Cannorth Canada North Environmental Services Limited Partnership

CanNorth Canada North Environmental Services Limited Partnership

GUNNAR SITE CHARACTERIZATION 2004 AND 2005 AQUATIC ASSESSMENTS

Final Report

Prepared by:

Canada North Environmental Services Saskatoon, Saskatchewan

Prepared for:

Saskatchewan Research Council Saskatoon, Saskatchewan

Project No. 1141

March 2006

A First Nations Partnership In Environmental Services www.cannorth.com #4 – 130 Robin Crescent, Saskatoon, Saskatchewan S7L 6M7 Telephone: (306) 652-4432 Facsimile: (306) 652-4431 TABLE OF CONTENTS

TABLE OF CONTENTS

LIST OF TABLES...... iii LIST OF FIGURES ...... vi EXECUTIVE SUMMARY ...... viii 1.0 INTRODUCTION ...... 1 1.1 Background ...... 1 1.2 Study Area...... 2 1.3 Study Objectives and Sample Collections ...... 3 2.0 METHODS ...... 5 2.1 Quality Control/Quality Assurance (QA/QC)...... 5 2.2 Bathymetry...... 5 2.2.1 Shoreline Development...... 5 2.2.2 Volume Development ...... 6 2.3 Limnological Measurements...... 6 2.4 Water Sampling...... 7 2.5 Sediment Sampling...... 7 2.6 Sedge Sampling...... 8 2.7 Fish Sampling ...... 8 2.7.1 Gillnetting ...... 9 2.7.2 Electrofishing...... 10 2.7.3 Minnow Traps...... 10 2.7.4 Angling...... 10 2.7.5 Fish Processing Procedures...... 10 2.8 Plankton and Benthic Macroinvertebrate Sampling ...... 11 2.8.1 Phytoplankton and Zooplankton ...... 11 2.8.2 Benthic Macroinvertebrates...... 11 2.8.3 Data Analyses...... 12 2.9 Fish Habitat Assessment ...... 13 2.9.1 Spawning Habitat Suitability Index ...... 14 3.0 RESULTS ...... 19 3.1 Bathymetry...... 19 3.2 Limnology...... 19 3.3 Water Chemistry...... 21 3.4 Sediment Chemistry...... 22 3.4.1 Back Bay and Zeemel Bay...... 23 3.4.2 Langley Bay and St. Mary’s Channel ...... 24 3.5 Sedge Chemistry...... 25 3.5.1 Concentration Ratios...... 26 3.6 Fish Chemistry ...... 27 3.6.1 Northern Pike...... 27 3.6.2 Lake Whitefish...... 28 3.7 Bufflehead Duck Chemistry...... 29 3.8 Phytoplankton ...... 29

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. i CanNorth TABLE OF CONTENTS

3.9 Zooplankton ...... 30 3.10 Benthic Macroinvertebrates...... 31 3.10.1 Back Bay and Zeemel Bay...... 31 3.10.2 Langley Bay and St. Mary’s Channel ...... 33 3.11 Fish Community...... 34 3.11.1 St. Mary’s Channel and Zeemel Bay ...... 34 3.11.2 Langley Bay...... 35 3.11.3 Back Bay...... 36 3.11.4 Dixon Bay...... 36 3.12 Fish Habitat Assessments...... 37 3.12.1 St. Mary’s Channel and Zeemel Bay ...... 37 3.12.2 Langley Bay...... 38 3.12.3 Back Bay...... 39 3.12.4 Dixon Bay...... 40 4.0 SUMMARY AND DISCUSSION...... 41 4.1 St. Mary’s Channel...... 41 4.2 Zeemel Bay...... 42 4.3 Langley Bay...... 44 4.4 Back Bay...... 45 5.0 LITERATURE CITED...... 47

APPENDIX A. DETAILED FISH CATCH DATA

APPENDIX B. DETAILED SEDIMENT CHEMISTRY DATA FROM DIXON BAY

APPENDIX C. GUIDELINES FOR CONSUMING FISH CONTAINING MERCURY

APPENDIX D. PHOTOGRAPHS OF AQUATIC HABITAT

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. ii CanNorth LIST OF TABLES

LIST OF TABLES

Table 1. Morphometric characteristics of Back Bay, September 2005.

Table 2. Limnological measurements taken in St. Mary's Channel and Langley Bay, September 2004.

Table 3. Limnological measurements taken in Dixon Bay, Langley Bay, Back Bay, St. Mary's Channel, and Zeemel Bay, September 2005.

Table 4. Water chemistry results from the Gunner mine site study area, 2004 and 2005.

Table 5. Comparison of radionuclide levels in water samples from Langley Bay in 1976, 1978, 1983, 2004, and 2005.

Table 6. Summary chemistry results from sediment samples collected in the Gunnar mine site study area, September 2004 and 2005.

Table 7. Comparison of mean radionuclide levels in sediment samples from Langley Bay in 1978, 1983, and 2004.

Table 8. Summary chemistry results from the sedge shoot, root, and sediment samples collected in the Gunnar mine site study area, September 2005.

Table 9. Radionuclide levels measured in the sedge shoot, root, and sediment samples collected in the Gunnar mine site study area, September 2005.

Table 10. Concentration ratios relating analyte concentrations in the sedge root samples to the sediment samples, September 2005.

Table 11. Concentration ratios relating analyte concentrations in the sedge shoot samples to the sedge root samples, September 2005.

Table 12. Summary chemistry results for northern pike flesh samples collected in the Gunnar mine site study area, September 2004 and 2005.

Table 13. Summary chemistry results for northern pike bone samples collected in the Gunnar mine site study area, September 2004 and 2005.

Table 14. Comparison of radionuclide levels in northern pike and lake whitefish bone and flesh samples from Langley Bay in 1983, 2004, and 2005.

Table 15. Summary chemistry results for lake whitefish flesh samples collected in the Gunnar mine site study area, September 2005.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. iii CanNorth LIST OF TABLES

Table 16. Summary chemistry results for lake whitefish bone samples collected in the Gunnar mine site study area, September 2005.

Table 17. Summary chemistry results for bufflehead duck samples collected from Back Bay, September 2005.

Table 18. Taxa identification, enumeration, and biomass of phytoplankton samples collected from the Gunnar mine site study area, September 2004 and 2005.

Table 19. Community metrics for phytoplankton and zooplankton samples collected in the Gunnar mine site study area, September 2004 and 2005.

Table 20. Taxa identification and enumeration of zooplankton samples collected from the Gunner mine site study area, September 2004 and 2005.

Table 21. Taxa identification and enumeration of benthic macroinvertebrates collected from Dixon Bay (Station 1), Back Bay, and Zeemel Bay, September 2005.

Table 22. Community metrics for benthic macroinvertebrate samples collected in Dixon Bay (Station 1), Back Bay, and Zeemel Bay, September 2005.

Table 23. Taxa identification and enumeration of benthic macroinvertebrate samples collected from Dixon Bay (Station 2), Langley Bay, and St. Mary's Channel, September 2004 and 2005.

Table 24. Community metrics for benthic macroinvertebrate samples collected in Dixon Bay (Station 2), Langley Bay, and St. Mary's Channel, September 2004 and 2005.

Table 25. List of fish species known to occur in Lake Athabasca.

Table 26. Summary results of the fish catch data from St. Mary's Channel, Langley Bay, Gunnar Pit, Back Bay, and Dixon Bay, September 2004 and 2005.

Table 27. Aquatic/wetland macrophytes identified in St. Mary's Channel/Zeemel Bay, Langley Bay, Back Bay, and Dixon Bay during the habitat assessments, September 2004 and 2005.

Table 28. Detailed description of habitat units in the St. Mary's Channel/ZeemelBay, September 2004.

Table 29. Legend for lake habitat assessments.

Table 30. Detailed description of habitat units in Langley Bay, September 2004.

Table 31. Detailed description of habitat units in Back Bay, September 2005.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. iv CanNorth LIST OF TABLES

Table 32. Detailed description of habitat units in the study area of Dixon Bay, September 2005.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. v CanNorth LIST OF FIGURES

LIST OF FIGURES

Figure 1. Study location.

Figure 2. Location of study areas, September 2004 and 2005.

Figure 3. Location of the limnology/water/plankton station, electrofishing areas, minnow trap sets, gillnet sets, and the sediment/benthic macroinvertebrate stations in St. Mary’s Channel, September 2004.

Figure 4. Location of the limnology/water/plankton station, electrofishing areas, minnow trap sets, gillnet sets, and the sediment/benthic macroinvertebrate stations in Langley Bay, September 2004.

Figure 5. Location of the limnology/water station and gillnet set in St. Mary’s Channel, and location of the limnology/water/plankton station, sediment/benthic macroinvertebrate stations, and the sedge stations in Zeemel Bay, September 2005.

Figure 6. Location of the limnology/water station, gillnet sets, and the sedge stations in Langley Bay, September 2005.

Figure 7. Location of the limnology/water/plankton station, minnow trap sets, gillnet sets, sediment/benthic macroinvertebrate stations, and the sedge stations in Back Bay, September 2005.

Figure 8. Location of the limnology/water/plankton station, minnow trap sets, electrofishing areas, gillnet sets, sediment/benthic macroinvertebrate stations, and the sedge stations in Dixon Bay, September 2005.

Figure 9. Bathymetric map of Back Bay, September 2005.

Figure 10. Concentrations of uranium in sediment, sedge root, and sedge shoot samples from Dixon Bay, Back Bay, Langley Bay, and Zeemel Bay, September 2005.

Figure 11. Length-weight curve and length-frequency distribution for northern pike captured in St. Mary’s Channel, September 2004 and 2005.

Figure 12. Length-weight curve and length-frequency distribution for northern pike captured in Langley Bay, September 2004 and 2005.

Figure 13. Length-weight curve and length-frequency distribution for northern pike captured in Back Bay, September 2005.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. vi CanNorth LIST OF FIGURES

Figure 14. Length-frequency distribution for northern pike captured in Dixon Bay, September 2005.

Figure 15. Habitat units identified in St. Mary’s Channel and Zeemel Bay, September 2004.

Figure 16. Habitat units identified in Langley Bay, September 2004.

Figure 17. Habitat units identified in Back Bay, September 2005.

Figure 18. Habitat units identified in Dixon Bay, September 2005.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. vii CanNorth EXECUTIVE SUMMARY

EXECUTIVE SUMMARY

Introduction

The Saskatchewan Research Council (SRC) is conducting a site characterization and remedial options review of the orphan Gunnar uranium mine site, located near Uranium City, Saskatchewan (Figure 1). As part of this project, Canada North Environmental Services (CanNorth) was retained to conduct aquatic investigations in areas of Lake Athabasca in September 2004, and follow-up studies in September 2005. This report discusses the findings of both studies.

Study Objectives and Areas

The objective of the aquatic investigations was to gather site-specific information to use in assessing remedial activities in these areas and in the risk assessment. These studies collected information on limnology; water, sediment, plant, and fish chemistry; plankton, benthic macroinvertebrate, and fish communities; and fish habitat from the following study areas in Lake Athabasca: St. Mary’s Channel, Zeemel Bay, Langley Bay, Back Bay, and Dixon Bay (Figure 2). In addition, a bathymetric survey was completed in Back Bay, and fish chemistry data was obtained from Gunnar pit.

St. Mary’s Channel is a large strait located directly south of the Gunnar mine site. Zeemel Bay is part of the St. Mary’s Channel study area and is located adjacent to the waste rock pile. Langley Bay is approximately 2 km north of the Gunnar mine site and the southeast side of the bay contains tailings deposits. Back Bay was isolated from Lake Athabasca by historical tailings deposition from the Gunnar mine site, however, it remains connected to Langley Bay through a narrow, intermittent channel. Dixon Bay was sampled as a reference area in Lake Athabasca.

Results 1. Bathymetry

The shore length of Back Bay is approximately 2 km long and it contains a surface area of 17.74 ha. Back Bay is relatively shallow with a mean depth of 1.8 m and a maximum

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. viii CanNorth EXECUTIVE SUMMARY

depth of 4 m. The total volume of Back Bay is 0.32 x 106 m3 and approximately 25% of the water is contained in the top 0.5 m.

2. Limnology

Limnology measurements were taken in St. Mary’s Channel and Langley Bay in 2004, and from all study areas in 2005. The water temperature in all study areas was uniform throughout the water column. Dissolved oxygen levels were relatively high in St. Mary’s Channel, Langley Bay, and Dixon Bay (9.4 to 11.3 mg/L), were slightly lower in Zeemel Bay (approximately 8.7 mg/L), and were much lower in Back Bay (3.4 to 3.9 mg/L). Specific conductance levels were the same in Dixon Bay and St. Mary’s Channel (57 µS/cm), slightly higher in Langley Bay (76 µS/cm in 2005 and approximately 96 µS/cm in 2004), and higher still in Zeemel Bay (112 µS/cm). In Back Bay, specific conductance was higher than at the other study areas, measuring approximately 435 µS/cm. The pH levels were slightly basic in all study areas (7.2 to 8.1 units).

3. Water Chemistry

Water samples were collected in St. Mary’s Channel and Langley Bay in 2004, and from all study areas in 2005. Water chemistry in St. Mary’s Channel was comparable to the reference station and metal concentrations were lower than applicable provincial and federal guidelines. In Zeemel Bay, the concentrations of numerous ions were higher than at the reference station in Dixon Bay. The radium-226 concentration of 0.02 Bq/L in Zeemel Bay was higher than in Dixon Bay (<0.005 Bq/L), however, this level remains well below the general surface water quality guideline set by the Saskatchewan Surface Water Quality Objectives (SSWQO) of 0.11 Bq/L. The uranium concentration in Zeemel Bay (220 µg/L) was much higher than all other study areas, where levels ranged between 0.4 and 11 µg/L. The Zeemel Bay sample was collected near the seep from the waste rock and this may be a localized effect.

Langley Bay contained levels of metals, trace elements, ions, and nutrients that were similar to the reference station in Dixon Bay. In Back Bay, water concentrations of ions, nutrients, and some metals, such as arsenic, iron, manganese, and strontium, were higher than at the reference station. The only metals above guidelines were iron and arsenic in Back Bay, which were above the federal guidelines, but were well below the SSWQO.

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Radionuclide concentrations in the water samples from both Langley and Back bays were higher than in Dixon Bay. The radium-226 concentrations in Langley Bay (0.16 Bq/L in 2004 and 0.12 Bq/L in 2005) and Back Bay (0.79 Bq/L) exceeded the SSWQO of 0.11 Bq/L.

4. Sediment Chemistry

Sediment samples were collected from a 5 m depth in St. Mary’s Channel and Langley Bay in 2004, and at a comparable depth from the reference area in Dixon Bay in 2005. Sediment samples were collected at a 2 m depth from Back, Zeemel, and Dixon bays in 2005. Data are only compared within each depth range.

