Water Quality

Water Quality

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Water Quantity

Changes in water quality have been reported by Indigenous communities and through scientific studies in some waterbodies in the Athabasca sub-basin. Indigenous communities have observed an increase in contaminants and sediment in lakes and rivers in the middle and lower Athabasca River and a change in the taste and colour of the water. These changes are thought to be associated with increased industrial activities, particularly oil sands mining and forestry, but studies also show localized influence of river channelization and straightening on water quality in the Lesser Slave watershed. Increases in blue-green algae blooms and nutrient enrichment in some lakes have been reported in studies by scientists, Indigenous communities, and local residents. Human footprint has increased over time and the downstream effects of industrial development remain a concern for local communities and there are significant concerns for how water contamination will continue to affect water quality and ecosystem health.

The following table summarizes the availability of information for each Water Quality indicator.

Signs and Signals

Indigenous Knowledge Information and Data

Indigenous Knowledge Availability in Public Sources1

Science Information and Data

Science Data Availability2

Water Quality

Local observations and oral histories of good water, poor water, seasonal differences, land-based consumption practices

Many observations from several locations.

Ambient surface and ground water concentrations

Many datasets and reports available.

Benthic Invertebrates

Not assigned to a Sign or Signal

Not assessed.

Relative abundance of aquatic macroinvertebrates

Several datasets and reports available.

Land Use Changes

Stories and oral histories of land use cover and practices

Many observations from several locations.

Map and statistics of current vs. past land cover and land use

Current and past data available.

Effluent Discharge

Not assigned to a Sign or Signal

Not assessed.

Volume of effluent discharges

Data available but not summarized for this report.

1 Qualifiers for the availability of local and Indigenous Knowledge observations in publicly available sources: Limited = 1-2 observations; Some = 3-4 observations; Many = 5 or more observations
2 Qualifiers for the availability of science data in publicly available sources: Low = Individual studies or locations; Many = Network of monitoring stations across the basin

Water Quality

Increases in contaminants, sediments, and concentrations of many substances in tributaries downstream of oil sands development have been observed in some waterbodies in the Athabasca sub-basin. More frequent blue-green algae blooms in some lakes have also been observed.

Denesuline elders from Black Lake and Fond du Lac have noted some contamination in the water near the west side of Lake Athabasca, which they attribute to tailings seepage from mining and uranium developments in the region.[33] Elders and river users from Mikisew Cree First Nation and Athabasca Chipewyan First Nation have similarly observed changes in the quality of the water linked to contamination, leading to abnormalities in animals and fish.[34] Similarly, Fort Chipewyan community members have expressed concern for the rare cancers in their community which they associate with contamination of the local water supply.[35] Combined with decreasing water levels on the Athabasca River from upstream industrial activities, these changes are limiting access to traditional land use areas and causing a loss of confidence in the quality of water among many communities located in the lower Athabasca.[36],[37],[38]

Tributary concentrations of many parameters were greater at sites downstream of oil sands development near their confluence with the Athabasca River. Analysis of historical water chemistry data (1972-2010) showed that concentrations and loads of total vanadium, dissolved selenium and dissolved arsenic were greater downstream of development compared to reference sites in the Lower Athabasca oil sands region.[39] A case study conducted on the Muskeg River (1972-2009 data) showed that concentrations and loads of the same three elements were greatest during the early land-clearing stage of mine development, with dissolved selenium remaining elevated during the subsequent expansion stage.[40] During the first three years of the new Oil Sands Monitoring program from 2011 to 2014, selenium was the only parameter that showed a clear increasing pattern in the Athabasca River mainstem from upstream of the Oil Sands to downstream, during spring freshet.[41] Analysis of Environment Canada data downstream of oil sands development showed an increasing trend from 2000 to 2018 in dissolved selenium for August of 0.001 ug/L per year (0.75% per year, n=31, p=0.001) and in total selenium for August of 0.001 ug/L (0.65% per year, n=30, p=0.045).

Many Aboriginal communities have observed a marked decline in water quality in the Athabasca River over the last 50 years,

Trend in August dissolved selenium concentrations in Athabasca River at Baseline 27 (2000-20018). Data from Environment and Climate Change Canada. Significance and slope of the trend were estimated using the Mann Kendall Trend Test. The Sen Slope (change in µg/L per year) and % change per year are displayed on the chart.

