or decisions made based on it, is the responsibility of such third parties. Ecofish Research Ltd. accepts no responsibility for damages, if any, suffered by any third party as a result of decisions or actions based on this memorandum. This memorandum is a controlled document. Any reproductions of this memorandum are uncontrolled and may not be the most recent revision.

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REFERENCES BCEAA (BC Environmental Assessment Act). 2002. [SBC 2002] Chapter 43. Available online at: http://www.bclaws.ca/civix/document/id/complete/statreg/02043_01. Accessed on May 3, 2016. CP (Creek Power Inc.). 2012. Application for Environmental Assessment Certificate for the Upper Lillooet Power Project. Available online at: https://projects.eao.gov.bc.ca/p/upper-lillooet- hydro/docs?folder=19 . Accessed on October 31, 2017. EAO (Environmental Assessment Office). 2012. Upper Lillooet Hydro Project Assessment Report. Available online at: https://projects.eao.gov.bc.ca/p/upper-lillooet-hydro/docs?folder=88. Accessed on October 31, 2017. EAO (Environmental Assessment Office). 2013. Environmental Assessment Certificate E13-01 for the Upper Lillooet Hydro Project dated January 8, 2013. Available online at: http://a100. gov. bc. ca/appsdata/epic/html/deploy/epic_document_357_35259. html. Accessed on October 31, 2017. EAO (Environmental Assessment Office). 2016. Seeking an Amendment to an Environmental Assessment Certificate Guidance for Certificate Holders. December 2016. Available online at http://www.eao.gov.bc.ca/guidance.html. Accessed on November 10, 2017. EAO (Environmental Assessment Office). 2017. Environmental Assessment Certificate Policy. September 2017. Available online at http://www.eao.gov.bc.ca/guidance.html. Accessed on November 10, 2017. FLNRO (Ministry of Forests, Lands and Natural Resource Operations). 2016. Upper Lillooet River Hydroelectric Facility – Leave to Commence Diversion. Letter to Julia Mancinelli, Upper Lillooet River Power Limited Partnership, from Remko Rosenboom, Water Manager, Ministry of Forests, Lands and Natural Resource Operations. November 21, 2016. KP (Knight Piésold Ltd.). 2016. Upper Lillooet Hydroelectric Project – Assessment of Dam Failure Downstream Consequence Classification. Memorandum to Derek McCoy, Engineering Manager, Innergex Renewable Energy, from Knight Piésold Consulting Ltd. March 10, 2016. KP (Knight Piésold Ltd.). 2017. Upper Lillooet River Stage Response to Full Load Rejection at the Upper Lillooet River Hydroelectric Facility. Memorandum to Tom Furst, Project Manager, Upper Lillooet River Power LP, from Knight Piésold Consulting Ltd. October 27, 2017. Mancinelli, J. 2016. Upper Lillooet River Hydroelectric Facility Leave to Commence Diversion Approval – Clause 23 and 24 – Signage; Navigable Water Protection Approval – Condition 9

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– Signage. Memorandum to Liz Scroggins, Grey Owl Consulting from Julia Mancinelli, Innergex Renewable Energy, Inc. December 12, 2016. Navigable Waters Protection Act. R.S.C., 1985, c. N-22. Version of document from 2009-03-12 to 2014- 03-31. Available online at http://laws-lois.justice.gc.ca/eng/acts/N- 22/20090312/P1TT3xt3.html. Accessed on November 5, 2017. Navigation Protection Act. 2017. R.S.C., 1985, c. N-22. Available online at http://laws- lois.justice.gc.ca/PDF/N-22.pdf. Accessed on November 5, 2017. SNC (SNC-Lavalin Environment). 2012a. Upper Lillooet Hydro Project Environmental Assessment Certificate Application. Section 7.0. Assessment of Social Effects. Consultant’s report prepared for Creek Power Inc. by SNC-Lavalin Environment. April 2012. SNC (SNC-Lavalin Environment). 2012b. Upper Lillooet Hydro Project Environmental Assessment Certificate Application. Section 9.0. Assessment of Potential Health Effects. Consultant’s report prepared for Creek Power Inc. by SNC-Lavalin Environment. April 2012. SNC (SNC-Lavalin Environment). 2012c. Upper Lillooet Hydro Project Environmental Assessment Certificate Application. Section 8.0. Assessment of Potential Heritage Effects. Consultant’s report prepared for Creek Power Inc. by SNC-Lavalin Environment. April 2012. Transport Canada. 2013. Approval for Independent Power Project under the Navigable Waters Protection Act. Letter to Upper Lillooet River Power Limited Partnership from Brent Magee, Officer, Navigable Waters Protection Program, Transport Canada. May 6, 2013.

