More information about the Canada-B.C. Water Quality Monitoring Program

The purpose of the network is to deliver water quality information using consistent and comparable methods.

We use this information to assess current water quality and biological conditions, look for changes over time, identify threats to aquatic life, as well as track results and outcomes.

We collect routine water samples from each station and analyze them based on a range of parameters.

We define a set of core parameters for every station, including:

• Metals
• Nitrogen
• Phosphorus
• Turbidity
• pH
• Specific conductance
• Hardness
• Suspended sediment
• Colour
• Organic carbon
• Calcium
• Magnesium
• Potassium
• Sodium
• Sulphate
• Chloride, and
• Temperature

We also add other parameters if there's a specific issue in the watershed.

We collect samples of benthic macroinvertebrates every 3 years to evaluate the ecosystem health of the river.

We use biomonitoring metrics and other analyses of the benthic macroinvertebrate community to assess monitoring stations.

We compare the benthic macroinvertebrate communities found at a station to those found in rivers with the same habitat types and little or no human activity using CABIN reference condition bioassessment models.

We calculate biomonitoring metrics that describe the numbers of different macroinvertebrates found, diversity of the community and their different ways of feeding and behaviour.

The biological status reports may include the following analyses and biomonitoring metrics: 

• CABIN assessment
• Bray-Curtis dissimilarity measure
• RIVPACS ratio
• Abundance metrics
• Biotic Index metrics
• Functional feeding group metrics
• Richness metrics

Download water quality data from Environment and Climate Change Canada’s Long-term National Water Quality catalogue.

Download biomonitoring data collected by the Canadian Aquatic Biomonitoring Network (CABIN) from the Government of Canada website.

Environment and Climate Change Canada uses the data to support the national water quality indicator.

It also supports reporting through various agreements between B.C. and the governments of Yukon, Alberta and the Northwest Territories.

Status measures if water is safe or suitable for a specific use based on recent results and guidelines.

These criteria describe the desired condition of a water body based on water uses, such as habitat for fish and aquatic life, recreation, agriculture, or public water supply.

Every year, Environment and Climate Change Canada reports water quality indicator scores and categories for water quality stations across Canada.

We compare water quality data from a single monitoring station based on water quality guidelines and create a score for each station (ECCC, 2025).

This score is called the water quality indicator. It provides a measure of how well a river can support the plants and animals that live there.

Environment and Climate Change Canada calculates the indicator using the water quality index calculation (CCME, 2001).

We compare concentration values over a three-year period for 5 to 15 parameters to their guideline values at each station.

An index score is calculated between 1 and 100 based on the selected parameters. Stations are assigned a category based on that score.

The score goes down if a parameter frequently exceeds its guideline and if specific sample concentrations exceed the guideline by a lot.

We use concentration values from the most recent 3 years of data at a station to calculate the water quality index.

The most recent indicator category and the years of sampling data that we used to calculate the score are displayed in the mapping tool.

Water quality stations are rated from poor to excellent.

For example, water quality is considered excellent when parameters do not exceed their guidelines.

Water quality is rated poor when parameters frequently exceed their guidelines, sometimes by a wide margin (ECCC, 2020 and CCME, 2001): 

• Excellent: Water quality is protected with a virtual absence of threat or impairment; conditions very close to natural or pristine levels
• Good: Water quality is protected with only a minor degree of threat or impairment; conditions rarely depart from natural or desirable levels
• Fair: Water quality is usually protected but occasionally threatened or impaired; conditions sometimes depart from natural or desirable levels
• Marginal: Water quality is frequently threatened or impaired; conditions often depart from natural or desirable levels
• Poor: Water quality is almost always threatened or impaired; conditions usually depart from natural or desirable levels

The water quality indicator is calculated at a subset of stations across Canada and is used for national reporting.

The focus is generally on regions where human activity is more prevalent because it's usually the main factor for deteriorating water quality.

Benthic macroinvertebrates are commonly used as water quality indicators for freshwater ecosystems (Mazor et al., 2019).

