Quw’utsun Sta’lo’ (Cowichan River) watershed: Water quality report for the 2024 dry season

Executive summary

Water is essential for life, and steps are needed to understand, protect and restore its health in fish habitat throughout British Columbia. The Raincoast Healthy Waters program was launched in 2023 to establish community-oriented water pollution monitoring in select BC watersheds. Two Healthy Waters sampling events take place every year in each watershed, the first in the dry season (summer), and the second being in the wet season (winter). This report highlights results from the first dry (summer) season sampling carried out with the support and participation of Cowichan Tribes. 

Briefly, the Healthy Waters – Cowichan Tribes team determined basic water properties (temperature, conductivity, pH, dissolved oxygen and turbidity) in situ at sampling sites on August 7, 2024. Water samples were collected from five water categories, including source water (3 samples), stream and river water (3 samples), road runoff (3 samples), tap water (10 samples) and marine water (3 samples). The samples were pooled into composite by category and then 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. Analysis of 6PPD-quinone is pending.

We detected 126 contaminants out of 573 measured in the stream and river category – i.e. fish habitat – for the Quw’utsun Sta’lo’ (Cowichan River) watershed, excluding nutrients, fecal coliform and physical parameters. Overall, Quw’utsun Sta’lo’ (Cowichan River) water quality was relatively good. Additional sampling and analysis will provide additional insight into any sources or activities that may be impacting the health of this valued watershed.

Cowichan River watershed

Key findings

• This is the second assessment of water quality in the Quw’utsun Sta’lo’ (Cowichan River) watershed; our understanding of water quality will build on the previous assessment, and will grow with additional sampling.
• We collected and analysed water in the Quw’utsun Sta’lo’ (Cowichan River) watershed during the dry season (August 7, 2024).
• Road runoff was the most contaminated water category in the dry season; it had the highest concentrations of nitrate, pesticides, PAHs, PFAS and BPs.
• Marine and tap water were tied for the second most contaminated water categories in the dry season; with the highest concentration of metals and sucralose; and PCBs and PPCPs, respectively.
• Source, and stream and river water, were less contaminated than the above water categories in the dry season.
• The concentrations of E. coli, PCBs, and PPCPs were notably higher in the dry season compared to the previous wet season.
• Nitrate and PAHs were higher in the previous wet season compared to the current dry season.
• Overall, the Quw’utsun Sta’lo’ (Cowichan River) watershed had relatively good water quality in the dry season:
  • There were two exceedances of Canadian Environmental Quality Guidelines.
  • There were two exceedances of Health Canada Water Quality Guidelines for Recreation and for Drinking Water.

Background

Raincoast’s Healthy Waters Program (https://www.raincoast.org/waters/) delivers high-resolution, community-oriented water quality analysis to watersheds across southern British Columbia. The goal of Healthy Waters is to empower communities with the understanding of the status of water quality in their watersheds, to allow for local advocacy regarding both point and nonpoint source pollution. 

Cowichan Tribes is the largest single First Nation Band in British Columbia with over 5,000 members, approximately half of whom live on Reserve. While archaeological evidence indicates that the Cowichan People have been present in the area as far back as 4,500 years, their collective historical memory says that they have been present here since time immemorial. 

Cowichan Tribes is made up of seven traditional villages: Kwa’mutsun, Qwum’yiqun’, Xwulqw’selu, S’amunu Lhumlhumuluts’, Xinupsum, and Tl’ulpalus distributed throughout the Cowichan River watershed and beyond.

Lulumexun are the Lands and Natural Resources department of the Cowichan Tribes. Lulumexun are caregivers and guardians – preserving and protecting Quw’utsun tumuhw (lands, waters, air) and all beings. They support the advancement of self-governance, the assertion of Quw’utsun Mustimuhw inherent rights and responsibilities, and keep Quw’utsun territory thriving for future generations. Their work includes activities such as, upholding Tumuhw (land code), referrals, environmental monitoring, cultural heritage preservation, fisheries, enforcement, community security and more.

