Chemainus River watershed: Water quality report for the 2024 dry season

Scott S, Moskal H, Noel M, and Ross PS. 2025. Chemainus River watershed: Water quality report for the 2024 dry season. Raincoast Conservation Foundation. https://doi.org/10.70766/2051.77 

Contributions by Halalt First Nation, SGS Axys: Pam Mackenzie and Richard Grace.

Editing by Dr. Peter Ross, Samantha Scott and Marie Noel

Financial support by Halalt First Nation

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 Halalt First Nation.

Briefly, the Healthy Waters – Halalt team determined basic water properties (temperature, conductivity, pH, dissolved oxygen and turbidity) in situ at sampling sites on August 8, 2024. Water samples were collected from five water categories, including source water (3 sites), stream and river water (3 sites), road runoff (3 sites), and tap water (10 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 91 contaminants out of 573 measured in the stream and river category – i.e. fish habitat – for the in the Chemainus River, excluding nutrients, fecal coliform and physical parameters. Overall, the Chemainus River watershed had relatively good water quality in the dry season, but additional sampling and analysis will provide additional insight into contamination impacts from forest fires, domestic wastewater, industrial chemicals and road runoff on the health of this valued watershed.

Key findings

• This is the second assessment of water quality in the Chemainus 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 Chemainus River watersheds during the dry season (August 8, 2024).
• Road runoff was the most contaminated water category in the dry season; it had the highest concentrations of PAHs, PPCPs, PFAS, and sucralose.
• Marine water was the second most contaminated water category in the dry season; it had the highest concentration of metals, pesticides, and PCBs.
• Source, tap, 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 all notably higher in the dry season compared to the previous wet season sampling.
• The concentrations of nitrate, PFAS, and sucralose were notably higher in the previous wet season sampling, compared to this dry season.
• Overall, the Chemainus River watershed had relatively good water quality in the wet season:

• There was one exceedance of Canadian Environmental Quality Guidelines; the temperature measured in the stream and river sites was above the BCMoE maximum daily value for temperature 19 ℃ for the protection of freshwater aquatic life with unknown fish distribution. .
• There were no exceedances of Health Canada Drinking Water Quality Guidelines.

Figure 1: The Chemainus River Watershed

The Chemainus River watershed covers an area of 356 km2, and runs eastwards from its source in the Vancouver Island Ranges, down towards the territories of the Halalt, Penelakut, and Lyackson First Nations, and the town of Chemainus, where it enters the Salish Sea. The Halalt originate from the village of xeláltxw, which means ‘marked houses’ or ‘painted houses’, a reference to the fact that the houseposts in this village were decorated. According to Cowichan oral history, the forefathers of both the Cowichan and Chemainus people (Siyóletse and St’éts’en respectively) originated from this village. Sampling sites were dispersed throughout the watershed in order to capture a wide spatial range to better understand potential impacts to water quality (Map by Brooke Gerle/ Raincoast Conservation Foundation).

Acknowledgements

We acknowledge the financial support of the Halalt First Nation. We are grateful for the enthusiastic support of Haley Moskal, Tim Thomas, Ken Thomas and Cosmo Roemer. We acknowledge the expert analytical support of Pam MacKenzie and Richard Grace at SGS-AXYS. We thank Nicole Van Zutphen, Sherwin Arnott, and Brooke Gerle for report design. Photo credit Peter Ross, Isabella Fiddes and Samantha Scott.

Team

• Raincoast Healthy Waters: Peter Ross, Samantha Scott, and Marie Noel
• Halalt First Nation: Haley Moskal, Tim Thomas, Cosmo Roemer

General introduction

Background

Raincoast’s Healthy Waters Program (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.

The Halalt People originate from the village of xeláltxw, which means ‘marked houses’ or ‘painted houses’, a reference to the fact that the houseposts in this village were decorated. According to information collected by Rozen (1985), this village was once located in the Cowichan Valley, at the spot where the Silver Bridge currently crosses the Cowichan River, at the south-eastern edge of the city of Duncan. According to Cowichan oral history, the forefathers of both the Cowichan and Chemainus people (Siyóletse and St’éts’en respectively) originated from this village.

The residents of this village later relocated to a village at the north end of Willy Island, the largest of the Shoal Islands located just off the mouth of the Chemainus River, perhaps in the early part of the 19th Century. When they moved, they took the village name with them. Rozen (1985) reports that, historically, there were at least five or six houses in the village on Willy’s Island. Although the entire island was designated an Indian Reserve (Halalt Island No. 1), the village was abandoned in the 1920s and the residents moved to the Westholme reserve on the lower Chemainus River (Halalt No. 2).

The Halalt have stewarded the land and waters of the Chemainus River watershed and surrounding areas since time immemorial.

A watershed based approach to sampling: Healthy Waters

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.

Methods

Field sampling

A total of 12 water samples were collected from field locations within the Chemainus watershed on August 8, 2024 by the Raincoast Healthy Waters team alongside representatives of the Halalt and Penelakut First Nations. An additional 10 samples of tap water were obtained from homes and businesses located on the Halalt First Nation Reserve on the same day. 

A portable water properties meter (YSI-ProDSS) was deployed to measure temperature, pH, conductivity, dissolved oxygen and turbidity.

Samples were submitted to three service labs for additional analyses: ALS Environmental, SGS-AXYS, and the Raincoast Conservation Genetics Lab. Contaminant analytes were determined in water samples according to established protocols (see Table 2).

Table 1: Sampling sites in the Chemainus River watershed

Site Number	Water Type	Site Name	Lat/Long
1	Source	Franklin	49°06’49.3 N, 123°55’19.6 W
2	Source	Meade	48°53’07.8 N, 124°00’30.5 W
3	Source	Boulder @ Chemainus River	48°50’41.0 N, 123°55’26.7 W
4	Stream and river	Chemainus @ Island Hwy	48°52’42.1 N, 123°40’27.0 W
5	Road runoff	Island Hwy Ditch	48°50’56.1 N, 123°43’22.8 W
6	Stream and river	Bonsall Creek	48°52’42.1 N, 123°40’27.0 W
7	Road runoff	Westholme Ditch	48°51’38.7 N, 123°42’19.5 W
8	Stream and river	Bonsall Slough	48°53’38.3 N, 123°40’54.5 W
9	Road runoff	Bramble Ditch	48°52’42.1 N, 123°40’27.0 W
10	Marine	Willy’s Island	48°53’55.5 N, 123°39’06.8 W
11	Marine	Boomsticks	48°53’56.2 N, 123°39’07.1 W
12	Marine	Mill	48°52’49.5 N, 123°37’34.0 W
13	Tap	Tap 10	various

Water quality analyses

Table 2: List of analytes, analysis locations, analytical methods, instruments, and number of samples submitted to service labs

Analyte	Laboratory	Analytical Method	Instruments	No.  samples analysed
Tier 1
Temperature (℃)	in situ		YSI ProDSS	13
Dissolved Oxygen (%, mg/L)	in situ	optical sensor	YSI ProDSS	13
Turbidity (FNU)	in situ		YSI ProDSS	13
Conductivity (uS/cm)	in situ		YSI ProDSS	13
pH	in situ		YSI ProDSS	13
Tier 2
Total Suspended Solids (TSS)	ALS Environmental	APHA 2540 D (mod)	gravimetry	13
Total Dissolved Solids (TDS)	ALS Environmental	APHA 2540 C (mod)	gravimetry	13
Hardness	ALS Environmental	APHA 2340B	calculated	13
Total Organic Carbon (TOC)	ALS Environmental	APHA 5310 B (mod)	combustion	13
Chemical Oxygen Demand (COD)	ALS Environmental	APHA 5220 D (mod)	colorimetry	13
Biological Oxygen Demand (BOD)	ALS Environmental	APHA 5210 B (mod)	dissolved oxygen meter	13
Nitrate	ALS Environmental	EPA 300.1 (mod)	ion chromatography	13
Ammonia	ALS Environmental	Method Fialab 100, 2018	fluorometry	13
Phosphate	ALS Environmental	APHA 4500-P F (mod)	colorimetry	13
Total Metals	ALS Environmental	EPA 200.2/6020B (mod)	Collision/Reaction Cell ICPMS	13
Total coliform	ALS Environmental	APHA 9223 (mod)	MPN	13
Fecal coliform	ALS Environmental	APHA 9223 (mod)	MPN	13
E. coli	ALS Environmental	APHA 9223 (mod)	MPN	13
MST (in Development)	RCF Conservation Genetics Lab (PSEC)	In development		5
6PPD-quinone	Pending		LCMS	5
Tier 3
Polycyclic Aromatic Hydrocarbons (PAHs)	SGS Axys Analytical	EPA 8270/ EPA 1625	GC-MS	5
Multiresidue Pesticides	SGS Axys Analytical	EPA 1699 (mod)	HRMS	5
Pharmaceuticals and Personal Care Products (PPCPs)	SGS Axys Analytical	EPA 1694	HPLC/MS/MS	5
Per and Poly-fluoroalkyl substances (PFAS)	SGS Axys Analytical	EPA 1633 Draft	LC-MS/MS	5
Polychlorinated biphenyls (PCBs)	SGS Axys Analytical	SGS AXYS METHOD MLA-210 Rev 01	GC-MS/MS	5
Alkylphenol Ethoxylates (APEs)	SGS Axys Analytical	SGS AXYS METHOD MLA-004 Rev 07	GC-MS	5
Bisphenols	SGS Axys Analytical	SGS AXYS METHOD MLA-113 Rev 01	LC-MS/MS	5
Sucralose	SGS Axys Analytical	MLA-116	LC-MS/MS	5

Data handling

In some cases, contaminants were not detected in our water samples and concentrations were therefore considered to be 0 for the calculations of totals.

