A water quality snapshot of Grafton Lake, Nexwlélexwm (Bowen Island)
Published on 2025 June 9.
DOI: 10.70766/31.2601
Ross PS, Scott S, Noël M. 2025. A water quality snapshot of Grafton Lake, Nexwlélexwm (Bowen Island). Raincoast Conservation Foundation. DOI: 10.70766/31.2601
Acknowledgements
We acknowledge the expert analytical support of Pam MacKenzie and Richard Grace at SGS-AXYS. We thank Raincoast colleagues Brooke Gerle for map design, and Sherwin Arnott for design and formatting. We gratefully acknowledge Margit Brenner, William D. Husby, Gregory Pollard, Kim A. Stephens (Partnership for Water Sustainability in BC ) and Bob Turner for invaluable feedback on an earlier version of this report. Photos by Peter S. Ross.
Executive summary
Water is essential for life, and steps are needed to understand, protect and restore its health throughout British Columbia (BC). The Raincoast Healthy Waters program (Raincoast Conservation Foundation) was launched in 2023 and conducts community-oriented water pollution monitoring in partnering BC watersheds.
The Healthy Waters team conducted a one-time visit to sample water at the outflow from Grafton Lake on Bowen Island (Figure 1), BC, on October 8, 2024. This ‘snapshot’ assessment was used to compare against the more comprehensive sampling done in other watersheds, and contributes to an understanding of threats to water quality, monitoring options and action priorities for the community.
The composite sample was analysed for coliform, nutrients (6), physical parameters, metals (37), pesticides (62), polycyclic aromatic hydrocarbons (PAHs; 76), pharmaceuticals and personal care products (PPCPs; 141), polychlorinated biphenyls (PCBs; 209), alkylphenol ethoxylates (APEs; 4), bisphenols (BPs; 6), per- and poly-fluoroalkyl substances (PFAS; 40), and sucralose. Results for the tire chemical breakdown product 6PPD-Quinone are pending. Results from Grafton Lake were compared to samples collected from source water (i.e. above built-up environments and generally an upstream reference sample for the watershed) in 12 other BC watersheds. Results were also compared to pertinent Drinking Water Quality Guidelines from Health Canada (n=35), Environmental Quality Guidelines from BC (n=56), the Canadian Council of Ministers of the Environment (n=43), and Federal Environmental Quality Guidelines (n=7).
We detected 125 contaminants out of 587 measured in Grafton Lake, excluding nutrients, fecal coliform and physical parameters. Grafton Lake ranked 8th most contaminated overall out of 21 source water samples from 12 watersheds in BC. This ranking was driven by relatively high concentrations of the human waste tracer sucralose (ranked 1 of 21), PCBs (3 of 21), PAHs (3 of 21), PPCPs (6 of 21), and PFAS (6 of 21). There were no exceedances of available Drinking Water Guidelines (for which we have Guidelines for just 6% of our analytes) or Environmental Quality Guidelines (for which we have Guidelines for just 10% of our analytes).
This lake is an important source of drinking water for Bowen island, as well as habitat for coho salmon and cutthroat trout. A combination of human waste and atmospheric deposition of pollutants into a relatively shallow lake (average depth 8.8 m; maximum depth 16 m; perimeter 14.7 km2) appear to be driving water quality profiles in Grafton Lake.
These initial findings point to the value of monitoring and enhanced protection measures for this important water body on Bowen Island, which serves people, fish and wildlife.
Key findings
- This preliminary assessment of water quality in the Grafton Lake watershed on Bowen Island (BC) reflects a one-time sampling visit, based on a single large sample, and a comprehensive analysis of a variety of contaminants.
- Grafton Lake ranked 8th most contaminated out of 21 source water samples analysed by Raincoast in 12 watersheds across BC, based on the average rankings for the concentrations of all contaminant classes.
- Overall, Grafton Lake had fair water quality:
- There were no exceedances of Health Canada Drinking Water Quality Guidelines (DWGs).
- There were no exceedances of Environmental Quality Guidelines (EQGs: BC, federal and CCME).
- There are DWGs for only 6% of the contaminants we measured, and EQGs for just 10%, constraining our ability to evaluate many contaminants of concern.