Sediment concentrations of sulphate, numerous metals and trace elements, and all radionuclides were substantially higher in Back Bay compared to Dixon Bay. Mean concentrations of copper, lead, and arsenic in Back Bay exceeded federal sediment quality guidelines. Mean chromium concentrations were higher than the guideline in both Dixon and Zeemel bays, indicating that high chromium levels are found naturally in parts of Lake Athabasca. Radionuclide concentrations were higher in Zeemel Bay than in Dixon Bay, however, they were much lower than in Back Bay, with the exception of uranium. In Zeemel Bay, sediment uranium concentrations were elevated at the stations located near the seep, measuring 291 and 316 µg/g, while the station located closer to the mouth of the bay contained a uranium level that was similar to reference (7 µg/g).

In St. Mary’s Channel, mean sediment concentrations of boron, chromium, lead, and radionuclides were higher than in the reference area. Langley Bay sediment contained mean concentrations of several metals, trace elements, and all radionuclides that were higher than reference. Federal sediment quality guidelines were exceeded by cadmium, copper, lead, and arsenic in Langley Bay, and chromium in St. Mary’s Channel. Sediment radionuclide concentrations in St. Mary’s Channel were higher at stations 1 and 2, located near the channel that previously connected Gunnar pit to Lake Athabasca. Although the sample size is small, these results suggest that there may be some localized sediment contamination resulting from historical mining activities.

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5. Sedge Chemistry

Sedge (Carex sp.) shoot and root samples were collected and chemically analyzed from Zeemel Bay, Langley Bay, Back Bay, and Dixon Bay in 2005. In addition, sediment samples were collected for chemical analyses from beneath the plants. There were several instances where mean metal and trace element concentrations were higher in the exposure areas compared to the reference area. Of particular note were the mean concentrations of iron, lead, manganese and arsenic, which were substantially higher in sedge root and shoot samples from Langley and Back bays than in the samples from Dixon Bay.

There were large differences in radionuclide concentrations between the exposure areas and the reference area. Mean levels of lead-210, polonium-210, radium-226, and thorium-230 were higher in Zeemel Bay compared to Dixon Bay and levels in Langley and Back bays were higher than those from Zeemel Bay. However, uranium showed a different pattern in that the highest concentrations were measured in the Zeemel Bay sediment, root, and shoot samples. Radionuclide levels were generally elevated in Langley and Back bays at the stations located closest to the tailings beach, and in Zeemel Bay at the stations located closest to the seep. Concentration ratios demonstrated that radionuclide levels were higher in sedge roots than in the shoots and sediment in Langley and Zeemel bays.

6. Northern Pike Chemistry

Northern pike (Esox lucius) were retained for chemical analyses from Gunnar pit, Langley Bay, and St. Mary’s Channel in 2004, and from St. Mary’s Channel, Langley Bay, Back Bay, and Dixon Bay in 2005.

Northern pike sampled from Gunnar pit in 2004 contained higher mean concentrations of barium, mercury, selenium, and arsenic in the flesh, nickel and selenium in the bone, and most radionuclides in both flesh and bone, than the 2005 samples from Dixon Bay. In addition, mercury concentrations in the three Gunnar pit northern pike (0.58 to 0.73 µg/g) warrant consumption restrictions according to provincial guidelines.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xi CanNorth EXECUTIVE SUMMARY

In the other study areas, the metal that demonstrated the most notable difference between reference and exposure northern pike was manganese. In the northern pike bone samples from Back Bay, the mean manganese concentration was 29.4 µg/g, which is elevated compared to Dixon Bay (mean = 8.12 µg/g). In Langley Bay, the 2005 data showed higher mean manganese concentrations than the reference area, but the 2004 data did not. Mercury concentrations in the northern pike from St. Mary’s Channel, Langley Bay, Back Bay, and Dixon Bay were all below provincial guidelines.

Most radionuclide concentrations in the northern pike from Langley and Back bays were higher than in Dixon Bay. Levels of polonium-210 and radium-226 in the bone samples from Back Bay were higher than in the other study areas, and averaged approximately 50 times higher than in the reference area. Northern pike from St. Mary’s Channel contained radionuclide levels that were comparable to reference, with the exception of uranium concentrations in the bone samples that were approximately 10-fold higher.

7. Lake Whitefish Chemistry

Lake whitefish (Coregonus clupeaformis) were captured for chemical analyses from St. Mary’s Channel, Langley Bay, and Dixon Bay in 2005. There were few notable differences in the metal and trace element concentrations between the exposure areas and the reference area. In the lake whitefish flesh samples, only selenium was notably higher in Langley Bay (mean = 0.49 µg/g) compared to Dixon Bay (mean = 0.22 µg/g). In the bone samples, mean manganese concentrations were higher in Langley Bay (mean = 8.52 µg/g) compared to Dixon Bay (mean = 4.82 µg/g). The mercury concentrations in all samples were well below provincial guidelines.

Uranium levels in the St. Mary’s Channel lake whitefish flesh and bone samples were approximately four times higher than reference. Radionuclide concentrations were generally higher in Langley Bay compared to reference, particularly in the lake whitefish bone samples. In Langley Bay, mean values of lead-210, radium-226, and uranium were lower in 2005 when compared to a single composite sample tested in 1983 (Waite et al. 1988).

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xii CanNorth EXECUTIVE SUMMARY

8. Phytoplankton Community

Phytoplankton samples were collected from Langley Bay and St. Mary’s Channel in September 2004, and from Dixon Bay, Back Bay, and Zeemel Bay in September 2005. The phytoplankton sample from Dixon Bay was relatively evenly distributed consisting of 29% Chrysophyta (golden algae), 21% Haptophyceae (dinoflagellates), 19% Cyanophyta (blue-green algae), and 17% Chlorophyta (green algae). The samples from Langley Bay, St. Mary’s Channel, and Zeemel Bay were all dominated by golden algae (approximately 40% of the sample populations). The phytoplankton sample from Back Bay was almost entirely comprised of the blue-green algae Aphanizomenon flos-aquae (94%).

Phytoplankton abundance in Back Bay was approximately twice as high as in the other study areas, however, measures of richness and diversity were much lower. The low Simpson’s diversity index (0.17) and evenness (0.20) in Back Bay reflects the dominance of the community by a single species. The community metrics for the other study areas indicated diverse and numerically even phytoplankton communities.

9. Zooplankton Community

Zooplankton samples were collected from Langley Bay and St. Mary’s Channel in September 2004, and from Dixon Bay, Back Bay, and Zeemel Bay in September 2005. The sample from Dixon Bay contained equal abundances of crustaceans and rotifers, while the samples from Langley Bay, Back Bay, and St. Mary’s Channel were dominated by rotifers (>75%). The sample from Zeemel Bay differed from the other areas in that it was dominated by crustaceans (70.5%).

The high abundance of organisms, low number of taxa, and high percentage of a single taxon resulted in low diversity indices for the zooplankton community in Back Bay. The zooplankton communities in Dixon Bay, Langley Bay, and St. Mary’s Channel attained high diversity and evenness values: 0.79 to 0.82 (Simpson’s diversity index) and 0.83 to 0.86 (evenness). Zeemel Bay contained slightly lower diversity indices, likely because of the low abundance of zooplankton in the sample.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xiii CanNorth EXECUTIVE SUMMARY

10. Benthic Macroinvertebrate Community

Benthic macroinvertebrate samples were collected from a 2 m depth in Back, Zeemel, and Dixon bays in September 2005. Overall, the most dominant taxon in Dixon Bay was Corynocera sp. from the Family Chironomidae, although they were largely contained within one of the three samples. In Back Bay, the Family Chironomidae occupied 74% of the sample population, with 35% from the genus Psectrocladius sp. In Zeemel Bay, 82% of the sample population was from the Family Chironomidae, with 55% from the genus Tanytarsus sp. However, similar to Dixon Bay, the high numbers of Tanytarsus sp. were only found in one of the three samples. Back Bay contained a higher mean density of organisms than Dixon Bay and Zeemel Bay. Although there was some variation between stations, mean values of richness, Simpson’s diversity, and evenness were highest in Dixon Bay, followed by Back Bay, and were lowest in Zeemel Bay.

Benthic macroinvertebrate samples were collected at a 5 m depth in St. Mary’s Channel and Langley Bay in 2004, and in Dixon Bay in 2005. The dominant taxon in Langley Bay was the genus Tanytarsus sp., which comprised 23% of the sample population. The dominant taxon from St. Mary’s Channel, the species Diporeia hoyi, comprised 63% of the sample population. The community in Dixon Bay was also dominated by organisms from the Family Haustoriidae, however, it was a different species than in St. Mary’s Channel. Pontoporeia hoyei comprised 30% of the Dixon Bay sample population.

Benthic macroinvertebrate density was much higher in the samples from Dixon Bay (18,868 organisms/m2) than in St. Mary’s Channel (6,944 organisms/m2) and Langley Bay (5,156 organisms/m2). Taxon richness was similar in Dixon Bay and St. Mary’s Channel, but was lower in Langley Bay. Conversely, diversity indices were almost the same in Langley Bay and Dixon Bay and were lower in St. Mary’s Channel. This is attributable to the relatively high proportion of a single species in St. Mary’s Channel.

11. Fish Community

During the 2004 fish community survey conducted in St. Mary’s Channel and Zeemel Bay, a total of 25 northern pike and six lake whitefish were captured by gillnets. Additionally, two juvenile northern pike , nine lake chub (Couesius plumbeus), two slimy sculpin (Cottus cognatus), and two burbot (Lota lota) were captured by electrofishing.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xiv CanNorth EXECUTIVE SUMMARY

Ciscoes (Coregonus artedii) were identified in the stomachs of northern pike. In 2005, one half standard gang gillnet set in St. Mary’s Channel in front of the mouth of Zeemel Bay resulted in the capture of nine northern pike, three lake trout (Salvelinus namaycush), and ten lake whitefish. The stomach contents of the three northern pike contained numerous slimy sculpin and ninespine stickleback (Pungitius pungitius).

The 2004 fish community survey conducted in Langley Bay resulted in the capture of ten northern pike and four lake whitefish by gillnets, and five juvenile northern pike and one yellow perch (Perca flavescens) by electrofishing. Additionally, one juvenile northern pike was identified from the stomach of a northern pike. In September 2005, three gillnets were set in Langley Bay and these captured four northern pike and 12 lake whitefish. A lake whitefish was also found in the stomach contents of one northern pike. The higher amount of lake whitefish captured in 2005 compared to 2004 is likely a result of the nets being set at a deeper depth.

A fish community survey was conducted in Back Bay in September 2005 and the only fish species captured was northern pike. A total of ten northern pike were captured in three gillnet sets. The only fish identified in the stomach contents of the five northern pike retained for chemical analyses was also northern pike. Considering the diverse stomach contents of the northern pike captured in the other study areas, this suggests that the species diversity is low in Back Bay and may be restricted to northern pike.

Dixon Bay contains a high abundance of fish. One gillnet set for 2.15 hours captured ten northern pike and five lake whitefish. Two burbot were captured electrofishing and one burbot was found in a northern pike stomach. In addition, one ninespine stickleback was captured electrofishing and one slimy sculpin was found in a northern pike stomach.

12. Fish Habitat

Fish habitat assessments were conducted in St. Mary’s Channel/Zeemel Bay and Langley Bay in 2004, and in Back Bay and Dixon Bay in 2005. Each study area was assessed for its potential to provide spawning habitat for northern pike, walleye (Stizostedion vitreum), lake whitefish, arctic grayling (Thymallus arcticus), lake trout, suckers, and yellow perch. The assessments included detailing information on the density and

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xv CanNorth EXECUTIVE SUMMARY

composition of aquatic/wetland macrophyte species in the littoral zone of each study area. None of the species identified are considered rare under provincial listings.

The study area within St. Mary’s Channel has an upland zone associated primarily with uranium mining activities. Some of the infrastructure has encroached into the water and has altered the shoreline and aquatic habitat. In most of the study area, the shoreline contained little or no vegetative cover, the substrate was predominantly sand/cobble/boulder, and the bottom slope was steep. High densities of aquatic/wetland macrophytes were restricted to Zeemel Bay and to the area south of the waste rock pile near Zeemel Bay. Zeemel Bay is a long, shallow, vegetated bay with organic substrate that was assessed as providing highly suitable spawning habitat for northern pike and yellow perch, and potential rearing habitat for northern pike. The remainder of the St. Mary’s Channel study area provided either marginally suitable spawning habitat, or unsuitable spawning habitat, for all of the fish species assessed.

The upland area surrounding Langley Bay contained a mature, mixed forest. Near the mouth of the bay, the aquatic/wetland macrophyte cover was generally sparse to moderate and the substrate was rocky. The south and eastern portions of Langley Bay constituted the area of Gunnar tailings deposition within the bay. The substrate consisted of tailings fines and was completely void of rocks. The depth remained shallow (<0.5 m) until approximately 20-30 m into the bay perpendicular to the shore. The littoral zone was largely covered in a good diversity and density of aquatic/wetland macrophytes. Langley Bay had an abundance of moderately suitable spawning habitat for walleye, lake whitefish, northern pike, and yellow perch due to the high densities of shallow cobble areas with near shore emergent aquatic/wetland macrophytes.

The deepest part of Back Bay was near the bedrock outcropping on the south side of the bay. The remainder of the bay contained a gentle to moderately sloped lake bottom with

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xvi CanNorth EXECUTIVE SUMMARY

high densities of aquatic vegetation. In the eastern part of the bay, the substrate consisted mostly of silt/clay/tailings, while in the western part of the bay, the substrate contained a high cobble/boulder content. There was an abundance of marginally to moderately suitable spawning habitat for northern pike and yellow perch, however, large densities of submergent vegetation and algae precluded the habitat from being rated as highly suitable. Suitable spawning habitat for other fish species was not identified.

Dixon Bay contains a diversity of habitat types that are typical of those found throughout Lake Athabasca. The initial part of the study area contained rocky substrate with sparse to moderate densities of vegetation. These areas provide potential spawning habitat for species that prefer to spawn on rocky substrate, including artic grayling, lake trout, lake whitefish, suckers, and walleye. The area of Dixon Bay sheltered behind the island contained high densities of emergent aquatic/wetland macrophytes, especially sedge, which provide good spawning habitat for northern pike and yellow perch.

Discussion

The potential environmental concerns identified in the study area of St. Mary’s Channel during the 2004 and 2005 aquatic investigations included: 1) elevated radionuclide levels measured in the sediment near the channel that previously connected Gunnar pit to Lake Athabasca, and 2) higher uranium levels in the fish tissues when compared to the fish from the reference area.

In Zeemel Bay, the waste rock pile seep continues to be a source of contamination and this may require addressing as part of the remediation strategy. There is the potential that high uranium concentrations measured in the water, sediment, and plant samples near the seep may impact the aquatic biota residing in the bay and terrestrial wildlife feeding there.