Denesuline elders from Black Lake and Fond du Lac have observed more sediment in the water near the west side of Lake Athabasca[42] and raised concerns about the ongoing impacts of mining activities on water quality within their territories.[43] The Lesser Slave Lake Cree have shared recent observations of dirty and murky water that were linked in one study to water diversion into Buffalo Bay on the west side of Lesser Slave Lake and sediment loading in rivers and streams due to runoff from nearby clear-cut areas.[44] An analysis of water quality in tributaries to Lesser Slave Lake showed that suspended sediment levels were highest in western tributaries, especially East Prairie River, where extensive river channelization and straightening intended for flood control has modified river beds and increased river-bed erosion.[45]
Fort Chipewyan elders have noticed an oily sheen on the surface of the Athabasca River when the river is calm and flowing smoothly and described how the water has a different taste than in the past.[46] Black and rust-coloured water in streams and other waterbodies have been noted by the Lesser Slave Lake Cree. Changes in water taste and colour are often attributed to the rise of contaminants and sediments in natural waterbodies linked to industrial activity in the region.[47],[48]
Some Indigenous communities and local residents have observed an increased abundance of plant and algae growth (also called eutrophication) in lakes in the middle Athabasca. Studies of sediments in Baptiste Lake and Lac LaBiche have shown that these lakes were naturally eutrophic but that further lake eutrophication occurred during the 20th century due to watershed development.[49],[50] In a study with the Lesser Slave Lake Cree, participants expressed concern regarding the ”greening” or eutrophication of Lesser Slave Lake and surrounding lakes witnessed in recent years.[51] Similarly, an analysis of algae remains in Lesser Slave Lake sediments indicated higher algal productivity in the east basin after the 1960s[52]. Residents of Baptiste and Island Lakes have also observed how blue-green algae blooms are more common in recent years and expressed concern for the impacts on fish and wildlife.[53] Trend analyses on water quality data from 1979 to 2009 in Baptiste Lake and Gregoire Lake showed significant increasing trends in total phosphorus, the nutrient most often responsible for eutrophication, while data for Island Lake were not sufficient for trend analysis.[54] Paleolimnological study in Baptiste Lake found that nutrient enrichment was related to watershed land use.[55]

Residents and users of both Baptiste and Island Lakes are concerned that frequent blue-green algae (cyanobacteria) blooms are adversely affecting fish and wildlife

Baptiste and Island Lakes Stewardship Society, 2019

Total Phosphorus Trend in Baptiste Lake, 1983 to 2007. Reproduced with Permission from Casey (2011) [15]

Water samples taken at the Athabasca River at Old Fort, just upstream of the Peace-Athabasca Delta between 2014 and 2017, repeatedly exceeded the annual mean triggers (i.e., historical averages and medians) established by the Lower Athabasca Region Surface Water Quality Management Framework[56] for dissolved compounds, such as dissolved lithium, dissolved uranium, potassium and sulphate. In addition, water samples consistently exceeded the annual peak triggers for dissolved uranium and in some years for other dissolved metals or sulphate.[57] Such exceedances of typical historical levels are early indicators of increasing trends. As of fall 2019, continued investigations for parameters that have undesirable trends in the region were recommended: chloride, dissolved iron, dissolved lithium, total nitrogen, potassium, sulphate and dissolved uranium.[58]

Extensive (monthly) sampling from 2012 onward and data analysis from 2012 to 2015 as part of the Canada-Alberta Joint Oil Sands Monitoring Program showed that increasing trends in many dissolved substances were associated with reductions in flows or part of a regional trend also seen in other major rivers not affected by oil sands development.[59] Analysis of data from 2000 to 2019 at Environment Canada monitoring stations along the Athabasca River indicated increasing trends for indicators of ionic strength for many months at all locations (this study). For example, mean monthly total hardness increased by 0.5 mg/L (0.4%) to 1.6 mg/L (1.5%) per year, pH increased by 0.004 (0.05%) to 0.042 (0.5%) per year, sulphate by 0.2 mg/L (0.7%) to 1 mg/L (3%) per year and dissolved uranium by 0.03 ug/L (0.8%) per year to 0.01 ug/L (3.4%) per year for different monthly datasets. Increasing trends in mean monthly concentrations for other dissolved metals were mainly observed downstream of the oil sands region, such as for dissolved aluminum by 0.5 ug/L (8.5%) to 3.1 ug/L (5.9%) per year, dissolved arsenic by 0.005 ug/L (0.9%) to 0.015 ug/L (4.2%) per year, dissolved iron by 2 ug/L (20%) to 9 ug/L (4.8%), and dissolved cobalt by 0.001 ug/L (1.2%) to 0.004 ug/L (6.5%) per year (this study). Sulphate remained well below the Alberta surface water quality guideline in all these samples, while dissolved aluminum and iron were close to or exceeded the guideline occasionally at the site downstream of oil sands development. Alberta Environment and Parks data analysis of water quality data from Athabasca River at Town of Athabasca also showed increasing trends in pH, dissolved solids, sulphate and some major ions.[60]

Trend in October sulphate concentrations in Athabasca River above Athabasca Falls (2000-2018). Data from Environment and Climate Change Canada. Significance and slope of the trend were estimated using the Mann Kendall Trend Test. The Sen Slope (change in mg/L per year) and % change per year are displayed on the chart.