They're found everywhere and are easy to collect. Since they can live in one place for a long time, they indicate local water quality over a period of months to years.

They also react differently to various disturbances, making them good indicators of ecosystem health. Plus, they play an important role in the aquatic food web.

A CABIN assessment tells us whether the benthic macroinvertebrate community at a station is similar to those at undisturbed reference sites with similar habitat features (Reynoldson et al., 1997). It can only be done in watersheds where a CABIN reference model exists.

We assume the reference sites are healthy, so if the community at a station is very different from the reference sites, it may not be healthy. This difference could be due to an ecosystem stressor like organic pollution, nutrient enrichment, sedimentation, or climate change.

A CABIN assessment cannot identify the exact stressor, but it can tell us how different the community is from the reference sites.

A CABIN reference model is a web-based biomonitoring tool used to assess the health of the aquatic ecosystem. It's developed from habitat and benthic macroinvertebrate community data from many undisturbed sites in a watershed (Reynoldson et al., 1995). These undisturbed sites are reference sites considered to have healthy ecosystems.

Reference sites with similar benthic macroinvertebrate communities are grouped together. Each model has several reference groups that can be described by certain habitat features.

The macroinvertebrate communities in that reference group represent the range of what a healthy macroinvertebrate community should look like at the station.

The RIVPACS ratio calculation is based on the work of Wright (1995). It can only be calculated in watersheds with a CABIN reference model.

The CABIN reference model provides the expected number of macroinvertebrate families that are expected if the stations are healthy. The sample collected at the station provides the number of macroinvertebrate families that were observed.

The RIVPACS ratio is the observed number divided by the expected number.

The Bray-Curtis dissimilarity measure (Bray and Curtis 1957) compares the benthic macroinvertebrate community at a station to the median community of the reference group predicted by the CABIN reference model.

This measure can only be calculated in watersheds with a CABIN reference model. The result is a value between 0 (identical) and 1 (completely different).

The values for the Summary of Station Metrics graph are adjusted for each metric to match the average and standard deviation of the reference group.

On the graph, the average value in the reference group is set to zero, and one standard deviation of the reference group above or below the mean is equal to one unit above or below zero.

The station’s metric value is displayed on the same scale for easy comparison.

A metrics graph is not shown for a station if the value was zero for the reference group and station in all years of sampling.

Pollution from urban, industrial, agricultural areas, mines and climate change pose a threat to water quality and aquatic life.

We assess data from the Network for trends to see if the water quality is changing over time.

We use publicly available data from the federal Open Government website.

Data with a status code of V (Validated) or P (Provisional) were included in the datasets.

Replicate and blank samples collected for quality assurance or quality control were not included.

Water quality parameters describe the physical and chemical conditions of a river or stream.

We analyze parameters with B.C. water quality guidelines for the protection of aquatic life:

• Nutrients: Ammonia, nitrate, nitrate+nitrite, nitrite, total nitrogen and total phosphorus
• Carbon: Dissolved organic carbon, total organic carbon
• Major ions and other inorganics: Chloride, fluoride, sulphate and hardness
• General: Total alkalinity, dissolved oxygen, pH, total suspended solids, specific conductance, turbidity and water temperature
• Metals (total and dissolved): Aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, selenium, silver, thallium, uranium, vanadium, zinc

We also included total phosphorus, nitrogen, hardness and specific conductance.

It's not possible for a laboratory to measure the concentration of a parameter in water to zero. Therefore, the laboratory defines a number for the lowest concentration that they can measure.

Laboratories refer to this as a method detection or reporting limit. When the concentration of a parameter in the water is too low to measure, the laboratory will report this limit with a less than sign (<). We refer to this value as 'value too low to detect.'

Detection limits change as laboratories improve their instruments or analytical methods over time. This can lead to multiple detection limits for a single parameter in the dataset.

We calculated trends for over 2 different 10-year periods from January 2005 to December 2014, and from January 2010 to December 2019.

There's a trend report available for each period in the interactive mapping tool. If the data for a station does not span the trend analysis period, we report it as 'trends not assessed.'