Personal Communications Mclean, R. 2017. Senior Dam Safety Engineer. BC Ministry of Forests, Lands and Natural Resource Operations, Water Management Branch. Email communication with Julia Mancinelli, Innergex Renewable Energy on March 21, 2017.

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Map 2.

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APPENDICES Appendix A. Upper Lillooet River Stage Response to Full Load Rejection at the Upper Lillooet River Hydroelectric Facility.

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www.knightpiesold .com

www.knightpiesold .com October 27, 2017 File No.:VA103-00279/06-A.01 Cont. No.:VA17-01627 Mr. Tom Furst Project Manager Upper Lillooet River Power LP c/o Innergex Renewable Energy Inc. 900 - 1185 West Georgia Street Vancouver, British Columbia Canada, V6E 4E6

Dear Tom,

Re: Upper Lillooet River Stage Response to Full Load Rejection at the Upper Lillooet River Hydroelectric Facility

1 – INTRODUCTION Upper Lillooet River Power Limited Partnership (ULRPLP) operates the Upper Lillooet River Hydroelectric Facility (HEF), located in the Pemberton Valley approximately 65 km northwest of Pemberton, British Columbia (BC). Environmental Assessment Certificate (EAC) E13-01 for the Upper Lillooet Hydro Project (the Project) was issued on January 8, 2013, and included the following clause (#35): Prior to operations, the Proponent must install an alarm or other signaling system acceptable to FLNR at the Pebble Creek Hot Springs and at the powerhouse locations to warn of potentially dangerous flow releases. The Proponent must post signs at Pebble Creek Hot Springs and at the powerhouses informing the public of how to respond to the signals. The EAC was issued in 2013 based on the feasibility design of the facility, and since that time, the activities related to the detailed design, construction and commissioning of the Upper Lillooet River HEF were completed. ULRPLP requested Knight Piésold Ltd. (KP) to assess the changes to the stage in the Upper Lillooet River at the Pebble Creek Hot Springs and at the powerhouse that would result from a full load rejection (i.e., emergency stop of the HEF at maximum licenced water diversion). The assessment was conducted using the model developed to assess the impact of a hypothetical sunny day dam breach scenario (KP 2016). This letter presents the results of the full load rejection scenario, which was assessed using the final design and the as-built conditions of the Upper Lillooet River HEF Intake.

2 – PREVIOUS STUDIES A preliminary study of the potential failure/breach of the Upper Lillooet River HEF Intake was conducted by KP in 2011 (KP 2011). The study was based on the feasibility design of the facility, which was different from the final design used for the construction of the facility. The feasibility design included an intake structure with three intake openings, a 5 m wide sediment sluiceway, an 18 m wide spillway with a 3 m high inflatable rubber dam, and a 20 m wide temporary diversion channel that would be dammed following the completion of the intake construction. The construction of the Upper Lillooet River HEF was completed in early 2017 and commissioning is ongoing. The constructed intake consists of an intake structure with two openings positioned almost perpendicularly to the 6 m wide sluiceway. The spillway with the rubber dam was not constructed as proposed in the feasibility design, nor was the diversion channel dammed upon construction completion. Instead, the diversion channel was left operational and the headpond level, as well as the flow through the channel, is controlled as needed by operating three 5.33 m wide Obermeyer gates. As required under BC Dam Safety Regulations, an assessment of the consequence of an intake failure in both sunny day and flood induced scenarios was conducted by KP in 2016