The tailings area in Langley Bay is being re-colonized by a diversity of aquatic vegetation which provides habitat for fish and a food source for wildlife. Even though the fish species chemically analyzed were large-bodied and potentially migratory, their tissue samples demonstrated elevated radionuclide levels compared to the reference fish. The elevated radionuclide levels measured in all media tested indicate that there are environmental impacts in Langley Bay related to the historical tailings deposition.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xvii CanNorth EXECUTIVE SUMMARY

Back Bay contains high contaminant levels, large algal blooms, and it appears that northern pike are residing there. It is of a sufficient size and depth to provide year-round fish habitat. In addition, the channel connecting Back Bay to Langley Bay permits fish migration when water levels are adequately high. At the time of the survey, Back Bay contained a high diversity and density of migratory ducks and there was beaver activity in the creek. Therefore, the habitat provided by Back Bay is used by aquatic and terrestrial wildlife who would be subject to contaminant exposure.

Saskatchewan Research Council – March 2006 2004 and 2005 Gunnar Site Aquatic Assessment. xviii CanNorth INTRODUCTION

1.0 INTRODUCTION

The Saskatchewan Research Council (SRC) is conducting a multidisciplinary site characterization and remedial options review of the orphan Gunnar uranium mine site, located near Uranium City, Saskatchewan. As part of the review process, Canada North Environmental Services (CanNorth) was retained to conduct aquatic investigations in waterbodies located near the former mine facilities.

In September 2004, aquatic investigations were conducted in St. Mary’s Channel and Langley Bay of Lake Athabasca, as well as in Gunnar pit1. These results were presented in the “Gunnar Site Characterization and Remedial Options Review” report published by SRC in January 2005. Subsequent to these aquatic assessments, it was determined that further studies were required in order to fully characterize the aquatic environment at the Gunnar site and to provide additional information for the risk assessments. This involved completing aquatic assessments in additional study areas (Back Bay and Zeemel Bay), collecting more data from St. Mary’s Channel and Langley Bay, and locating and sampling a reference area in Lake Athabasca to be used for comparative purposes. These studies were completed in September 2005. In order to conduct a thorough assessment and to have all data from the study area presented simultaneously, this report builds on the 2004 report and integrates the information from both sampling years.

1.1 Background

The Gunnar uranium mine is one of a number of orphan mines in the Beaverlodge area, located on the north shore of Lake Athabasca, northern Saskatchewan (Figure 1). During mine operations, between 1955 and 1964, a total of 5.5 x 106 tonnes of ore were removed from the open pit and underground mine (Tones 1982). The narrow rock ridge separating the pit from St. Mary’s Channel was breached after the mine was closed in 1964. The open pit mine filled with water from Lake Athabasca and the breach was subsequently closed with crushed rock in 1966. Between 1971 and 1981, a fish processing plant piped wash water and offal (fish waste) into the flooded pit.

1 A comprehensive study in Gunnar pit was completed in 2002 (CanNorth 2004a). During the 2004 survey, only fish chemistry was examined.

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During operations of the Gunnar uranium mine, mill tailings, consisting of 32% solids, were discharged into a small lake located 500 m north of the mill, referred to as Gunnar Main Tailings. Eventually this basin filled and a small rock outcrop was blasted to allow the tailings to flow from the Main Tailings area to a small depression, referred to as Gunnar Central Tailings. Once this small depression filled, the tailings flowed downhill and eventually entered Langley Bay of Lake Athabasca (KHS Environmental Management Group Ltd. 2003). The volume of tailings discharged into Langley Bay was sufficient to eventually fill in a large area of the bay, dividing Langley Bay into two distinct portions: Langley Bay, connected directly to Lake Athabasca, and a smaller, isolated area now referred to as Back Bay (Figure 2). Back Bay is connected to Langley Bay by a narrow channel.

In 1981, a study was completed by SRC on the physical, chemical, and biological characteristics of the Gunnar pit. In 2002, Canada North Environmental Services (CanNorth) was retained by COGEMA Resources Inc. to conduct a reconnaissance survey to repeat selected monitoring components of the SRC study (CanNorth 2004a). Upon request of SRC, CanNorth expanded investigations in September 2004, conducting similar aquatic assessments in the area of St. Mary’s Channel near the Gunnar site and in Langley Bay of Lake Athabasca (Figure 2). In September 2005, further assessments were completed in St. Mary’s Channel, Langley Bay, Back Bay, Zeemel Bay as well as in Dixon Bay, a reference site located in Lake Athabasca (Figure 2).

1.2 Study Area

Langley Bay is located approximately 2 km north of the Gunnar mine site. The bay is connected to Lake Athabasca via a long, shallow channel at the northwest side of the bay. Back Bay flows into Langley Bay through a small channel, approximately 485 m in length. The channel commences at the northeast corner of Back Bay, flows through the tailings deposition area, and ends at the south side of Langley Bay (Figure 2).

St. Mary’s Channel is a large strait located directly south of the Gunnar mine site on the southern end of the Crackingstone Peninsula. The study area extended from the site of the former sports field to the point east of Zeemel Bay (Figure 2). Sampling was conducted mainly in the littoral areas near the shoreline within the study area. Zeemel Bay is located adjacent to the waste rock pile and has inflow from Zeemel Creek.

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A suitable reference site was located in Dixon Bay of Lake Athabasca (Figure 2). Since Lake Athabasca is so much larger than all other lakes in the area, it was considered most appropriate to use a bay within the lake in order to maintain consistency in habitat characteristics with the exposure areas. Several bays were examined and Dixon Bay was selected because it contains suitable depth, substrate, vegetation, and fish species. Dixon Bay should not be impacted by the Gunnar mine site since it is located approximately 5 km west (upstream)2 of the site.

1.3 Study Objectives and Sample Collections

The primary objective of this study was to collect chemical and biological data from waterbodies associated with the Gunnar mine site in order to obtain current information on the state of the aquatic environment in the study area. The purpose of collecting this information is to gather site specific information for the risk assessment and to assist in assessing the need and potential options for remedial activities in these areas.

Sample collections and analyses conducted in 2004 and 2005 were similar to the 2002 Gunnar pit investigations (CanNorth 2004a). The 2004 aquatic investigations were focused on Langley Bay and St. Mary’s Channel of Lake Athabasca, with some sampling completed in Zeemel Bay. Since the 2005 sampling program was designed to fill data gaps and information needs that were identified as a result of the 2004 aquatic investigations, the same samples were not collected from all waterbodies in the study area. The main components of the 2005 sampling program included:

• collection of a complete suite of samples from Back Bay and Dixon Bay; • creation of a bathymetric map for Back Bay; • collection and chemical analyses of sedge (Carex sp.) from the study area; • collection and chemical analyses of additional northern pike (Esox lucius) from the study area in order to increase the sample size; and • collection and chemical analyses of a bottom-feeding fish species, lake whitefish (Coregonus clupeaformis), from the study area.

2 Lake Athabasca’s main inflow is the Fond-du-Lac River. It enters from the east and the outflow exits in the west through the Athabasca River. Therefore, the general flow pattern is from east to west, however, local flow patterns are not known.

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The following table summarizes the data collections that occurred during the 2004 and 2005 sampling programs:

Gunnar St. Mary’s Langley Bay Back Bay Zeemel Bay Dixon Bay Samples Collected Pit Channel 20041 2004 2005 2005 2004 2005 2004 2005 2005 Bathymetry - - - √ - - - - - Limnology/Water - 1 1 1 1 1 - 1 1 Phytoplankton and - 1 - 1 1 - - 1 1 Zooplankton Sediment and Benthic - 3 - 3 3 - - 3 62 Macroinvertebrates Sedge (Sediment, - - 3 3 - -3 - 4 3 Roots, and Shoots) Northern Pike 3 3 3 5 3 3 - -3 5 Lake Whitefish - - 5 -4 - 5 - -3 5 Fish Community and - √ - √ √ - √ - √ Habitat Bufflehead Ducks5 - - - √5 - - - - - Notes: 1Limnology, water, phytoplankton, zooplankton, sediment, benthic macroinvertebrate, and fish community information were collected from Gunnar pit in 2002 and this information is presented in CanNorth (2004a). 2 Two sets of sediment/benthic macroinvertebrate samples were collected in the reference area (Dixon Bay) in order to match the depths sampled in Zeemel and Back bays (2 m), and in Langley Bay and St. Mary’s Channel (5 m). 3 Since Zeemel Bay is located adjacent to St. Mary’s Channel, not all samples were collected in both areas. 4 Lake whitefish would have been retained for chemical analyses from Back Bay but they were not captured there. 5Four bufflehead ducks (Bucephala albeola) were unintentionally captured in the gillnets set in Back Bay and were therefore retained for chemical analyses.

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2.0 METHODS

The 2004 field survey was conducted from September 9th to 15th and the 2005 field survey was conducted from September 7th to 14th.

2.1 Quality Control/Quality Assurance (QA/QC)

All field sampling and handling procedures completed by CanNorth personnel adhered to CanNorth’s Field Sampling Methodologies and Standard Operating Procedures Manual (CanNorth 2000). Chain-of-custody forms were completed and filed for all samples submitted for laboratory analyses. The SRC laboratory in Saskatoon that conducted chemical analyses on the water, sediment, vegetation, fish, and ducks is accredited and will provide QA/QC procedures upon request. Benthic macroinvertebrate laboratory procedures, including QA/QC requirements (i.e., sort checks, split checks, etc.), follow those outlined in the Metal Mining EEM guidelines (Environment Canada 2002; Glozier et al. 2002). Samples are archived for a period of time for QA/QC requirements.

2.2 Bathymetry

A series of intersecting depth sounding transects were completed in Back Bay during the September 2005 survey in order to create a detailed bathymetric map. The depths were recorded using a Eagle Cuda 128 depth sounder. A constant speed was maintained during each transect and the water depth was recorded to the nearest 0.1 m every 10 seconds. The location and elevation at which each depth measurement was taken was simultaneously recorded using a Garmin GPS Map 76. The depth and location data were imported and bathymetric maps were generated with Surfer (version 5.0) and AutoCad 2000 computer applications. Shore length, surface area, volume, and shoreline and volume development (discussed below) were calculated. These parameters are useful in characterizing waterbody morphology.

2.2.1 Shoreline Development

Shoreline development is an index relating shoreline length to the circumference of a circle that has the same area as the lake. The smallest possible number is 1.0, which indicates a perfectly circular lake (Cole 1983; Wetzel 1983). As the value increases

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above 1.0 the shoreline becomes more irregular. Shoreline development is of interest because it reflects the potential for greater development of the littoral (shore) communities, which are usually of higher biological productivity (Wetzel and Likens 1991).

2.2.2 Volume Development

Volume development is a relative expression of the shape of the lake bottom. It compares the shape of the lake to an inverted cone whose height is equal to the maximum depth and whose basal area is equivalent to the lake’s surface area. As the value for volume development approaches 1.0, the shape of the lake bottom approaches the shape of a cone. A waterbody with a smaller volume than a cone would have a value below 1.0, whereas a value greater than 1.0 indicates that the waterbody's basin cross section is more U shaped (Wetzel 1975). A study by Koshinsky (1970) of 68 Precambrian Shield lakes in northern Saskatchewan found that the average volume development was 1.23.

2.3 Limnological Measurements

In 2004, limnology measurements were taken at the deepest point located in Langley Bay and at a similar depth in St. Mary’s Channel (Figures 3 and 4). The approximate locations of these stations were re-established and sampled during the 2005 sampling program (Figures 5 and 6). In Back Bay, the limnology station was also established in the deepest part of the bay, at a depth of approximately 4 m (Figure 7). In Zeemel Bay, the limnology station was positioned to be near to a previously identified seep coming from the Gunnar site waste rock pile (Seep-1; Figure 5). Limnology measurements were taken in Dixon Bay at a comparable depth to the stations sampled in Langley Bay and St. Mary’s Channel, approximately 8.5 m (Figure 8).

Limnological measurements were taken at one-metre intervals from the surface to the lake bottom. The exception was in Zeemel Bay where measurements were taken at half metre intervals because the station was shallow (<2 m deep). A YSI Model 650 multi- parameter unit was used for measuring water temperature, dissolved oxygen, specific conductance, and pH at each station. Water transparency was measured using a standard black and white Secchi disk (20 cm diameter).

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2.4 Water Sampling

Water samples were collected at the same stations as the limnological measurements in both 2004 and 2005 (Figures 3 to 8). A Kemmerer water sampling bottle was used to collect composite water samples from the top, middle, and bottom of the water column. The exception was in Zeemel Bay where a discrete water sample was obtained from the middle of the water column because of its shallow depth. Samples were preserved with acid, where required, and delivered to SRC in Saskatoon for chemical analyses. The specific analytes measured in this investigation match those measured during the 2002 Gunnar pit study (CanNorth 2004a).

2.5 Sediment Sampling

Sediment samples were collected from three replicate stations in St. Mary’s Channel and Langley Bay in 2004 at depths of approximately 5 m (Figures 3 and 4). In order to have reference samples to compare with these exposure areas, three replicate samples were collected at a similar depth in Dixon Bay during the 2005 sampling program (Station 2; Figure 8).

Zeemel Bay and Back Bay are both too shallow to sample depths of 5 m, thus three replicate stations were established at depths of approximately 1.5 m in Zeemel Bay (Figure 5), and 2 m in Back Bay (Figure 7) in 2005. To compare with these samples, a second set of sediment samples were collected from Dixon Bay at depths ranging between 1.7 and 1.9 m (Station 1; Figure 8).

Sediment samples were collected using an Ekman dredge (0.052 m2) and consisted of the 0-5 cm sediment horizon. Samples from each station were collected from similar depths within a water body and each sample consisted of a single Ekman dredge grab. A scoop was used to retain the 0-5 cm horizon and the sample was placed into a labelled bag and frozen prior to submission for chemical analyses.

The sediment samples were submitted to SRC for chemical analyses. The specific analytes measured in this investigation match those measured in the 2002 Gunnar pit study (CanNorth 2004a). The data from each area are reported as a mean ± standard deviation.

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2.6 Sedge Sampling

A large component of the 2005 sampling program was to collect vegetation samples for chemical analyses from the Gunnar mine site study area. This adds valuable information on the chemical concentrations in aquatic food sources for some wildlife species that will be used in the risk assessments. Sedge3 samples were collected from three stations in each of Langley Bay, Back Bay, and Dixon Bay, and from four stations in Zeemel Bay. Samples were not collected from St. Mary’s Channel since it does not support large densities of sedge and Zeemel Bay is part of the St. Mary’s Channel study area.

The sediment, roots, and shoots of the sedge samples were collected using a shovel. The shovel was thoroughly cleaned with distilled water between sampling locations. The plants were dug out of the ground and the roots and shoots were separated using Teflon coated scissors. The roots were then washed to clean off the attached sediment. Approximately 500 g of roots and shoots were retained for chemical analyses. The sediment located underneath the plants was extracted using the shovel and approximately 100 g was retained for chemical analyses. Samples were frozen prior to submission to SRC laboratories.

