You’re flowing EAST into the Atlantic ocean: you’re based in the Upper St. Lawrence, which is part of the St. Lawrence Drainage Area.
The OVERALL health score of the
Upper St. Lawrence
subwatershed
is Fair
Enough data? Moderately sufficient
The Upper St. Lawrence Subwatershed (02M) includes the section of the St. Lawrence River from Lake Ontario to just past Cornwall, Ontario, forming part of the Canada-U.S. border. It is a heavily regulated waterway with hydroelectric dams, major shipping routes, and significant urban and industrial development.
Did you know? The Mohawk Nation of Akwesasne has lived along this section of the river for generations, maintaining a strong cultural and political presence in the region.
JURISDICTION
Ontario, Quebec, New York (USA), Vermont (USA)
POPULATION CENTER(S)
Kingston
WATERSHED SIZE
6,139 km² (0.1% of Canada)
How to interpret the scores
Very good | Good | Fair | Poor | Very poor | Data deficient | Not scored |
Our freshwater health scores are based on four key metrics: water quality, hydrology (flow), benthic macroinvertebrates, and fish populations. For each metric, we use standardized criteria—such as exceedance of federal and provincial water quality guidelines, long-term trends in river flow, tolerance values for invertebrates, and native fish species richness—to assess conditions across watersheds.
To make these scientific results easier to understand, we translate them into a simple 1 to 5 scale: 1 = VERY POOR and 5 = VERY GOOD
These scores provide an overall picture of freshwater health, helping both experts and the public quickly see where attention is needed.
It’s important to remember:
- We calculate scores at a national scale, using the best available data. While this provides a valuable snapshot, it may not capture every local nuance.
- For some regions and specific waterbody types (like northern areas or mud-bottom prairie rivers), certain metrics—like the Hilsenhoff Biotic Index (HBI) for invertebrates—may not fully reflect local conditions. We’ve flagged these cases.
- Data sufficiency is a key consideration: Some watersheds have long-term, robust data. Others may be classified as “Data Deficient” due to many reasons besides lack of data, including monitoring that is incompatible with the FHA, inaccessible data, and the Covid pandemic. Learn more on our data sources page.
For more detail on how each score is calculated, including thresholds, trend analyses, and limitations, please visit our About the Indicators page or consult our Tech Doc for the full methodology.
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Datapoints
This analysis includes all the data we could access—whether from open platforms, agency reports, or historical records. Some datasets were readily available, while others came from hardcopy reports and handwritten notes that we digitized and formatted. We’re grateful to all data providers for sharing their data. Even so, this is only part of the picture. Learn more about data accessibility challenges.
103,657
59,078
6,098
2,916
Water quality
The water quality score for the Upper St. Lawrence watershed is Fair (It was previously FAIR).
The overall water quality score assesses many parameters on how often they met water quality guidelines in the last 5 years, but to understand health, it’s important to understand what’s passed and failed and what’s missing. Then, we compare that with 5 years previous to help us determine how it’s changing.
Common water health tests
These are the most commonly monitored parameters that tell us about general water health and nutrients.
Ammonia | Very poor | 42% passed |
Chloride | Very good | 95% passed |
Dissolved oxygen | Good | 88% passed |
Nitrate | Very good | 100% passed |
Nitrite | Very good | 100% passed |
pH | Good | 80% passed |
Total nitrogen | Poor | 64% passed |
Total Phosphorus | Very poor | 15% passed |
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Metals
Metals are important to monitor to determine contamination from pollution or natural sources.
Aluminum | Fair | 65% passed |
Arsenic | Very good | 100% passed |
Cadmium | Very poor | 18% passed |
Copper | Very good | 96% passed |
Iron | Very poor | 44% passed previously VERY POOR |
Lead | Very poor | 25% passed |
Mercury | Very good | 100% passed |
Nickel | Very good | |
Uranium | Very good | 100% passed |
Zinc | Fair | 78% passed |
Pollutants
Pollutants are often expensive to test (requiring specialized equipment like mass spectrometers). Many of these are not tested (data-deficient) unless there’s a specific concern.
.gamma.-hexachloro-cyclohexane | Data deficient |
|
2,4-D | Data deficient | 100% passed |
Acenaphthene | Data deficient |
|
Acridine | Data deficient |
|
Aldrin | Data deficient |
|
Anthracene | Data deficient |
|
Atrazine | Very good | 100% passed |
Bentazone | Data deficient |
|
Benz[a]anthracene | Data deficient |
|
Benzo[a]pyrene | Data deficient |
|
benzyl.butyl.phtalate | Data deficient |
|
bisphenol.a | Data deficient |
|
Bromoxynil | Data deficient |
|
Chlordane | Data deficient |
|
ddt | Data deficient |
|
Dicamba | Data deficient | 100% passed previously DATA DEFICIENT |
Dieldrin | Data deficient |
previously DATA DEFICIENT |
dimethyl.phthalate | Data deficient | previously DATA DEFICIENT |
Fluoranthene | Data deficient | previously DATA DEFICIENT |
Fluorene | Data deficient | previously DATA DEFICIENT |
Glyphosate | Data deficient | 100% passed previously DATA DEFICIENT |
MCPA | Data deficient | 100% passed previously DATA DEFICIENT |
Mirex | Data deficient | |
Naphthalene | Data deficient | 100% passed |
Naphthalene | Data deficient |
|
Pyrene | Data deficient | previously DATA DEFICIENT |
Quinoline | Data deficient | |
Total PCBs | Data deficient | |
Toxaphene | Data deficient | |
about our analysis
The overall water quality score is based on how frequently key water quality parameters exceed established guidelines. Individual parameters provide insight into specific concerns, but water quality is complex, and further investigation is encouraged before drawing conclusions about the factors influencing the scores. Here, we’re showing you the percentage of samples within the recommended thresholds over the past five years (2018–2023). These results are compared to the five years preceding (2014–2018) to assess trends. You can visit our glossary page in our Tech Doc for descriptions of each parameter and our standards page to understand the thresholds used in this region.