Knight Piésold Ltd. | Suite 1400 – 750 West Pender St, Vancouver, BC Canada V6C 2T8 | p. +1.604.685.0543 f. +1.604.685.0147

(KP 2016), where the failure of the Obermeyer gates was investigated for the sunny day scenario. The results were reviewed and approved by a Senior Dam Safety Engineer, Robert McLean, of the BC Ministry of Forests, Lands, Natural Resource Operations and Rural Development (FLNRO) in writing on March 31, 2017. Considering the substantial changes in the constructed intake design compared to the feasibility design (albeit still consistent with the Project’s EAC Certified Project Description), the results of the preliminary intake breach study that was conducted in 2011 (KP 2011) are no longer applicable. The 2011 preliminary results of a failure of the rubber weir, the entire intake structure, or the dam in the diversion channel, all predicted considerably higher peak flows than the modelled sunny day failure of the constructed intake (KP 2016). The scenarios assessed in 2011 are no longer possible, and hence, ULRPLP requested a full load rejection scenario to be assessed in addition to the intake failure study previously completed in 2016. The full load rejection would represent an emergency condition in which the water diversion through the HEF is completely stopped and all flows are released at the intake into the diversion reach. Possible causes for such event are discussed in more detail in Section 4 of this letter, and even though such circumstances are not considered likely, this event represents a potential operational scenario that required assessment of the degree of risk to potential users of the Pebble Creek Hot Springs pools.

3 – PEBBLE CREEK HOT SPRINGS The Pebble Creek Hot Springs are an unestablished recreation site that is partially accessed using a newly constructed (2014) trail from the Upper Lillooet River Forest Service Road, which ends approximately 325 m from the hot springs that are located on the river’s edge. The hot springs are located in the diversion reach of the Upper Lillooet River HEF, approximately 2 km downstream of the intake and 1.5 km downstream of Keyhole Falls. On October 4, 2017, Justin Murray from KP joined a field visit to these hot springs led by Matt Kennedy from ULRPLP. Liz Scroggins from Grey Owl Consulting and Autumn Cousins from Ecofish Research Ltd. (Ecofish) were also present. The field team hiked to the hot springs and undertook a survey of the pool crests in reference to the water surface, and took photos of the pools and the river channel. There are five hot spring pools: four grouped together along a trail to the river’s edge and one farther downstream along the access trail. The four upstream pools are shown in Photo 1 while the downstream pool is shown in Photo 2.

NOTES: 1. A 2.2 m SURVEY ROD PHOTOGRAPHED ON THE CREST OF THE UPPER MIDDLE POOL FOR REFERENCE. Photo 1 Four Upstream Hot Spring Pools, Looking Upstream

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Four Upstream Hotspring Pools

Photo 2 Downstream Hot Spring Pool, Looking Upstream During this site visit, the Upper Lillooet River HEF was not operating and the streamflow remained relatively steady. At the time of the survey, the hydrology gauge downstream of the powerhouse, UL DSPH, measured a streamflow of 14.2 m3/s and the tributary inflow between the hydrology gauge and the hot springs was estimated to be 1.2 m3/s. The streamflow at the Pebble Creek Hot Springs at the time of the survey was therefore estimated to be 13 m3/s. The elevation of the pool crests were surveyed and their height relative to the water surface was recorded. These relative heights are presented on Figure 1 for the four upstream pools and on Figure 2 for the downstream pool.