A watershed based approach to sampling

We collect samples from five different categories of water in each of our partner watersheds: from source water, upstream of human impacts, down to the marine environment. 

Source water serves as an upstream reference sample, allowing us to determine which contaminants are being introduced as water traces its path down through the watershed. 

Stream and river samples allow us to investigate the quality of fish habitat directly, by collecting samples from streams, creeks, and rivers used by salmon and other fish species (either currently or historically). 

Road runoff serves as an impacted sample category of current concern, as many contaminants, including  PAHs, metals, surfactants and chemicals such as 6-PPD quinone can be washed off roadways and into fish habitat during rain events. 

We include tap water samples in our analysis as a way 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).

Marine water samples provide insight into those contaminants that may degrade fish and whale habitat in the ocean, and enable an understanding of the contribution of land-based pollutants from the adjacent watershed to the marine environment.

Collectively, the lessons learned from our partnering watersheds will contribute to a greater understanding of threats to water quality across British Columbia, and ultimately what policy changes can be implemented to preserve the quality of water for the future of salmon, whales, and people.

References

Berthiaume, A., Galarneau, E., & Marson, G. (2021). Polycyclic aromatic compounds (PACs) in the Canadian environment: Sources and emissions. Environmental Pollution, 269, 116008. DOI: 10.1016/j.envpol.2020.116008

B.C. Ministry of Water, Land, and Resource Stewardship. 2025. 6PPD-quinone Water Quality Guidelines – Freshwater Aquatic Life. Water Quality Guideline Series, WQG-24. Prov. B.C., Victoria B.C. https://www2.gov.bc.ca/assets/gov/environment/air-land-water/water/waterquality/water-quality-guidelines/approved-wqgs/6ppd-quinon_wqg_technical_report.pdf 

Canadian Council of Ministers of the Environment, 1999. Canadian Sediment Quality Guidelines for the protection of aquatic life: Endrin. 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. 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. 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. https://ccme.ca/en/res/guidancemanualfordevelopingnutrientguidelinesforriversandstreams.pdf 

Davis, J. 1975. Minimal Dissolved Oxygen Requirements of Aquatic Life with Emphasis on Canadian Species: a Review. Journal of the Fisheries Board of Canada. DOI: 10.1139/f75-268

Ding, Y., Hayward, S. J., Westgate, J. N., Brown, T. N., Lei, Y. D., & 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. DOI: 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. DOI: 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. https://www.canada.ca/content/dam/eccc/documents/pdf/cepa/En14-517-2023-eng.pdf.  Accessed in May 2024. 

Environment and Climate Change Canada (ECCC) and Health Canada, 2023. Draft State of Per and polyfluoroalkyl substances (PFAS). https://www.canada.ca/en/environment-climate-change/services/evaluating-existing-substances/draft-state-per-polyfluoroalkyl-substances-report.html. Accessed in May 2024. 

Giardina A, Larson SE, Wisner B, Wheeler J, Chao M. Long-term and acute effects of zinc contamination of a stream on fish mortality and physiology. Environ Toxicol Chem. 2009 Feb;28(2):287-95. DOI: 10.1897/07-461.1. PMID: 18937529.

Government of Canada, Environment and Climate Change Canada and Health Canada, 1994. Canadian Environmental Protection Act – Priority substances list assessment report – Polycyclic Aromatic Hydrocarbons. 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. Accessed in May 2024.

Government of Canada, 2017. Toxic substances list – hexachlorobenzene (HCB). https://www.canada.ca/en/environment-climate-change/services/management-toxic-substances/list-canadian-environmental-protection-act/hexachlorobenzene.html. Accessed in May 2024. 

Health Canada, 2007. Pesticides and Health. https://www.canada.ca/content/dam/hc-sc/migration/hc-sc/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/pesticides-eng.pdf. Accessed in May 2024. 

Health Canada, 2010. Polychlorinated biphenyls. https://www.canada.ca/en/health-canada/services/chemical-substances/fact-sheets/chemicals-glance/polychlorinated-biphenyls.html. Accessed in May 2024. 

