Arsenic in Lake Water Around Yellowknife

YELLOWKNIFE (June 15, 2018) –  The NWT Chief Public Health Officer is updating the advice provided to residents and visitors about precautions they can take to avoid exposure to elevated arsenic levels found in some of the lakes located around Yellowknife.

This public health advice is based on the most current environmental data available and may be adjusted as more information becomes available from ongoing or future monitoring or research activities. Results from the recently released Human Health and Ecological Risk Assessment (HHERA) have been incorporated in this public health advisory.  

A number of small lakes have been added to the public health advisory map, including Niven, Range, and Fiddler Lake and additional surface soil data has resulted in the expansion of the “area of interest”, which is defined as areas of land adjacent to water bodies with elevated arsenic, in close proximity to a mine site, or where high arsenic soil concentrations have been documented. 

Map of Arsenic Concentrations Measured in Water Bodies in the Yellowknife Area (June 7, 2018)

(Click here for PDF Version)

View Larger Map

How to use the interactive map:

To zoom in and out, click on the “+” and “-“ buttons found on the left side of the map.

To view the legend, click on the “>>” found on the left side of the map.

To see concentration level of arsenic on a specific lake, click on the coloured circle. This will also show you the longitudinal and latitude coordinates of the lake.

Please note to the best of our knowledge lakes without dots have not been tested.

Yellowknife River and Cameron River have been regularly tested for arsenic for many years and have always been shown to be well below drinking water guidelines. It is safe to swim and fish in these rivers; however it is recommended not to drink untreated water anywhere.

Data Sources:

  1. Canada North Environmental Services. (2018). Giant Mine Human Health and Ecological Risk Assessment, Final Report. Prepared for: Public Services and Procurement Canada – Western Region, Project No. 2385.
  2. Cheney, C. (2017). University of Ottawa. Unpublished data.

  3. Environment & Climate Change Canada. (2017). Unpublished data.

  4. GNWT Environment & Natural Resources. (2017). Unpublished data.

  5. Houben, A.J., D’Onofio, R., Kokelj, S.V. and J.M. Blais. (2016). Factors affecting elevated arsenic and methyl mercury concentrations in small shield lakes surrounding gold mines near the Yellowknife, NT, (Canada) region; PLOSOne, http://dx.doi.org/10.1371/journal.pone.0150960.

  6. Jamieson, H.E., Maitland, K.M., Oliver, J.T. and M.J. Palmer. (2017). Regional distribution of arsenic in near-surface soils in the Yellowknife area; Northwest Territories Geological Survey, NWT Open File 2017-03 28p.

  7. Palmer, M.J., Galloway, J.M., Jamieson, H.E., Patterson, R.T., Falck, H. and S.V. Kokelj. (2015). The concentration of arsenic in the lake waters of the Yellowknife area; Northwest Territories Geological Survey, NWT Open File 2015-06 25p.

  8. Palmer, M.J. (2018). Carleton University. Unpublished data.

  9. Thienpont, J. (2017). University of Ottawa. Unpublished data.

Lakes with green points:

Arsenic levels are below Health Canada’s drinking guidelines. It is recommended not to drink untreated water from any lake. However, these lakes are considered safe for swimming and fishing.

Lakes with yellow points:

Arsenic levels are above Health Canada’s drinking water guidelines; however, occasional exposure does not pose a significant risk for arsenic-related health effects. It is recommended not to drink untreated water from any lake. These lakes are considered safe for swimming and fishing.

Lakes with orange, red or purple points:

Arsenic levels are elevated (52 parts per billion and above). Water should not be consumed from these lakes. It is also recommended to avoid fishing, swimming, and harvesting berries, mushrooms and other edible plants within this zone. However, walking through this area does not pose a health hazard. 

For more information contact:

Damien Healy
Manager Communications
Health and Social Services
(867) 767-9052 ext. 49034