With each batch of samples, analytical laboratories 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 contaminants. These levels in blanks were subtracted from the concentrations measured in each of our environmental samples (‘blank correction’).

Environmental Quality Guidelines

We interpreted contaminant concentrations using three sets of Canadian environmental quality guidelines (EQGs): provincial (British Columbia (BC)), federal, and those developed by the Canadian Council of the Ministers of the Environment (CCME). The latter CCME guidelines are derived in consultation with the environment ministers from the federal, provincial and territorial governments. Relevant EQGs and DWQGs are summarized in Appendix 1.

The British Columbia Ministry of Environment and Climate Change Strategy (BC MoECCS) has developed Water Quality Guidelines (WQGs) that are considered as protective for different water uses. We refer to WQGs and EQGs interchangeably to simplify the use of terminology from different sources across Canada. We apply EQGs for the protection of aquatic life (source, stream and rivers and Road runoff samples) and marine aquatic life (marine water samples). All approved BC WQGs can be found on the BC MoECCS website.

Federal Environmental Quality Guidelines (FEQGs) are developed to support emerging federal environmental quality monitoring, risk assessment and risk management activities, and are derived to complement those developed by the CCME. They are only available for a limited number of chemicals captured in this list of EQGs (Government of Canada 2024).

In addition, Working Water Quality Guidelines (WWQGs) are available for some contaminants for which a completed EQG is not yet available and can be obtained from various Canadian provincial and federal jurisdictions (primarily the Canadian Council of the Ministers of the Environment (CCME)).

It is important to note that exceeding a WQG/EQG or WWQG does not imply that unacceptable risk exists but rather that the potential for adverse health effects is increased (BC MoECCCS 2023). Conversely, EQGs may not fully capture the sensitivity of all species to different contaminants, such that adverse effects may occur in some species even at levels below a EQG. EQGs, therefore, serve as a benchmark based on best available evidence, and are subject to change as new evidence emerges.

Drinking Water Quality Guidelines

Guidelines are available to protect human health from different contaminants in drinking water. These have been developed at the federal level by Health Canada in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water (CDW) and other federal government departments (Health Canada 2022). Guidelines for Canadian Drinking Water Quality are developed specifically for contaminants that meet all of the following criteria (Health Canada 2022):

• Exposure to the contaminant could lead to adverse health effects in humans;
• The contaminant is frequently detected or could be expected to be found in a large number of drinking water supplies throughout Canada; and,
• The contaminant is detected, or could be expected to be detected, in drinking water at a level that is of possible human health significance.

In BC, the First Nations Health Authority (FNHA) oversees drinking water safety on reserves, where the Chief and Council are responsible for drinking water infrastructure and monitoring. Monitoring of drinking water relies on meeting the Health Canada DWQGs.  Drinking water quality guidelines can be found on the Health Canada website. In addition to the guidelines listed in Table 3, Health Canada maintains a Beach Action Value (BAV) for safe recreational use of water based E.coli being detected at less than 235 CFU/100 mL.

Table 3: Analyte classes and number of available Environmental (or Water) Quality Guidelines (EQGs or WQGs) and Drinking Water Quality Guidelines (DWGs) and Objectives

Analyte Class	Number of Analytes Measured	Drinking WQGs	Federal EQGs	BC WQGs	CCME EQGs
Basic Water Properties	5	1	0	4	5
Coliform	3	2	0	0	0
Nutrients	4	3	0	4	4
Metals	37	20	4	20	17
PAHs	76	1	0	10	10
Pesticides	62	7	0	10	7
PPCPs	141	0	1	1	0
PFAS	40	3	1	1	0
PCBs	209	0	0	5	0
Alkylphenols	4	0	0	0	0
Bisphenols	6	0	1	1	0
Sucralose	1	0	0	0	0
6PPD-Quinone	1	0	0	1	0
Total	587	36	7	57	43

We applied three sets of EQGs and one set of DWQGs to our water quality data: The Federal government’s Federal Environmental Quality Guidelines (FEQGs), the BC Government’s Approved Water Quality Guidelines (BC WQGs), and the Canadian Council of Ministers of the Environment’s (CCME)  Canadian Environmental Quality Guidelines (CCME CEQGs); and Health Canada’s Drinking Water Quality Guidelines. These guidelines were all designed to protect aquatic life.

International Guidelines and emerging PFAS concerns

There exist several thousand PFAS compounds, but only two are regulated in Canada: PFOA and PFOS, which were banned in 2011. Since it takes many years to finalize guidelines and in light of increasing concerns over PFAS as a contaminant of concern, Health Canada has also established screening values for nine PFAS (Appendix 4). These screening values provide guidance where there is a need for quick response. They are based on risk assessment approaches that are similar to formal guidelines (Health Canada 2023), and therefore serve as guidance when evaluating the risk of PFAS exposure from tap water consumption and are considered in the present report.

In addition, more recently, a ‘proposed objective’ of 30 ng/L for total PFAS was developed which set out a goal for a maximum level of PFAS in drinking water. This proposed objective is based on the sum of specific individual PFAS (29 individual PFAS that are quantified by US EPA methods 533 and 537.1). This objective, when finalized, will replace the two existing drinking water guidelines and nine screening values (Health Canada 2023).

Given the limited guidance afforded by Canadian guidelines for the rapidly emerging PFAS concerns, we have included guidelines derived internationally for this contaminant class (USA European Union and WHO).

Table 4: Environmental Quality Guidelines for PFAS (USA and Canada)

Compound	Guideline (mg/L)	Issuing Agency	Notes
PFOS	0.0068	Canadian FEQG	EQG – PFOA under development
PFOS	3	US EPA	DRAFT EQG – Acute
PFOS	0.0084	US EPA	DRAFT EQG – Chronic
PFOA	49	US EPA	DRAFT EQG – Acute
PFOA	0.094	US EPA	DRAFT EQG – Chronic

Very few Environmental Quality Guidelines are available for PFAS. A Canadian Federal EQG was set for PFOS, while a guideline value for PFOA is currently in development.

Table 5: Drinking Water Quality Guidelines for PFAS

Compound	Guideline (ng/L)	Issuing Agency	Notes
Sum of 25 PFAS	30	Health Canada – Drinking Water Quality Objective	Objective expected to become Guideline
PFOS	600	Health Canada
PFOS	4	US EPA	New in 2024
PFOA	200	Health Canada
PFOA	4	US EPA	New in 2024
PFHxS	10	US EPA
PFNA	10	US EPA
HFPO-DA	10	US EPA
Total PFAS	500	EU – Drinking Water Directive

Most available guidelines address the two PFAS compounds suspected to be of greatest concern to human health: PFOA and PFOS.

Water properties

Capsule

Basic water properties provided elementary information on the quality of fish habitat in the Chemainus River watershed. Source water sites were found to have the lowest temperature, and the highest dissolved oxygen (mg/l) among freshwater samples. Road runoff had the highest conductivity among non-marine samples.

Introduction

Water properties including temperature (℃), dissolved oxygen, conductivity, pH, and turbidity are commonly measured as a preliminary method of assessing the quality of fish habitat. Temperature and dissolved oxygen are of particular significance to fish – as increased temperatures and low dissolved oxygen are often associated with summertime fish kills (La 2011), a particular concern for sensitive cold-water species such as salmonids. Conductivity and turbidity measurements can act as proxies for total dissolved solids (TDS) (Rusydi 2018) and total suspended solids (TSS) respectively (Rügner et al 2013). These parameters can be relevant as increased TDS and TSS in a body of water can indicate contamination from road salt, nutrients, or flushing of disturbed sediments into the waterway. Unusual conductivity measurements suggest the need for more in-depth analysis for contaminants (Ribeiro de Sousa 2014).

Methods

A YSI ProDSS was used to take three measurements at each site of the following parameters: temperature (°C), dissolved oxygen (mg/L and %), specific conductivity (uS/cm), pH, and turbidity (FNU).