Health Canada, 2011. Discontinuation of endosulfan. https://publications.gc.ca/collections/collection_2011/sc-hc/H113-5-2011-1-eng.pdf. Accessed in May 2024.

Health Canada, 2016. Special review of simazine: proposed decision for consultation. https://publications.gc.ca/collections/collection_2016/sc-hc/H113-5-2016-9-eng.pdf. Accessed in May 2024.

Jadaa, W., Mohammed, H.K. 2023. Heavy Metals – Definition, Natural and Anthropogenic Sources of Releasing into Ecosystems, Toxicity, and Removal Methods – An Overview Study. J. Ecol. Eng. 2023; 24(6):249-27. DOI: 10.12911/22998993/162955

Krista A. Barzen-Hanson, Simon C. Roberts, Sarah Choyke, Karl Oetjen, Alan McAlees, Nicole Riddell, Robert McCrindle, P. Lee Ferguson, Christopher P. Higgins, and Jennifer A. Field. 2017. Environmental Science & Technology 51: 2047-2057. DOI: 10.1021/acs.est.6b05843

La, Van T. and Cooke, Steven J.(2011) ‘Advancing the Science and Practice of Fish Kill Investigations’, Reviews in Fisheries Science, 19: 1, 21 — 33, First published on: 15 December 2010 (iFirst). DOI: 10.1080/10641262.2010.531793

La Guardia, M.J., Hale, R.C., Harvey, E., and Mainor, T.M. 1999. Alkylphenol Ethoxylate Degradation Products in Land-Applied Sewage Sludge (Biosolids). Environ. Sci. Technol. 1999, 33, 9, 1366–1372. DOI: 10.1021/es980966z

Lalonde, B., Garron, C. Nonylphenol, Octylphenol, and Nonylphenol Ethoxylates Dissemination in the Canadian Freshwater Environment. Arch Environ Contam Toxicol 80, 319–330 (2021). DOI: 10.1007/s00244-020-00807-x

Li E, Saleem F, Edge TA, Schellhorn HE. Biological Indicators for Fecal Pollution Detection and Source Tracking: A Review. Processes. 2021; 9(11):2058. DOI: 10.3390/pr9112058

Lo, B. P., Marlatt, V. M., Liao, X., Reger, S., Gallilee, C., Ross, A. R. S., Brown, T. M. (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), 741-947. DOI: 10.1002/etc.5568

Longpré, D., Lorusso, L., Levicki, C., Carrier, R., and 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: 10.1016/j.eti.2020.100752

Malhotra, N., Ger, T-R., Uapipatanakul, B., Huang, J-C., Chen K. H. C., Hsiao, C-D. 2020. Review of Copper and Copper Nanoparticle Toxicity in Fish. Nanomaterials. 10(6), 1126. DOI: 10.3390/nano10061126

Marvin, C. H., Berthiaume, A., Burniston, D. A., Chibwe, L., Dove, A., Evans, M., … & Tomy, G. T. (2021). Polycyclic aromatic compounds in the Canadian Environment: Aquatic and terrestrial environments. Environmental Pollution, 285, 117442. DOI: 10.1016/j.envpol.2021.117442

Mehwish Faheem, Ramji Kumar Bhandari, Faheem, M., and Bhandari, R.K.. 2021. Detrimental Effects of Bisphenol Compounds on Physiology and Reproduction in Fish: A Literature Review. Environmental Toxicology and Pharmacology. Volume 81: 103497. DOI: 10.1016/j.etap.2020.103497

Metcalfe, C., Miao, XS., Hua, W., Letcher, R., Servos, M. (2004). Pharmaceuticals in the Canadian Environment. In: Kümmerer, K. (eds) Pharmaceuticals in the Environment. Springer, Berlin, Heidelberg. DOI: 10.1007/978-3-662-09259-0_6

Möller, A., Ahrens, L., Surm, R., Westerveld, J., van der Wielen, F., Ebinghaus, R., and de Voogt, P. 2010. Distribution and sources of polyfluoroalkyl substances (PFAS) in the River Rhine watershed. Environmental Pollution 158: 3243-3250. DOI: 10.1016/j.envpol.2010.07.019 

