GAHCHO KUÉ PROJECT ENVIRONMENTAL IMPACT STATEMENT SECTION 8 KEY LINE OF INQUIRY: WATER QUALITY AND FISH IN KENNADY LAKE December 2010 09-1365-1004 Gahcho Kué Project 8-i December 2010 Environmental Impact Statement Section 8 TABLE OF CONTENTS SECTION PAGE 8 KEY LINE OF INQUIRY: WATER QUALITY AND FISH IN KENNADY LAKE ...................... 8-1 8.1 INTRODUCTION ......................................................................................................... 8-1 8.1.1 Context ......................................................................................................... 8-1 8.1.2 Purpose and Scope ..................................................................................... 8-2 8.1.3 Study Area ................................................................................................... 8-9 8.1.3.1 General Location ...................................................................... 8-9 8.1.3.2 Study Area Selection ................................................................ 8-9 8.1.3.3 Kennady Lake Study Area ...................................................... 8-11 8.1.3.4 Content ................................................................................... 8-13 8.2 SUMMARY ................................................................................................................ 8-15 8.3 EXISTING ENVIRONMENT ...................................................................................... 8-26 8.3.1 General Setting .......................................................................................... 8-26 8.3.2 Climate ....................................................................................................... 8-30 8.3.2.1 Methods .................................................................................. 8-30 8.3.2.2 Results .................................................................................... 8-31 8.3.3 Permafrost .................................................................................................. 8-40 8.3.3.1 Methods .................................................................................. 8-40 8.3.3.2 Results .................................................................................... 8-40 8.3.4 Hydrogeology ............................................................................................. 8-44 8.3.4.1 Methods .................................................................................. 8-44 8.3.4.2 Results .................................................................................... 8-44 8.3.4.3 Groundwater Quality .............................................................. 8-56 8.3.4.4 Groundwater Flow .................................................................. 8-59 8.3.5 Surface Water Quantity .............................................................................. 8-62 8.3.5.1 Methods .................................................................................. 8-62 8.3.5.2 Results .................................................................................... 8-62 8.3.6 Surface Water and Sediment Quality ........................................................ 8-68 8.3.6.1 Methods .................................................................................. 8-68 8.3.6.2 Results .................................................................................... 8-71 8.3.7 Lower Trophic Levels ................................................................................. 8-88 8.3.7.1 Methods .................................................................................. 8-88 8.3.7.2 Results .................................................................................... 8-89 8.3.8 Fish .......................................................................................................... 8-102 8.3.8.1 Methods ................................................................................ 8-103 8.3.8.2 Results .................................................................................. 8-109 8.4 WATER MANAGEMENT PLAN SUMMARY ........................................................... 8-140 8.4.1 Introduction .............................................................................................. 8-140 8.4.2 Construction Phase .................................................................................. 8-145 8.4.2.1 Diversion of A, B, D and E Watersheds ............................... 8-145 8.4.2.2 Use of Area 8 as the Potable Water Supply ......................... 8-148 8.4.2.3 Dewatering of Kennady Lake ............................................... 8-148 8.4.3 Operations Phase .................................................................................... 8-151 8.4.3.1 Water Management Pond .................................................... 8-152 8.4.3.2 Fine Processed Kimberlite Containment Facility (Areas 1 and 2) ..................................................................... 8-153 De Beers Canada Inc. Gahcho Kué Project 8-ii December 2010 Environmental Impact Statement Section 8 8.4.3.3 Coarse Processed Kimberlite Pile ........................................ 8-153 8.4.3.4 Mine Rock Piles .................................................................... 8-153 8.4.3.5 Open Pits .............................................................................. 8-154 8.4.3.6 Water Management in Area 6 and Area 7 ............................ 8-156 8.4.3.7 Water Management in Area 4 .............................................. 8-156 8.4.3.8 Sewage Treatment Plant ...................................................... 8-157 8.4.3.9 Process Water ...................................................................... 8-157 8.4.3.10 On-site Surface Water Management .................................... 8-158 8.4.4 Closure Phase .......................................................................................... 8-158 8.4.4.1 Restoration of Kennady Lake ............................................... 8-159 8.4.4.2 Site-wide Closure Drainage Patterns ................................... 8-160 8.4.5 Water Balance .......................................................................................... 8-161 8.4.5.1 Inflows .................................................................................. 8-163 8.4.5.2 Outflows ................................................................................ 8-164 8.4.5.3 Area 8 ................................................................................... 8-164 8.4.6 Potential Sources of Change to Site Water Quality ................................. 8-166 8.4.6.1 Landfill .................................................................................. 8-166 8.4.6.2 Explosives ............................................................................ 8-166 8.4.6.3 Petroleum Products .............................................................. 8-168 8.4.6.4 Other Fluids .......................................................................... 8-169 8.4.6.5 Mine Rock and Processed Kimberlite .................................. 8-169 8.4.7 Potential Accidents and Malfunctions Relevant to Water Management ............................................................................................ 8-170 8.4.7.1 Petroleum Spills .................................................................... 8-171 8.4.7.2 Ammonium Nitrate Spills ...................................................... 8-172 8.4.7.3 Dyke Failure ......................................................................... 8-172 8.4.7.4 Dykes C and D ..................................................................... 8-172 8.5 ASSESSMENT APPROACH ................................................................................... 8-175 8.5.1 Pathway Analysis ..................................................................................... 8-175 8.5.2 Valued Components ................................................................................ 8-176 8.5.2.1 Water Quality ........................................................................ 8-176 8.5.2.2 Fish ....................................................................................... 8-179 8.5.3 Assessment Endpoints and Measurement Endpoints ............................. 8-185 8.5.4 Spatial and Temporal Boundaries............................................................ 8-187 8.5.5 Effects Analysis ........................................................................................ 8-188 8.5.6 Cumulative Effects ................................................................................... 8-190 8.5.7 Residual Impact Classification ................................................................. 8-190 8.5.7.1 Criteria .................................................................................. 8-191 8.5.7.2 Significance .......................................................................... 8-191 8.5.8 Uncertainty ............................................................................................... 8-192 8.5.9 Monitoring and Follow-up ......................................................................... 8-193 8.6 PATHWAY ANALYSIS ............................................................................................ 8-194 8.6.1 Methods ................................................................................................... 8-194 8.6.2 Results ..................................................................................................... 8-196 8.6.2.1