Results

Table 6: Average water property results for categories of water sampled in the Chemainus watershed (DRY Season 2024)

Parameter	Source(n=3)	Stream and river(n=3)	Road runoff(n=3)	Tap(n=10)	Marine(n=3)
Temperature (℃)	14.0 ± 0.84(10.5-16.0)	19.8 ± 1.37(14.4-23.4)	16.3 ± 0.48(15.8-17.7)	NA	21.2 ± 0.14(20.6-21.6)
DO %	91.8 ± 2.95(79.6-98.6)	93.0 ± 7.80(60.5-111)	77.6 ± 13.1(38.4-91.3)	NA	148 ± 1.55(141-154)
DO (mg/L)	9.43 ± 0.144(8.83-9.85)	8.37 ± 0.522(6.14-9.70)	7.65 ± 1.34(3.64-9.04)	NA	11.3 ± 0.118(10.9-11.8)
pH	7.8 ± 0.05(7.5-8.0)	7.5 ± 0.14(7.0-8.1)	7.4 ± 0.19(6.8-7.6)	NA	8.3 ± 0.01(8.2-8.4)
Conductivity (uS/cm)	56.8 ± 2.92(45.1-75.2)	93.6 ± 8.04(76.3-127)	233 ± 74.8(158-458)	NA	41700 ± 31.1(41600-41800)
Turbidity (FNU)	-0.14 ± 0.02(-0.20-(-0.08))	2.96 ± 1.81(-0.500-14.0)	1.2 ± 0.38(0.83-2.4)	NA	-0.22 ± 0.02(-0.30-(0.11))

Data presented above represent mean +/- Standard Error of the Mean (SEM), with the Range in parentheses (min-max). DO = Dissolved Oxygen. uS/cm = MicroSiemens per cm. FNU = Formazin Nephelometric Units. Flow was not determined for marine or tap water samples.

Conclusions

• pH, and dissolved oxygen values were within EQG ranges for the protection of aquatic life.
• The temperature measured in the stream and river water sites exceeded the BC MoE Maximum Daily Value of 19 ℃ for the protection of freshwater aquatic life with unknown fish distribution.
• Turbidity could not be assessed in relation to EQGs as it requires knowledge of background turbidity.

Coliform bacteria

Capsule

Coliform bacteria in water indicate a potentially serious threat to human health. Total and fecal coliform concentration (MPN) was highest in the road runoff sample, while the stream and river sample had the highest concentrations of both E. coli (MPN). No coliform bacteria were detected in the tap water sample.

Introduction

Coliform bacteria have historically been used to gauge water quality with respect to implications for human recreational use and drinking water consumption (van Elsas et al. 2013). Most recently, the spotlight has been on counts (MPN of CFU) of the gram-negative coliform bacteria species Escherichia coli as an indicator of recent contamination with wastewater, and to determine the risk to human health posed by consumption and recreational use of waterways (Li 2021). There are no Environmental Quality Guidelines for coliform bacteria, reflecting the general idea that these potentially pathogenic bacteria are not likely to present a risk to aquatic life.

Results

Table 7: Counts (MPN/100ml) of coliform bacteria for categories of water sampled in the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Stream and river(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Coliform, Total	461	1550	>2420	0	270
Coliform, Fecal	420	84	1200	0	6
E. coli	96	127	56	0	55

Figure 2: Coliform counts (MPN) in composite samples for categories of water sampled in the Chemainus watershed (DRY Season 2024)

The highest concentration of total coliform and fecal coliform bacteria were both detected in the road runoff water sample, whereas the highest concentration of E. coli was detected in the stream and river sample.

Conclusions

• Total E. coli concentrations for the five water categories were ranked from highest to lowest as follows: stream and river > source > road runoff > marine > tap.
• E. coli values in all water samples were well below Recreational Use Guidelines set by Health Canada (>235 CFU/100 mL). CFU and MPN are both methods for laboratory culture of bacteria, and can be used interchangeably with regards to Guideline values.
• The E. coli concentration detected in the source water sample exceeds the Health Canada guideline for source water of <10 MPN for drinking water sources prior to chlorination. It should be noted that the source water sites are not currently used as community drinking water sources.
• No coliform were detected in the tap water sample, confirming the safety of drinking water in the homes tested.

Nutrients and Physical parameters

Capsule

Nutrients can readily degrade fish habitat by increasing plant and algal growth and causing a subsequent reduction in dissolved oxygen. Nitrate and phosphate were the most frequently detected nutrients in water samples from the Chemainus River watershed, and were each found in four out of five samples. The highest concentration of nitrate was detected in the tap water sample. There were no exceedances of EQGs or DWGs.

Introduction

Nutrients such as nitrogen and phosphorus compounds can be naturally occurring, and are critical for the health and growth of plants and animals (CCME 2016). However, nutrients from fertilizers and wastewater that are released into a body of water can put it at risk of eutrophication – a process which is characterized by an overgrowth of plants and algae and resulting in oxygen depletion (Putt et al. 2019). Eutrophication poses a significant risk to aquatic life, as low oxygen levels create an inhospitable environment for the survival of fish – in particular salmonids who require relatively high levels of dissolved oxygen for survival and reproduction (Davis 1975).

In addition, some nutrients such as total ammonia are considered to be acutely toxic to freshwater fish species at concentrations that vary by pH and temperature of the water (CCME 2010).

Results

Table 8: Concentrations (mg/L) of physical and chemical properties in each water category for the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Hardness	22.8	33.0	120	32.1	5220
Solids, total dissolved [TDS]	40	55	216	60	32400
Solids, total suspended [TSS]	<3.0	<3.0	6.8	<3.0	<3.0
Carbon, total organic [TOC]	0.54	1.39	5.92	<0.50	1.69
Biochemical oxygen demand [BOD]	<2.0	<2.0	4.2	<2.0	<2.0
Chemical oxygen demand [COD]	<10	<10	29	<10	739

Table 9: Nutrient concentrations (mg/L) in each water category for the Chemainus watershed (DRY Season 2024).

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Ammonia, total (as N)	<0.0050	0.0153	0.0166	<0.0050	<0.0050
Nitrate (as N)	0.0746	0.290	0.0897	1.14	<0.500
Nitrate + Nitrite (as N)	0.0746	0.294	0.0897	1.14	<0.510
Nitrite (as N)	<0.0010	0.0044	<0.0010	<0.0010	<0.100
Nitrogen, total	0.120	0.379	0.808	1.06	0.059
Phosphate, ortho-, dissolved (as P)	<0.0010	0.0105	0.0106	0.0014	0.0093

Water samples were analyzed for the following nutrients: total nitrogen, nitrate (NO-3), ammonia (NH3), phosphate (PO43) and nitrite (NO-2).

Figure 3: Mean Nutrient concentrations (mg/L) in five water categories in the Chemainus watershed (DRY Season 2024)

Nitrate (NO-3) and Phosphate (PO43) were the most commonly detected nutrients in water samples from the Chemainus watershed.

Conclusions

• Nitrate concentrations in the five water categories were ranked from highest to lowest as follows: tap > stream and river > road runoff > source > marine.
• Nitrate and phosphate were the most frequently detected nutrients in water samples from the Chemainus River watershed.
• No nutrient values exceeded available EQGs for the protection of aquatic life.

Metals

Capsule

Metals can be present in water due to both natural and anthropogenic inputs. Lead was detected in the road runoff and tap water samples but at concentrations which did not exceed EQGs or DWGs.

Introduction

Metals are present in aquatic environments as a result of both natural and anthropogenic sources, with baseline levels reflecting the unique geology of the area surrounding a body of water (Jadaa et al. 2023). Anthropogenic sources of metal contamination in waterways may originate from industrial effluent, municipal wastewater, agricultural practices, and urban runoff.

Many metals are capable of impacting the health of aquatic life, with some representing a priority concern in fish habitat, including zinc (Giardina et al. 2009) and copper (Malholtra et al. 2020).

Results

Table 10: Concentrations (mg/L) of the metals that were detected in all five water categories in the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Aluminum, total	0.0112	0.0285	0.0540	0.0036	<0.150
Antimony, total	<0.00010	<0.00010	<0.00010	<0.00010	<0.00500
Arsenic, total	0.00012	0.00	0.00	<0.00010	<0.00500
Barium, total	0.0090	0.0129	0.0169	0.00248	0.00718
Beryllium, total	<0.000020	<0.000020	<0.000020	<0.000020	<0.00100
Bismuth, total	<0.000050	<0.000050	<0.000050	<0.000050	<0.00250
Boron, total	0.016	0.017	0.014	0.013	3.61
Cadmium, total	<0.0000050	0.0000077	<0.0000050	0.0000059	<0.000250
Calcium, total	7.72	11.10	34.20	10.6	344
Chromium, total	<0.00050	<0.00050	<0.00050	<0.00050	<0.0250
Cobalt, total	<0.00010	<0.00010	0.00	0.00	<0.00500
Copper, total	0.00089	0.0022	0.0013	0.1130	<0.0250
Iron, total	<0.010	0.166	0.156	<0.010	<0.500
Lead, total	<0.000050	<0.000050	<0.000050	0.00064	<0.00250
Lithium, total	<0.0010	<0.0010	<0.0010	<0.0010	0.151
Magnesium, total	0.852	1.28	8.45	1.36	1060.00
Manganese, total	0.00084	0.02280	0.10200	0.00073	<0.00500
Mercury, total	<0.0000050	<0.0000050	<0.0000050	<0.0000050	<0.0000050
Molybdenum, total	0.00018	0.00017	0.00014	0.00009	0.00815
Nickel, total	<0.00050	<0.00050	0.00085	0.00100	<0.0250
Phosphorus, total	<0.050	<0.050	0.075	<0.050	<2.50
Potassium, total	0.114	0.364	0.732	0.236	314
Selenium, total	<0.000050	<0.000050	0.00007	0.00008	<0.00250
Silicon, total	3.18	2.88	9.75	4.57	<5.00
Silver, total	<0.000010	<0.000010	<0.000010	<0.000010	<0.000500
Sodium, total	1.75	3.79	14.0	2.84	7760
Strontium, total	0.025	0.043	0.278	0.038	6.17
Sulfur, total	0.58	1.03	7.02	0.98	768.00
Thallium, total	<0.000010	<0.000010	<0.000010	0.000018	<0.000500
Tin, total	<0.00010	<0.00010	0.00035	<0.00010	<0.00500
Titanium, total	<0.00030	0.00086	0.00273	<0.00030	<0.0150
Uranium, total	<0.000010	<0.000010	<0.000010	<0.000010	0.00255
Vanadium, total	<0.00050	0.00054	0.00080	0.00052	<0.0250
Zinc, total	<0.0030	<0.0030	<0.0030	0.22	<0.150
Zirconium, total	<0.00020	<0.00020	<0.00020	<0.00020	<0.0100
Total metals	14.3	20.7	74.9	21.0	10,256