- Traces of several pharmaceuticals and personal care products, and some industrial chemicals, suggest that human activities in or adjacent to the lake are affecting water quality.
- Concentrations of Arsenic, Zinc and Lead were high relative to other metals and to other BC watersheds, but fell within Drinking Water Quality Guidelines.
- Moderate levels of certain pesticides, PCBs and PAHs suggest that the atmosphere also delivers contaminants to this lake from distant sources.
- Grafton Lake is highly vulnerable to a deterioration of water quality as a function of its small size and relatively shallow nature, an impervious nearby road, recreational access to the shoreline and lake, and an encroaching built-up environment supported by septic fields in the upstream reaches of the watershed.
- Previous assessments have noted water quality concerns related to failing septic systems, and identified the monitoring and mitigation of fecal coliform contamination of the lake.
- Excellent educational materials produced in recent decades for Bowen Island provide an opportunity to update public educational initiatives based on new scientific findings, new project developments on Bowen Island, and consumer awareness concerns (Turner et al 2005).
- Our findings highlight the importance of monitoring, source control and best practices within the watershed in order to protect drinking water for residents and protect aquatic habitats for fish and wildlife into the future.
Figure 1: The Grafton Lake Watershed, Bowen Island, BC
General introduction
Background
Raincoast’s Healthy Waters Program delivers high-resolution, community-oriented water quality analysis to watersheds across southern British Columbia (Figure 2). The goal of Healthy Waters is to empower communities with the understanding of the status of water quality in their watersheds, and to allow for local stewardship regarding both point and nonpoint source pollution.
”A watershed is the area of land that drains into rivers and lakes, which, in turn, flow to a common outlet. Watersheds are separated from one another by the height of the land” (- Agriculture Canada)Grafton Lake collects rainwater from a third of the Bowen Island (Nexwlélexwm) landmass. Grafton Lake provides drinking water to approximately 48% of the island’s 4,000 residents among 650 homes and businesses as part of the Cove Bay Water System. Freshwater quantity and quality remain significant concerns on islands (Turner et al, 2005).
Source water from Grafton Lake is chlorinated to protect human health from potential pathogens, but there exists a boil water advisory for people with compromised immune systems (Bowen Island Municipality). While the addition of chlorine destroys many pathogens prior to distribution to homes and businesses, an unintended consequence is that the chlorine creates carcinogenic by-products (trihalomethanes or THMs) as a result of interactions with organic material in lake water.
With THM levels in treated drinking water chronically exceeding Health Canada Drinking Water Quality Guidelines, the Vancouver Coastal Health Authority asked the Municipality of Bowen Island in 2014 to build a treatment plant to address the issue of E. coli, viruses and parasites, turbidity, manganese, THMs and cysts before distribution of drinking water. Grafton Lake also supports fish habitat in downstream Terminal Creek and the estuary at Kwilákm (Deep Bay/Mannion Bay; Bowen Island Conservancy), and supplies water for the Bowen Island fish hatchery (Bowen Island Fish and Wildlife Club).
The Raincoast Healthy Waters program conducted a one-time spot sampling of Grafton Lake water on October 8, 2024, and submitted samples to partnering service laboratories for the analysis of nutrients, metals, physical parameters, fecal coliform, pesticides, polychlorinated biphenyls (PCBs), alkylphenol ethoxylates (APEs), bisphenols (BPs), per- and poly-fluoroalkyl substances (PFAS), pharmaceuticals and personal care products, polycyclic aromatic hydrocarbons (PAHs), and sucralose (Splenda).The Raincoast Healthy Waters program typically collects water twice a year from five water categories within partnering watersheds in BC. These include source water, which serves as an upstream reference sample, allowing us to determine which contaminants are being introduced as water traces its path down through the watershed. We also sample stream and river samples to investigate the quality of fish habitat; road runoff which serves as an impacted sample category of current concern, as many contaminants can be washed off roadways and into fish habitat; tap water samples from a dozen residents or businesses provides a means to bring our homes into the conversation – we borrow water from the environment in the form of municipal or well water, and generally return it to aquatic habitats in a more-degraded state in the form of storm and sewage effluent (treated or untreated); and marine water samples, which provide insight into those contaminants that end up in the ocean adjacent to our watersheds. Funding is secured by Raincoast from a variety of sources, including MetroVancouver, Capital Regional District, Port of Vancouver, the federal department of Fisheries and Oceans Canada, Indigenous Nations, the Vancouver Foundation and the Whistler Lakes Conservation Foundation.