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Figure 1 Relative Pool Crest Elevation for the Four Upstream Hot Spring Pools

Figure 2 Relative Pool Crest Elevation for the Downstream Hot Spring Pool

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4 – MODELLED SCENARIO – FULL LOAD REJECTION The critical operational scenario of interest investigated in this assessment is when the Upper Lillooet River HEF is operating at full capacity diverting 53 m3/s to the powerhouse, while the instream flow requirement (IFR) is being released at the intake. Under these conditions, the streamflow in the Upper Lillooet River upstream of the HEF would be equal to 53 m3/s plus the applicable IFR. The HEF has a seasonally varied IFR, depending on the time of year. The IFR criteria are shown in Table 1, as per the Conditional Water Licence (C130613; File 2002561). Table 1 IFR for the Upper Lillooet River HEF

Instream Flow Requirement Date (m3/s)

October 1 to March 31 2.3

April 1 to April 30 3.8

May 1 – September 30 4.5

For all other conditions when the HEF is operating at full capacity of 53 m3/s, the streamflow in the Upper Lillooet River would be higher than 53 m3/s plus the applicable IFR, and consequently, the flows in the diversion reach would be higher than the IFR, as the additional flows would be spilled over the intake and remain in the river. Therefore, the largest expected change in water depth (i.e. stage change) within the diversion reach would occur if a full load rejection occurred when the flow in the diversion reach was equal to the IFR and the facility was operating at full capacity of 53 m3/s. The 18 year long synthetic daily flow series developed by KP (KP 2014) was reviewed to assess the frequency of occurrence of the critical flow scenario described above. This dataset was screened for the number of days when the streamflow was ±10% with respect to the flow scenario of 53 m3/s plus the applicable IFR. This flow scenario may occur on 14 days per year on average (4% of the time) based on the daily synthetic flow record, most often in May (10% of the month) on the rising limbs of the spring freshet, and in September (23% of the month) at the tail end of the summer glacial melt. Although this flow condition is rare during the winter, it does occur in October and November (2% and 1% of the month, respectively), It should be noted that this flow scenario would be encountered more often when using a finer time-step that would capture the flow changes within a day; however, the daily dataset provides a reasonable estimate of when this flow condition typically occurs. The largest flow change in the diversion reach is expected if a full load rejection occurs when the facility is operating at the full design capacity while the IFR is being released past the intake into the diversion reach (no additional spill). This condition would result in cessation of flows previously diverted to the powerhouse and all streamflow (i.e., IFR plus the previous facility flow) now being redirected over the intake in a short period of time. This operational scenario, although unlikely, could occur under the following circumstances: 1. Scenario #1 - A simultaneous closure of all four Turbine Inlet Valves (TIVs), which takes approximately 7 minutes and 45 seconds. 2. Scenario #2 - A full facility trip causing a simultaneous closure of the wicket gates for all four turbines, which takes approximately 100 seconds, combined with a simultaneous failure of all four bypass valves. For background, during a normal (non-emergency) turbine shutdown, the wicket gates close to stop water flow into each turbine. This is balanced by an equal but opposite increase in flow through a dedicated and independently controlled full-capacity bypass valve, which allows water to continue to be returned to the river uninterrupted. While a full facility trip causing a simultaneous closure of all four turbine wicket gates is possible, a simultaneous failure of all four bypass valves is considered remote. The total relative change in the water surface elevation within the diversion reach would be very similar for any of the three IFR conditions during a full load rejection; however, the starting water surface elevation would be lower

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for the lower IFR conditions. Considering that the purpose of this study is to evaluate whether the water surface would reach the Pebble Creek Hot Springs pools or the powerhouse, the highest IFR condition was selected for modelling. The modelled inflow for Scenario #1 has diversion reach flows linearly increasing from IFR flow of 4.5 m3/s to 57.5 m3/s in 7.5 minutes, while the modelled inflow for Scenario #2 has diversion reach flows linearly increasing from IFR flow of 4.5 m3/s to 57.5 m3/s in 2 minutes. This difference in the time to reach the full flows in the diversion reach did not result in any material differences to the results of routing the full load rejection flows through the diversion reach, and hence, only the results of the faster Scenario #2 are discussed in Section 6 of this letter.

