Mackenzie Great Bear – Water Quality

Water Quality

Changes in water quality have been observed in parts of the Mackenzie Great Bear sub-basin, and for some water characteristics, affect the ability of some Indigenous communities to practice traditional land uses. Elders and harvesters from the Mackenzie River Delta and Dehcho regions have observed warmer water temperatures than experienced in the past, as well as murkier water in the Mackenzie Delta and changes in the color, smell and taste of the Mackenzie River. Scientific analyses have detected increasing trends in a few dissolved metals in recent years. The downstream effects of industrial development are a concern for local communities in the sub-basin. The downstream effects of industrial development are a concern for local communities in the sub-basin, but scientific water quality data did not show any evidence of this.

Information Availability

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	Several ongoing surface water monitoring programs; minimal groundwater data.
Benthic Invertebrates	Not assigned to a Sign or Signal	Observations not recorded.	Relative abundance of aquatic macroinvertebrates	CABIN* database contains benthic data.
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	Georeferenced data available, but limited data on change over time.
Effluent Discharge	Not assigned to a Sign or Signal	Observations not recorded.	Volume of effluent discharges	National reporting programs (NPRI, WSER) and Water Board Registries contain effluent data, not collected for this project.

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
* CABIN = Canadian Aquatic Biomonitoring Network

Water Quality

A reduction in water quality and warmer water temperatures have been observed in some locations in the Mackenzie Great Bear sub-basin.

Indigenous communities have observed warmer water temperatures and scientific data indicates a rise in water temperatures in Great Bear Lake

In the Mackenzie River Delta and Dehcho regions of the Northwest Territories, the Inuvialuit, members of the Dehcho First Nations and land users in the Sahtu have observed warmer water temperatures than experienced in the past. The warmer temperatures have been linked to fish with ”softer” textures, and in some cases, changes in which areas are good for fishing.Scientific studies suggest that water temperatures in Great Bear Lake have increased over time and caused the Tavish Arm to turn from an annually fully mixed water column to a thermally stratified (layered) water column, which can influence fish quality, behaviour and habitat. Monitoring data from the Mackenzie River did not show any clear trends in water temperature (this study).

[T]he water is warmer than it used to be in the Delta, which is leading to softer fish or changes in the location of good fishing areas.
Fisheries Joint Management Committee in Parlee and Maloney, 2017

Reduced water quality in Mackenzie River has been observed by Indigenous communities, but is not clearly evident in scientific data

The Inuvialuit have noticed the water in the Mackenzie River Delta appears dirtier and murkier in recent years, taking on a different colour, and has poor smell and taste. In the Dehcho region, members of the Dehcho First Nations have noticed a change in colour of the Mackenzie River and raised concerns about mercury levels. The GNWT-supported Community-based Monitoring Program (CBMP) identified elevated suspended sediment levels in the Peel River that feeds into the Mackenzie River Delta, which may be a result of recent permafrost degradation due to climate warming. At CBMP stations in Norman Wells, increasing trends were observed in conductivity and dissolved aluminium, lithium, selenium, sulphate and magnesium between 2012 and 2016. Trend analysis on Environment and Climate Change Canada data from 2000-2018 showed similar trends in dissolved constituents (this study). For example, October sulphate in the Mackenzie River above Arctic Red River increased by 1.8 mg/L (4%) per year during that time.

Trend in October sulphate concentrations in Mackenzie River above Arctic Red River (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.

Water quality in the Great Bear River is unimpacted by contaminants

Great Bear River has low proportions, frequency and degree of aquatic life guideline exceedances, as indicated by the “good” rating in the Canadian Water Quality Index for 2016-2018.

Great Bear Lake, which feeds Great Bear River.

Benthic Invertebrates

Expected populations of benthic macroinvertebrates have been observed in the Mackenzie Great Bear sub-basin.

Benthic invertebrate community composition was related to naturally varying habitat.

Benthic macroinvertebrates are small organisms that live at the bottom of lakes, rivers, and streams, and their species diversity is often used as a sign or signal of water quality. The types of benthic macroinvertebrates found in streams of the Mackenzie Basin in the Northwest Territories were as expected under unimpacted (pristine) conditions. Their community composition was related to the naturally varying nutrient availability, habitat stability, substrate characteristics, and winter ice conditions.

Land Use

Changes in Indigenous land use practices are occurring in the Mackenzie Great Bear sub-basin.

Many Indigenous communities have expressed a loss of confidence in water and fish in the Mackenzie Great Bear sub-basin due to the possibility of contamination:

The downstream effects of industrial development are a concern for many Indigenous communities in the sub-basin and affects their ability to practice traditional land uses. In the Dehcho and Sahtu regions of the Northwest Territories, community members have raised concerns about the presence of mercury and other contaminants, leading some people to lose confidence in the safety of local drinking water and country foods.Similarly, the Inuvialuit have voiced concerns about the degree of industrial development upstream from the Mackenzie River Delta and the potential impacts to fish and fish habitat.

Land use change is expected to be limited in the Mackenzie Great Bear sub-basin

Mining and other types of resource extraction are the main land disturbances in the Mackenzie Great Bear sub-basin. Only a small percentage of the land base has been developed for human settlements and agriculture. Mapping indicates that urban areas only account for 0.02% of the land base in the sub-basin. Trends over time in land use cover are a data gap in the scientific literature, but given the small urban footprint, land use change is expected to be limited in the Mackenzie Great Bear sub-basin. The Government of Northwest Territories provides the “Inventory of Landscape Change Webviewer”, an online mapping feature that displays human disturbance and other landscape changes, such as fires as an interactive tool.

Norman Wells airport, Norman Wells NT.

There is no measurable human impact on land cover

Forest covers almost half of the sub-basin (45%), followed by grassland (17% and Barren lands (10%). Water makes up 16% of the sub-basin area, because of Great Bear Lake, the largest lake entirely in Canada. There is currently no measurable degree of human impact on land cover.

Land Cover	Percent Land Cover
Forest	45%
Grassland	17%
Water	16%
Barren	10%
Shrubland	8%
Wetland	3%
Urban	0%
Cropland	0%

Land Cover for Mackenzie Great Bear sub-basin

Effluent Discharges

Effluent data are available but were not assessed.

Industrial effluent from oil and gas operations in Norman Wells and small-scale municipal effluents from settled communities are discharged into the Mackenzie River provided they meet the limits included in their respective licenses.

Information on effluent volumes and quality is available on Public Registries of the Land and Water Boards, but were not assessed as part of this project.

References

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