Figure 2: Water quality results from this Grafton Lake snapshot study were compared against ‘source water’ samples collected in other BC watersheds, thereby providing a means to interpret findings
High costs precluded a fulsome evaluation of a comprehensive water quality approach across the watershed, but this study provides an initial glimpse into issues of potential concern. The collection and analysis of a source water sample from Grafton Lake on Bowen Island provides a snapshot of threats to water quality, the activities likely contributing to its degradation, and data to inform source control or remediation.
Methods
Field sampling
A single, composite water sample (12L) was collected from Grafton Lake on Bowen Island, BC on October 8, 2024, using a pre-cleaned stainless steel container.
A portable water properties meter (YSI-ProDSS) was deployed in situ to measure temperature, pH, conductivity, dissolved oxygen and turbidity.
Samples were submitted to two service labs: ALS Environmental (Burnaby BC) and SGS-AXYS (Sidney BC). Contaminant analyses were determined in water samples according to established protocols (see Appendix 2A).
Data handling
In some cases, contaminants were not detected and concentrations were therefore considered to be 0 for the calculations of totals.
With each batch of samples, analytical laboratories also ran blank samples (e.g. samples that go through the same laboratory processes as our environmental samples) that should, in theory, not contain any contaminants. However, in some cases, blank samples contained low concentrations of some contaminants. These levels were subtracted from the concentrations measured in each of our environmental samples (‘blank correction’).
Comparison to other Healthy Waters findings
Grafton Lake data were compared to findings from 21 other source water samples collected in 12 BC watersheds as part of the Raincoast Healthy Waters program. Reports are available for these other watersheds and for an assessment of water quality in the Sumas area during the floods of late 2021 (Ross et al 2022).
Comparison to Drinking Water (DWQGs) and Environmental Quality Guidelines (EQGs)
While the majority of analytes that we measured have no Guidelines available against which to evaluate, those with Guidelines available were compared against pertinent Drinking Water Quality Guidelines from Health Canada (n=35), Environmental Quality Guidelines from BC (n=56), the Canadian Council of Ministers of the Environment (n=43), and Federal Environmental Quality Guidelines (n=7) (Appendix 5A).
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References
Agriculture Canada: Understanding watersheds [cited 2025 May 26]: https://agriculture.canada.ca/en/environment/resource-management/managing-water-sustainably/understanding-watersheds#a1
Barzen-Hanson KA, Roberts SC, Choyke S, Oetjen K, McAlees A, Riddell N, McCrindle R, Ferguson PL, Higgins CP, Field JA. 2017. Discovery of 40 Classes of Per- and Polyfluoroalkyl Substances in Historical Aqueous Film-Forming Foams (AFFFs) and AFFF-Impacted Groundwater. Environmental Science & Technology. 51(4):2047–2057. doi: https://doi.org/10.1021/acs.est.6b05843.
Berthiaume A, Galarneau E, Marson G. 2021. Polycyclic aromatic compounds (PACs) in the Canadian environment: Sources and emissions. Environmental Pollution. 269:116008. doi: https://doi.org/10.1016/j.envpol.2020.116008.