Noël, M., Dangerfield, N., Hourston, R. A., Belzer, W., Shaw, P., Yunker, M. B., & Ross, P. S. (2009). Do trans-Pacific air masses deliver PBDEs to coastal British Columbia, Canada?. Environmental Pollution, 157(12), 3404-3412. DOI: 10.1016/j.envpol.2009.06.025

OppenheimerJ., Eaton, A., Badruzzaman, M., Haghani, A.W., and Jacangelo, J.G. 2011. Occurrence and suitability of sucralose as an indicator compound of wastewater loading to surface waters in urbanized regions. Water Research 45: 4019-4027: DOI: 10.1016/j.watres.2011.05.014

Othman, N., Ismail, Z., Selamat, M. I., Sheikh Abdul Kadir, S. H., & Shibraumalisi, N. A. (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: 10.3390/ijerph192113923

Putt AE, MacIsaac EA, Herunter HE, Cooper AB, Selbie DT. Eutrophication forcings on a peri-urban lake ecosystem: Context for integrated watershed to airshed management. PLoS One. 2019 Jul 24;14(7):e0219241. DOI: 10.1371/journal.pone.0219241. PMID: 31339893; PMCID: PMC6655610.

Ribeiro de Sousa, D.N., Mozeto, A.A., Carneiro, R.L., Fadini, P.S. 2014. Electrical conductivity and emerging contaminant as markers of surface freshwater contamination by wastewater, Science of The Total Environment, Volume 484:19-26. DOI: 10.1016/j.scitotenv.2014.02.135

Rochester, J.R. 2013. Bisphenol A and human health: A review of the literature, Reproductive Toxicology 42: 132-155. DOI: 10.1016/j.reprotox.2013.08.008

Ross, P. S., Ellis, G. M., Ikonomou, M. G., Barrett-Lennard, L. G., & Addison, R. F. (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: 10.1016/S0025-326X(99)00233-7

Ross, P.S., Noël, M., Lambourn, D.M., Dangerfield, N., Calambokidis, J.C., and Jeffries, S.J. 2013. Declining concentrations of PCBs, PBDEs, PCDEs and PCNs in harbor seals from the Salish Sea. Progress in Oceanography 115: 160-170. DOI: 10.1016/j.pocean.2013.05.027

Rügner, H., Schwientek, M., Beckingham, B. et al. Turbidity as a proxy for total suspended solids (TSS) and particle facilitated pollutant transport in catchments. Environ Earth Sci 69, 373–380 (2013). DOI: 10.1007/s12665-013-2307-1

Rusydi, A.F. 2018 IOP Conf. Ser.: Earth Environ. Sci. 118 012019. DOI: 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:  10.2134/jeq2004.4190

Schwartz, H., Marushka, L., Chan, H.M. et al. Pharmaceuticals in source waters of 95 First Nations in Canada. Can J Public Health 112 (Suppl 1), 133–153 (2021). DOI: 10.17269/s41997-021-00499-3

Shang, D., Macdonald, R.W. and Ikonomou, M.G. 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. Environ. Sci. Technol.: 33, 9, 1366–1372. DOI: 10.1021/es980966z

Tian et al. (2021). A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon. Science 371,185-189. DOI: 10.1126/science.abd6951

UNEP. 2025. United Nations Environment Programme: Stockholm Convention on Persistent Organic Pollutants. Accessed June 2025: https://www.pops.int/partners/unep/overview/tabid/255/default.aspx

van Elsas, J.D., Semenov, A.V., Costa, R., Trevors, J.T. Survival of Escherichia coli in the environment: fundamental and public health aspects, The ISME Journal, Volume 5, Issue 2, February 2011, Pages 173–183. DOI: 10.1038/ismej.2010.80

van Stempvoort, D.L., Brown, S.J. Spoelstra, J., Garda, D., Robertson, W.D., and Smyth, S.A.. 2020. Variable persistence of artificial sweeteners during wastewater treatment: Implications for future use as tracers. Water Research 184: 116124. DOI: 10.1016/j.watres.2020.116124