5 – HYDRODYNAMIC MODEL The full load rejection scenario was modelled using the model developed to assess stage responses during a sunny day dam breach scenario (KP 2016). The model was developed using the one-dimensional hydrodynamic modelling software HEC-RAS with 1 m LiDAR contours in the Upper Lillooet River reach. A Manning’s n value of 0.05 was used for the river channel and 0.1 was used for the overbank floodplain. The Upper Lillooet River just downstream of the Upper Lillooet River HEF Intake flows through a steep and deep canyon in the approach to a 30 m vertical waterfall at Keyhole Falls. The 1 m LiDAR contours do not provide adequate resolution to model the IFR through this section, and hence, the modelled section begins 500 m below the intake, just below the Keyhole Falls (~1.5 km upstream of the hot springs). The full load rejection hydrograph was input into the model at this location without estimating any attenuation between the intake and the falls. The modelled flow scenario was then routed through the diversion reach of the Upper Lillooet River to 500 m downstream of the Upper Lillooet River HEF Powerhouse to determine the impacts of the full load rejection scenario on the river flows and water surface elevations.

6 – RESULTS 6.1 GENERAL The results of the full load rejection modelling are summarized on Figure 3. At arbitrary time 00:00 a turbine trip occurs and at the first cross-section below Keyhole Falls, the water elevation or stage increases over two minutes. The stage at the Pebble Creek Hot Springs begins to increase 17 minutes after the facility trip occurred, while the stage at the Upper Lillooet River HEF Powerhouse begins to increase 27 minutes after the trip. Table 2 summarizes the stage and stage response at each location of interest. Stage increase after the full load rejection is estimated to be 0.67 m at the Pebble Creek Hot Springs, while the stage increase at the Powerhouse is estimated to be 0.69 m. The results of a sunny day dam breach are also presented on Figure 3 for comparison (KP, 2016). These results show the response to a sunny day dam breach when only the IFR of 4.5 m3/s is flowing through the diversion reach before the breach occurs. The stage response to the sunny day breach event is similar or somewhat larger in magnitude, and propagates through the diversion reach more quickly than the response to a facility trip.

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Figure 3 Predicted Stage Response during Full Load Rejection and Sunny Day Dam Breach Scenarios Table 2 Predicted Stage Response to Full Load Rejection with IFR of 4.5 m3/s

At Pebble Below Just Above Location Creek Hot Keyhole Falls Powerhouse Springs

Stage At IFR 572.28 519.11 470.03 (masl) After Full Load Rejection 573.03 519.78 470.72

Stage Response (m) 0.75 0.67 0.69

6.2 PEBBLE CREEK HOT SPRINGS KP has annotated a photo of the Pebble Creek Hot Springs (taken on October 4, 2017 by Justin Murray) to visually assess the effect of the stage response to the full load rejection. The estimated streamflow at the time the photograph was taken (13 m3/s) was also modelled using the HEC-RAS model and a water surface elevation for this condition is predicted to be 519.33 m at the hot springs. The pool crest elevations were adjusted to this datum using the relative heights presented in Figures 1 and 2. The pool crest elevations, mean annual discharge, and July mean monthly streamflow are also presented on Figure 4 for reference. Figure 5 presents the same photo; however, various return period flood elevations are also shown along with the peak elevation from the full load rejection and the sunny day dam breach. All typical hydrologic flows and return period floods were defined during an earlier hydrologic analysis for this facility (KP 2014), and the various flows were then routed using the same HEC RAS model. It is worth noting that the vertical scale on these photos is skewed due the angle of the photo, as indicated with the scale bar on the left side of the photos.