Bowen Island Fish and Wildlife Club. [Cited 2025 May 26]. Available from: https://bowenhatchery.org/
Bowen Island Conservancy: Discovering Kwilákm. Available from: https://bowenislandconservancy.org/stories/discovering-kwila%CC%93km/
Bowen Island Municipality: Cove Bay Water System: Advisory for people with compromised immune systems. [Cited 2025 May 26]. Available from: https://bowenislandmunicipality.ca/services/water-and-sewer/drinking-water-advisory/
British Columbia. Available from: https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/fish-fish-habitat/riparian-areas-regulations/rar-brochure-2016_final_web.pdf
British Columbia Ministry of Environment and Climate Change Strategy. Approved Water Quality Guidelines. [cited 2025 May 29]. Available from:
B.C. Ministry of Water, Land and Resource Stewardship 2025. Working Water Quality Guidelines: Aquatic Life, Wildlife & Agriculture. Water Quality Guideline Series, WQG-08-01. Prov. B.C., Victoria B.C. Available from: https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/waterquality/water-quality-guidelines/bc_working_water_quality_guidelines.pdf
British Columbia Medications Return Program. British Columbia Pharmacy Association. Available from: https://www.bcpharmacy.ca/resource-centre/health-issues/medication-return
Canadian Council of Ministers of the Environment. 1999. Canadian Sediment Quality Guidelines for the protection of aquatic life: Endrin. [cited 2025 May 7] Available from: https://www.ccme.ca/en/res/endrin-canadian-sediment-quality-guidelines-for-the-protection-of-aquatic-life-en.pdf
CCME (Canadian Council of Ministers of the Environment). 1999. Canadian water quality guidelines for the protection of aquatic life–Dissolved oxygen (freshwater). Winnipeg. [cited 2025 May 7] Available from: https://ccme.ca/en/res/dissolved-oxygen-freshwater-en-canadian-water-quality-guidelines-for-the-protection-of-aquatic-life.pdf
Canadian Council of Ministers of the Environment. 2010. Canadian water quality guidelines for the protection of aquatic life: Ammonia. In: Canadian environmental quality guidelines, 1999, Canadian Council of Ministers of the Environment, Winnipeg. [cited 2025 May 7] Available from: https://ccme.ca/en/res/ammonia-en-canadian-water-quality-guidelines-for-the-protection-of-aquatic-life.pdf
CCME (Canadian Council of Ministers of the Environment). 2016. Guidance Manual For Developing Nutrient Guidelines For Rivers and Streams. [cited 2025 May 7] Available from: https://ccme.ca/en/res/guidancemanualfordevelopingnutrientguidelinesforriversandstreams.pdf
Davis JC. 1975. Minimal Dissolved Oxygen Requirements of Aquatic Life with Emphasis on Canadian Species: a Review. Journal of the Fisheries Research Board of Canada. 32(12):2295–2332. doi: https://doi.org/10.1139/f75-268.
Ding Y, Hayward SJ, Westgate JN, Brown TN, Lei YD, Wania F. 2023. Legacy and current-use pesticides in Western Canadian mountain air: Influence of pesticide sales, source proximity, and altitude. Atmospheric Environment. 308:119882–119882. doi: https://doi.org/10.1016/j.atmosenv.2023.119882.
Dongyoung Lee, Kyungho Choi. 2019. Comparison of regulatory frameworks of environmental risk assessments for human pharmaceuticals in EU, USA, and Canada. Science of The Total Environment 671, 1026-1035. https://doi.org/10.1016/j.scitotenv.2019.03.372.
Environment and Climate Change Canada (ECCC). 2023. Update on Canada’s National Implementation plan – Under the Stockholm Convention on Persistent Organic Pollutants. [cited 2025 May 7] Available from: https://www.canada.ca/content/dam/eccc/documents/pdf/cepa/En14-517-2023-eng.pdf.
Environment and Climate Change Canada (ECCC) and Health Canada. 2023. Draft State of Per and polyfluoroalkyl substances (PFAS). [cited 2025 May 7] Available from: https://www.canada.ca/en/environment-climate-change/services/evaluating-existing-substances/draft-state-per-polyfluoroalkyl-substances-report.html.
Environmental 360 Solutions [cited 2025 May 27]. Available from https://www.bcpharmacy.ca/resource-centre/health-issues/medication-return
FNHA. First Nations Health Authority. 2025. [cited 2025 May 29]. Available from: https://www.fnha.ca/what-we-do/environmental-health/drinking-water-safety-program
Giardina A, Larson SF, Wisner B, Wheeler J, Chao M. 2009. Long-term and Acute Effects of Zinc Contamination of a Stream on Fish Mortality and Physiology. Environmental Toxicology and Chemistry 28(2): 287. doi: https://doi.org/10.1897/07-461.1.
Georgia Strait Alliance. ToxicSmart. Available from: https://georgiastrait.org/education-and-outreach/toxic-smart-solutions/
Government of Canada, Environment and Climate Change Canada and Health Canada. 1994. Canadian Environmental Protection Act – Priority substances list assessment report – Polycyclic Aromatic Hydrocarbons. [cited 2025 May 7] Available from: https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/psl1-lsp1/hydrocarb_aromat_polycycl/hydrocarbons-hydrocarbures-eng.pdf.