2.7 Fish Sampling

There were two main objectives of the fish sampling program: 1) to identify which fish species are residing in the study areas, and 2) to capture fish for chemical analyses. In 2004, fish community surveys were completed in Langley Bay, St. Mary’s Channel, and Zeemel Bay. Three northern pike were retained for chemical analyses from each of Langley Bay, St. Mary’s Channel, and Gunnar pit. Zeemel Bay is located adjacent to St. Mary’s Channel, thus separate fish samples were not obtained from this bay. The fish from St. Mary’s Channel were captured near the mouth of Zeemel Bay and they are considered representative of both study areas. However, it should be noted that although the fish were caught in the study areas, their residency time and degree of exposure are not known.

3 Sedge samples consisted of water sedge (Carex aquatalis) and/or beaked sedge (Carex rostrata).

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During the 2005 sampling program, fish community surveys were completed in Back Bay and Dixon Bay. In order to provide a larger sample size of northern pike chemistry data for the risk assessment modelling, three additional northern pike were retained for chemical analyses from Langley Bay and St. Mary’s Channel. Five northern pike were retained for chemical analyses from Back Bay and Dixon Bay. It was also desirable to conduct chemical analyses on a bottom feeding fish species. Thus, five lake whitefish were retained for chemical analyses from each of Langley Bay, St. Mary’s Channel, and Dixon Bay. Lake whitefish from Back Bay would have been tested, but none were captured.

A variety of fish capture methods were used during the surveys. These included the following:

• half standard gang and short-length gillnets; • electrofishing; • minnow traps; and • angling (in Gunnar pit only).

The fish were collected under the authority of Special Collection Permits issued by Saskatchewan Environment in La Ronge. Fish sampling details are subsequently presented.

2.7.1 Gillnetting

Large-bodied fish were captured using half standard gang gillnets and short length gillnets. A half standard gang gillnet consists of six panels, each 22.85 m long and 1.8 m deep, of the following mesh sizes (stretch measure): 3.8 cm (1.5"), 5.1 cm (2"), 7.6 cm (3"), 10.2 cm (4"), 12.7 cm (5"), and 14.0 cm (5.5"). Two sets of short length gillnets were used in some study areas. One consisted of four 10 m panels; three with a 6.4 cm (2.5") mesh size and one with a 7.6 cm (3") mesh size. The second consisted of two 10 m long panels with a 7.6 cm (3") mesh size. In order to minimize fish mortality, gillnets were set for short intervals and were not set overnight. The locations of the net sets are shown in Figures 3 to 8 and details on the net set times are provided in Appendix A.

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2.7.2 Electrofishing

A backpack electrofisher (Smith-Root Inc., Model 12) was used to collect information during the fish community survey conducted in Langley Bay, St. Mary’s Channel, and Zeemel Bay in 2004. Total electrofishing effort was recorded in seconds. The electrofisher was set at 200 to 1000 volts and a frequency of 60 hertz. Several locations adjacent to the shoreline were assessed by electrofishing (Figures 3 and 4).

An effort was made to use backpack electrofishing as a sampling method during the 2005 survey, however, due to equipment malfunction the effort was limited. A small amount of sampling was conducted in Dixon Bay (Figure 8).

2.7.3 Minnow Traps

To determine the presence of small-bodied and juvenile fish species residing in the study areas, cylindrical minnow traps were placed throughout the study areas of St. Mary’s Channel and Zeemel Bay in 2004 (Figure 3), Langley Bay in 2004 (Figure 4), Back Bay in 2005 (Figure 7), and Dixon Bay in 2005 (Figure 8). These traps measure 41 cm in length and 22 cm in diameter (at the widest point), with a 6.4 mm wire mesh. The traps were set for a single diurnal cycle in all study areas. Bread was placed in the minnow traps to attract fish.

2.7.4 Angling

In order to minimize unnecessary fish mortality, angling was the exclusive method used for northern pike capture in Gunnar pit. Fishing was conducted by casting from shore.

2.7.5 Fish Processing Procedures

All fish captured were identified to species. Fork length was measured to the nearest mm and an external health assessment was completed. Larger fish (>15 cm) were weighed to the nearest 1 g, 5 g, or 20 g4.

4 Scale accuracies are as follows: 0 - 100 g range, 1 g accuracy; 0 - 500 g range, 5 g accuracy; 0 - 5,000 g range, 20 g accuracy.

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A more detailed assessment was conducted on the fish sacrificed and submitted for chemical analyses. For each fish, the sex was determined, the stomach contents were recorded, and a health assessment was conducted. In addition, ageing structures (cleithra for northern pike and otoliths for lake whitefish) were collected and analyzed. The flesh and bone samples were submitted to SRC for chemical analyses.

2.8 Plankton and Benthic Macroinvertebrate Sampling 2.8.1 Phytoplankton and Zooplankton

One phytoplankton sample and one zooplankton sample were collected at the limnology/water sampling stations in St. Mary’s Channel and Langley Bay in 2004 (Figures 3 and 4), and at the limnology/water sampling stations in Zeemel Bay, Back Bay, and Dixon Bay in 2005 (Figures 5, 7, and 8).

The phytoplankton samples were collected using weighted Nalgene tubing (12.7 mm inside diameter). The tubing was lowered to near station bottom encompassing the entire water column. This ensured that the sample contained organisms from all depths typically inhabited by phytoplankton, in the event of non-random vertical distribution. The sample contained a composite of two hauls. The samples were preserved in 1% Lugol's solution (Slack et al. 1973). The phytoplankton samples were submitted to a qualified taxonomist for enumeration, taxonomic identification, and biomass estimation.

The zooplankton samples were collected using an 80 µm Wisconsin plankton net (20 cm mouth diameter and 56 cm in length). The plankton net was drawn vertically from near the station bottom to the surface to circumvent any non-random zooplankton distribution within the water column. It was retrieved at a constant speed of 1 m/sec. Each sample was a composite of two hauls. The samples were fixed with formalin at a concentration of 5% (Slack et al. 1973). The zooplankton samples were submitted to a qualified taxonomist for enumeration and taxonomic identification.

2.8.2 Benthic Macroinvertebrates

Benthic macroinvertebrate samples were collected at the same three replicate stations as the sediment chemistry samples in all study areas (Figures 3 to 8). At each station, the sample consisted of a composite of three Ekman dredge grabs (0.052 m2). Samples were

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washed in the field through a 500 µm Nitex wash bag. The material retained by the bag was placed in a sample jar and preserved in 10% formalin. The benthic macroinvertebrate samples were submitted to a qualified taxonomist for enumeration and taxonomic identification.

2.8.3 Data Analyses

To assist in the interpretation of the phytoplankton, zooplankton, and benthic macroinvertebrate results, the data are presented in several formats. These include: abundance (number of organisms), taxon richness (number of taxa), and several biotic indices (Simpson’s diversity index, evenness, and Bray-Curtis index). These are the same diversity indices used in Environment Canada’s Environmental Effects Monitoring program (Environment Canada 2002). Brief explanations of each biotic index are provided below.

Simpson’s Diversity Index

Simpson’s diversity index is a measure of diversity which takes into account both richness and evenness (Simpson 1949). This index is calculated by determining the proportion of individuals for each taxonomic group that contribute to the total number of individuals in the sample. The value of the Simpson’s diversity index ranges between 0 and 1 where the greater the value, the greater the sample diversity suggesting a more stable biological community.

Evenness

Evenness can be quantified by expressing the calculated Simpson’s diversity index as a proportion of the maximum possible value of the index that would occur if individuals were completely evenly distributed among the taxa in each sample (Environment Canada 2001). Values range between 0 and 1 and higher values indicate a more evenly distributed biological community.

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Bray-Curtis Index

The Bray-Curtis index is a distance coefficient that reaches a maximum value of one for two sites that are entirely different and a minimum value of zero for two sites that possess identical descriptors (Environment Canada 2002). To calculate this index, the number of individuals in each taxon was compared to a calculated reference median and the percentage of difference between the sites is measured. Most of the previous biotic indices are numerical measures of total abundance or total richness and do not take into account possible differences in species composition in biological communities. The Bray-Curtis index summarizes the overall difference in community structure, including species composition, between reference and exposure samples.

2.9 Fish Habitat Assessment

A detailed assessment of the quantity and quality of critical fish habitat in the study areas of Langley Bay, St. Mary’s Channel, Zeemel Bay, Back Bay, and Dixon Bay was conducted. The documentation of potential critical fish habitat was modified after the Habitat Evaluation Procedure (HEP) developed by the U.S. Fish and Wildlife Service (Cowardin et al. 1979; Busch and Sly 1992) and guidance documents (e.g., DFO and BC Ministry of Environment and Parks 1987; Orth 1989; Ontario MNR 1989; Plafkin et al. 1989; Langhorne et al. 2001) recommended in the “Habitat Mapping and Classification” section of the Metal Mining Guidance Document for Aquatic Environmental Effects Monitoring (Environment Canada 2002). The habitat assessments were conducted in the following manner:

I. Delineate Habitat Units Each study area was divided into a series of habitat units based on physical characteristics.

II. Description of Habitat Units The littoral zone of each habitat unit included a description of the following:

bottom gradient characterized as a gentle, moderate, or steep slope;

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substrate classifications include: silt/clay, sand, gravel, cobble, boulder, bedrock, and organic; aquatic vegetation density of submergent, floating leaved, or emergent macrophytes as well as algal and moss growth; cover classifications include: large woody debris, rock, overhanging vegetation, aquatic macrophytes, undercut, and industrial structures (for the St. Mary’s Channel site only); and shoreline vegetation primarily near-shore vegetation characteristics.

In addition, the habitat in the upland and riparian areas are described.

2.9.1 Spawning Habitat Suitability Index

Spawning habitat assessments were conducted for the following large-bodied and commercial fish species: northern pike, walleye (Stizostedion vitreum), lake trout (Salvelinus namaycush), lake whitefish, white sucker (Catostomus commersoni), longnose sucker (Catostomus catostomus), arctic grayling (Thymallus arcticus), and yellow perch (Perca flavescens). Selection of fish species for which critical habitat was evaluated in the study areas was based on species known to inhabit Lake Athabasca5.

Each habitat unit was rated for its suitability as spawning habitat for each of the species investigated. This determination of suitability was based on known spawning habitat characteristics that have been described in the literature and includes the appropriate habitat suitability models, where available, that have been developed for the species. The information provided in the habitat suitability models have been supplemented with additional data collected from investigations from the regional area. The index ratings

5 Goldeye (Hiodon alosoides) are also known to occur in Lake Athabasca. However, this species is excluded from the spawning habitat evaluations because specific spawning habitat requirements were not met within either study area. Goldeye typically spawn in turbid rivers or turbid river widenings (Scott and Crossman 1973). Furthermore, this species was not found in the study area during the fish community survey.

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range from not suitable (0) to most or highly suitable (3). The assessment of spawning habitat was based on the following characteristics:

Northern Pike1

Not Suitable (0) - an area that does not support aquatic plant growth and predominantly consists of a rock or sand substrate; Marginal (1) - an area supporting a sparse growth of aquatic plants, usually Carex (sedge); Moderate (2) - an area that supports moderate to dense aquatic plant growth; and Most Suitable (3) - an area similar to (2) but the substrate is found in water <0.5 m in depth with little or no current and is covered with aquatic plant material, particularly “feather” moss but also senesced aquatic plants.

1Sources: Scott and Crossman 1973; Krochak and Crosby 1975; Inskip 1982; Casselman and Lewis 1996; Minns et al. 1996.

Walleye2

Not Suitable (0) - an area with an organic or silt substrate, particularly with aquatic plant debris; Marginal (1) - an area with a sand and/or silt substrate but free of aquatic plant debris; Moderate (2) - an area with a clean gravel, cobble, and boulder substrate, in <1.5 m of water, particularly with spaces or crevices between the rock; and Most Suitable (3) - an area similar to (2) but found in a shoal or reef area of a lake or riffle of a stream with good water circulation or movement from wave action or current.

2Sources: Johnson 1961; Busch et al. 1975; Chevalier 1977; Scott and Crossman 1973; Chen 1980.

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Lake Trout3

Not Suitable (0) - an area with organic or silt substrate and/or aquatic plant debris; Marginal (1) - an area with sand and/or rock substrate but with an absence of crevices between the rock; Moderate (2) - an area with a clean cobble and boulder substrate, in <3 m of water, with spaces or crevices between the rock; Most Suitable (3) - an area similar to (2) but found in a shoal or reef area, particularly if the habitat has the potential for some water movement during the over-winter incubation of spawned eggs.

3Sources: Martin 1956, Loftus 1957; Rawson 1961; Carlander 1969; McPhail and Lindsey 1970; Scott and Crossman 1973; Johnson 1975; Chen 1979; Marcus et al. 1984; TAEM 1989b, 1991a, 1991b.

Lake Whitefish4

Not Suitable (0) - an area with an organic or silt substrate, particularly with aquatic plant debris; Marginal (1) - an area with sand and/or silt substrate but free of aquatic plant debris; Moderate (2) - an area with a clean cobble and boulder substrate, in <3 m of water, particularly with spaces or crevices between the rock; and Most Suitable (3) - an area similar to (2) but found in a shoal, reef, or stream, particularly if the area has the potential for some water movement during the over-winter incubation of spawned eggs.

4Sources: Quadri 1955, 1968; Scott and Crossman 1973; IES 1985, 1986a, 1986b; TAEM 1989a, 1989b, 1993.

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White Sucker and Longnose Sucker5

Not Suitable (0) - an area with an organic, silt, or sand substrate, particularly with aquatic plant debris; Marginal (1) - an area with a predominantly sand and/or silt substrate with some gravel and/or cobble but free of aquatic plant debris; Moderate (2) - an area with a clean gravel and/or cobble substrate, in <0.5 m of water with some water movement; and Most Suitable (3) - an area, particularly in a stream, with a clean gravel substrate, in <0.3 m of water with good water movement due to currents.

5Sources: Harris 1962; Green et al. 1966; Scott and Crossman 1973; Edwards 1983; Twomey et al. 1984.

Arctic Grayling6

Not Suitable (0) - an area with an organic or silt substrate, particularly with aquatic plant debris or other substrate with little or no current; Marginal (1) - an area with a sand, cobble, boulder, and/or bedrock substrate and free of aquatic plant debris, particularly with some current; Moderate (2) - an area with a clean, predominantly gravel substrate, in <3 m of water with some current; and Most Suitable (3) - an area similar to (2) but found in stream sections with a moderate to strong current.

6Source: Brown 1938; Rawson 1950; Nelson 1954; Wojcik 1954; Reed 1964; Bishop 1971; Sawchyn 1973; Scott and Crossman 1973; Kratt and Smith 1977; Hubert et al. 1985; Merkowsky 1989.

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Yellow Perch7

Not Suitable (0) - an area that does not support aquatic plant growth and consists of a cobble or boulder substrate, especially with a moderate or strong current; Marginal (1) - a relatively shallow area that does not support aquatic plant growth and consists of a sand or gravel substrate with little or no current; Moderate (2) - an inshore area that supports sparse rooted aquatic plant growth, particularly with some submerged brush and/or fallen trees and little or no current; and Most Suitable (3) - an inshore area that supports moderate to dense rooted aquatic plant growth, particularly with significant amounts of submerged brush and/or fallen trees and little or no current.