How's it flowing?
Exploring how flow has changed over time
The Upper St. Lawrence subwatershed scored Good.
For some watersheds, there’s been only a minor change, while others have seen shifts including increases and decreases. The Upper St. Lawrence watershed trend is: ↓ Minor decrease in flow.
We wanted to dive deeper than the score into how flow has changed over time. We took the daily average flow for the Upper St. Lawrence watershed from the past 30 years (1994-2023) and compared it to the previous 30 years (1964-1993).
Total daily flow
Upper St. Lawrence subwatershed’s average daily flow from 1994-2023 compared to 1964-1993. (N=1)
How much has it changed?
The magnitude of change (%) for Upper St. Lawrence subwatershed’s total daily flow – 1994-2013 compared to 1964-1993. (N=1))
about our analysis
We used flow data from HYDAT for this watershed, focusing on stations with long-term records—at least 50 years of data and a minimum of 6 months of valid daily flow data per year. This approach ensures inclusion of stations in colder regions, where rivers may freeze part of the year. We then calculated average daily flows across two 30-year periods: 1964–1993 and 1994–2023. By comparing these periods, we smoothed out short-term events like floods or droughts to better understand long-term changes in flow patterns. Learn more about our hydrology calculations in our Tech Doc.
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most common benthic invertebrate taxa observed
Detritus worms (Naididae)
The score for benthic invertebrates for the Upper St. Lawrence watershed is Very poor.
Benthic (meaning bottom-dwelling) macroinvertebrates are small aquatic animals and the aquatic larval stages of insects. They include dragonfly and stonefly larvae, snails, worms, and beetles. These creatures make up the backbone of the ecosystem and, since they live there full time, are a great way to understand its health!
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The most frequently reported taxa is the Detritus worms (Naididae), with 30% of all samples containing them.
About Detritus worms (Naididae)
Naididae feed on organic waste produced by plants and animals, making them an important part of freshwater ecosystems. Organic detritus (meaning waste or debris of any kind) is their food source, and where they get their common name – detritus worms! Feeding on detritus reduces oxygen levels, meaning Naididae species (and other detritus-feeding organisms) are often observed in low-oxygen, pollution-affected streams.
about our analysis
We assessed benthic macroinvertebrate health using the Hilsenhoff Biotic Index (HBI), which measures how tolerant invertebrate communities are to pollution. We used data from CABIN, the Royal Ontario Museum, Conservation Authorities, and regional programs, focusing on samples identified to at least the family level. For most sub-watersheds, we calculated an average HBI score and assigned a health rating from 1 (very poor) to 5 (very good). However, in some regions—such as the North and certain Prairie rivers—HBI is not considered an appropriate tool due to ecological differences or data limitations. In these cases, we marked the sub-watershed as Not Scored. You can learn more about how we evaluated benthics on our Guidelines and Tolerances page and our Tech Doc.
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Most frequently reported fish:
American Eel
The fish score for the Upper St. Lawrence is Good.
Fish, like invertebrates, are an important way to understand water health, since they live in the water full-time.
Here we list out those reported in the past ten years. We also include reported invasive fish species (which are not included in the score calculation, but we thought you’d want to know!).
Here are all the reported fish species for Upper St. Lawrence watershed during the past 10 years*: american eel, central mudminnow, brook stickleback, northern redbelly dace, golden shiner, brown bullhead, kiver, white sucker, creek chub, bluegill, yellow perch, brassy minnow, blacknose shiner, finescale dace, fathead minnow, common shiner, rock bass, banded killifish, bluntnose minnow, northern pike, largemouth bass, mimic shiner, black crappie, johnny darter, logperch, fallfish
*Because fish sampling is sparse and sampling bias is likely strong, this list is not comprehensive.
about our analysis
The fish health score is based on trends in native fish species richness, which can reflect overall ecosystem health. Fish monitoring in Canada often relies on presence/absence data, limiting detailed community-level assessments. Still, tracking species richness over time provides valuable insights. In addition to the scores, we present the trend in native species richness over the past ten years (2014–2023) and compare it to the preceding decade (2004–2013) to assess changes. Watersheds are classified into three categories: Good (no significant decline), Fair (a significant decline in either median or total species richness), and Poor (a significant decline in both). Read more in our Tech Doc.
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Dive deeper
Other resources
We recognize that these Reports are a zoomed out way to understand watershed health. You may have additional questions about your local waterbody. We encourage you to find out more about the local conservation work and testing happening in your region. Some regions produce report cards for individual waterbodies, but often this is dependent on resources.
Many regions have opportunities to take action to collect water quality data and get involved in restoration and education opportunities. Learn more about how you might get involved.
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