Figure 4: Total metal concentrations (mg/L) in five water categories in the Chemainus watershed (DRY Season 2024)

Total metal concentrations are shown with a logarithmic transformation to allow for visualization of the data. The marine water sample had considerably higher concentrations of metals than the four non-marine samples.

Table 11: Lead (Pb) is a noteworthy contaminant in some drinking water samples: Concentrations (mg/L) of lead detected in the five water categories in the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Lead (mg/L)	<0.000050	<0.000050	<0.000050	0.00064	<0.00250

No lead concentrations exceeded available EQGs or DWGs.

Conclusions

• Total metal concentration for the five water categories was ranked from highest to lowest as follows: marine > road runoff > tap > stream and river > source.
• Lead was detected in the pooled tap water sample, and was present at concentrations of 0.00064 mg/L. This is below the Drinking Water Quality Guideline set by Health Canada (0.005 mg/L).
• No other analytes exceeded EQGs or DWQGs.

Polycyclic Aromatic Hydrocarbons (PAHs)

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Polycyclic aromatic hydrocarbons (PAHs) were detected in all five water samples, with the highest concentrations observed in the road runoff sample (this sample had the lowest concentrations during the wet season) and the lowest in the source sample. The average PAH concentrations across all water categories were double what was reported during the wet season. The PAH profile in the stream and river and road runoff samples appeared to be related to wood combustion, and for tap water,  it appeared to be of liquid fuel origin. WQGs were only available for a few PAHs, but no exceedances were observed for any of our samples, similar to the wet season. The tap water sample did not exceed the one PAH guideline available for drinking water, similar to the wet season..

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are a complex group of compounds found in coal, petroleum and plant materials. They can enter waterways in the form of liquid petroleum products (gasoline, diesel, oil) or via the incomplete combustion of coal, oil, gas, wood garbage or other organic substances. They can occur naturally or as a result of human activities (anthropogenic). In Canada, forest fires are the single most important natural source of PAHs, while anthropogenic sources include residential wood heating, aluminum smelters, creosote-treated products, spills of petroleum products and metallurgical and coking plants (Government of Canada, ECCC and Health Canada 1994; Marvin et al. 2021).

Hydrocarbons can enter aquatic ecosystems either directly through oil spills or discharges from vessels (Morales-Caselles et al. 2017) or indirectly through atmospheric deposition, runoff and discharge from wastewater treatment plants. Depending on their molecular size, PAHs vary in toxicity and have been classified as toxic under the Canadian Environmental Protection Act (CEPA).

Results

We measured 76 different parent and alkylated PAHs in the five water samples collected in the Chemainus watershed during the dry season.

Figure 5: Number of PAHs detected in water samples from the Chemainus watershed (DRY Season 2024)

PAHs were detected in all five water categories. The number of PAHs detected ranged from 19 (source) to 54 (road runoff) with an average of 34.6 ± 6.4, 1.7 times higher than during the wet season.

Figure 6: Total PAH concentrations in water samples from the Chemainus watershed (DRY Season 2024)

Total PAH concentrations ranged from 16.6 (source) to 160 ng/L (road runoff), with an average across all water categories of 51.8 ± 27.3 ng/L, double what was reported for the wet season.

When comparing with levels from the wet season, we found that:

• PAH concentrations were highest in the road runoff sample during the dry season as opposed to source sample during the wet season.
• PAH levels in the stream and river samples were similar between the dry and wet seasons.
• PAH levels were 1.5 and 1.4 times lower in the dry season compared to the wet season for the source and marine samples, respectively.
• PAH levels were 7.9 and 1.3 times higher in the dry season compared to the wet season for the road runoff and tap samples, respectively.

Ratios of certain PAHs can be used to evaluate sources. Given that only a limited number of PAHs were detected in the water samples, the Fluoranthene – Pyrene ratio was the only one that could be calculated reliably except for the source  and marine sample where pyrene levels were 0.

Figure 7: PAH profiles from wood combustion and fuels in water samples from the Chemainus River watershed (DRY Season 2024)

Stream and river (0.72) and road runoff (0.56) water samples had Fl/(Fl+Pyr) ratios higher than 0.5, suggesting the contribution of combustion of solid fuel such as wood, plant material or coal as the source of PAHs. The ratio in the tap sample (0.45) suggested a dominance of liquid fuel combustion. (*indicates that no data is available for source and marine water).

Conclusions

• PAH concentrations were ranked as follows from highest to lowest: road runoff > tap > marine > stream and river > source.
• Total PAH concentrations in Chemainus River watershed water samples ranged from 16.6 to 160 ng/L with an average across all water categories double what was reported for the wet season.
• Fluoranthene – Pyrene ratios revealed that PAHs in the stream and river and road runoff samples originated primarily from the combustion of solid fuel such as wood or plant material. This is consistent with wood burning for heating homes, and wildfires as being major sources of PAHs in Canada (Berthiaume et al. 2021). In addition, biomass burning in Asia has been shown to deliver PAHs to Canada through air masses traveling across the Pacific Ocean (Berthiaume et al. 2021).
• Fluoranthene -Pyrene ratio in the tap water samples pointed more to the combustion of liquid fuel as a source of PAHs which is different from the wet season when they originated mostly from the combustion of solid fuel.
• All water samples were well below the BC WQGs available for individual PAHs (naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, chrysene, benzo-a-pyrene and benzo-a-anthracene), similar to the wet season.
• A single DWQG is available for PAHs: benzo-a-pyrene (40 ng/L), which was not detected in the tap water sample, similar to the wet season.

Pesticides

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A limited number of pesticides were detected in all five water samples, with the highest concentrations in the marine water sample, and the lowest in the source sample. On average, across all water categories, total pesticide concentrations were similar between the two seasons. Beta- endosulfan (100% of samples) and alpha-endosulphan (80%) were detected most frequently. Beta-endosulphan was detected in the majority of samples during the wet season.Out of the pesticides detected in environmental samples, WQGs were only available for endosulfan, atrazine and permethrin, but no exceedances for these pesticides were observed for any of the water samples, similar to the wet season. There were no DWGs available for the two pesticides detected in tap water.

Introduction

Pesticides have been developed to control, destroy or inhibit the activities of pests. They have a wide range of applications in agriculture such as insecticide to prevent crop damage and fungicides to prevent plant disease but also in forestry, industry as well as in our own backyards for lawn care or weed and insect control. In Canada, all pesticides used, sold or imported are regulated by Health Canada’s Pest Management Agency (PMRA) (Health Canada 2007).

While pesticides are mostly applied on terrestrial habitats, they can reach aquatic environments through overspray or drift during application, surface runoff, and through long range atmospheric transport and deposition. It is estimated that 10% of pesticides applied to soil reach non-target areas, leading to their widespread presence in surface waters worldwide (Schulz 2004; Anderson et al 2022).

Organochlorine pesticides (OCP) were heavily used from the 1940s to the 1980s, but have been restricted due to their persistence, toxicity and potential for bioaccumulation. Current-use pesticides (CUPs) were subsequently favoured as an alternative to OCPs, and have been widely applied in recent decades (Ding et al. 2023). These tend to be more water-soluble and may be more mobile in fish habitat (Harris et al. 2008).

Results

We measured 62 different pesticides, including both legacy and CUPs in the five water samples collected within the Chemainus watershed during the dry season.

Figure 8: Number of pesticide detections in water sampled in the Chemainus watershed (DRY Season 2024)

The number of pesticides detected ranged from 2 (tap) to 5 (marine)  with an average of 3.8 ± 0.5, almost half what was detected during the wet season..

Figure 9: Total pesticide concentrations in water sampled in the Chemainus watershed (DRY Season 2024).