Government of Canada. 2025. Available from: https://www.canada.ca/en/health-canada/services/chemical-substances/fact-sheets/federal-environmental-quality-guidelines.html
Government of Canada. 2017. Toxic substances list – hexachlorobenzene (HCB). [cited 2025 May 7] Available from: https://www.canada.ca/en/environment-climate-change/services/management-toxic-substances/list-canadian-environmental-protection-act/hexachlorobenzene.html.
Grafton Lake, BC MoE Habitat Wizard Lakes Report March 2025, BC Ministry of Environment. [cited 2025 May 27] Available from: https://a100.gov.bc.ca/pub/reports/rwservlet?habitat_wizard_lakes_report&p_title=%22Ministry%20of%20Environment%22&P_LAKE_ID=339951
Health Canada. 2007. Pesticides and Health. [cited 2025 May 7] Available from: https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/pesticides-eng.pdf.
Health Canada. 2010. Polychlorinated biphenyls. [cited 2025 May 7] Available from: https://www.canada.ca/en/health-canada/services/chemical-substances/fact-sheets/chemicals-glance/polychlorinated-biphenyls.html.
Health Canada. 2011. Discontinuation of endosulfan. [cited 2025 May 7] Available from: https://publications.gc.ca/collections/collection_2011/sc-hc/H113-5-2011-1-eng.pdf.
Health Canada. 2016. Special review of simazine: proposed decision for consultation. [cited 2025 May 7] Available from: https://publications.gc.ca/collections/collection_2016/sc-hc/H113-5-2016-9-eng.pdf.
Health Canada. 2023. Per- and poly-fluoroalkyl substances in drinking water. [cited 2025 May 29]. Available from: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/water-quality/water-talk-per-polyfluoroalkyl-substances-drinking-water.html
Health Canada. 2025. Guidelines for Canadian Drinking Water Quality. [cited 2025 May 29]. Available from:
Hirvonen, HE. 1976. Bowen Island: A Landscape Analysis. Canadian Forestry Service. Victoria, British Columbia Report BC-X-122. [cited 2025 May 7] Available from: https://publications.gc.ca/collections/collection_2020/eccc/fo143/Fo143-5-122-eng.pdf
Jadaa W, Mohammed H. 2023. Heavy Metals – Definition, Natural and Anthropogenic Sources of Releasing into Ecosystems, Toxicity, and Removal Methods – An Overview Study. Journal of Ecological Engineering. 24(6):249–271. doi: https://doi.org/10.12911/22998993/162955.
La VT, Cooke SJ. 2010. Advancing the Science and Practice of Fish Kill Investigations. Reviews in Fisheries Science. 19(1):21–33. doi: https://doi.org/10.1080/10641262.2010.531793.
La Guardia MJ, Hale RC, Harvey E, Mainor TM. 2001. Alkylphenol Ethoxylate Degradation Products in Land-Applied Sewage Sludge (Biosolids). Environmental Science & Technology. 35(24):4798–4804. doi: https://doi.org/10.1021/es0109040.
Lalonde B, Garron C. 2021. Nonylphenol, Octylphenol, and Nonylphenol Ethoxylates Dissemination in the Canadian Freshwater Environment. Archives of Environmental Contamination and Toxicology. 80(2):319–330. doi: https://doi.org/10.1007/s00244-020-00807-x.
Li E, Saleem F, Edge TA, Schellhorn HE. 2021. Biological Indicators for Fecal Pollution Detection and Source Tracking: A Review. Processes. 9(11):2058. doi: https://doi.org/10.3390/pr9112058.
Lo BP, Marlatt VL, Liao X, Reger S, Carys Gallilee, Andrew R.S. Ross, Brown TM. 2023. Acute Toxicity of 6PPD‐Quinone to Early Life Stage Juvenile Chinook (Oncorhynchus tshawytscha) and Coho (Oncorhynchus kisutch) Salmon. Environmental Toxicology and Chemistry. 42(4):815–822. doi: https://doi.org/10.1002/etc.5568.