After we collect a sample, it takes time to complete the laboratory analysis and validate the data.

It also takes time to analyze and review results before releasing them.

We have a set of screening criteria so results can be compared between stations across the network.

Some water quality datasets may not be suitable for trend analysis. Samples are missed due to high water or bad weather.

We analyze data from each station and 10 year period separately.

If a parameter does not meet the criteria, then it's excluded from the analysis for that specific period:

• Each of the first and last 2 years of data must be at least 74% complete
• The remaining middle years must be at least 60% complete
• No more than 80% of values are below the highest method detection limit

Data may also be affected by operational changes, like a change in laboratory or a change in sampling location. Parameters were also screened out if the trends may have been affected by an operational change.

Monitoring varies between stations. The Canada-B.C. monitoring program has a core set of variables it typically monitors for at each station.

We also monitor extra parameters based on water quality threats at specific stations.

Parameters are also excluded if they did not meet the screening criteria above.

This study analyses a large number of water quality parameters collected from many stations. We analyzed the data using a method that can be applied consistently to a wide variety of data. For this reason, we use a non-parametric statistical method. Non-parametric methods are less affected by characteristics commonly found in water quality data.

We use a censored Seasonal Kendall test to identify if the trend is up or down and statistically significant. Then we use the seasonal Akritas-Theil-Sen (ATS) test to estimate the slope or the size of the trend (Akritas et al., 1995).

We use this test because it accounts for values below the detection limit, it does not make assumptions about the distribution of the data, and it allows for missing values without biasing the analysis (Hirsch et al., 1982).

Trend results are classified as increasing, decreasing, or 'no evidence of trend.'

Categories are based on the statistical significance and direction of a detected trend:

• Increasing Trend: The trend is significantly different from zero with an increasing trend
• No evidence of trend: There's not enough evidence to conclude if an increasing or decreasing trend is present
• Decreasing Trend: The trend is significantly different from zero with a decreasing trend

A trend is classified as increasing or decreasing when the censored Seasonal Kendall test for trend was found to be statistically significant (p-value < 0.1).

When the trend is ‘not significant’ (p >= 0.1), it was classified as 'no evidence of trend.' This means that there's insufficient evidence to confidently determine if the trend is increasing or decreasing. It does not mean there's 'no trend.'

The graphs display the concentrations for a single water quality parameter over time for the trend period. We use a single concentration value from each month over a 10-year period to analyze for a trend.

We collect water samples from the river and send them to a laboratory to be analyzed for specific water quality parameters. Solid circles on the graph represent concentration values above the laboratory detection limit. The detection limit is the lowest concentration that the laboratory can report for a given parameter.

Open circles on the graph are concentration values of the detection limit, not the 'true' concentration of a parameter in the water because the actual concentration is below what the laboratory can measure. We call this a 'value too low to detect.'

The estimated trend is shown as a straight orange line. The trend box above the graph shows the direction and estimated slope or size of the trend in concentration units per year. If the box says 'no evidence of trend,' this means there's not enough evidence to determine if there's an increasing or decreasing trend. It does not mean that there is 'no trend.'

We estimate the slope or size of the trend using a different test, so it's possible for a trend to be increasing or decreasing and have a slope estimate of zero.

B.C. has guidelines to assess potential risks to water quality for different water uses such as aquatic life, irrigation, recreation, and wildlife. The B.C. guideline value for the protection of aquatic life is in the light blue box to provide context and help you determine if the trend presents a risk to fish or other aquatic life.

For example, a parameter may have a statistically significant increasing trend, but it may not pose a risk to aquatic life because it's much lower than the guideline. We convert guideline values to match the units on the graph if they're different.

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Bray, J. R. and J.T. Curtis. 1957. An Ordination of the Upland Forest Communities of Southern Wisconsin. Ecological Monographs 27(4): 325–349.

Canadian Council of Ministers of the Environment (2017) CCME Water Quality Index 2.0 User’s Manual (PDF; 1.60 MB). https://ccme.ca/en/res/wqimanualen.pdf. Accessed on June 11, 2025.

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