Total pesticide levels ranged from 0.73 (source) to 1.1 ng/L (marine), with an average across all water categories of 0.9 ± 0.1 ng/L, similar to the wet season.

When comparing with levels from the wet season, we found that:

• Pesticide concentrations were highest in the marine water sample during the dry season while there were the highest in the tap sample during the wet season.
• Pesticide levels were lowest in the source sample during the dry season while they were the lowest in the marine sample during the wet season.
• Pesticide levels were similar in the stream and river samples for both seasons.
• Pesticide levels were 1.9 and 2 times lower in the dry season compared to the wet season for the source and tap samples, respectively.
• Pesticide levels were 1.6 and 4.5 times higher in the dry season compared to the wet season for the road runoff and marine samples, respectively.

Figure 10: Most frequently detected pesticides in water categories sampled in the Chemainus watershed (DRY Season 2024)

Numbers refer to water categories (1: Source, 2: Stream and river, 3: Road runoff, 4: Tap, 5: Marine). For example, beta-endosulphan was detected in all samples while alpha-endosulphan and dieldrin were the only two pesticides detected in tap water in addition to beta-endosulphan. Permethrin and atrazine (highlighted in green) were the only pesticides detected that were still in use at the time of sampling.

Beta- endosulfan (100% of samples) and alpha-endosulphan (80%) were detected in the majority of samples. Of note, beta-endosulphan was also detected in the majority of samples during the wet season. Endosulfan is a restricted-use insecticide and acaracide used to control a broad range of insect and arthropod pests on a wide variety of food, feed and ornamental crops (Health Canada 2011). The commercial mixture contains both alpha- and beta- endosulfan. endosulfan has been banned in Canada since 2016 and is banned or restricted in most other countries (ECCC 2023).    

Atrazine and permethrin were the only pesticides detected that are still currently in use in Canada, similar to the wet season:

• Atrazine is a selective herbicide used to control grass and broadleaf weeds in crops (corn and sorghum in Canada). In light of additional scientific information becoming available regarding potential human health (drinking water) and environmental risk from atrazine in surface water, Health Canada initiated, in 2017, a special review of all registered pest control products containing atrazine (Health Canada 2023).  Health Canada is currently consulting on its second special review of atrazine (Health Canada 2023).  
• Permethrin is an insecticide and is an active ingredient used in some household products to control insects, biting flies, wasps, cockroaches and spiders. In addition, some clothing may be treated with permethrin to protect against mosquitoes and ticks (Health Canada 2020) .

Conclusions

• Pesticide concentrations were ranked as follows from highest to lowest: marine > stream and river > road runoff > tap > source.
• Total pesticide concentrations ranged from 0.74 to 1.1 ng/L, with an average across all water categories similar to the wet season.
• The majority of pesticides detected, except atrazine and permethrin, were no longer in use in Canada at the time of sampling. Their detection likely reflects historical use nearby as well as deposition following long-range atmospheric transport. Interestingly, hexachlorobenzene and endosulfan were the most abundant pesticides detected in air samples collected from four mountains across British Columbia, including Grouse Mountain in North Vancouver (Ding et al. 2023).
• Endosulfan, atrazine and permethrin were the only pesticides detected that had EQGs (Appendix 1), and their concentrations did not exceed these, similar to the wet season.
• Only endosulphan and dieldrin were detected in tap water and no Canadian DWQ guidelines were available for these pesticides.

Pharmaceuticals and Personal Care Products

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Pharmaceuticals and Personal Care Products (PPCPs) are a category of contaminants that can enter the environment via wastewater, and are typically not removed during treatment. DEET was detected in all five water samples, while theophylline and caffeine were detected in four out of five water samples. The highest concentration of total PPCPs was detected in the road runoff sample. The greatest number of PPCP analytes detected in a single sample were found in the stream and river sample.

Introduction

Pharmaceuticals and Personal Care Products (PPCPs) comprise a wide range of products and chemical formulations. The common link among these compounds is their use in human health, veterinary health and personal care. Many PPCPs are introduced into the environment via wastewater streams, and are not reliably removed during treatment at wastewater treatment plants (WWTPs).

Pharmaceuticals may enter the environment by way of WWTP effluent, land-applied biosolids and/or septic tank failures (Metcalfe et al 2004). Monitoring of source water is deemed an important means of assuring the safety of drinking water, especially First Nations (Schwartz et al. 2021). However, the lack of Environmental Quality Guidelines and Drinking Water Quality Guidelines in Canada for PPCPs and internationally constrains a fulsome risk-based evaluation of environmental concentrations (Lee and Choi 2019).

DEET (N,N-diethyl-meta-toluamide) is a widely used insect repellent. Caffeine is a plant-derived stimulant found in widely-consumed beverages. Theophylline is an asthma/pulmonary medication.

Caffeine has been used as an indicator of human wastewater in the environment – as it is relatively stable and persistent in surface waters, but sucralose is increasingly used in its place.

Results

Table 12: PPCP concentrations (ng/L) for all analytes detected in each water category for the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
2-Hydroxy-ibuprofen	0	0	48.2	0	0
Penicillin G	0	0.9	0	3.08	1.48
Caffeine	0	6.56	8.09	20	8.58
1,7-Dimethylxanthine	0	6	0	11.6	0
Amphetamine	0	0	0.056	0	0
Cotinine	0	0.705	2.37	0	1.02
Metformin	0	0.643	1.913	0	21.283
Cocaine	0	0.211	0	0.144	0
DEET	9.13	5.97	2.88	1.26	1.21
10-hydroxy-amitriptyline	0	0	0	0	0.161
Theophylline	0	17.8	17.5	21	8.17
Total PPCP Concentration	9.1	38.8	81.0	57.1	41.9
Total No. PPCPs	1	8	7	6	7

Conclusions

• PPCP Concentrations in each water sample from highest to lowest are as follows: road runoff > tap > marine > stream and river > source.
• There are no EQGs available in Canada for any of the PPCPs we detected in water samples for the Chemainus River watershed.
• The only PPCP for which there is an environmental quality guideline is Ethinylestradiol (EE), which is used widely as one of the hormonal components of birth control – as it has been shown to negatively impact both reproductive and immune function in some fish species. EE was not detected in any of the water sampled in the Chemainus River watershed.

Per- and poly-fluoroalkyl substances (PFAS)

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Per- and poly-fluoroalkyl substances (PFAS) were detected in all samples except the marine water sample. The highest PFAS concentrations were observed in road runoff similar to the wet season and the lowest in the source sample. Average PFAS concentrations across all water categories were similar between the two seasons. Perfluorooctanesulfonamide (PFOSA) was detected in the majority of samples except the marine sample. While PFOSA was the only PFAS detected in tap water during the wet season, it was also detected during the dry season in addition to perfluorooctanoic Acid (PFOA). None of the samples exceeded the environmental quality guidelines available (PFOS) or drinking water guidelines (PFOS and PFOA), or the new Drinking Water Quality Objective of 30 ng/L for the sum of 25 measured PFAS compounds, similar to the wet season.

Introduction

Per- and poly-fluoroalkyl substances (PFAS) are large group (~15,000 compounds) of human-made substances used in a wide variety of products such as food packaging, non-stick cookware, clothing, and cosmetics, but also lubricants, oil/water repellents, and notably – aqueous firefighting foams (AAAF; Barzen-Hanson et al. 2017). They are extremely stable and therefore persistent in the environment, which has led to the use of the term “forever chemicals” for this category of chemical.

PFAS can be released into the environment from point sources such as manufacturing plants, or sites where firefighting foams have been used. PFAS can also be released through consumer use and disposal of PFAS-containing products. PFAS has been found in all environmental compartments (Moller et al. 2010; ECCC and Health Canada, 2023).

Evidence of adverse effects on the environment and on human health has led Canada to prohibit the manufacture, use, sale, offer for sale and import of a limited number of PFAS including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic Acid (PFOA), long-chain perfluorocarboxylic acids and their salts and precursors under the Prohibition of Certain Toxic Substances Regulations and the Canadian Environmental Protection Act (CEPA) (ECCC and Health Canada 2023b). Advancing regulatory aspects pertaining to rapidly emerging concerns about the many PFAS being detected in the environment is a current priority in Canada (Longpre et al. 2020).

Results

SGS Axys measured 40 different PFAS in the five water samples collected within the Chemainus River watershed during the dry season.

Figure 11: Number of PFAS substances detected in water samples from the Chemainus watershed (DRY Season 2024)

PFAS were detected in all water samples except the marine water. The number of PFAS detected ranged from 0 (marine) to 10 (road runoff) with an average of 2.8 ± 1.8, 1.8 times lower than during the wet season.

Figure 12: Total PFAS concentrations in water sampled in the Chemainus watershed (DRY Season 2024)

Total PFAS levels ranged between 0 (marine) and 23.1 ng/L (road runoff) with an average across all water categories of 5.2 ± 4.5 ng/L, similar to the wet season.