Longpré D, Lorusso L, Levicki C, Carrier R, Cureton P. 2020. PFOS, PFOA, LC-PFCAS, and certain other PFAS: A focus on Canadian guidelines and guidance for contaminated sites management. Environmental Technology & Innovation. 18:100752. doi: https://doi.org/10.1016/j.eti.2020.100752.
Malhotra N, Ger T-R, Uapipatanakul B, Huang J-C, Chen KH-C ., Hsiao C-D. 2020. Review of Copper and Copper Nanoparticle Toxicity in Fish. Nanomaterials. 10(6):1126. doi: https://doi.org/10.3390/nano10061126.
Marvin CH, Berthiaume A, Burniston DA, Chibwe L, Dove A, Evans M, Hewitt LM, Hodson PV, Muir DCG, Parrott J, et al. 2021. Polycyclic aromatic compounds in the Canadian Environment: Aquatic and terrestrial environments. Environmental Pollution. 285:117442. doi: https://doi.org/10.1016/j.envpol.2021.117442.
MetroVancouver. Managing stormwater in your yard. Available from: https://metrovancouver.org/services/liquid-waste/managing-stormwater-in-your-yard
Faheem M, Bhandari RK. 2021. Detrimental Effects of Bisphenol Compounds on Physiology and Reproduction in Fish: A Literature Review. Environmental Toxicology and Pharmacology. 81:103497. doi: https://doi.org/10.1016/j.etap.2020.103497.
Metcalfe C, Miao X-S ., Hua W, Letcher R, Servos M. 2004. Pharmaceuticals in the Canadian Environment. Pharmaceuticals in the Environment: 67–90. doi: https://doi.org/10.1007/978-3-662-09259-0_6.
Möller A, Ahrens L, Surm R, Westerveld J, van der Wielen F, Ebinghaus R, de Voogt P. 2010. Distribution and sources of polyfluoroalkyl substances (PFAS) in the River Rhine watershed. Environmental Pollution. 158(10):3243–3250. doi: https://doi.org/10.1016/j.envpol.2010.07.019.
Noël M, Dangerfield N, Hourston RAS, Belzer W, Shaw P, Yunker MB, Ross PS. 2009. Do trans-Pacific air masses deliver PBDEs to coastal British Columbia, Canada? Environmental Pollution. 157(12):3404–3412. doi: https://doi.org/10.1016/j.envpol.2009.06.025.
Oppenheimer J, Eaton A, Badruzzaman M, Haghani AW, Jacangelo JG. 2011. Occurrence and suitability of sucralose as an indicator compound of wastewater loading to surface waters in urbanized regions. Water Research. 45(13):4019–4027. doi: https://doi.org/10.1016/j.watres.2011.05.014.
Othman N, Ismail Z, Selamat MI, Sheikh Abdul Kadir SH, Shibraumalisi NA. 2022. A Review of Polychlorinated Biphenyls (PCBs) Pollution in the Air: Where and How Much Are We Exposed to? International Journal of Environmental Research and Public Health. 19(21):13923. doi: https://doi.org/10.3390/ijerph192113923.
PMRA (Pest Management Regulatory Agency; Health Canada). [cited 2025 Mat 29). Available from: https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/pesticides-eng.pdf
Putt AE, MacIsaac EA, Herunter HE, Cooper AB, Selbie DT. 2019. Eutrophication forcings on a peri-urban lake ecosystem: Context for integrated watershed to airshed management. Swann G, editor. PLOS ONE. 14(7):e0219241. doi: https://doi.org/10.1371/journal.pone.0219241.
Raincoast Conservation Foundation (a), Sidney BC: https://www.raincoast.org/waters/
Raincoast Conservation Foundation (b), Sidney BC: https://www.raincoast.org/press/groups-urge-federal-government-to-investigate-tire-chemical-implicated-in-mass-salmon-deaths/
de Sousa DNR, Mozeto AA, Carneiro RL, Fadini PS. 2014. Electrical conductivity and emerging contaminants as markers of surface freshwater contamination by wastewater. Science of The Total Environment. 484:19–26. doi: https://doi.org/10.1016/j.scitotenv.2014.02.135.
Rochester JR. 2013. Bisphenol A and human health: A review of the literature. Reproductive Toxicology. 42(42):132–155. doi: https://doi.org/10.1016/j.reprotox.2013.08.008.