7Sources: Scott and Crossman 1973; Atton and Merkowsky 1983; Miles and Sawchyn 1988; TAEM 1990.

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3.0 RESULTS 3.1 Bathymetry

A bathymetric map of Back Bay is provided in Figure 9 and the morphometric characteristics are detailed in Table 1. The shore length of Back Bay is approximately 2 km long and it contains a surface area of 17.74 ha. There are no islands in the bay. Back Bay is relatively shallow with a mean depth of 1.8 m and a maximum depth of 4 m. The deepest spot is located off the south shore near a bedrock outcropping (Figure 9).

The total volume of Back Bay is 0.32 x 106 m3 and approximately 25% of the water is contained in the top 0.5 m. The volume development index (1.36) and the distribution of the percent volume by depth are indicative of a U-shaped basin. The shoreline development index (1.37) suggests that the shoreline is not entirely circular and displays some irregularities.

3.2 Limnology

Table 2 presents the limnological data collected from St. Mary’s Channel and Langley Bay in September 2004, and Table 3 presents the limnological data collected from St. Mary’s Channel, Langley Bay, Back Bay, Zeemel Bay, and Dixon Bay in 2005.

The water temperature in all waterbodies was uniform throughout the water column, indicating no thermal stratification. In 2004, temperatures were slightly warmer in Langley Bay (10.5 to 11.3°C) compared to St. Mary’s Channel (9.5°C). The water temperatures in 2005 were warmer than in 2004 and measured approximately 13°C in all study areas.

Dissolved oxygen concentrations were relatively high throughout the water column in St. Mary’s Channel and Langley Bay ranging from 10.1 to 11.3 mg/L in 2004, and 9.4 to 10.2 mg/L in 2005. Similar concentrations were measured in the reference area, Dixon Bay, in 2005 (9.8 to 10.3 mg/L). Dissolved oxygen concentrations were above provincial and federal guideline levels for the protection of freshwater aquatic life of 5.5 to 9.5 mg/L (SERM 1997; CCME 2005).

Dissolved oxygen concentrations were slightly lower in Zeemel Bay, approximately 8.7 mg/L, likely because it is a secluded, shallow bay that is not exposed to wave action

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which would distribute oxygen through the water in the channels and larger bays of Lake Athabasca. The dissolved oxygen levels measured in Back Bay in 2005 were very low throughout the water column measuring between 3.4 and 3.9 mg/L. Back Bay is separated from the main body of Lake Athabasca and it is a sheltered, eutrophic bay with a high content of algae and vegetation. These low dissolved oxygen levels would be limiting to some aquatic life and are well below provincial and federal guideline levels (5.5 to 9.5 mg/L) for the protection of freshwater aquatic life (SERM 1997; CCME 2005).

Specific conductance levels were the same in Dixon Bay and St. Mary’s Channel (57 µS/cm), slightly higher in Langley Bay (76 µS/cm in 2005 and approximately 96 µS/cm in 2004), and higher still in Zeemel Bay (112 µS/cm). In Back Bay, specific conductance was higher than the other study areas, measuring approximately 435 µS/cm. This concentration is also higher than those typically measured in waterbodies located in northern Saskatchewan, <75 µS/cm (CanNorth 2004b), and is likely related to tailings exposure.

The pH levels were consistent throughout the water column and were slightly basic at all locations in 2005, measuring between 7.7 and 8 units. These values are slightly higher than the pH levels measured in Langley Bay and St. Mary’s Channel in 2004 of approximately 7.2 units. The pH values were well within the guideline range (6.5 to 9) recommended in water quality objectives (SERM 1997; CCME 2005).

A Secchi disc was used to measure the transparency of water to light. This provides an indication of the water clarity, but it is also a subjective measure that can be biased by the examiners vision, sunlight, and wave action. Therefore, the results should be interpreted with caution. The Secchi disk depths for St. Mary’s Channel and Langley Bay in 2004 were both 3.0 m, while deeper measurements of 4.6 m and 4.12 m, respectively, were measured in 2005. The Secchi disc depth in Dixon Bay was greater, measuring 5 m. In Zeemel Bay, the disc could be seen on the lake bottom (1.35 m), while in Back Bay, the water transparency was low, with the Secchi disc depth measuring 1.15 m. This is consistent with the higher turbidity level measured in the water sample from Back Bay (Table 4).

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3.3 Water Chemistry

Table 4 presents the water chemistry results from the 2004 and 2005 sampling programs. Also included in the table are the applicable Saskatchewan Surface Water Quality Objectives (SSWQO) for the protection of aquatic life (SERM 1997) and the Canadian Environmental Quality Guidelines for the protection of aquatic life (CCME 2005). Historical water chemistry data are available for Langley Bay and these are presented in Table 5 and are included in the discussion below6.

The majority of metals and trace elements were below analytical test detection limits in the samples from all waterbodies. Similar results have been reported for Langley Bay during previous studies (Table 5, EPS 1981; Waite et al. 1988). The 2005 results indicated that Back Bay contained higher concentrations of arsenic, iron, manganese, and strontium than the other study areas. The only analytes above guidelines were iron and arsenic in Back Bay, which were above the federal guidelines but were well below the SSWQO.

Concentrations of inorganic ions were similar in St. Mary’s Channel, Langley Bay, and the reference area, Dixon Bay. Sulphate levels were slightly higher in the Langley Bay sample (14 mg/L in 2004 and 7.4 mg/L in 2005) compared to Dixon Bay (2.9 mg/L). When compared to historical data, sulphate levels in Langley Bay were lower than those of 25 mg/L and 30 mg/L previously reported by Waite et al. (1988) and (EPS 1981), respectively.

In Zeemel Bay, concentrations of bicarbonate, calcium, inorganic carbon, magnesium, sulphate, specific conductivity, sum of ions, total alkalinity, total carbon, total dissolved solids, total hardness, and total suspended solids were greater than twice the concentrations in Dixon Bay. The concentrations of these analytes, plus chloride, potassium, and sodium, were substantially higher in Back Bay compared to all other study areas, including Zeemel Bay (Table 4). Additionally, certain nutrient concentrations, including organic carbon, phosphorus, and total Kjeldahl nitrogen, were a minimum of five times higher in Back Bay compared to Dixon Bay.

6 Data comparisons should be interpreted with caution since laboratory methods and analytical test detection limits have changed over time.

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Radionuclide concentrations in the water samples from Langley Bay and Back Bay were higher than in Dixon Bay. The radium-226 concentrations in Langley Bay (0.16 Bq/L in 2004 and 0.12 Bq/L in 2005) and Back Bay (0.79 Bq/L) exceeded the SSWQO general surface water quality objective of 0.11 Bq/L (SERM 1997). Previous investigations conducted in Langley Bay in 1976 and 1978 (EPS 1981) and in 1983 (Waite et al. 1988) measured radium-226 and uranium levels that were marginally higher than levels in the current study (Table 5). Insufficient data prevented completing a similar comparison for other radionuclides.

The radionuclide concentrations measured in the water samples from St. Mary’s Channel collected in 2004 and 2005 were generally similar to those measured in Dixon Bay in 2005.

In Zeemel Bay, the radium-226 concentration of 0.02 Bq/L was higher than in Dixon Bay (<0.005 Bq/L), however, this level remains well below the SSWQO. The uranium concentration (220 µg/L) was much higher in Zeemel Bay than in all other study areas, where the levels ranged between 0.4 and 11 µg/L. Water samples collected in Zeemel Creek upstream of Zeemel Bay by SRC in the summers of 2004 and 2005 contained low uranium concentrations of 0.5 to 0.8 µg/L (Table 4). These results demonstrate that the elevated uranium concentration measured in Zeemel Bay in September 2005 is a result of the close proximity of the water sampling station to the seepage site from the nearby Gunnar mine site waste rock pile. The spatial extent of elevated uranium levels downstream of the seep was not established, however, the sediment sample collected near the mouth of the Zeemel Bay contained uranium levels that were equivalent to reference (refer to Section 3.4).

3.4 Sediment Chemistry

Table 6 presents a summary of the chemistry results, as well as applicable federal guidelines since provincial guidelines are not available. Sediment samples were collected at a 2 m depth in Dixon Bay, Back Bay, and Zeemel Bay, and at a 5 m depth in Dixon Bay, Langley Bay, and St. Mary’s Channel. The results are compared within each depth range.

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3.4.1 Back Bay and Zeemel Bay

Sediment concentrations of sulphate, numerous metals and trace elements, and all radionuclides were substantially higher in Back Bay compared to Dixon Bay7. Of the metals and trace elements, mean concentrations of barium, copper, iron, lead, manganese, molybdenum, selenium, tin, arsenic, beryllium, and vanadium showed notable differences. Mean levels of lead-210, polonium-210, thorium-230, and radium-226 were a minimum of 200 times higher in Back Bay than in Dixon Bay, while uranium levels were approximately twelve times higher.

Sediment concentrations of ions, nutrients, metals, and trace elements were similar between Dixon Bay and Zeemel Bay. Radionuclide concentrations were higher in Zeemel Bay than in Dixon Bay, however, they were much lower than in Back Bay with the exception of uranium. Sediment uranium concentrations were high near the seeps from the waste rock pile measuring 291 µg/g at Station 1 and 316 µg/g at Station 2 in Zeemel Bay (locations shown in Figure 5). At Station 3, located closer to the mouth of Zeemel Bay, the sediment uranium concentration (7 µg/g) was similar to reference (mean = 6.6 µg/g). Thus it appears that sediment contamination in Zeemel Bay is restricted to areas located near the waste rock pile.

Current federal guidelines provide interim sediment quality guidelines (ISQG)8 and probable effects levels (PEL)9 for a limited number of sediment quality parameters (CCME 2005) (Table 6). In Back Bay, mean concentrations of copper were higher than the ISQG and mean concentrations of lead and arsenic were higher than the PEL. Mean chromium concentrations were higher than the ISQG in Dixon Bay and Zeemel Bay, but not Back Bay, indicating that high chromium levels are found naturally in parts of Lake Athabasca. Currently no guidelines exist for radionuclide concentrations in sediment.

7 One of the three samples from Dixon Bay was not included in the data analyses since it contained inexplicably higher radionuclide levels than all other sediment samples collected from Dixon Bay. These data are presented in Appendix B. 8 ISQG: The interim sediment quality guideline represents the concentration of a parameter below which there is unlikely to be adverse biological effects. 9 PEL: The probable effects level is the established level above which adverse effects are expected to frequently occur.

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3.4.2 Langley Bay and St. Mary’s Channel

The sediment samples from Langley Bay and St. Mary’s Channel were collected in 2004, and the samples from Dixon Bay were collected in 2005. Since the Dixon Bay samples are reference, sediment chemistry should not change markedly over time. Thus, the temporal difference should not be a factor in data comparability. Historical sediment chemistry data are available for Langley Bay and these are presented in Table 7 and have been included in the discussion below10.

In St. Mary’s Channel, mean concentrations of boron, chromium, lead, and radionuclides were higher than reference, but were lower than in Langley Bay, with the exception of chromium. The Langley Bay sediment contained mean concentrations of boron, cadmium, copper, iron, lead, manganese, molybdenum, arsenic, beryllium, cobalt, and all radionuclides that were higher than in Dixon Bay. Many of these analytes are the same ones that were elevated in Back Bay sediment and the radionuclide concentrations in Langley Bay were similar to Back Bay. The ISQGs were exceeded by mean concentrations of cadmium, copper, lead, and arsenic in the Langley Bay samples, and chromium in St. Mary’s Channel. Mean values further exceeded PELs in Langley Bay for cadmium, lead, and arsenic.

Within Langley Bay, there was little spatial variability in the radionuclide concentrations between stations. In St. Mary’s Channel, sediment radionuclide concentrations were generally higher at stations 1 and 2 than those measured at Station 3. These stations are located closer to Gunnar pit (Figure 3). In addition, uranium and radium-226 showed a successive decrease in concentrations from Station 1 to Station 3. The following table demonstrates the differences in radionuclide concentrations between the three stations in St. Mary’s Channel:

Radionuclide Station 1 Station 2 Station 3 Uranium (µg/g) 194 31.8 5.1 Lead-210 (Bq/g) 0.40 0.38 0.06 Polonium-210 (Bq/g) 0.34 0.25 0.05 Radium-226 (Bq/g) 0.33 0.11 0.05 Thorium-230 (Bq/g) 0.94 1.0 0.21

10 Data comparisons should be interpreted with caution since laboratory methods and analytical test detection limits have changed over time. In addition, there were some unit inconsistencies.

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Metal and radionuclide concentrations measured in sediment samples collected in 1978 (EPS 1981) and 1983 (Waite et al. 1988) in Langley Bay were generally similar to the 2004 sediment concentrations (Table 7). Lead-210 and radium-226 levels were slightly higher, while uranium and thorium-230 levels were slightly lower, in the historical data when compared to the 2004 data. The most notable difference was in manganese concentrations, which were nine times higher in 2004 than in 1983.

3.5 Sedge Chemistry

Summary chemistry results from the sedge shoot, root, and sediment samples collected from Dixon Bay, Langley Bay, Back Bay, and Zeemel Bay are presented in Table 8. There were several instances where mean metal and trace element concentrations were higher in the exposure areas compared to the reference area. Of particular note were the mean concentrations of iron, lead, manganese and arsenic, which were substantially higher in sedge root and shoot samples from Langley and Back bays than in the samples from Dixon Bay.

There were large differences in the radionuclide concentrations between the exposure areas and the reference area. The only case where differences did not occur was the uranium levels in the shoot samples from Langley and Back bays, which were similar to Dixon Bay. Mean levels of lead-210, polonium-210, radium-226, and thorium-230 were higher in Zeemel Bay compared to Dixon Bay, but were higher still in Langley and Back bays compared to Zeemel Bay. For example, the radium-226 concentration in the sedge root samples averaged 5.73 Bq/g in Langley Bay, 4.23 Bq/g in Back Bay, 0.82 Bq/g in Zeemel Bay, and 0.04 Bq/g in Dixon Bay. However, uranium showed a different pattern in that the highest concentrations were measured in the Zeemel Bay sediment, root, and shoot samples.

There were notable differences in radionuclide levels between stations within each exposure area. The radionuclide levels measured at each station in the sediment, root, and shoot samples are presented in Table 9 and the uranium levels are shown graphically in Figure 10. In Langley Bay, radionuclide concentrations were generally higher at stations 2 and 3 than at Station 1. The sediment data showed a clear trend with the lowest concentrations at Station 1 and the highest concentrations at Station 3, however, the sedge chemistry was more variable. These results are logical considering the proximity of the stations to the tailings area (Figure 6). Similarly in Back Bay, many of the

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radionuclide levels were higher at stations 2 and 3, which are located closer to the tailings area than Station 1 (Figure 7). In Zeemel Bay, the station located closest to Seep-1 (Station 2) generally contained the highest radionuclide levels, particularly in the sedge samples. This was especially evident for the uranium levels in the sedge root samples which measured 4,690 µg/g at Station 2, 1,610 µg/g at Station 3 (also located near the seep), and was lower at stations 1 and 4, measuring 580 and 810 µg/g, respectively (Figure 10).