When comparing with levels from the wet season, we found that:

• PFAS concentrations were highest in the road runoff sample compared to other water categories in both seasons with levels in the dry season being 1.4 times higher compared to the wet season.
• There were no PFAS detected in the marin water samples in both seasons.
• Total PFAS concentrations were 4.4 and 1.9 times lower in the stream and river and tap samples, respectively, during the dry season compared to the wet season.
• While total PFAS concentrations were 0.37 ng/L in the source sample during the dry season, they were not detected during the wet season.

Figure 13: Most frequently detected PFAS in water sampled in the Chemainus watershed (DRY Season 2024)

Numbers refer to the water category (1: source, 2: Stream and river, 3: Road runoff, 4: Tap, 5: Marine).Perfluorooctanesulfonamide (PFOSA) was detected in all samples except marine water and  Perfluorooctanoic Acid (PFOA) was only detected in road runoff and rap water samples.

When comparing dry season findings with wet season findings, the following similarities were observed: Perfluorooctanesulfonamide (PFOSA) was detected in the tap sample during both seasons and perfluorooctanoic Acid (PFOA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluorooctanoic Acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were detected in the road runoff sample during both seasons.

There were also some differences between dry and wet seasons. While 6.2 fluorotelomersulfonic acid (6.2 FTS) was detected in the majority of samples during the wet  season, it was detected in any samples during the dry season.  On the other hand, while PFOSA was detected in the majority of samples during the dry season, it was only detected in tap water during the wet season.

Conclusions

• PFAS concentrations were ranked as follows from highest to lowest: road runoff > tap > stream and river > source > marine.
• Total PFAS levels in water samples collected from the Chemainus River  watershed ranged from 0 to 23.1 ng/L, with an average across all categories similar to the wet season.
• PFAS concentrations were in the lower range of PFAS levels (0 – 138 ng/L) reported for 29 ambient freshwater surface sites across Canada between 2013 and 2020 (ECCC and Health Canada 2023).
• All the environmental samples were below the available EQGs (PFOS: Federal Environmental Quality Guideline (FEQG) = 6.8 ug/L; BC Working Water Quality Guideline (WWGG) = 3.4 ug/L), similar to the wet season.
• The total PFAS concentration detected in the tap water sample was below the new Health Canada Drinking Water Quality Objective of 30 ng/L for the sum of 25 different PFAS compounds.
• PFOSA and PFOA were the only two PFAS detected in tap water for which there was only a guideline for the latter (Health Canada: PFOA = 200 ng/L) which was not exceeded.
• Total PFAS concentrations in tap water were below the The European Union Water Directive drinking water quality guideline (500 ng/L), similar to the wet season.

Polychlorinated Biphenyls (PCBs)

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Despite having been targeted for phase out in Canada in 1977, with some closed uses allowed until December 31, 2029, industrial PCBs continue to be found in the environment, reflecting their stability and persistence. Polychlorinated biphenyls (PCBs) were detected in all five water samples, with the highest concentration observed in the marine sample and the lowest in stream and river water differing from the wet season (stream and river and tap for highest and lowest, respectively. Across all water categories, PCB concentrations were 1.7 times higher during the dry season. Tap and marine water samples had the ‘lightest’ PCB signature similar to the wet season and the stream and river, road runoff and the source had the ‘heaviest’. None of the samples exceeded the water quality guidelines for individual PCB congeners (PCB-77, -105, -126 and -169) or total PCBs, similar to the wet season. No guidelines are available for drinking water.  

Introduction

Polychlorinated biphenyls (PCBs) comprise 209 congeners that are structurally related but have differing degrees of chlorination. The commercial production of PCBs began in 1929, after which they were heavily used in electrical and hydraulic equipment, as well as in paint additives, sealing and caulking compounds and inks. Due to their adverse health effects, the production of PCBs was banned in the late 1970s around the world (Othman et al. 2022). PCBs are among the first 12 Persistent Organic Pollutants (POPs) – often referred to as the “dirty dozen” – defined by the Stockholm Convention, an international treaty aimed at eliminating or restricting the production and use of POPs (UNEP 2025).

PCBs were never produced in Canada, but were widely used, and are currently specified on the List of Toxic Substances under the Canadian Environmental Protection Act (ECCC 2010). Despite restrictions beginning in 1977, PCBs continue to pose a threat due to their persistence in the environment and their release from products that were manufactured before the ban, and/or were improperly disposed of (Othman et al. 2022). Closed use applications in the electricity generation sector may continue in Canada until final phase out in December 2029 (ECCC 2023) . Military uses of PCBs may continue thereafter.

In British Columbia (BC), PCBs remain the number one contaminant of concern in marine food webs with the iconic killer whales being among some of the most-PCB contaminated marine mammals in the world (Ross et al. 2000). Regulatory steps in the 1970s and since have led to declining PCB concentrations in aquatic animals in BC (Ross et al. 2013).

Results

We measured 159 out of a total 209 PCB congeners in the five water samples collected within the Chemainus watershed during the dry season.

Figure 14: Number of PCB detections in water sampled from the Chemainus watershed (DRY Season 2024)

PCBs were detected in all five water categories. The number of PCBs detected ranged from 32 (stream and river) to 77 (source) with an average of 50.4 ± 7.5, 1.5 times higher than during the wet season.

Figure 15: Total PCB concentrations in water sampled from the Chemainus watershed (DRY Season 2024)

Total PCB levels ranged between 12.4 (stream and river) and 50.2 pg/L (marine)  with an average across all water categories of 29.1 ± 6.7 pg/L, 1.7 times higher than during the wet season.

When comparing with concentrations from the wet season, we found that:

• While PCB concentrations were highest in the marine water sample during the dry season, they were the highest in the stream and river category during the wet season.
• PCB concentrations were higher during the dry season for all water categories except for stream and river water samples where levels were 3.6 times lower during the dry season compared to the wet season.
• The biggest difference in PCB concentrations was for tap water samples with levels being 21.2 times higher during the dry season compared to the wet season.
• PCB levels were 5.6, 2.4, and 2.4 times higher in the dry season compared to the wet season in source, road runoff and marine water samples, respectively.

The 209 individual PCBs have different degrees of chlorination, with each individual PCB containing between 1 and 10 chlorine atoms in their structure. PCBs can be categorized by their degree of chlorination into homologue groups. For example, all PCBs with one chlorine will fall into the mono-chlorinated homologue group and all PCBs with five chlorines will fall into the penta-chlorinated PCBs. In general, the more chlorines bound to a biphenyl ring, the ‘heavier’ the PCB molecule is. Heavier PCBs tend to not travel far from their sources, whereas lighter PCBs are more volatile and can undergo long-range transport. PCBs are strongly lipophilic – fat-soluble – such that they have a tendency to bind to organic particles and fatty tissues, rather than dissolve in water.

Figure 16: Homologue group contribution to total PCBs in water sampled from the Chemainus watershed (DRY Season 2024)

The lighter colours represent ‘lighter’ PCB homologue groups, such that the tap water had a ‘lighter’ pattern followed by the marine sample and then the source, stream and river and road runoff having ‘heavier’ signatures.

Overall, PCB signatures in source, stream and water and road runoff were lighter during the dry season compared to the wet season while PCB signature in tap water was heavier during the dry season. Marine water samples had similar PCB signatures between the two seasons.

Conclusions

• PCB concentrations were ranked as follows from highest to lowest: marine > source > tap > road runoff > stream and river.
• Average PCB concentrations across all water categories were 1.8 times higher during the dry season compared to the wet season.
• The PCB levels reported here were in the same range as those reported in the background stream and river samples from the Northwest of Lake Ontario (Zhang et al. 2020). In their study of air samples in coastal British Columbia , Noël et al. (2004) also observed uniform background levels for this legacy compound.
• There were no water quality guideline exceedances for any of the four individual PCBs for which they are available (PCB-77, -105, -126 and -169), as well as total PCBs, similar to the wet season.
• There are no guidelines for PCBs in drinking water in Canada. The US Environmental Protection Agency’s enforceable Maximum Contaminant Level (MCL) for PCBs in public water systems is 500,000 pg/L (EPA 2001), well above the levels reported in the current tap water sample, similar to the wet season.

Alkylphenol Ethoxylates

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Alkylphenol ethoxylates (APEs) are industrial grade surfactants that have been found in wastewater and industrial discharges. No APEs were detected in any of the water samples collected from within the Chemainus River watershed in the 2024 Dry season.  

Introduction

Alkylphenol ethoxylates are non-ionic surfactants used in industrial and consumer applications. APEs and their breakdown products are considered estrogenic and can disrupt reproductive development in fish. These surfactants can be released into the environment via municipal and industrial discharges (Lalonde et al. 2021). Once released, APEs may reside in aquatic sediments and/or undergo some breakdown into shorter chain APEs; their half-life is estimated at over 60 years (Shang et al. 1999).

The endocrine-disrupting potential of APEs and their breakdown products in fish and wildlife has represented a concern in receiving waters around municipal wastewater treatment plants (La Guardia et al. 2001).

Results

Table 13: Alkylphenol concentration (ng/L) in water samples from the Chemainus River watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
4-Nonylphenols	0	0	0	NQ	0
4-Nonylphenol monoethoxylates	0	0	0	NQ	0
4-Nonylphenol diethoxylates	0	0	0	NQ	0
4-n-Octylphenol	0	0	0	NQ	0
Total Alkylphenols	0	0	0	NQ	0

NQ indicates that this analytes was determined to be “Not Quantifiable” by our partner lab.