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~524 m Highest Pool Crest Estimated Elevation ~ 523.63 m

~523 m

Pool Crest Estimated Elevation ~ 522.23 m ~522 m Downstream Pool Crest Esimated Elevation ~521.86 m Pool Crest Estimated Elevation ~ 521.55 m

~521 m

Lowest Pool Crest Estimated Elevation ~ 520.61 m

Estimated July Mean Monthly Streamflow Elevation ~ 520.34 m, Q = 117.5 m3/s

~520 m

Estimated Mean Annual Discharge Elevation ~ 519.70 m, Q = 41.25 m3/s

Estimated Photographed Water Level Elevation ~ 519.33 m, Q = 13 m3/s

NOTES: UPPER LILLOOET RIVER POWER LP 1. ALL ELEVATIONS ARE REFERENCED TO THE MODELED WATER ELEVATION AT THE ESTIMATED UPPER LILLOOET RIVER HYDROELECTRIC FACILITY PHOTOGRAPHED STREAMFLOW. 2. RELATIVE DISTANCE BETWEEN THE WATER SURFACE AND POOL CREST ELEVATIONS WAS SURVEYED USING A TOTAL STATION. SURVEYED ESTIMATED TYPICAL STREAMFLOW 3. MODELED STREAMFLOW ELEVATIONS ARE LOCATED ON THIS FIGURE USING THE SURVEYED RETURN PERIOD FLOOD ELEVATIONS POOL CREST AND WATER SURFACE.

P/A NO. REF. NO. VA103-279/6 VA17-01627

0 13OCT'17 ISSUED WITH LETTER AA VM REV FIGURE 4 0 REV DATE DESCRIPTION PREP'D RVW'D M:\1\03\00279\06\A\Data\Task 400 - TiV closing\[Plant Trip Data Summary]Annotated Photo (2) Print 10/27/2017 9:38 AM

~524 m

~523 m Estimated 1:500 Year Flood Elevation ~ 522.82 m, Q = 663 m3/s

Estimated 1:100 Year Flood Elevation ~ 522.33 m, Q = 532 m3/s ~522 m Estimated 1:20 Year Flood Elevation ~ 521.86 m, Q = 415 m3/s

Estimated 1:2 Year Flood Elevation ~ 521.39 m, Q = 309 m3/s

~521 m

Estimated Lowest Pool Crest Elevation ~ 520.61 m

~520 m Estimated Peak Sunny Day Dam Breach Elevation ~ 519.94 m, Q = 67 m3/s Estimated Peak Full Load Rejection Elevation ~ 519.78 m, Q = 57.5 m3/s

Estimated Photographed Water Elevation ~ 519.33 m, Q = 13 m3/s

NOTES: UPPER LILLOOET RIVER POWER LP 1. ALL ELEVATIONS ARE REFERENCED TO THE MODELED WATER ELEVATION AT THE UPPER LILLOOET RIVER HYDROELECTRIC FACILITY ESTIMATED PHOTOGRAPHED STREAMFLOW. 2. RELATIVE DISTANCE BETWEEN THE WATER SURFACE AND POOL CREST ELEVATIONS WAS ESTIMATED RETURN PERIOD FLOOD ELEVATIONS AND SURVEYED USING A TOTAL STATION. WATER ELEVATIONS DURING SUNNY DAY DAM BREACH 3. MODELED RETURN PERIOD FLOOD ELEVATIONS AND OTHER WATER ELEVATIONS FROM AND FULL LOAD REJECTION OTHER EVENTS ARE LOCATED ON THIS FIGURE USING THE SURVEYED POOL CRESTS AND WATER SURFACE. P/A NO. REF. NO. VA103-279/6 VA17-01627