3.5.1 Concentration Ratios

Concentration Ratios (CRs) relating analyte concentrations between the sedge roots and sediment (root:sediment), and sedge shoots and roots (shoot:root), are presented in Tables 10 and 11, respectively. These provide an estimate of the amount of uptake of contaminants by the plant11. CRs that are greater than one reflect higher analyte concentrations in the sedge roots/shoots than in the surrounding sediment/roots.

There is variability between stations and analytes, however, in general the CRs for root:sediment were higher in Langley Bay and Zeemel Bay than in Back Bay, particularly for the radionuclides. In Back Bay, the CRs suggest that radionuclide levels in the sediment are higher than, or close to, levels in the sedge roots, with the exception of radium-226 and thorium-230 at Station 1 (Table 10). In Langley Bay, root:sediment CRs for radionuclides were higher than one at all stations and the greatest values were found at Station 3, located near the tailings area. In Zeemel Bay, radionuclide CRs were also greater than one at all stations. The CRs for uranium were very high ranging from 19 at Station 3 to 162 at Station 2. These results show that the sedge roots in Zeemel Bay contained substantially higher amounts of uranium than the surrounding sediment.

In all study areas, the CRs for sedge shoot:root were substantially lower than the CRs for root:sediment, indicating that the majority of the contaminants are contained within the roots. Almost all shoot:root CRs for radionuclides were well below one, including uranium in Zeemel Bay. However, this does not mean that the shoots are free of

11 Sedge shoots could also uptake contaminants from the surrounding water. However, water chemistry information from each sedge sampling sites was not available for the calculation of CRs.

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contaminants since many of the shoot samples from the exposure areas contained metal and radionuclide levels that were elevated above background (Tables 8 and 9, Figure 10).

3.6 Fish Chemistry 3.6.1 Northern Pike

Northern pike flesh and bone chemistry results for Gunnar pit, Langley Bay, and St. Mary’s Channel in 2004, and Dixon Bay, Langley Bay, Back Bay, and St. Mary’s Channel in 2005, are presented in Tables 12 and 13.

There were some differences between the 2004 and 2005 data in St. Mary’s Channel and Langley Bay. In both areas, arsenic, barium, and selenium concentrations were higher in all northern pike flesh samples in 2004 than in 2005, while in the northern pike bone samples, the reverse was found with mean iron and manganese concentrations higher in 2005 than in 2004. Reasons for these temporal variations in the data are not known.

For the metals and trace elements, northern pike sampled in Gunnar pit in 2004 contained higher mean concentrations of barium, mercury, selenium, and arsenic in the flesh, and nickel and selenium in the bone, than the 2005 samples from Dixon Bay.

In the other study areas, the metal that demonstrated the most notable difference between reference and exposure northern pike was manganese. In Back Bay, manganese concentrations in the northern pike flesh samples averaged 0.5 µg/g, while in the remainder of the waterbodies the mean concentrations ranged between 0.08 and 0.19 µg/g. However, elevated levels were only measured in two of the fish from Back Bay (0.64 and 1.4 µg/g) and the other three fish contained manganese levels similar to reference (0.14 to 0.17 µg/g). In the northern pike bone samples from Back Bay, the average manganese concentration was 29.4 µg/g (range = 18 to 61 µg/g), which is elevated compared to Dixon Bay (mean = 8.12 µg/g). In Langley Bay, the 2005 data showed higher mean manganese concentrations than reference, but the 2004 data did not.

Mean iron concentrations in the northern pike bone samples from Back Bay and St. Mary’s Channel in 2005 were more than twice as high as in Dixon Bay. The remainder of the metals and trace elements were generally in the same range in both the exposure and reference areas.

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Most radionuclide concentrations in the northern pike from Gunnar pit, Langley Bay, and Back Bay were higher than in the fish from Dixon Bay (Tables 12 and 13). Levels of polonium-210 and radium-226 in the northern pike bone samples from Back Bay were higher than in the other areas and averaged approximately 50 times higher than reference. Northern pike from St. Mary’s Channel contained radionuclide levels that were comparable to reference, with the exception of uranium concentrations in the bone samples that were approximately 10-fold higher.

Currently, few guidelines exist for analyte concentrations in fish. Saskatchewan Environment has developed guideline levels for mercury consumption in fish, based on concentrations in flesh (SERM 1999). Under the rating system, northern pike from Langley Bay, St. Mary’s Channel, Back Bay, and Dixon Bay would receive a rating of 0, (levels below 0.5 µg/g) and there are no fish consumption restrictions recommended. However, the three northern pike collected from Gunnar pit had mercury concentrations between 0.58 to 0.73 µg/g, warranting a mercury rating level of 1. Explanations of subsequent consumption recommendations are provided in Appendix C.

A comparison of radionuclide levels in the bone and flesh of northern pike from Langley Bay captured in 2005, 2004, and 1983 (Waite et al. 1988) is presented in Table 14. The levels of lead-210 and radium-226 measured in 2004 and 2005 northern pike bone samples were slightly higher than in the single composite sample from 1983 (Waite et al. 1988). Differences in detection limits between years make the uranium concentrations from 2004 and 2005 difficult to compare with the 1983 data.

3.6.2 Lake Whitefish

Summary chemistry results for the lake whitefish flesh and bone samples from Dixon Bay, Langley Bay, and St. Mary’s Channel are presented in Tables 15 and 16. There were few notable differences in the metals and trace element concentrations between the exposure areas and the reference area. In the lake whitefish flesh samples, selenium was notably higher in Langley Bay (mean = 0.49 µg/g) compared to Dixon Bay (mean = 0.22 µg/g). In the bone samples, mean manganese concentrations were higher in Langley Bay (mean = 8.52 µg/g) compared to Dixon Bay (mean = 4.82 µg/g). The mercury concentrations in all samples were well below provincial guidelines (Appendix C).

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Radionuclide concentrations were generally higher in Langley Bay compared to reference, particularly in the lake whitefish bone samples. For example, radium-226 concentrations in the bone samples from Dixon Bay and St. Mary’s Channel averaged 0.002 Bq/g, which is approximately 40 times lower than in Langley Bay (0.076 Bq/g).

The only radionuclide that was elevated in the St. Mary’s Channel lake whitefish was uranium. In the flesh samples, two fish from St. Mary’s Channel contained similar levels to reference (0.003 µg/g), however, the remaining three fish contained higher uranium levels of 0.021 to 0.024 µg/g. In the bone samples, four lake whitefish from St. Mary’s Channel contained uranium levels between 0.24 to 0.31 µg/g and one fish contained a higher level of 1.7 µg/g. These levels are all higher than the reference mean of 0.14 µg/g.

Table 14 presents a comparison of the lead-210, radium-226, and uranium levels measured in the lake whitefish samples in 2005 with the levels measured in a single composite sample tested in 1983 (Waite et al. 1988). The levels of all three radionuclides were higher in the 1983 sample when compared to the mean values from the 2005 data. However, this may be a result of differences in the detection limits between years.

3.7 Bufflehead Duck Chemistry

Four bufflehead ducks were captured incidentally in the gill nets set for fish capture in Back Bay. The ducks were chemically analyzed to provide additional information for the risk assessment modelling. The chemistry results for the flesh and bone samples are summarized in Table 17. The radionuclide concentrations were variable and one duck contained a higher uranium level than the others. The bone sample from Duck 1 contained a uranium level of 1.2 µg/g, while the remainder of the ducks had levels of 0.2 µg/g. It is difficult to interpret this information since there are no other data to compare with the values from Back Bay. It should also be noted that bufflehead ducks are migratory and their residency time in Back Bay is not known.

3.8 Phytoplankton

Phytoplankton samples were collected from Langley Bay and St. Mary’s Channel in September 2004, and from Dixon Bay, Back Bay, and Zeemel Bay in September 2005. Table 18 presents the phytoplankton taxa enumeration and biomass data from each

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waterbody. Table 19 presents the community metric values, including abundance, richness, and biotic indices. Caution should be taken when comparing data between years since communities can demonstrate temporal differences.

The phytoplankton sample from Dixon Bay was relatively evenly distributed consisting of 29% Chrysophyta (golden algae), 21% Haptophyceae (dinoflagellates), 19% Cyanophyta (blue-green algae), and 17% Chlorophyta (green algae)12. The samples from Langley Bay, St. Mary’s Channel, and Zeemel Bay were all dominated by golden algae, which comprised approximately 40% of the sample populations. The phytoplankton sample from Back Bay was almost entirely comprised of the blue-green algae Aphanizomenon flos-aquae (94%). This species commonly forms dense water blooms in eutrophic lakes and its abundance was apparent in Back Bay.

Phytoplankton abundance in Back Bay was approximately twice as high as in the other study areas, however, measures of richness and diversity were much lower (Table 19). Taxa richness were similar in Dixon Bay, Langley Bay, and St. Mary’s Channel (23, 26, and 28 taxa, respectively), slightly lower in Zeemel Bay (17 taxa), and much lower in Back Bay (8 taxa). In all study areas, except Back Bay, the Simpson’s diversity indices ranged between 0.85 and 0.88 and the evenness values ranged between 0.89 and 0.92. These results indicate diverse and numerically even phytoplankton communities in these study areas. The low Simpson’s diversity index (0.17) and evenness (0.20) in Back Bay reflects the dominance of the community by a single species.

3.9 Zooplankton

Results of the zooplankton taxonomic enumeration are presented in Table 20. The sample from Dixon Bay contained equal abundances of crustaceans and rotifers while the samples from Langley Bay, Back Bay, and St. Mary’s Channel were dominated by rotifers (>75%). The sample from Zeemel Bay differed from the other areas in that it was dominated by crustaceans (70.5%), consisting mainly of water fleas (Bosmina longirostris) (55.7%). Rotifers from the Family Synchaetidae dominated the community abundance in Dixon Bay and St. Mary’s Channel. In Langley Bay and Back Bay, the

12 Due to a large proportion of unidentified species, composition was compared at the Division level.

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samples were dominated by rotifers from the Genus Keratella; 37.8% Keratella cochlearis in Langley Bay and 70.1% Keratella quadrata in Back Bay.

Abundance, richness, and biotic indices calculated for the zooplankton samples are summarized in Table 19. The total abundance of zooplankton was lowest in Zeemel Bay (13 organisms/L) and highest in Back Bay (1,164 organisms/L). However, these bays had similar richness values (8 taxa in Back Bay and 9 taxa in Zeemel Bay) that were lower than in the other areas (16 taxa in Dixon Bay, 17 taxa in Langley Bay, and 19 taxa in St. Mary’s Channel).

The high abundance of organisms, low number of taxa, and high percentage of a single taxon resulted in low diversity indices for the zooplankton community in Back Bay (Simpson’s diversity index of 0.47 and evenness of 0.51). The zooplankton communities in Dixon Bay, Langley Bay, and St. Mary’s Channel had high diversity indices ranging between 0.79 to 0.82 for the Simpson’s diversity index and 0.83 to 0.86 for evenness. These results indicate that the zooplankton communities at these locations are diverse and numerically even. Zeemel Bay contained slightly lower diversity indicies than the remainder of the waterbodies (Simpson’s diversity index of 0.66 and evenness of 0.72), likely because of the low abundance of zooplankton in the sample.

3.10 Benthic Macroinvertebrates

Benthic macroinvertebrate samples were collected at a depth of approximately 5 m in Langley Bay and St. Mary’s Channel in 2004. In order to provide reference data for these areas, samples were collected at this depth range from Dixon Bay in 2005 (Station 2). In 2005, benthic macroinvertebrate samples were collected in Back Bay and Zeemel Bay, however, depths of approximately 2 m were sampled because of the shallow nature of these bays. Therefore, a second set of samples was collected from Dixon Bay at this depth range (Station 1). Data are only compared within each depth range.

3.10.1 Back Bay and Zeemel Bay

The benthic macroinvertebrate communities in Back Bay, Zeemel Bay, and Dixon Bay differed from one another (Table 21). Overall, the most dominant taxon in Dixon Bay was Corynocera sp. from the Family Chironomidae, although they were largely contained within one of the three samples. The Family Chironomidae accounted for

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nearly half of the sample population, however, if the high abundance of Corynocera sp. in the one sample is removed, the Family Chironomidae comprises only 30% of the sample population. There were relatively high densities of scuds (Hyalella azteca) and roundworms (Phylum: Nematoda).

In Back Bay, the Family Chironomidae occupied 74% of the sample population, with 35% from the genus Psectrocladius sp. In Zeemel Bay, 82% of the sample population was from the Family Chironomidae, with 55% from the genus Tanytarsus sp. However, similar to Dixon Bay, the high numbers of Tanytarsus sp. were only found in one of the three samples.

Density, richness, and biotic indices for the benthic macroinvertebrate samples are presented in Table 22. Of the three areas, mean benthic macroinvertebrate density was lowest in Zeemel Bay (10,303 organisms/m2), although Station 2 contained a higher density (22,269 organisms/m2) than Station 1 (3,340 organisms/m2) and Station 3 (5,301 organisms/m2) because of the large amount of Tanytarsus sp. Similarly in Dixon Bay, density was higher at Station 3 (31,122 organisms/m2) than at Station 1 (18,436 organisms/m2) and Station 2 (10,083 organisms/m2) because of the high numbers of Corynocera sp. Back Bay contained a higher mean density than Dixon Bay and Zeemel Bay and the numbers were relatively similar between stations ranging between 23,218 and 30,923 organisms/m2.

Although there was some variation between stations, mean values of richness, Simpson’s diversity, and evenness were highest in Dixon Bay, followed by Back Bay, and were lowest in Zeemel Bay. Dixon Bay contained a rich and diverse community with a total of 36 taxa and mean Simpson’s diversity and evenness of 0.81 ± 0.13 and 0.85 ± 0.13, respectively. In Back Bay, a total of 27 taxa were identified and the measures of diversity were slightly lower than reference (Simpson’s diversity = 0.73 ± 0.13; evenness = 0.78 ± 0.14). The sample population in Zeemel Bay contained a richness of 23 taxa, Simpson’s diversity index of 0.64 ± 0.04, and evenness of 0.71 ± 0.06. The Bray-Curtis indices reflect the differences in community composition between the exposure areas and the reference area. The high index values of 0.79 ± 0.08 in Back Bay and 0.78 ± 0.06 in Zeemel Bay show that the communities differ from those found in Dixon Bay.

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3.10.2 Langley Bay and St. Mary’s Channel

Taxa identification and enumeration results for the benthic macroinvertebrate samples from Dixon Bay (Station 2), Langley Bay, and St. Mary’s Channel are presented in Table 23.