 Conclusions

• No APEs were detected in the Chemainus River watershed samples in the 2024 Dry season.
• In the previous wet season sampling APEs were detected in only the marine water sample.

Bisphenols

Capsule

Bisphenols are plastic additives with widely reported estrogenic (endocrine disrupting) properties. Bisphenol A (BPA) was the only bisphenol compound detected in the Chemainus River watershed, and it was detected in four out of five samples. BPA was detected in the highest concentration in the source water sample.

Introduction

Bisphenols are used widely in the manufacturing sector, and are primarily used in the production of plastics and resins. Both single and multi-use plastic containers are frequently produced using bisphenol compounds, the most popular of which is Bisphenol A (BPA). Bisphenols are endocrine-disrupting chemicals that have been found to negatively impact reproductive development in fish, amphibians, and mammals (Faheem and Bhandari, 2021; Marlatt et al. 2022).

BPA has come under intense regulatory scrutiny in recent years. The widespread use of these chemicals in food packaging, beverage containers, and in water delivery systems has led to exposure in the general population, and associations with adverse outcomes in humans (Rochester 2013).

Results

Table 14: Concentration (ng/L) of bisphenols in water samples from the Chemainus River watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
Bisphenol E (BPE)	0	0	0	0	0
Bisphenol F (BPF)	0	0	0	0	0
Bisphenol A (BPA)	4.33	2.24	0	4.18	3.61
Bisphenol AF (BPAF)	0	0	0	0	0
Bisphenol B (BPB)	0	0	0	0	0
Bisphenol S (BPS)	0	0	0	0	0
Total bisphenols	4.33	2.24	0	4.18	3.61

BPA was the only bisphenol compound detected in the Chemainus River watershed.

Conclusions

• Bisphenol concentrations in water samples from highest to lowest are as follows: source > tap > marine > stream and river > road runoff.
• The only bisphenol compound detected in the Chemainus River watershed was BPA.
• There is currently no Guideline for Bisphenol A in drinking water from Health Canada.
• A FEQG is set at 1.4 ug/L (or 1400 ng/L) for BPA is 300 times higher than the concentration we measured in the source water sample (4.33 ng/L).
• In the previous wet season sampling BPs were only detected in the road runoff sample.

Sucralose

Capsule

Sucralose is a popular artificial sweetener (trade name ‘Splenda’) used in foods and beverages. Because it survives the wastewater treatment process, sucralose has become a useful tracer of domestic wastewater. Sucralose was detected in two out of five water samples collected within the Chemainus River watershed. It was detected at the highest concentration in the road runoff sample, followed by  the marine sample.

Introduction

Sucralose (Splenda) is an artificial sweetener used in the production of sugar-free food and beverage products. Its popularity and its resistance to breakdown during the wastewater treatment process have led to its adoption as a useful tracer of human wastewater infiltration (Oppenheimer et al. 2011). It is not generally considered to be toxic, such that its utility as a tracer provides an opportunity to better understand the source of other more harmful pollutants in a given body of water.

Sucralose is not fully metabolized by the human body following consumption, and is not removed during the wastewater treatment process. Therefore, its detection in environmental samples indicates the presence of treated or untreated sewage (van Stempvoort et al. 2020).

Results

Table 15: Sucralose concentration (ng/L) in categories of water from the Chemainus River watershed (DRY Season 2024)

Analyte	Source	Stream and river	Road runoff	Tap	Marine
Sucralose (ng/L)	0	0	57	0	24.3

Sucralose was detected in the highest concentration in the road runoff sample. The second highest concentration was detected in the marine sample.

Conclusions

• Sucralose concentrations in water samples from highest to lowest were as follows: road runoff > marine > stream and river = source = tap.
• The highest concentration of the artificial sweetener sucralose was detected in the road runoff sample.
• There are no current Canadian Environmental Quality Guidelines available for sucralose.
• There are no current Health Canada Drinking Water Guidelines available for sucralose.
• Sucralose was detected in two samples during the dry season, compared to the previous wet season sampling where it was detected in three water samples.

6PPD-Quinone

Capsule

The breakdown product of an anti-oxidant and anti-ozonant chemical in vehicle tires (6PPD-Quinone) has been associated with significant and repeated instances of coho salmon mortality events in Washington State and in British Columbia. Measurements for this contaminant are pending.

Introduction

6PPD is a chemical that is added to automotive tire rubber during the manufacturing process in order to extend the life of tires. When 6PPD comes into contact with air, it oxidizes and becomes 6PPD-Quinone – a transformation product that in recent years was discovered to be lethal to Coho salmon (Onchorhynchus kitsutch) at low concentrations (Lo et al. 2023; Tian et al. 2021). 6PPD-Quinone is the causative agent of what has been deemed Urban Runoff Mortality Syndrome (URMS) – which has seen mortality rates of up to 90 percent. Research is being conducted to assess the risk to other fish species.

Results

Table 16: 6PPD-Quinone concentration (ng/L) in categories of water from the Chemainus watershed (DRY Season 2024)

Analyte	Source(n=1)	Streams and rivers(n=1)	Road runoff(n=1)	Tap(n=1)	Marine(n=1)
6PPD-Quinone (ng/L)	Pending

Low levels of 6PPD-Quinone were detected previously in water samples from the Chemainus River watershed.

Conclusions

• Analysis is pending.

• The BC EQG 6PPD-Quinone in the freshwater environment is 10 ug/L.
• There are no DWQs for 6PPD-quinone.
• The LC50 (the concentration that is lethal to 50% of an experimental population of individuals within 24 hours) for 6PPD-Quinone in coho salmon is 41 ng/L (Lo et al. 2023).

Dry season water quality summary

Figure 17: Water categories for the Chemainus River watershed ranked by number of contaminant classes detected at highest concentrations in each (DRY Season 2024)

The larger the circle, the greater the number of contaminant classes that were detected in the highest concentration. Road runoff had the highest number of contaminant classes with the highest concentration (n=6). It was not surprising to find road runoff to be relatively contaminated.

A comparison of wet and dry season water quality

Figure 18: Seasonal differences were observed in the different analyte classes that were detected in the Chemainus River watershed

This figure indicates whether ‘concentration’ or ‘dilution’ occurs between dry and wet seasons. The bars depict the number of times greater the total concentration of the 9 analyte classes were observed in both the wet and dry season, with those in pink being higher in the dry season, and those in blue being higher in the wet season.

This report encapsulates a single dry season water sampling event comprising composite samples in five water categories: source water, stream & river water, road runoff, tap water, and marine water. This report presents findings from the 2nd of four planned sampling events in the Chemainus River.

Results suggest that Chemainus waters are in relatively good condition, but follow-up study is warranted to confirm or build upon initial observations of some contaminants of concern in the watershed. Collectively, these findings will provide an integrated evaluation of the contaminants, activities and sectors that are influencing water quality in the Chemainus River watershed. This may, in turn, provide guidance on mitigation, stewardship and restoration initiatives that protect and restore fish habitat throughout the Chemainus watershed.

List of acronyms

Abbreviation	Meaning
APE	Alkylphenol ethoxylates
BC EMA	British Columbia Environmental Management Act
CCME	Canadian Council of Ministers of the Environment
CEC	Contaminants of Emerging Concern
CEPA	Canadian Environmental Protection Act
CUP	Current-use pesticide
DO	Dissolved oxygen
DRIPA	Declaration on the Rights of Indigenous Peoples Act
ECCC	Environment and Climate Change Canada
MOE	Ministry of Environment
MST	Microbial Source Tracking
NP	Nonylphenol
PAH	Polycyclic aromatic hydrocarbons
PCB	Polychlorinated biphenyls
PFAS	Polyfluoroalkyl substances
PFOA	Perfluorooctanoic acid
PFOS	Perfluorooctane sulfonate
POP	Persistent organic pollutant
PPCP	Pharmaceutical and personal care products
PVC	Polyvinyl chloride
TDS	Total dissolved solids
TOC	Total organic carbon
TSS	Total suspended solids
TWP	Tire wear particle
WQGs	Water Quality Guidelines
WQI	Water Quality Index
WWTP	Wastewater treatment plant

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Appendix

Appendix 1: Environmental and Drinking water quality guidelines relevant for the present study. These guidelines were retrieved in May 2024.

