Quw’utsun Sta’lo’ (Cowichan River) watershed: Water quality report for the 2025 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 second 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 July 20, 2025. 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 128 contaminants out of 576 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.

The Quw’utsun Sta’lo’ (Cowichan River) Watershed

Key findings

• This is the fourth assessment of water quality in the Quw’utsun Sta’lo’ (Cowichan River) watershed; our understanding of water quality will build on the previous assessments.
• We collected and analysed water in the Quw’utsun Sta’lo’ (Cowichan River) watershed during the dry season (July 30, 2025).
• Road runoff was the most contaminated water category in the dry season; it had the highest concentrations of E.coli, nitrate, PAHs, alkylphenols and bisphenols.
• Stream and river water was the second most contaminated water category in the dry season with the highest concentration of PPCPs, sucralose, PFAS and pesticides.
• Tap water had the highest concentration of PCBs.
• Marine water had the highest concentration of metals.
• Source water was the least contaminated than the above water categories in the dry season.
• Overall, the Quw’utsun Sta’lo’ (Cowichan River) watershed had relatively good water quality in the dry season:
  • There were six exceedances of Canadian Environmental Quality Guidelines.
  • Exceedances included:
    • Temperature in the stream and river sample; 
    • Aluminum, iron, phosphate and dissolved oxygen in the road runoff sample;
    • Boron in the marine sample. 
  • There were no Drinking Water Quality Guideline exceedances.
  • There was one exceedance of Health Canada Water Quality Guidelines for Recreation.

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 Quw’utsun Sta’lo’ (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, food sovereignty & security, 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.