The dominant taxon in Langley Bay was the genus Tanytarsus sp. of the Family Chironomidae, which comprised 22.6% of the sample population. The species Diporeia hoyi of the Family Haustoriidae was the second most abundant taxon (14.4%), followed by bivalves of the Family Sphaeriidae (13.1%).

The dominant taxon from St. Mary’s Channel, the species Diporeia hoyi, comprised well over half (63%) of the sample population. The second most abundant taxon was aquatic worms from the Family Tubificidae, accounting for 8.3% of the community composition.

The community in Dixon Bay was also dominated by organisms from the Family Haustoriidae, however, it was a different species than in St. Mary’s Channel. Pontoporeia hoyei comprised 29.5% of the Dixon Bay sample population. Dixon Bay also contained relatively high densities of aquatic worms from the Family Naididae (9.7% of the sample population).

Density, richness, and biotic indices for the benthic macroinvertebrate samples are presented in Table 24. Benthic macroinvertebrate density was much higher in the samples from Dixon Bay (18,868 ± 3,905 organisms/m2) than St. Mary’s Channel (6,944 ± 831 organisms/m2) and Langley Bay (5,156 ± 136 organisms/m2). Taxon richness was similar in Dixon Bay and St. Mary’s Channel, but was lower in Langley Bay. Conversely, diversity indices were almost the same in Langley Bay and Dixon Bay and were lower in St. Mary’s Channel. Simpson’s diversity averaged 0.82 in Langley and Dixon bays, which was much higher than the average value of 0.56 in St. Mary’s Channel. Similarly, evenness averaged 0.86 ± 0.06, 0.87 ± 0.04, and 0.59 ± 0.06 in Dixon Bay, Langley Bay, and St. Mary’s Channel, respectively. The lower indices calculated for the benthic macroinvertebrate samples from St. Mary’s Channel are attributable to the relatively high proportion of a single species, Diporeia hoyi. Bray- Curtis indices were not calculated since the exposure and reference data were collected in different years.

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Benthic macroinvertebrate sampling was conducted in Langley Bay in 1978 (EPS 1981) and some general comparisons can be made13. The 1978 survey found that the benthic macroinvertebrate community consisted of three families, with the highest abundance occurring from the Family Chironomidae, similar to the current study. In 2004, samples contained benthic macroinvertebrates from a higher total number of families (8). Species from the Family Valvatidae (valve snails) were found during both the 2004 and 1978 surveys, while species from the Family Empididae (dance flies) were present in 1978, but were not identified in the samples from the current study.

3.11 Fish Community

There are 23 species of fish known to occur in Lake Athabasca (Table 25). In order to identify which species are utilizing the study areas, fish community surveys were completed in St. Mary’s Channel and Langley Bay in 2004, and in Back Bay and Dixon Bay in 2005. Additional fish data were obtained from St. Mary’s Channel and Langley Bay during the 2005 study since nets were set to capture fish for chemical analyses. A detailed description of the fish catch data is provided in Appendix A and a summary is provided in Table 26. It is noted that the results of the fish community survey are restricted to the study period and do not preclude the presence of additional species residing in the study areas, particularly for migratory large-bodied fish.

3.11.1 St. Mary’s Channel and Zeemel Bay

During the 2004 fish community survey, a total of 25 northern pike and six lake whitefish were captured by gillnets. Additionally, two juvenile northern pike14, nine lake chub (Couesius plumbeus), two slimy sculpins (Cottus cognatus), and two burbot (Lota lota) were captured by electrofishing. The northern pike were captured in Zeemel Bay, while the slimy sculpin, burbot, and lake chub were captured in rocky areas of the channel. Ciscoes (Coregonus artedii) were also identified from the stomachs of northern pike. There were no small-bodied fish captured in the minnow traps.

13 Due to spatial variability and differences in sampling methods and sample analyses all comparisons should be interpreted with a degree of caution. 14 Three more northern pike were observed, but not captured.

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In 2005, one half standard gang gillnet was set in St. Mary’s Channel in front of the mouth of Zeemel Bay for the purpose of capturing fish for chemical analyses. This resulted in the capture of nine northern pike, three lake trout, and ten lake whitefish. The stomach contents of the three northern pike retained for chemical analyses contained numerous slimy sculpin and ninespine stickleback (Pungitius pungitius).

A length-weight curve and length-frequency distribution for the northern pike captured in St. Mary’s Channel in 2004 and 2005 are presented in Figure 11. There was a broad size distribution ranging from 11 to 98 cm and a good correlation (r2 = 0.93) between fork length and weight. The length-frequency distribution indicates that the most dominant size classes were 44 and 72 cm (Figure 11). The three lake trout captured had an average length of 67 cm and an average weight of 3417 g. The average length and weight of the lake whitefish captured in 2004 was slightly higher than in 2005 (Table 26). External observations of the fish indicated no apparent health problems.

3.11.2 Langley Bay

In September 2005, three gillnets were set in Langley Bay and these captured four northern pike and 12 lake whitefish. A lake whitefish was also found in the stomach contents of one northern pike. The higher amount of lake whitefish captured in 2005 compared to 2004 is likely a result of the nets being set at a deeper depth.

Figure 12 presents a length-weight curve and length-frequency distribution for the northern pike captured in Langley Bay in 2004 and 2005. There was a high correlation between northern pike fork length and weight (r2=0.97) and a broad range of size classes (10 to 88 cm). The yellow perch captured was a juvenile measuring 2.8 cm. The lake whitefish in Langley Bay were larger, on average, than those captured in St. Mary’s Channel, but were smaller than in Dixon Bay (Table 26). External observations of the fish indicated no apparent health problems.

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3.11.3 Back Bay

A fish community survey was conducted in Back Bay in September 2005 and the only fish species captured was northern pike. A total of ten northern pike were captured in three gillnet sets (Appendix A, Table 2). Overnight sets of eight minnow traps did not capture any fish. Unfortunately, electrofishing could not be completed in Back Bay due to equipment difficulties.

The majority of the northern pike ranged between 38 and 56 cm, however, one smaller fish measuring 16.9 cm was also retained (Figure 13). The length-weight curve shown in Figure 13 demonstrates there is a high correlation between northern pike fork length and weight (r2 = 0.97) in Back Bay, although the sample size is low.

The only fish identified in the stomach contents of the five northern pike retained for chemical analyses was also a northern pike. Considering the diverse stomach contents of the northern pike captured in the other study areas, this suggests that the species diversity is low in Back Bay and may be restricted to northern pike. The northern pike looked generally healthy, although one fish contained a small, hardened lump near one operculum.

3.11.4 Dixon Bay

Dixon Bay contains a high abundance of fish and is known to be a good fishing area by local residents (Delbert Augier, pers.comm.). One gillnet set for 2.15 hours captured ten northern pike and five lake whitefish. Two burbot were captured electrofishing and one burbot was found in a northern pike stomach. In addition, one ninespine stickleback was captured during electrofishing and one slimy sculpin was identified in a northern pike stomach.

The northern pike captured were quite large measuring between 64 and 99 cm (Figure 14) with an average length of 83.6 cm (Table 26). A length-weight curve was not completed because not all of the fish were weighed and therefore, the sample size was too low. The lake whitefish retained were also large with an average length of 47 cm and an average weight of 1676 g.

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3.12 Fish Habitat Assessments

The habitat assessments included detailing information on the density and composition of aquatic/wetland macrophyte species in the littoral zone of each study area. Table 27 provides a list of species located in St. Mary’s Channel/Zeemel Bay, Langley Bay, Back Bay, and Dixon Bay during the surveys. A higher number of plant species were located in Dixon Bay (20) compared to St. Mary’s Channel/Zeemel Bay (14), Langley Bay (11), and Back Bay (10). None of these species are considered rare under provincial listings (SKCDC 2003).

3.12.1 St. Mary’s Channel and Zeemel Bay

Table 28 presents a description of the habitat units (HUs) for St. Mary’s Channel, which includes Zeemel Bay (Table 29 provides the legend). A total of 15 HUs were identified and their locations are presented in Figure 15. The study area within St. Mary’s Channel has an upland zone associated primarily with uranium mining activities and related infrastructure. Some of this development has encroached into the water (e.g., old tires, building materials, and docks), either as part of mining operations or the ensuing deterioration of remaining infrastructure, and has subsequently altered the shoreline and related aquatic habitat (Appendix D, Photos 1 and 2).

In most of the study area, the shoreline of St. Mary’s Channel surrounding the Gunnar mine infrastructure and waste rock piles contained little or no vegetative cover (HUs 1-8, 10, and 11; Appendix D, Photos 3 and 4). The substrate was predominantly sand/cobble/boulder and the bottom slope was steep. In HUs 4 and 6, where docking facilities are located, the water depth was greater than 2 m and, although the lake bottom could not be seen, the substrate was assumed to be similar to the adjacent areas. In this section of the study area there was some fish cover identified near shore by large woody debris and rocks, as well as by industrial debris materials and structures.

High densities of aquatic/wetland macrophytes were restricted to Zeemel Bay and to the area south of the waste rock pile near Zeemel Bay (HUs 9, and 12-14; Appendix D, Photos 5 and 6). Zeemel Bay is a long, shallow, weedy bay containing an almost entirely organic substrate. The common aquatic/wetland macrophyte species included sedge, manna grass (Glyceria spp.), and northern reed grass (Calamagrostis stricta). As the bay

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emerges into St. Mary’s Channel, the substrate became increasingly rocky on the eastern shore and HU15 contained a shallow cobble/boulder habitat.

Each HU was assessed for its potential as spawning habitat for northern pike, walleye, lake whitefish, arctic grayling, lake trout, longnose sucker, white sucker, and yellow perch. The majority of the HUs provided either marginally suitable spawning habitat or unsuitable spawning habitat for all of the fish species assessed, due largely to the industrial land use and steep banks within the study location. However, small areas did contain some moderately suitable spawning habitats for all fish species assessed. Only Zeemel Bay (HUs 12 and 13) contained highly suitable spawning habitat for northern pike and yellow perch, and potential rearing habitat for northern pike.

3.12.2 Langley Bay

A total of 14 HUs were identified in Langley Bay. Table 30 provides a detailed description of each HU (Table 29 provides the legend) and Figure 16 shows the position of each HU identified within Langley Bay.

The upland area surrounding Langley Bay contained a mature, mixed forest. Near the mouth of the bay (HUs 1, 2, and 14), the aquatic/wetland vegetation was generally sparse to moderate and the substrate was rocky (Appendix D, Photo 7). Within the bay, there were small areas with no vegetation (HUs 3, 7, and 13; Appendix D, Photo 8), however, the majority of the HUs contained moderate to dense stands of emergent macrophytes (Appendix D, Photo 9). With the exception of the tailings area discussed below, the substrate throughout the bay was mainly cobble/boulder with some sand and gravel.

The south and eastern portions of Langley Bay constituted the area of Gunnar tailings deposition within the bay. Historically, Langley Bay extended through this area and included Back Bay, however, the volume of tailings discharged into the bay resulted in the separation of the bay into two basins. During the assessment, the area surrounding the creek mouth adjoining Langley Bay to Back Bay (HU 9) supported sparse densities of vegetation in the riparian and littoral zones (Appendix D, Photo 10). The substrate consisted of tailings fines and, unlike the remainder of the littoral habitat units in Langley Bay, was completely void of rocks. The depth remained shallow (<0.5 m) until approximately 20 to 30 m into the bay perpendicular to the shore. The tailings area extended along the eastern shore and covered a large portion of the Langley Bay

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shoreline (HU10). In HU10, the upland and riparian zones were similar to the remainder of the bay and the littoral zone was largely covered in a good diversity (number of taxa = 10) and density of mainly emergent aquatic/wetland macrophytes (Appendix D, Photo 11). The creek connecting Langley Bay to Back Bay was lined with high densities of emergent plant species, particularly cattails (Typha latifolia; Appendix D, Photo 12).

The HUs in Langley Bay were assessed for critical habitat potential for the same fish species as the study area in St. Mary’s Channel. Langley Bay had an abundance of moderately suitable spawning habitat for walleye, lake whitefish, northern pike, and yellow perch due to the high densities of shallow cobble areas with near shore emergent aquatic/wetland vegetation. The tailings area, HU 9, did not contain any potential spawning habitat for the fish species assessed, however, in HU10 there was moderately suitable spawning habitat for northern pike and yellow perch due to the abundance of shallow areas supporting emergent vegetation.

3.12.3 Back Bay

Back Bay was separated from the main body of Lake Athabasca by former tailings deposition from the Gunnar mine site, however, it remains connected to Langley Bay through a narrow, intermittent channel. The amount of water in the channel varies seasonally and annually. During the September 2005 survey, the water level was higher than in September 2004 (Appendix D, Photos 12 to 14), and the channel was passable by boat. There was a high diversity of aquatic macrophytes in the channel consisting predominantly of sedge and cattails. The channel width ranged from 4 to 8 m and the depths ranged from 0.7 to 1 m. At the time of the survey, beaver (Castor canadensis) activity was observed in the study area.

The habitat assessment completed in Back Bay in September 2005 resulted in the description of 10 HUs (Table 31; Figure 17). A photographic record of each unit is presented in Appendix D, Photos 15 to 24. Similar to Langley Bay, Back Bay is surrounded by a mature, mixed forest, with the exception of the upland area of HU4 where the regenerating tailings beach is located (Appendix D, Photo 18).

The deepest part of Back Bay was near the bedrock outcropping on the south side of the bay (HUs 1 and 10). The remainder of the bay contained a gentle to moderately sloped lake bottom with high densities of aquatic vegetation. The predominant emergent

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vegetation was marsh reed grass (Calamagrostis canadensis), water sedge, and cattails and the predominant submergent vegetation was Eurasian watermilfoil (Myriophyllum spicatum). There were high densities of moss/algae, particularly in the area nearest to the tailings beach (HUs 2, 3, and 4). In the eastern part of the bay, the substrate consisted mostly of silt/clay/tailings, although rock could be felt underneath. In the western part of the bay (HUs 6 to 10), the substrate contained a high cobble/boulder content.

Although only northern pike were captured in Back Bay during the survey, the habitat spawning suitability was assessed for the same large-bodied fish species as in the other study areas since these species have the potential of migrating to Back Bay. There was an abundance of marginally to moderately suitable spawning habitat for northern pike and yellow perch, however, large densities of submergent vegetation and algae precluded the habitat from being rated as highly suitable. Suitable spawning habitat for other fish species was not identified.

A total of ten northern pike were captured in Back Bay during the survey and it is possible that they are using the bay as spawning and/or rearing grounds. In addition, Back Bay is sufficiently deep that it could provide overwintering habitat, thus there is the potential for fish to reside there year-round.