Trend in February dissolved arsenic concentrations in Athabasca River at Baseline 27 (2001-2019). Data from Environment and Climate Change Canada. Significance and slope of the trend were estimated using the Mann Kendall Trend Test. The Sen Slope (change in mg/L per year) and % change per year are displayed on the chart.

Long-term trend analysis of data from Old Fort showed that for 2000- 2014 several parameter concentrations declined, including dissolved phosphorus (0.3 ug/L per year) and ammonia (degree of decline not reported).[61] Total phosphorus concentrations, which previously had been increasing, were stable from 2000 to 2018 (this study). This stabilization was attributed to treatment upgrades at the Fort McMurray wastewater treatment facility and pulp and paper mills upstream and the subsequent reductions to total loadings within the Athabasca River basin.[61]   Water quality studies in the Athabasca River in the early 1990s recorded large effects from phenols, chlorinated phenols, resin acids, and trace organics. These were not observed during a 2015 winter synoptic survey, possibly indicating an improvement in water quality conditions owing to more stringent effluent regulation and advancements in technology and wastewater treatment processes within the pulp and paper industry.

Discharge from secondarily treated pulp mill and municipal effluent have caused localized issues of nutrient enrichment below wastewater outfalls in the Athabasca River. In addition, tributary and wastewater inputs cumulatively contribute to a decline in dissolved oxygen during winter along the length of the Athabasca River, mainly due to elevated biochemical oxygen demand in pulp and paper mill effluent. During the 2015 winter synoptic survey, dissolved oxygen concentrations in the Pembina and Muskeg rivers were below the short-term surface water quality guideline, and dissolved oxygen levels in the Firebag River were below the long-term surface water quality guideline.[62]
As part of the Joint Oil Sands Monitoring Program set up in 2011, sixty-two tributary locations were sampled, of which fourteen were sampled at up to daily frequency during spring freshet and forty-eight sites monthly, seasonally, or annually. Data from 2012-2015 showed that concentrations of dissolved arsenic, dissolved selenium, total vanadium, total mercury and total polycyclic aromatic compounds followed hydrologic discharge with concentrations typically greatest during snowmelt (i.e., April-May). Patterns in methyl mercury were slightly different: concentrations increased during high flows but were greatest during mid-to-late summer months (late June to mid-August) when production via microbial pathways is highest in aquatic ecosystems.[63]

Benthic Invertebrates

Sub-basin-wide trends in benthic invertebrate communities reflect natural factors, but benthic abundance increased locally in response to point-source discharges.

Oil Sands Monitoring from 2012 to 2014[112] indicated that the lower Athabasca River mainstem generally has a good ecological condition with a high abundance of sensitive benthic invertebrate taxa at all sites. However, the sites in middle reaches (near large surface mines) show signs of mild environmental stress. Good ecological condition in lower Athabasca River tributaries was generally indicated by the presence of intolerant taxa (Ephemeroptera, Plecoptera, Trichoptera) across sites. However, assemblages in areas with increased disturbance were divergent from reference conditions, which suggest that communities in the lower reaches of the major tributaries are experiencing potential cumulative impacts of on-going and expanded mining development.

Localized areas of nutrient enrichment are a concern: This is particularly significant downstream of municipal and industrial point source discharges in major municipalities (i.e. Hinton, Whitecourt, Athabasca and Fort McMurray). For example, relatively low increases in phosphorus from inputs of municipal wastewater effluent was observed to result in a 4- to 30-fold increase in the abundance of benthic algae and macroinvertebrates downstream of Jasper, Alberta.[64]

Basin-wide spatial trends in invertebrate communities reflect natural factors: An assessment of various benthic invertebrate data sets indicated that longitudinal trends in benthic invertebrates in the mainstem and tributaries of the Athabasca River reflect natural changes in geomorphologic and hydrologic factors associated with river size and gradient. Impacts of anthropogenic disturbance in the form of municipal wastewater, industrial point-source inputs, diffuse agricultural inputs, and disruptions in flow regimes were not detected at this scale.[65]  Given the multiple lines of evidence about point source impacts on benthic invertebrates in the Athabasca River, this may be a methodological limitation of combining multiple datasets over a large region in this specific study.


Land Use

Contamination of aquatic ecosystems and generally lower water levels are leading to changes in Indigenous land use practices in the Athabasca sub-basin. Land cover in the sub-basin is dominated by forests; however, there is significant human footprint due to forestry in the entire sub-basin, agriculture in the Pembina watershed and surface bitumen mining footprints in the lower Athabasca.