0 13OCT'17 ISSUED WITH LETTER AA VM REV FIGURE 5 0 REV DATE DESCRIPTION PREP'D RVW'D

July has the highest mean monthly streamflow (KP 2014) and the lowest pool crest is estimated to be about 15 cm above the water surface for this condition. Typical mean monthly streamflows for all other months are lower than the July streamflow, and are consequently all below the lowest pool crest (KP 2014). The various return period floods indicate that the 1:2 year flood elevation is just below the crest of the lower middle pool, while the 1:500 year flood elevation is 0.8 m below the highest pool. The peak water surface elevations from a full load rejection or the sunny day dam breach are well below the crest of the lowest pool, and also well below the July mean monthly streamflow. Although the increase in flow after a full load rejection is predicted to occur in about two minutes at the Pebble Creek Hot Springs, there is no risk to the recreational users present in any of the pools, or on the trail above the hot spring pools. Recreational users that are in the river or near the water edge anywhere within the diversion reach of the Upper Lillooet River HEF at the time the full load rejection flow was passing through, may not however, have sufficient time to move to safety. A similar flow and stage response would be expected to occur in diversion reaches of other run of river projects under similar full load rejection conditions. To better understand the conditions during low flows in the diversion reach, a couple of photos are presented below. Photo 3 was taken by Ecofish on March 29, 2017 when the estimated streamflow was equivalent to the winter IFR of 2.3 m3/s (Ecofish 2017). At winter IFR conditions, there is clear access to the water edge. Photo 4 presents a view of the river below the lowest pool on October 4, 2017. The water at the water edge was surveyed to be 0.2 m deep with the bed sloping down towards the thalweg; however, the maximum depth of the pool formed in the stream channel at this location, or the thalweg depth are unknown. Similar to other run-of-river hydroelectric facilities in BC, there are areas below the hot pools and elsewhere in the diversion reach that could be used safely by recreational users during lower streamflow conditions, but would become unsafe at higher flows, or during natural or facility induced rapidly varying flow conditions.

Pebble Creek Hot Springs

NOTES: 1. REPRODUCED FIGURE FROM FIGURE 45 OF HYDRAULIC CONNECTIVITY STUDY (ECOFISH 2017). Photo 3 Photo of Pebble Creek Hot Springs on March 29, 2017 (Winter IFR of 2.3 m3/s)

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Photo 4 Looking downstream of the Lowest Hot Spring Pool on October 4, 2017 (Estimated Streamflow of 13 m3/s) 6.3 POWERHOUSE Risk to the Upper Lillooet River HEF Powerhouse and associated infrastructure during this event is negligible. The Powerhouse and Switchyard are situated on a natural bench approximately 5 m above the river bed. The Powerhouse Control Room elevation is at 475.0 m (KP, 2016), while the river bed at this location is at 470.0 m. The Powerhouse was designed to have no structural damage in the 500-year peak instantaneous flood event occurring in the Upper Lillooet River (KP, 2012), which is significantly higher in flow magnitude than the full load rejection flow. During a facility trip, the Upper Lillooet River below the Powerhouse would have an abrupt drop in streamflow down to the IFR level, and then an increase back to the initial flow condition as the full load rejection flow propagates past the Powerhouse approximately 27 minutes later.

7 – CONCLUSIONS A full load rejection at the Upper Lillooet River HEF caused by a sudden facility trip will result in a fast rise of flows and water levels occurring over approximately two minutes and gradually progressing downstream through the diversion reach of the facility. In terms of potential risk to the recreational users that may be within the diversion reach, the most critical conditions under which this scenario may occur are considered to develop when the facility is operating at full capacity and the flow in the diversion reach is at an IFR level. Under such conditions, the change in water level is estimated to be 0.67 m at the Pebble Creek Hot Springs, and 0.69 m at the Powerhouse for the modelled IFR of 4.5 m3/s, respectively. The increase in water level would be very similar if the starting IFR was lower at 2.3 m3/s or 3.8 m3/s. The peak water level under this condition would be well below the lowest hot spring pool and below the highest mean monthly streamflow in July. Consequently, there is no risk to the recreational users present in any of the pools, or on the trail above the hot pools. Recreational users that are in the river or near the water edge within the diversion reach could, however, be at risk due to a sudden change in flow conditions.

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