You’re flowing WEST into the Pacific ocean: you’re based in the Alsek, which is part of the Pacific Drainage Area.

 The OVERALL health score of the

Alsek

subwatershed

is Data deficient

Enough data? Insufficient

The Alsek River originates in the Yukon and flows through glacial valleys before reaching the Pacific Ocean in Alaska. It is a key corridor for salmon and grizzly bears in Kluane National Park.

Did you know? The Alsek River carries icebergs from Kaskawulsh Glacier, making it one of Canada’s few rivers with floating ice!

JURISDICTION
British Columbia, Yukon Territory

POPULATION CENTER(S)
Haines Junction

WATERSHED SIZE
31,192 km² (0.3% of Canada)

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.

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

9,403

Water quality

25,041

Flow

2,640

Invertebrates

340

Fish

Water quality

The water quality score for the Alsek 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 

Data deficient


previously DATA DEFICIENT

Chloride   

Very good

100% passed
previously VERY GOOD

Dissolved oxygen   

Data deficient


previously DATA DEFICIENT 

Nitrate   

Data deficient


previously DATA DEFICIENT

Nitrite   

Data deficient


previously DATA DEFICIENT

pH   

Very good

100% passed
previously VERY GOOD

Total nitrogen   

Very good

99% passed
previously VERY GOOD

Total Phosphorus   

Very poor

13% passed
previously VERY POOR

Metals

Metals are important to monitor to determine contamination from pollution or natural sources.

Aluminum 

Very poor

6% passed
previously VERY POOR

Arsenic   

Very good

99% passed
previously VERY GOOD

Cadmium   

Good

94% passed
previously GOOD

Copper   

Poor

55% passed
previously POOR 5%

Iron   

Very poor

0% passed previously VERY POOR

Lead   

Good

80% passed
previously GOOD

Mercury   

Data deficient

 
previously DATA DEFICIENT

Nickel   

Very good

99% passed
previously VERY GOOD

Uranium   

Very good

100% passed
previously VERY GOOD

Zinc   

Fair

74% passed
previously POOR

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


previously DATA DEFICIENT

2,4-D   

Data deficient


previously DATA DEFICIENT

Acenaphthene   

Data deficient


previously DATA DEFICIENT

Acridine   

Data deficient


previously DATA DEFICIENT

Aldrin   

Data deficient


previously DATA DEFICIENT

Anthracene   

Data deficient


previously DATA DEFICIENT

Atrazine   

Data deficient


previously DATA DEFICIENT

Bentazone   

Data deficient


previously DATA DEFICIENT

Benz[a]anthracene   

Data deficient


previously DATA DEFICIENT

Benzo[a]pyrene   

Data deficient


previously DATA DEFICIENT

benzyl.butyl.phtalate   

Data deficient


previously DATA DEFICIENT

bisphenol.a   

Data deficient


previously DATA DEFICIENT

Bromoxynil   

Data deficient


previously DATA DEFICIENT

Chlordane   

Data deficient


previously DATA DEFICIENT

ddt   

Data deficient


previously DATA DEFICIENT

Dicamba   

Data deficient

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

previously DATA DEFICIENT

MCPA   

Data deficient

previously DATA DEFICIENT

Mirex   

Data deficient


previously DATA DEFICIENT

Naphthalene   

Data deficient


previously DATA DEFICIENT

Naphthalene   

Data deficient


previously DATA DEFICIENT

Pyrene   

Data deficient

previously DATA DEFICIENT

Quinoline   

Data deficient


previously DATA DEFICIENT

Total PCBs   

Data deficient


previously DATA DEFICIENT

Toxaphene   

Data deficient


previously DATA DEFICIENT

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 Alsek subwatershed scored Data deficient.  

We wanted to dive deeper than the score into how flow has changed over time. We took the daily average flow for the Alsek watershed from the past 30 years (1994-2023) and compared it to the previous 30 years (1964-1993).

Total daily flow

Alsek subwatershed’s average daily flow from 1994-2023 compared to 1964-1993. (N=1)  

Month - Day

How much has it changed?

The magnitude of change (%) for Alsek subwatershed’s total daily flow – 1994-2013 compared to 1964-1993. (N=1)) 

Month - Day

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

Small minnow mayflies (Baetidae)

The score for benthic invertebrates for the Alsek watershed is Not scored.  

 

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!

This watershed was not scored.

We determined that it would be inappropriate to score some watersheds with the assessment criteria. This included northern regions and some parts of central Canada where they have mud-bottomed rivers. 

In northern regions, there are fewer types and quantities of benthic invertebrates because of naturally harsh, cold conditions! The scoring system that works for more Southern areas does not work well in the North because the species found there are naturally tolerant to cold and extreme conditions. In the Central region, mud bottomed rivers in productive landscapes have more tolerant species, too. For both regions, this can lead to misleading scores, making healthy ecosystems appear unhealthy. Therefore, we chose not to score benthic invertebrates in the northern tolerance zones and some central tolerance zones (you’ll see “Not scored”. Learn more in our Tech Doc). We hope to change how we score these regions in the future. We still crunched data, and if we had records, we still spotlighted the most abundant species found there.

The most frequently reported taxa is the Small minnow mayflies (Baetidae), with 22% of all samples containing them.   

About Small minnow mayflies (Baetidae)

Baetidae (or small minnow mayflies) are some of the smallest mayfly species living in Canadian freshwaters. Baetidae species have a range of pollution tolerances and thrive in diverse environments. Their streamlined bodies and minnow-like shape make them strong swimmers, and they are frequently used as models for fly-fishing lures.

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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We have no fish records for this watershed

The Alsek’s fish score is Data deficient. That’s a shame, since fish, like invertebrates, are a great way to understand water health (since fish live there full time). Monitoring for fish is time consuming, requires expertise, and it’s expensive to do well.

Some monitoring for fish may had happened in this watershed but we couldn’t access the data. The best way for fish data to be included is to share it with national or regional data hubs.

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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