Changes in land use and the rise of industrial activity have led to contamination of aquatic ecosystems and a general decline in water levels, as observed by Indigenous communities in the Athabasca sub-basin.[66] Poor water quality in rivers and lakes and observations of unhealthy fish have been reported in the lower Athabasca by elders and river users from the Mikisew Cree[67],[68] Athabasca Chipewyan[69], and Fort Chipewyan communities[70], linked to an increase in industrial activities along the middle and lower reaches of the Athabasca River. In the middle Athabasca, the Cree of Lesser Slave Lake have reported discoloured and murky water and the drying up of streams, creeks, and wetlands near Lesser Slave Lake associated with the effects of nearby hydroelectric projects and forestry operations.[71] For many communities, it is also more difficult and unsafe to travel by boat or barge along sections of the Athabasca River and Peace-Athabasca Delta in the summer months due to the lower water levels experienced in recent years.[72] These changes have led to disruptions in fishing, hunting and other land use practices among Indigenous communities in the sub-basin.

An oil sands mine along the Athabasca River in northeastern Alberta. Photo by Thomas Dyck.

Land cover in the Athabasca sub-basin is primarily forest (48%) with temperate or sub-polar needleleaf forest being the most prolific type. Shrubland (14%), grassland (13%) and water (12%) are also significant types of land cover in the basin. Cropland is localized in the Pembina watershed, where a significant portion of land surface is cultivated and pressure from agricultural land use on water quality was rated as “high” based on >60% agricultural land use.[73]

Minor recent basin-wide increase in cropland and urban land cover. Cropland and urban land cover increased and natural cover decreased slightly from 1990 to 2010, but these changes only represented 0.5% of the Athabasca sub-basin surface area. Settlement areas more than doubled, increasing from 0.2% to 0.5% of the sub-basin, while cropland increased from 3.5% to 3.6% in the sub-basin. These changes mostly displaced forest and wetlands but didn’t change their overall percentage due to their much larger overall area in the sub-basin (Agriculture Agri-Food Canada).[74]

Map of Land Cover in the Athabasca sub-basin


Land Cover Statistics for Athabasca sub-basin (NRCAN 2015)[115]. Note that the wetland category is likely an underestimate, as shown in the table below.

Land Cover

Percent Land Cover

















Change in Land Cover 1990 to 2010 (Agriculture and Agri-Foods Canada)[74]

Land Cover Type

Area 1990 (km2)
Area 2010 (km2)
Change (km2)

Change (%)

1990 % cover

2010 % cover






















Forest / Trees



































The largest degree of human land conversion between 1973/1974 and 2009 occurred in the Pembina watershed due to agricultural conversion (up to 20% change) and in the lower Athabasca watershed associated with Oil Sands development (8% change), as estimated from satellite imagery.

The total area of human footprint in the Lower Athabasca Region increased by 3.2 percentage points from 5.5% in 1999 to 8.7% in 2017. This increase was driven by the expansion of the forestry footprint, which more than doubled in size during this time from 1.0% to 2.5%. However, this increase in forestry footprint is lower (1.2%, from 0.6% to 1.8%) when recovery of regenerating forest is included. The remaining human footprint categories each had small increases of < 1.0 percentage point between 1999-2017, with energy footprint showing the next largest increase from 1.0% to 1.8%.

The total area of human footprint in the Upper Athabasca Region increased by 7.7 percentage points from 22.4% in 1999 to 30.1% in 2017. This increase in human footprint was driven by the expansion of forestry footprint, which more than doubled in size during this time from 5.4% to 11.8%. However, this increase in forestry footprint is lower (5.4%, from 3.0% to 8.4%) when recovery of regenerating forest is included. The remaining human footprint categories each had small increases of < 1.0 percentage point between 1999-2017, with agriculture footprint showing the next largest increase from 12.8% to 13.5%.

Trend in the percentage area of total human footprint, and by human footprint category in the Upper and Lower Athabasca Regions between 1999 and 2017. Reproduced with permission from Alberta Biodiversity Monitoring Institute. [76]

Effluent Discharges

Effluent volume data were not collected but point sources discharge a variety of substances of potential concern for receiving aquatic environments.

Effluent is discharged to the upper Athabasca River from municipal wastewater treatment facilities, coal mines, and pulp mills. Variables of concern from point source discharges in the upper Athabasca River were identified based on a review of effluent data, supporting information in the literature and river impact analyses.  The leading variables of concern were total phosphorus, total nitrogen, total suspended solids, and biochemical oxygen demand, due to their prominence in all effluent types and their observed impact on the river. Selenium is an important coal mining contaminant in the headwaters but is also related to pulp and paper discharges. Other identified parameters of concern included metals (e.g., zinc, cadmium, and cobalt) conductivity, fecal coliforms, sulphate and sulphide, phenolic compounds, and chloride.[77]


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