Ross PS, Ellis GM, Ikonomou MG, Barrett-Lennard LG, Addison RF. 2000. High PCB Concentrations in Free-Ranging Pacific Killer Whales, Orcinus orca: Effects of Age, Sex and Dietary Preference. Marine Pollution Bulletin. 40(6):504–515. doi: https://doi.org/10.1016/s0025-326x(99)00233-7.
Ross PS, Noël M, Lambourn D, Dangerfield N, Calambokidis J, Jeffries S. 2013. Declining concentrations of persistent PCBs, PBDEs, PCDEs, and PCNs in harbor seals (Phoca vitulina) from the Salish Sea. Progress in Oceanography. 115:160–170. doi: https://doi.org/10.1016/j.pocean.2013.05.027.
Ross PS, Walters KE, Yunker M and Lo B. 2022. A lake re-emerges: Analysis of contaminants in the Semá:th X̱ó:tsa (Sumas Lake) region following the BC floods of 2021. Raincoast Conservation Foundation. Sidney BC Canada. ISBN 978-1-9993892-6-0 www.raincoast.org/reports/flood-water/
Rügner H, Schwientek M, Beckingham B, Kuch B, Grathwohl P. 2013. Turbidity as a proxy for total suspended solids (TSS) and particle facilitated pollutant transport in catchments. Environmental Earth Sciences. 69(2):373–380. doi: https://doi.org/10.1007/s12665-013-2307-1.
Rusydi AF. 2018. Correlation between conductivity and total dissolved solid in various type of water: A review. IOP Conference Series: Earth and Environmental Science. 118(1):012019. doi: https://doi.org/10.1088/1755-1315/118/1/012019.
Schulz R. 2004. Field Studies on Exposure, Effects, and Risk Mitigation of Aquatic Nonpoint-Source Insecticide Pollution: A Review. Journal of Environmental Quality. 33(2):419–448. doi: https://doi.org/10.2134/jeq2004.4190.
Schwartz H, Marushka L, Chan HM, Batal M, Sadik T, Ing A, Fediuk K, Tikhonov C. 2021. Pharmaceuticals in source waters of 95 First Nations in Canada. Canadian Journal of Public Health. 112(S1):133–153. doi: https://doi.org/10.17269/s41997-021-00499-3.
Shang DY, Macdonald RW, Ikonomou MG. 1999. Persistence of Nonylphenol Ethoxylate Surfactants and Their Primary Degradation Products in Sediments from near a Municipal Outfall in the Strait of Georgia, British Columbia, Canada. Environmental Science & Technology. 33(9):1366–1372. doi: https://doi.org/10.1021/es980966z.
Stockholm Convention. 2025. Available from: https://www.pops.int/
Tian Z et al. 2021. A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. Science 371,185-189(2021).DOI:10.1126/science.abd6951
Turner, B, Franklin R, Journeay M, Hocking D, France de Ferriere A, Chollat A, Dunster J, Whitehead A, Blair-Whitehead DG. 2005. Geological Survey of Canada Miscellaneous Report 88. Available from: https://bowenislandconservancy.org/wp-content/uploads/2017/07/Waterscape-Bowen-Island-Bowen-Water-Booklet.pdf
UBC. University of British Columbia [cited 2025 May 26]. Available from: https://news.ubc.ca/2023/12/ubc-led-initiative-protects-salmon-against-toxic-road-runoffs/
van Elsas JD, Semenov AV, Costa R, Trevors JT. 2010. Survival of Escherichia coli in the environment: fundamental and public health aspects. The ISME Journal. 5(2):173–183. doi: https://doi.org/10.1038/ismej.2010.80.
Van Stempvoort DR, Brown SJ, Spoelstra J, Garda D, Robertson WD, Smyth SA. 2020 Jul. Variable persistence of artificial sweeteners during wastewater treatment: Implications for future use as tracers. Water Research.:116124. doi: https://doi.org/10.1016/j.watres.2020.116124.
Whitehead Environmental Consultants. 2010. Review of Environmental Issues for theDevelopment of the Grafton Lake Lands, Bowen Island, BC. [cited 2025 May 7] Available from: https://bowenislandconservancy.org/files/2015-Grafton%20Lake%20Lands%20-%20Environmental%20Review%20(June%2029,%202015%20final).pdf