3.12.4 Dixon Bay

Dixon Bay contains a diversity of habitat types that are typical of those found throughout Lake Athabasca. In the study area of Dixon Bay, 15 HUs were identified. Detailed descriptions are provided in Table 32, locations of each HU are shown in Figure 18, and photographic records are presented in Appendix D, Photos 25 to 39. The upland zone consisted of a mature, mixed forest and the riparian zone contained a mixture of trees, shrubs, and grasses, with bedrock outcrops in some areas. The initial part of the study area (HUs 1 to 5) contained rocky substrate with sparse to moderate densities of vegetation. These areas provide potential spawning habitat for species that prefer to spawn on rocky substrate, including artic grayling, lake trout, lake whitefish, suckers, and walleye. The area of Dixon Bay sheltered behind the island (HUs 12 to 15) contained high densities of emergent aquatic/wetland macrophytes, especially sedge, which provide good spawning habitat for northern pike and yellow perch.

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4.0 SUMMARY AND DISCUSSION 4.1 St. Mary’s Channel

The results of the 2004 and 2005 surveys completed in the study area of St. Mary’s Channel demonstrated a high level of water quality, with all parameter concentrations below provincial and federal guidelines. Biotic indices calculated for the zooplankton and phytoplankton samples indicated that evenly distributed, diverse communities were residing in the water column of St. Mary’s Channel. In the northern pike and lake whitefish samples, the only analyte with levels notably higher than in the reference fish was uranium. This is interesting since the fish were captured at the mouth of Zeemel Bay, which contained elevated uranium levels in the water, sediment, and sedge samples collected at the station near the seepage site from the Gunnar mine site waste rock pile (refer to Section 4.2 below). Considering that large volumes of water flow through St. Mary’s Channel, it is not surprising that there are no direct signs of contamination in the water column and little evidence of impacts on the biota that reside there.

Metal concentrations in the sediment samples from St. Mary’s Channel were all below CCME (2005) guidelines, with the exception of chromium. However, sediment chromium concentrations in Dixon Bay were also above the guideline, indicating that naturally high chromium levels occur in areas of Lake Athabasca. Sediment radionuclide concentrations in St. Mary’s Channel were higher at stations 1 and 2, located near the channel that previously connected Gunnar pit to Lake Athabasca. Although the sample size is small, these results suggest that there may be some localized sediment contamination resulting from historical mining activities.

Benthic macroinvertebrate communities in the study area of St. Mary’s Channel contained a high number of taxa (35), however, diversity indices were lower due to a high abundance of amphipods, Diporeia hoyi, from the Family Haustoriidae. In general, amphipods are not considered highly pollution tolerant taxa and Diporeia spp. are common in benthic communities of oligotrophic waters (Sibley et al. 2000; Mandaville 2002). In the Great Lakes, Diporeia spp. is a keystone species, present in high abundances, and they provide a main food source for numerous bottom-feeding fish (Nalepa et al. 2000; Owens and Dittman 2003). Therefore, it is postulated that the high abundance of this species in St. Mary’s Channel acts as an important food source for the fish residing in the area and its high abundance is not linked to contaminant exposure.

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During the 2004 and 2005 fish surveys, six species of fish were captured in the study area, with northern pike being the most numerically dominant. The fish community in the study area was diverse and abundant. The aquatic habitat located near the Gunnar mine site infrastructure may provide additional fish cover in the area, but was not considered good critical habitat for the large-bodied fish species residing there.

In summary, the potential environmental concerns identified in the study area of St. Mary’s Channel during the 2004 and 2005 aquatic investigations included: 1) elevated radionuclide levels measured in the sediment near the channel that previously connected Gunnar pit to Lake Athabasca, and 2) higher uranium levels in the fish tissues when compared to the fish from the reference area.

4.2 Zeemel Bay

Zeemel Bay was studied as part of the St. Mary’s Channel study area during the 2004 aquatic investigations. It was found to contain highly suitable critical habitat for northern pike due to the high densities of aquatic macrophytes, particularly sedge. The presence of juvenile northern pike residing in Zeemel Bay was confirmed by electrofishing and a large number of adult northern pike were captured at the mouth of the bay in St. Mary’s Channel. The 2004 study concluded that since Zeemel Bay receives water from a waste rock seep and may be an important habitat for northern pike, further studies were warranted (SRC 2005).

The water, sediment, and sedge chemistry data collected in September 2005 showed that Zeemel Bay contains elevated uranium levels near the location of the seep from the waste rock pile. The data suggests that the impact in Zeemel Bay is localized. For example, sediment uranium levels at the stations located near the seep were 219 and 316 µg/g, while the station located closer to the mouth of Zeemel Bay contained a uranium level of 7 µg/g, which is similar to reference (mean = 6.6 µg/g).

Currently, there are no environmental quality objectives in Canada for uranium. Some laboratory studies have been completed examining uranium toxicity to various freshwater organisms through water or sediment exposure. A recent study commissioned by the Canadian Nuclear Safety Commission examined uranium toxicity in the water to six freshwater species (Vizon 2004). In general, the study found that Hyalella azteca, Ceriodaphnia dubia, and Selenastrum capricornutum were the most sensitive species

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with toxicity estimates ranging between 17 and 340 µg/L. A laboratory study examining the effects of uranium exposure to white sucker eggs collected from northern Saskatchewan found that there were no significant effects on survival and that fry displayed significantly lower mean weights and lengths only at the highest exposure concentration of 25,600 µg/L (Liber et al. 2004). The study mentions that lake trout and northern pike fry displayed very comparable toxicity responses. Spiked sediment toxicity 15 tests completed by Beak (1998) identified an LC50 value for uranium of 57 µg/g for juvenile Hyalella azteca and 436 µg/g for adults.

It is noted that the laboratory studies examined uranium toxicity exposure strictly through one medium (i.e., water or sediment) and do not account for cumulative exposure that may occur in Zeemel Bay through the water, plants, and sediment. The uranium level measured in the water sample of Zeemel Bay during the 2005 study was 220 µg/L, which is much lower than those found to impact fish embryo development. The sediment uranium level in Zeemel Bay was highest at Station 2, located near the seep (316 µg/g), however, this station also contained the highest abundance of Hyalella azteca out of the three samples (235 organisms). It is often difficult to apply laboratory toxicity results to the field environment, thus it is important to examine the phytoplankton, zooplankton, and benthic macroinvertebrate communities located in Zeemel Bay.

The phytoplankton data from Zeemel Bay was indicative of a diverse, numerically even community that was comparable to the reference area. However, the zooplankton and benthic macoinvertebrate communities contained abundance, richness, and diversity indices that were lower than the reference area. In the benthic macroinvertebrate samples, 82% of the taxa were from the Family Chironomidae. It is well documented that many genera of chironomids are more pollution tolerant than other taxa of benthic macroinvertebrates (Johnson et al. 1993; Beltman et al. 1999; Mandaville 2002). At Station 2, located closest to the seep, the number of chironomids from the genus Tanytarsus sp. was substantially higher than at the other stations in Zeemel Bay. Previous studies in the Uranium City area have found this genus to be dominant in sediments containing tailings from uranium mining and milling operations (CanNorth 2002, 2005).

15 LC50 is defined as the concentration of a substance that is estimated to be lethal to 50% of the test organisms over a specified period of time.

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In summary, the waste rock pile seep continues to be a source of contamination in Zeemel Bay and this will require consideration when assessing remediation strategies. There is the potential that high uranium concentrations measured near the seep are negatively impacting the biota, although a direct cause-effect relationship has not been established. In addition to the aquatic biota, the high uranium levels measured in the sedge shoot, root, and sediment samples may be a concern for terrestrial wildlife feeding on these plants.

4.3 Langley Bay

The water samples taken from the centre of Langley Bay in 2004 and 2005 indicate the only parameter which has historically been, and currently remains, above provincial guideline levels is radium-226 (0.11 Bq/L). However, the radium-226 concentrations measured in 2004 (0.16 Bq/L) and 2005 (0.12 Bq/L) are slightly lower than in previous studies (0.2 to 0.6 Bq/L) (EPS 1981; Waite et al. 1988; Beak 1989). Waite et al. (1989) found that the flux of radionuclides from the tailings material deposited on the bottom of Langley Bay provides a consistent source of dissolved radionuclides to the surface water. There may also be radium-226 entering Langley Bay through inflow from the Gunnar central tailing area or water exchange with Back Bay. The phytoplankton and zooplankton samples collected at the same station as the water samples from the centre of the bay contained densities, richness, and biotic indices that were comparable to the reference station and were indicative of diverse communities.

Radionuclide concentrations in the northern pike and lake whitefish tissues from Langley Bay were on average higher than the fish tested from the reference area in Dixon Bay. This was particularly evident in the bone samples. The effects that these body burdens have on the fish has not been extensively studied. Waite et al. (1990) found no significant differences in physiological parameters, including parasite infestations, blood hematocrit, histopathology, and condition factor, between the northern pike and lake whitefish from Langley Bay compared to a control site in Lake Athabasca. Although, the interpretation of such results is probably confounded by unknown fish migration patterns and the residency times of large-bodied fish in Langley Bay.

Sediment and sedge samples collected from areas of Langley Bay covered by deposited tailings contained substantially higher concentrations of numerous metals, trace elements, and radionuclides than the samples collected from Dixon Bay. Benthic

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macroinvertebrate samples collected at the sediment sampling stations in 2004 contained lower abundance and richness than the reference area sampled in 2005, however, the diversity indices were high in both bays reflecting diverse and numerically even communities. Similar to Zeemel Bay, the genus Tanytarsus sp. from the Family Chironomidae was the numerically dominant taxon in Langley Bay. As mentioned above, this genus is prevalent in other sediments contaminated by tailings from uranium mining and milling operations (CanNorth 2002, 2005).

The tailings area in Langley Bay is being re-colonized by a diversity of aquatic vegetation which provides habitat for fish and a food source for wildlife. Even though the fish species chemically analyzed were large-bodied and potentially migratory, their tissue samples demonstrated elevated radionuclide levels compared to the reference fish. The elevated radionuclide levels measured in all media tested indicated that there are environmental impacts in Langley Bay related to the historical tailings deposition.

4.4 Back Bay

The water quality in Back Bay contained low dissolved oxygen levels and concentrations of ions, nutrients, radionuclides, and some metals that were elevated above reference. There was a very high density of blue-green algae which formed thick blooms, particularly in the areas located closest to the tailings beach on the east side of the bay. This resulted in a high abundance, but low richness and diversity of phytoplankton in the sample retained for taxonomic analyses. Similarly, the zooplankton sample contained low richness and diversity and was dominated by a single species (70% Keratella quadrata). The only fish species identified in the bay was northern pike. Thus, the diversity of aquatic organisms residing in Back Bay was much lower than in the other study areas examined in Lake Athabasca.

The residency time of the northern pike in Back Bay is not known. There was a high density of aquatic/wetland macrophytes in the bay that could provide spawning, rearing, and feeding habitat for northern pike. Average concentrations of a few parameters, including arsenic, manganese, polonium-210, and radium-226, were higher in the northern pike from Back Bay compared to those from Langley Bay.

Sediment and sedge samples from Back Bay contained higher concentrations of numerous metals, trace elements, and all radionuclides than the reference area in Dixon

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Bay. When compared to the CCME (2005) guidelines, Back Bay sediment concentrations of copper were higher than the ISQG, and mean concentrations of arsenic and lead exceeded the PEL. Although the sediment contained elevated contaminant levels, the benthic macroinvertebrate community was reasonably abundant and diverse. Benthic macroinvertebrate abundance was higher in Back Bay than in the reference samples. The community was dominated by the Family Chironomidae (74% of the sample population), including some metal tolerant genera. However, 14 out of a total of 27 taxa were not from the Family Chironomidae and the average Simpson’s diversity and evenness indices were only slightly lower than reference.

One analyte of interest in Back Bay is manganese, which was measured in higher concentrations in all media tested when compared to the reference data. The water sample from Back Bay contained 231 times more manganese than the water sample from Dixon Bay and the remainder of the media had approximately a 3.5 fold difference. Manganese may be more prevalent in the water column of Back Bay because of its anaerobic environment since manganese has increased solubility under chemically reducing conditions (Lasier et al. 2000). The International Programme on Chemical Safety recommends an overall guidance value of 0.2 mg/L in soft water for freshwater environments (Howe et al. 2004). However, numerous toxicity tests have shown that manganese concentrations in the water need to be higher than those measured in Back Bay (0.37 mg/L) to elicit toxic responses in freshwater organisms (Lasier et al. 2000; Howe et al. 2004).

In summary, the ecosystem in Back Bay differs from the remainder of Lake Athabasca as a result of its separation from the waterbody by tailings deposition. The bay contains high contaminant levels, large algal blooms, and it appears that northern pike are the only fish species utilizing it. Back Bay is of a sufficient size and depth to provide year-round fish habitat. In addition, the channel connecting Back Bay to Langley Bay permits fish migration when water levels are adequately high. At the time of the survey, Back Bay contained a high diversity and density of migratory ducks and there was beaver activity in the channel. Therefore, the habitat provided by Back Bay is used by aquatic and terrestrial wildlife who would be subject to contaminant exposure from the tailings area.

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5.0 LITERATURE CITED

Augier, Delbert. September 2005. Personal communication. Uranium City, Saskatchewan.

Atton, F.M. and J.J. Merkowsky. 1983. Atlas of Saskatchewan fish. Sask. Dept. Parks Renew. Resources, Fish. Tech. Rep. 83-2. 281 pp.

BEAK Consultants Limited (Beak). 1989. An evaluation of potential environmental and public safety impacts of Gunnar and Lorado facilities in northern Saskatchewan, Volume 1: Summary of existing baseline data. 14 Abacus Road, Brampton, Ontario L6T 5B7.

BEAK International Inc. (Beak). 1998. Toxicity of uranium and trace metals discharged to the aquatic environment. Prepared for the Canadian Nuclear Safety Commission, Ottawa, Ontario.

Beltman, D.J., W.H. Clements, J. Lipton, and D. Cacela. 1999. Benthic macroinvertebrate metals exposure, accumulation, and community-level effects downstream from a hard-rock mine site. Env. Toxicol. Chem. 18(2): 299-307.

Bishop, F.G. 1971. Observations on spawning habitats and fecundity of the arctic grayling. Prog. Fish-Cult. 3:12-19.

Brown, C.J.D. 1938. Observations on the life history and breeding habits of the Montana grayling. Copeia 1938(3):132-139.

Busch, W.D., R.L. Scholl, and W.L. Hartman. 1975. Environmental factors affecting the strength of walleye (Stizostedion vitreum) year-classes in western Lake Erie, 1960-70. J. Fish. Res. Board Can. 32:1733-1743.

Busch W.D.N., and P.G. Sly. 1992. The development of an aquatic habitat classification system for lakes. CRC Press, Boca Raton. 225 pp.

Canadian Council of Ministers of the Environment (CCME). 2005. Canadian environmental quality guidelines. Canadian Council of Ministers of the Environment, Winnipeg, Manitoba.

Canada North Environmental Services (CanNorth). 2000. Field sampling methodologies and standard operating procedures.

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