Analyte Class	Federal EQGs1	BC WQGs		CCME EQGs2		Drinking WQGs
		Freshwater	Marine	Freshwater	Marine
Basic Water Properties
Temperature	–	19 (short-term)	+1°C per hourchange from background	narrative	max change of +0.5°C per hour	–
pH	–	6.5-9.0	7.0-8.7	6.5-9.0	7.0-8.7	7.0-10.5
Dissolved oxygen	–	>8.0 (long-term)>5.0 (short-term)	–	6.5-9.5 mg/L	80 mg/L	–
Conductivity	–	–	–	–	–	–
Turbidity	–	–	–	narrative	narrative	≤ 1.0 NTU
Metals (mg/L)
Aluminum	–	variable	–	0.005 if pH < 6.5	–	2.9
Lead	–	3 when ≤ 8 mg/L CaCO3 (short-term)	<140 ug/L	equation	–	0.005
Nutrients (mg/L)
Nitrate (as N)	–	3.0 (long-term) 32.8 (short-term)	3.7 (long-term)	550	200 (long-term) 1500 (short-term)	10
Nitrite (as N)	–	table	0.02 when Cl- ≤ 2 (long-term) 0.06 when Cl- ≤ 2 – (short-term)	0.06	–	1.0
Ammonia (Total as N)	–	table	table	table	–	–
Phosphate	–	0.015 (long-term)	–	–	–	–
Coliform
Total coliform	–	–	–	–	–	0
Fecal coliform	–	–	–	–	–	0
E. coli	–	–	–	–	–	0
PAHs (ug/L)
Naphthalene	–	1	–	1.1	1.4	–
Acenaphthene	–	6	6	5.8	–	–
Fluorene	–	12	12	3	–	–
Anthracene	–	4	–	0.012	–	–
Phenanthrene	–	0.3	–	4.4	–	–
Fluoranthene	–	4	–	0.04	–	–
Pyrene	–	0.02	–	0.025	–	–
Chrysene	–	–	0.1	–	–	–
Benzo-a-anthracene	–	0.1	–	0.018	–	–
Benzo-a-pyrene	–	0.01	–	0.015	–	0.04
Alkylphenols	0					0
Bisphenols	1			0		0
PCBs (ng/L)
Total PCBs	–	0.1	–	–	–	–
PCB-105	–	0.09	–	–	–	–
PCB-169	–	0.06	–	–	–	–
PCB-77	–	0.04	–	–	–	–
PCB126	–	0.00025	–	–	–	–
PPCPs	1			0		0
PFAS (ug/L)
Perfluorooctane Sulfonate (PFOS)	6.8 (fresh)	3.4	–	–	–	0.6
Perfluorooctanic acid (PFOA)	–	–	–	–	–	0.2
Pesticides (ug/L)
Atrazine	–	1.83	–	1.8	–	5
Chlorothalonil	–	–	–	0.18	–	–
Cyanazine	–	2	–	–	–	–
Chlorpyrifos	–	0.02	0.002	–	–	90
Diazinon	–	0.0043	–	–	–	–
Dimethoate	–	–	–	6.2	–	20
Endosulfan	–	0.0007 (active ingredient)	–	0.06 (short-term)0.003 (long-term)	0.09 (short-term)0.002 (long-term)	–
Malathion	–	0.1	–	–	–	290
Metribuzin	–	13	–	1.0	–	80
Permethrin	–	0.0043	–	0.004	0.001	–
Picloram	–	29	–	–	–	–
Simazine	–	103	–	10	–	10

1 Federal EQGs apply to both fresh and marine waters unless otherwise stated. 2 CCME EQGs are reported for long-term effects unless otherwise stated. 3 Represents CCME guidelines that the BC government has adopted as working water guidelines

Appendix 2: Top 6 PAHs with the highest concentrations in each water sample from the Chemainus watershed (DRY Season)

	Source	Stream and river	Road runoff	Tap	Marine
	C2-Biphenyls(3.9)	Naphthalene(3.6)	Naphthalene(31.1)	C4-Phenanthrenes – anthracenes(4.8)	Naphthalene(4.4)
	Naphthalene(2.3)	C12-Biphenyls(2.7)	Acenaphthene(19.0)	C3-Dibenzothiophenes(4.8)	C1-Naphthalenes(3.9)
	C2 Naphthalenes(1.7)	C1- Naphthalenes(2.2)	C1- Naphthalenes(13.5)	C4-Dibenzothiophenes(3.7)	2 – Methylnaphthalene(2.5)
	C3- Naphthalenes(1.4)	C2- Naphthalenes(1.7)	Phenanthrene(10.6)	C3-Fluoranthenes – Pyrenes(1.8)	Phenanthrene(1.9)
	C1- Naphthalenes(1.3)	Phenanthrene(1.6)	C2-Naphthalenes(9.8)	C2-Benzofluoranthenes – Benzopyrenes(1.7)	C2-Naphthalenes(1.7)
	Acenaphthene(0.99)	Acenaphthene(1.5)	1 Methylnaphthalene(7.6)	C2-Fluoranthenes – Pyrenes(1.7)	1-Methylnaphthalene(1.4)
Total concentrations of top 6 (% contribution to total PAHs)	11.7 (70%)	13.3 (63%)	94.5 (59%)	18.6 (49%)	15.8 (69%)

Appendix 3: The top 6 PCBs in each water category sampled in the Chemainus River watershed and their concentrations (DRY Season)

	Source	Stream and  river	Road runoff	Tap	Marine
	PCB-44+47+65	PCB-85+166+177	PCB-187	PCB-44+47+65	PCB-44+47+65
	(1.9)	(1.6)	(1.2)	(2.7)	(4.5)
	PCB-1	PCB-153+168	PCB-190	PCB-11	PCB-93+95+98+100+102
	(1.7)	(1.0)	(1.1)	(1.9)	(3.8)
	PCB-78	PCB-1	PCB-44+47+65	PCB-131	PCB-11
	(1.6)	(0.89)	(0.99)	(1.2)	(2.2)
	PCB-129+138+160+163	PCB-131	PCB-174	PCB-31	PCB-77
	(1.4)	(0.84)	(0.91)	(0.99)	(2.2)
	PCB-128+166	PCB-44+47+65	PCB-147+149	PCB-52	PCB-133
	(1.1)	(0.80)	(0.88)	(0.99)	(1.7)
	PCB-153+168	PCB-37	PCB-153+168	PCB-37	PCB-188
	(0.95)	(0.57)	(0.81)	(0.96	(1.6)
Total concentrations of top 6 (% contribution to total PCBs)	8.6 (22%)	5.7 (46%)	5.9 (27%)	8.7 (37%)	15.9 (32%)

Appendix 4: Total analyte concentrations in water sampled in the Chemainus watershed (DRY Season)

Analyte	Source	Stream and river	Road runoff	Tap	Marine
E. coli (MPN)	96	127	56	0	55
Nitrate(mg/L)	0.0746	0.290	0.0897	1.14	0
Metals (mg/L)	14.3	20.7	74.9	21.0	10,256
Pesticides (ng/L)	0.74	1.1	0.83	0.76	1.1
PCBs (pg/L)	37.8	12.4	21.6	23.3	50.2
PAHs (ng/L)	16.6	21.2	160.1	37.9	23.1
PPCPs (ng/L)	9.1	38.8	81.0	57.1	41.9
PFAS (ng/L)	0.37	0.59	23.1	2.1	0
APEs (ng/L)	0	0	0	0	0
bisphenols (ng/L)	4.33	2.24	0	4.18	3.61
Sucralose (ng/L)	0	0	57	0	24.3
6-PPDq (ng/L)

Bold indicates the highest concentrations across water categories for each contaminant.

Appendix 4:  Ratios between average values of each contaminant class for the two sampling seasons (WET and DRY)

	Dry/wet ratio	Wet/dry ratio
E. coli (MPN)	42	0.1
Nitrate(mg/L)	1.2	3.0
Metals (mg/L)	1.4	0.8
PAHs (ng/L)	1.5	1.2
Pesticides (ng/L)	6.0	0.9
PPCPs (ng/L)	2.3	1.0
PFAS (ng/L)	10.7	0.8
PCBs (pg/L)	0.7	1.8
APEs (ng/L)	–	–
bisphenols (ng/L)	–	0.0
sucralose (ng/L)	0.5	1.5
6-PPDq (ng/L)

Appendix 4: Health Canada Screening values for nine different PFAS compounds

Compound Name	Acronym	Screening value (mg/L)	Screening value (ug/L)
perfluorobutanoate	PFBA	0.03	30
perfluorobutane sulfonate	PFBS	0.015	15
perfluorohexanesulfonate	PFHxS	0.0006	0.6
perfluoropentanoate	PFPeA	0.0002	0.2
perfluorohexanoate	PFHxA	0.0002	0.2
perfluoroheptanoate	PFHpA	0.0002	0.2
perfluorononanoate	PFNA	0.00002	0.02
6:2 fluorotelomer sulfonate	6:2 FTS	0.0002	0.2
8:2 fluorotelomer sulfonate	8:2 FTS	0.0002	0.2

Adapted from https://www.canada.ca/en/services/health/publications/healthy-living/water-talk-drinking-water-screening-values-perfluoroalkylated-substances.html 

Chemainus River watershed: Water quality report for the 2024 dry season

Scott S, Moskal H, Noel M and Ross PS. 2025. Chemainus River watershed: Water quality report for the 2024 dry season. Raincoast Conservation Foundation. https://doi.org/10.70766/2051.77 

Raincoast Healthy Waters | Watershed report: Chemainus River | 2024 DRY Season                                            
DOI: 10.70766/2051.77